1
|
Wei L, Zhu J, Zhao D, Pei Y, Guo L, Guo J, Guo Z, Cui H, Li Y, Gao J. Microbial fungicides can positively affect aubergine photosynthetic properties, soil enzyme activity and microbial community structure. PeerJ 2024; 12:e17620. [PMID: 38952982 PMCID: PMC11216198 DOI: 10.7717/peerj.17620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 05/31/2024] [Indexed: 07/03/2024] Open
Abstract
Background This study examined the effects of microbial agents on the enzyme activity, microbial community construction and potential functions of inter-root soil of aubergine (Fragaria × ananassa Duch.). This study also sought to clarify the adaptability of inter-root microorganisms to environmental factors to provide a theoretical basis for the stability of the microbiology of inter-root soil of aubergine and for the ecological preservation of farmland soil. Methods Eggplant inter-root soils treated with Bacillus subtilis (QZ_T1), Bacillus subtilis (QZ_T2), Bacillus amyloliquefaciens (QZ_T3), Verticillium thuringiensis (QZ_T4) and Verticillium purpureum (QZ_T5) were used to analyse the effects of different microbial agents on the inter-root soils of aubergine compared to the untreated control group (QZ_CK). The effects of different microbial agents on the characteristics and functions of inter-root soil microbial communities were analysed using 16S rRNA and ITS (internal transcribed spacer region) high-throughput sequencing techniques. Results The bacterial diversity index and fungal diversity index of the aubergine inter-root soil increased significantly with the application of microbial fungicides; gas exchange parameters and soil enzyme activities also increased. The structural and functional composition of the bacterial and fungal communities in the aubergine inter-root soil changed after fungicide treatment compared to the control, with a decrease in the abundance of phytopathogenic fungi and an increase in the abundance of beneficial fungi in the soil. Enhancement of key community functions, reduction of pathogenic fungi, modulation of environmental factors and improved functional stability of microbial communities were important factors contributing to the microbial stability of fungicide-treated aubergine inter-root soils.
Collapse
Affiliation(s)
- Longxue Wei
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Jinying Zhu
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Dongbo Zhao
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Yanting Pei
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Lianghai Guo
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Jianjun Guo
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Zhihui Guo
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Huini Cui
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Yongjun Li
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| | - Jiansheng Gao
- Dezhou Institute of Agricultural Science, Dezhou, Shandong, China
| |
Collapse
|
2
|
Fan K, Wang Z, Sze CC, Niu Y, Wong FL, Li MW, Lam HM. MicroRNA 4407 modulates nodulation in soybean by repressing a root-specific ISOPENTENYLTRANSFERASE (GmIPT3). THE NEW PHYTOLOGIST 2023; 240:1034-1051. [PMID: 37653681 DOI: 10.1111/nph.19222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 07/28/2023] [Indexed: 09/02/2023]
Abstract
MicroRNAs (miRNAs) are important regulators of plant biological processes, including soybean nodulation. One miRNA, miR4407, was identified in soybean roots and nodules. However, the function of miR4407 in soybean is still unknown. MiR4407, unique to soybean, positively regulates lateral root emergence and root structures and represses a root-specific ISOPENTENYLTRANSFERASE (GmIPT3). By altering the expression of miR4407 and GmIPT3, we investigated the role of miR4407 in lateral root and nodule development. Both miR4407 and GmIPT3 are expressed in the inner root cortex and nodule primordia. Upon rhizobial inoculation, miR4407 was downregulated while GmIPT3 was upregulated. Overexpressing miR4407 reduced the number of nodules in transgenic soybean hairy roots while overexpressing the wild-type GmIPT3 or a miR4407-resistant GmIPT3 mutant (mGmIPT3) significantly increased the nodule number. The mechanism of miR4407 and GmIPT3 functions was also linked to autoregulation of nodulation (AON), where miR4407 overexpression repressed miR172c and activated its target, GmNNC1, turning on AON. Exogenous CK mimicked the effects of GmIPT3 overexpression on miR172c, supporting the notion that GmIPT3 regulates nodulation by enhancing root-derived CK. Overall, our data revealed a new miRNA-mediated regulatory mechanism of nodulation in soybean. MiR4407 showed a dual role in lateral root and nodule development.
Collapse
Affiliation(s)
- Kejing Fan
- School of Life Sciences and Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Zhili Wang
- School of Life Sciences and Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Ching-Ching Sze
- School of Life Sciences and Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Yongchao Niu
- School of Life Sciences and Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Fuk-Ling Wong
- School of Life Sciences and Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Man-Wah Li
- School of Life Sciences and Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| | - Hon-Ming Lam
- School of Life Sciences and Centre for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China
| |
Collapse
|
3
|
Lu M, Huang L, Wang Q, Cao X, Lin Q, He Z, Feng Y, Yang X. Soil properties drive the bacterial community to cadmium contamination in the rhizosphere of two contrasting wheat (Triticum aestivum L.) genotypes. J Environ Sci (China) 2023; 128:117-128. [PMID: 36801027 DOI: 10.1016/j.jes.2022.07.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/17/2022] [Accepted: 07/17/2022] [Indexed: 06/18/2023]
Abstract
Cadmium (Cd) bioavailability in the rhizosphere makes an important difference in grain Cd accumulation in wheat. Here, pot experiments combined with 16S rRNA gene sequencing were conducted to compare the Cd bioavailability and bacterial community in the rhizosphere of two wheat (Triticum aestivum L.) genotypes, a low-Cd-accumulating genotype in grains (LT) and a high-Cd-accumulating genotype in grains (HT), grown on four different soils with Cd contamination. Results showed that there was non-significant difference in total Cd concentration among four soils. However, except for black soil, DTPA-Cd concentrations in HT rhizospheres were higher than those of LT in fluvisol, paddy soil and purple soil. Results of 16S rRNA gene sequencing showed that soil type (52.7%) was the strongest determinant of root-associated community, while there were still some differences in rhizosphere bacterial community composition between two wheat genotypes. Taxa specifically colonized in HT rhizosphere (Acidobacteria, Gemmatimonadetes, Bacteroidetes and Deltaproteobacteria) could participate in metal activation, whereas LT rhizosphere was highly enriched by plant growth-promoting taxa. In addition, PICRUSt2 analysis also predicted high relative abundances of imputed functional profiles related to membrane transport and amino acid metabolism in HT rhizosphere. These results revealed that the rhizosphere bacterial community may be an important factor regulating Cd uptake and accumulation in wheat and indicated that the high Cd-accumulating cultivar might improve Cd bioavailability in the rhizosphere by recruiting taxa related to Cd activation, thus promoting Cd uptake and accumulation.
Collapse
Affiliation(s)
- Min Lu
- Key Laboratory of Environmental Remediation and Ecosystem Health, Ministry of Education (MOE), College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China; Tea Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
| | - Lukuan Huang
- Key Laboratory of Environmental Remediation and Ecosystem Health, Ministry of Education (MOE), College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China
| | - Qiong Wang
- College of Ecology, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xuerui Cao
- Zhejiang Institute of Landscape Plants and Flowers, Hangzhou 311251, China
| | - Qiang Lin
- Key Laboratory of Environmental Remediation and Ecosystem Health, Ministry of Education (MOE), College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China
| | - Zhenli He
- University of Florida, Institute of Food and Agricultural Sciences, Indian River Research and Education Center, Fort Pierce, FL 34945, USA
| | - Ying Feng
- Key Laboratory of Environmental Remediation and Ecosystem Health, Ministry of Education (MOE), College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiaoe Yang
- Key Laboratory of Environmental Remediation and Ecosystem Health, Ministry of Education (MOE), College of Environmental and Resources Sciences, Zhejiang University, Hangzhou 310058, China.
| |
Collapse
|
4
|
El-Sherbeny TMS, Mousa AM, Zhran MA. Response of peanut (Arachis hypogaea L.) plant to bio-fertilizer and plant residues in sandy soil. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:253-265. [PMID: 35697953 PMCID: PMC9884651 DOI: 10.1007/s10653-022-01302-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
Nitrogen (N) fertilizer has been intensively used to improve peanut productivity. However, the high cost of N fertilizer, and the need for sustainable alternative fertilizer sources have increased the strategic importance of nitrogen fixation (NF). Thus, field experiments were conducted in an experimental farm with a drip irrigation system, at the Atomic Energy Authority, Inshas, Egypt, in order to measure the impact of efficiency symbiotic Bradyrhizobium sp. and asymbiotic Azotobacter sp. on NF, from air and soil, in the presence or absence of plant residues on the growth and yield of peanut plant. All treatments received nitrogen fertilizer at a rate of 72 kg N per hectare. Nitrogen dose was applied using ammonium sulphate 15N labeled of 10% atom excess from the peanut. Results indicated that the application of Bradyrhizobium sp. with plant residues significantly increased fresh and dry weight/m2, pod and seed weight/plant-1,100- seed weight, and biological yield kg ha-1, where the highest mean values of seed yield (4648 and 4529 kg ha-1), oil % (52.29 and 52.21%), seed protein percentage (16.09 and 15.89%), as well as nitrogen derived from air (63.14 and 66.20%) in the first and second seasons were recorded under the application of Bradyrhizobium sp, respectively. Bradyrhizobium sp. inoculation showed nearly close portions of Ndfa to those recorded with Azotobacter sp., in both the presence and absence of plant residue application through the two seasons. The investigated yield signs and their properties were significantly enhanced by bacterial inoculation with plant residue application. The present study shows that both possibility of NF of peanut, and nitrogen uptake in the soil are enhanced by field inoculation with effective Bradyrhizobium sp. with plant residue application. In practice, inoculation is a great strategy to improve soil fertility for subsequent planting, since it helps boost the import of nitrogen from plant biomass into the soil.
Collapse
Affiliation(s)
- T M S El-Sherbeny
- Nuclear Research Center, Plant Research Department, Egyptian Atomic Energy Authority, Cairo, Egypt
| | - Abeer M Mousa
- Nuclear Research Center, Soil and Water Research Department, Egyptian Atomic Energy Authority, Cairo, 13759, Egypt
| | - Mostafa A Zhran
- Nuclear Research Center, Soil and Water Research Department, Egyptian Atomic Energy Authority, Cairo, 13759, Egypt.
| |
Collapse
|
5
|
Adaptive Evolution of Rhizobial Symbiosis beyond Horizontal Gene Transfer: From Genome Innovation to Regulation Reconstruction. Genes (Basel) 2023; 14:genes14020274. [PMID: 36833201 PMCID: PMC9957244 DOI: 10.3390/genes14020274] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/22/2023] Open
Abstract
There are ubiquitous variations in symbiotic performance of different rhizobial strains associated with the same legume host in agricultural practices. This is due to polymorphisms of symbiosis genes and/or largely unexplored variations in integration efficiency of symbiotic function. Here, we reviewed cumulative evidence on integration mechanisms of symbiosis genes. Experimental evolution, in concert with reverse genetic studies based on pangenomics, suggests that gain of the same circuit of key symbiosis genes through horizontal gene transfer is necessary but sometimes insufficient for bacteria to establish an effective symbiosis with legumes. An intact genomic background of the recipient may not support the proper expression or functioning of newly acquired key symbiosis genes. Further adaptive evolution, through genome innovation and reconstruction of regulation networks, may confer the recipient of nascent nodulation and nitrogen fixation ability. Other accessory genes, either co-transferred with key symbiosis genes or stochastically transferred, may provide the recipient with additional adaptability in ever-fluctuating host and soil niches. Successful integrations of these accessory genes with the rewired core network, regarding both symbiotic and edaphic fitness, can optimize symbiotic efficiency in various natural and agricultural ecosystems. This progress also sheds light on the development of elite rhizobial inoculants using synthetic biology procedures.
Collapse
|
6
|
Baymiev AK, Akimova ES, Koryakov IS, Vladimirova AA, Baymiev AK. The Composition of Lotus corniculatus Root Nodule Bacteria Depending on the Host Plant Vegetation Stage. Microbiology (Reading) 2022. [DOI: 10.1134/s0026261722601154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
7
|
Parish AJ, Rice DW, Tanquary VM, Tennessen JM, Newton ILG. Honey bee symbiont buffers larvae against nutritional stress and supplements lysine. THE ISME JOURNAL 2022; 16:2160-2168. [PMID: 35726020 PMCID: PMC9381588 DOI: 10.1038/s41396-022-01268-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/17/2022] [Accepted: 06/07/2022] [Indexed: 02/07/2023]
Abstract
Honey bees have suffered dramatic losses in recent years, largely due to multiple stressors underpinned by poor nutrition [1]. Nutritional stress especially harms larvae, who mature into workers unable to meet the needs of their colony [2]. In this study, we characterize the metabolic capabilities of a honey bee larvae-associated bacterium, Bombella apis (formerly Parasaccharibacter apium), and its effects on the nutritional resilience of larvae. We found that B. apis is the only bacterium associated with larvae that can withstand the antimicrobial larval diet. Further, we found that B. apis can synthesize all essential amino acids and significantly alters the amino acid content of synthetic larval diet, largely by supplying the essential amino acid lysine. Analyses of gene gain/loss across the phylogeny suggest that four amino acid transporters were gained in recent B. apis ancestors. In addition, the transporter LysE is conserved across all sequenced strains of B. apis. Finally, we tested the impact of B. apis on developing honey bee larvae subjected to nutritional stress and found that larvae supplemented with B. apis are bolstered against mass reduction despite limited nutrition. Together, these data suggest a novel role of B. apis as a nutritional mutualist of honey bee larvae.
Collapse
Affiliation(s)
- Audrey J Parish
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - Danny W Rice
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - Vicki M Tanquary
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - Jason M Tennessen
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - Irene L G Newton
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
| |
Collapse
|
8
|
Wang J, Ma C, Ma S, Zheng H, Feng H, Wang Y, Wang J, Liu C, Xin D, Chen Q, Yang M. GmARP is Related to the Type III Effector NopAA to Promote Nodulation in Soybean (Glycine max). Front Genet 2022; 13:889795. [PMID: 35692823 PMCID: PMC9184740 DOI: 10.3389/fgene.2022.889795] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 05/05/2022] [Indexed: 11/23/2022] Open
Abstract
Type III effectors secreted by rhizobia regulate nodulation in the host plant and are important modulators of symbiosis between rhizobia and soybean (Glycine max), although the underlying mechanisms are poorly understood. Here, we studied the type III effector NopAA in Sinorhizobium fredii HH103, confirming its secretion into the extracellular environment under the action of genistein. The enzyme activity of NopAA was investigated in vitro, using xyloglucan and β-glucan as substrates. NopAA functions were investigated by the generation of a NopAA mutant and the effects of NopAA deficiency on symbiosis were analyzed. Soybean genes associated with NopAA were identified in a recombinant inbred line (RIL) population and their functions were verified. NopAA was confirmed to be a type III effector with glycosyl hydrolase activity, and its mutant did not promote nodulation. Quantitative trait locus (QTL) analysis identified 10 QTLs with one, Glyma.19g074200 (GmARP), found to be associated with NopAA and to positively regulate the establishment of symbiosis. All these results support the hypothesis that type III effectors interact with host proteins to regulate the establishment of symbiosis and suggest the possibility of manipulating the symbiotic soybean–rhizobia interaction to promote efficient nitrogen fixation.
Collapse
Affiliation(s)
- Jinhui Wang
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
| | - Chao Ma
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
| | - Shengnan Ma
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
| | - Haiyang Zheng
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
| | - Haojie Feng
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
| | - Yue Wang
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
| | - Jiangxu Wang
- Heilongjiang Academy of Agricultural Sciences, Harbin, China
| | - Chunyan Liu
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
| | - Dawei Xin
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
- *Correspondence: Dawei Xin, ; Qingshan Chen, ; Mingliang Yang,
| | - Qingshan Chen
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
- *Correspondence: Dawei Xin, ; Qingshan Chen, ; Mingliang Yang,
| | - Mingliang Yang
- College of Agriculture, Key Laboratory of Soybean Biology in Chinese Ministry of Education, Northeast Agricultural University, Harbin, China
- *Correspondence: Dawei Xin, ; Qingshan Chen, ; Mingliang Yang,
| |
Collapse
|
9
|
Zboralski A, Biessy A, Filion M. Bridging the Gap: Type III Secretion Systems in Plant-Beneficial Bacteria. Microorganisms 2022; 10:187. [PMID: 35056636 PMCID: PMC8780523 DOI: 10.3390/microorganisms10010187] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 12/30/2022] Open
Abstract
Type III secretion systems (T3SSs) are bacterial membrane-embedded nanomachines translocating effector proteins into the cytoplasm of eukaryotic cells. They have been intensively studied for their important roles in animal and plant bacterial diseases. Over the past two decades, genome sequencing has unveiled their ubiquitous distribution in many taxa of Gram-negative bacteria, including plant-beneficial ones. Here, we discuss the distribution and functions of the T3SS in two agronomically important bacterial groups: the symbiotic nodule-forming nitrogen-fixing rhizobia and the free-living plant-beneficial Pseudomonas spp. In legume-rhizobia symbiosis, T3SSs and their cognate effectors play important roles, including the modulation of the plant immune response and the initiation of the nodulation process in some cases. In plant-beneficial Pseudomonas spp., the roles of T3SSs are not fully understood, but pertain to plant immunity suppression, biocontrol against eukaryotic plant pathogens, mycorrhization facilitation, and possibly resistance against protist predation. The diversity of T3SSs in plant-beneficial bacteria points to their important roles in multifarious interkingdom interactions in the rhizosphere. We argue that the gap in research on T3SSs in plant-beneficial bacteria must be bridged to better understand bacteria/eukaryotes rhizosphere interactions and to support the development of efficient plant-growth promoting microbial inoculants.
Collapse
Affiliation(s)
| | | | - Martin Filion
- Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada; (A.Z.); (A.B.)
| |
Collapse
|
10
|
Jorrin B, Maluk M, Atoliya N, Kumar SC, Chalasani D, Tkacz A, Singh P, Basu A, Pullabhotla SVSRN, Kumar M, Mohanty SR, East AK, Ramachandran VK, James EK, Podile AR, Saxena AK, Rao DLN, Poole PS. Genomic Diversity of Pigeon Pea ( Cajanus cajan L. Millsp.) Endosymbionts in India and Selection of Potential Strains for Use as Agricultural Inoculants. FRONTIERS IN PLANT SCIENCE 2021; 12:680981. [PMID: 34557206 PMCID: PMC8453007 DOI: 10.3389/fpls.2021.680981] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 08/06/2021] [Indexed: 05/27/2023]
Abstract
Pigeon pea (Cajanus cajan L. Millsp. ) is a legume crop resilient to climate change due to its tolerance to drought. It is grown by millions of resource-poor farmers in semiarid and tropical subregions of Asia and Africa and is a major contributor to their nutritional food security. Pigeon pea is the sixth most important legume in the world, with India contributing more than 70% of the total production and harbouring a wide variety of cultivars. Nevertheless, the low yield of pigeon pea grown under dry land conditions and its yield instability need to be improved. This may be done by enhancing crop nodulation and, hence, biological nitrogen fixation (BNF) by supplying effective symbiotic rhizobia through the application of "elite" inoculants. Therefore, the main aim in this study was the isolation and genomic analysis of effective rhizobial strains potentially adapted to drought conditions. Accordingly, pigeon pea endosymbionts were isolated from different soil types in Southern, Central, and Northern India. After functional characterisation of the isolated strains in terms of their ability to nodulate and promote the growth of pigeon pea, 19 were selected for full genome sequencing, along with eight commercial inoculant strains obtained from the ICRISAT culture collection. The phylogenomic analysis [Average nucleotide identity MUMmer (ANIm)] revealed that the pigeon pea endosymbionts were members of the genera Bradyrhizobium and Ensifer. Based on nodC phylogeny and nod cluster synteny, Bradyrhizobium yuanmingense was revealed as the most common endosymbiont, harbouring nod genes similar to those of Bradyrhizobium cajani and Bradyrhizobium zhanjiangense. This symbiont type (e.g., strain BRP05 from Madhya Pradesh) also outperformed all other strains tested on pigeon pea, with the notable exception of an Ensifer alkalisoli strain from North India (NBAIM29). The results provide the basis for the development of pigeon pea inoculants to increase the yield of this legume through the use of effective nitrogen-fixing rhizobia, tailored for the different agroclimatic regions of India.
Collapse
Affiliation(s)
- Beatriz Jorrin
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Marta Maluk
- The James Hutton Institute, Dundee, United Kingdom
| | | | - Shiv Charan Kumar
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
| | - Danteswari Chalasani
- Department of Plant Sciences, School of Life Science, University of Hyderabad, Hyderabad, India
| | - Andrzej Tkacz
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | - Prachi Singh
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
| | - Anirban Basu
- Department of Plant Sciences, School of Life Science, University of Hyderabad, Hyderabad, India
| | - Sarma VSRN Pullabhotla
- Department of Plant Sciences, School of Life Science, University of Hyderabad, Hyderabad, India
| | - Murugan Kumar
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
| | | | - Alison K. East
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| | | | | | - Appa Rao Podile
- Department of Plant Sciences, School of Life Science, University of Hyderabad, Hyderabad, India
| | - Anil Kumar Saxena
- ICAR-National Bureau of Agriculturally Important Microorganisms, Mau, India
| | - DLN Rao
- ICAR-Indian Institute of Soil Science, Bhopal, India
| | - Philip S. Poole
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
11
|
Chang D, Gao S, Zhou G, Cao W. Spectroscopic characteristics of water-extractable organic matter from different green manures 1. ENVIRONMENTAL TECHNOLOGY 2021; 42:3688-3697. [PMID: 32126945 DOI: 10.1080/09593330.2020.1738560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/27/2020] [Indexed: 05/27/2023]
Abstract
Water-extractable organic matter (WEOM) plays an important role in many chemical processes and in soil organic matter accumulation. Large amounts of WEOM can be released by green manure when being incorporated into the soil. However, the characteristics of WEOM extracted from different green manures (GMs) are unclear. In this study, WEOM samples were extracted from Chinese milk vetch (Astragalus sinicus L), radish (Raphanus sativus L), ryegrass (Lolium perenne L), hairy vetch (Vicia villosa L), February orchid (Orychophragmus violaceus) and rye (Secale cereale L) and their characteristics were studied by spectroscopic analysis. WEOM generated from legume GMs contained more water-extractable organic carbon (WEOC) than other GMs and Chinese milk vetch was the highest. UV-visible spectroscopy analysis revealed that all the samples were rich in C=C and C=O functional groups. Carboxylic acid, alcohol, phenol, fatty acids, aliphatic aromatic and amide compounds were found by FTIR spectroscopy in these WEOM samples. WEOM derived from Chinese milk vetch contained more carboxylic acid and inorganic sulphates only appeared in WEOM extracted from the radish. The aromaticity index, humification index, and FTIR absorption ratio 1650/2925 and 1650/2850 showed that WEOM extracted from Chinese milk vetch and hairy vetch had a relatively lower aromaticity and humification degree than other GMs. The fluorescence regional integration (FRI) analysis showed that Chinese milk vetch and hairy vetch had a higher portion of protein-like substance fractions than other GMs. We may deduce that WEOM generated from Chinese milk vetch and hairy vetch has higher chemical activity than other GMs.
Collapse
Affiliation(s)
- Danna Chang
- Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture and Rural Affairs / Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China
| | - Songjuan Gao
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, People's Republic of China
| | - Guopeng Zhou
- Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture and Rural Affairs / Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China
| | - Weidong Cao
- Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture and Rural Affairs / Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, People's Republic of China
| |
Collapse
|
12
|
Huo H, Wang X, Liu Y, Chen J, Wei G. A Nod factor- and type III secretion system-dependent manner for Robinia pseudoacacia to establish symbiosis with Mesorhizobium amorphae CCNWGS0123. TREE PHYSIOLOGY 2021; 41:817-835. [PMID: 33219377 DOI: 10.1093/treephys/tpaa160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 11/15/2020] [Indexed: 06/11/2023]
Abstract
Under nitrogen-limiting conditions, symbiotic nodulation promotes the growth of legume plants via the fixation of atmospheric nitrogen to ammonia by rhizobia in root nodules. The rhizobial Nod factor (NF) and type III secretion system (T3SS) are two key signaling pathways for establishing the legume-rhizobium symbiosis. However, whether NF signaling is involved in the nodulation of Robinia pseudoacacia and Mesorhizobium amorphae CCNWGS0123, and its symbiotic differences compared with T3SS signaling remain unclear. Therefore, to elucidate the function of NF signaling in nodulation, we mutated nodC in M. amorphae CCNWGS0123, which aborted NF synthesis. Compared with the plants inoculated with the wild type strain, the plants inoculated with the NF-deficient strain exhibited shorter shoots with etiolated leaves. These phenotypic characteristics were similar to those of the plants inoculated with the T3SS-deficient strain, which served as a Nod- (non-effective nodulation) control. The plants inoculated with both the NF- and T3SS-deficient strains formed massive root hair swellings, but no normal infection threads were detected. Sections of the nodules showed that inoculation with the NF- and T3SS-deficient strains induced small, white bumps without any rhizobia inside. Analyzing the accumulation of 6 plant hormones and the expression of 10 plant genes indicated that the NF- and T3SS-deficient strains activated plant defense reactions while suppressing plant symbiotic signaling during the perception and nodulation processes. The requirement for NF signaling appeared to be conserved in two other leguminous trees that can establish symbiosis with M. amorphae CCNWGS0123. In contrast, the function of the T3SS might differ among species, even within the same subfamily (Faboideae). Overall, this work demonstrated that nodulation of R. pseudoacacia and M. amorphae CCNWGS0123 was both NF and T3SS dependent.
Collapse
Affiliation(s)
- Haibo Huo
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, People's Republic of China
| | - Xinye Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, People's Republic of China
| | - Yao Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, People's Republic of China
| | - Juan Chen
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water conservation, Northwest A&F University, 26 Xinong Road, Yangling 712100, Shaanxi, People's Republic of China
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, People's Republic of China
| |
Collapse
|
13
|
Swarnalakshmi K, Yadav V, Tyagi D, Dhar DW, Kannepalli A, Kumar S. Significance of Plant Growth Promoting Rhizobacteria in Grain Legumes: Growth Promotion and Crop Production. PLANTS 2020; 9:plants9111596. [PMID: 33213067 PMCID: PMC7698556 DOI: 10.3390/plants9111596] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/24/2020] [Accepted: 10/28/2020] [Indexed: 02/01/2023]
Abstract
Grain legumes are an important component of sustainable agri-food systems. They establish symbiotic association with rhizobia and arbuscular mycorrhizal fungi, thus reducing the use of chemical fertilizers. Several other free-living microbial communities (PGPR—plant growth promoting rhizobacteria) residing in the soil-root interface are also known to influence biogeochemical cycles and improve legume productivity. The growth and function of these microorganisms are affected by root exudate molecules secreted in the rhizosphere region. PGPRs produce the chemicals which stimulate growth and functions of leguminous crops at different growth stages. They promote plant growth by nitrogen fixation, solubilization as well as mineralization of phosphorus, and production of phytohormone(s). The co-inoculation of PGPRs along with rhizobia has shown to enhance nodulation and symbiotic interaction. The recent molecular tools are helpful to understand and predict the establishment and function of PGPRs and plant response. In this review, we provide an overview of various growth promoting mechanisms of PGPR inoculations in the production of leguminous crops.
Collapse
Affiliation(s)
| | - Vandana Yadav
- Division of Microbiology, ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110012, India
| | - Deepti Tyagi
- Division of Microbiology, ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110012, India
| | - Dolly Wattal Dhar
- Division of Microbiology, ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110012, India
| | - Annapurna Kannepalli
- Division of Microbiology, ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110012, India
| | - Shiv Kumar
- International Centre for Agricultural Research in the Dry Areas (ICARDA), Rabat 10112, Morocco
| |
Collapse
|
14
|
Genomic Comparison of Insect Gut Symbionts from Divergent Burkholderia Subclades. Genes (Basel) 2020; 11:genes11070744. [PMID: 32635398 PMCID: PMC7397029 DOI: 10.3390/genes11070744] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 01/01/2023] Open
Abstract
Stink bugs of the superfamilies Coreoidea and Lygaeoidea establish gut symbioses with environmentally acquired bacteria of the genus Burkholderia sensu lato. In the genus Burkholderia, the stink bug-associated strains form a monophyletic clade, named stink bug-associated beneficial and environmental (SBE) clade (or Caballeronia). Recently, we revealed that members of the family Largidae of the superfamily Pyrrhocoroidea are associated with Burkholderia but not specifically with the SBE Burkholderia; largid bugs harbor symbionts that belong to a clade of plant-associated group of Burkholderia, called plant-associated beneficial and environmental (PBE) clade (or Paraburkholderia). To understand the genomic features of Burkholderia symbionts of stink bugs, we isolated two symbiotic Burkholderia strains from a bordered plant bug Physopellta gutta (Pyrrhocoroidea: Largidae) and determined their complete genomes. The genome sizes of the insect-associated PBE (iPBE) are 9.5 Mb and 11.2 Mb, both of which are larger than the genomes of the SBE Burkholderia symbionts. A whole-genome comparison between two iPBE symbionts and three SBE symbionts highlighted that all previously reported symbiosis factors are shared and that 282 genes are specifically conserved in the five stink bug symbionts, over one-third of which have unknown function. Among the symbiont-specific genes, about 40 genes formed a cluster in all five symbionts; this suggests a "symbiotic island" in the genome of stink bug-associated Burkholderia.
Collapse
|
15
|
Abstract
Gibberellin (GA) phytohormones are ubiquitous regulators of growth and developmental processes in vascular plants. The convergent evolution of GA production by plant-associated bacteria, including both symbiotic nitrogen-fixing rhizobia and phytopathogens, suggests that manipulation of GA signaling is a powerful mechanism for microbes to gain an advantage in these interactions. Although orthologous operons encode GA biosynthetic enzymes in both rhizobia and phytopathogens, notable genetic heterogeneity and scattered operon distribution in these lineages, including loss of the gene for the final biosynthetic step in most rhizobia, suggest varied functions for GA in these distinct plant-microbe interactions. Therefore, deciphering GA operon evolutionary history should provide crucial evidence toward understanding the distinct biological roles for bacterial GA production. To further establish the genetic composition of the GA operon, two operon-associated genes that exhibit limited distribution among rhizobia were biochemically characterized, verifying their roles in GA biosynthesis. This enabled employment of a maximum parsimony ancestral gene block reconstruction algorithm to characterize loss, gain, and horizontal gene transfer (HGT) of GA operon genes within alphaproteobacterial rhizobia, which exhibit the most heterogeneity among the bacteria containing this biosynthetic gene cluster. Collectively, this evolutionary analysis reveals a complex history for HGT of the entire GA operon, as well as the individual genes therein, and ultimately provides a basis for linking genetic content to bacterial GA functions in diverse plant-microbe interactions, including insight into the subtleties of the coevolving molecular interactions between rhizobia and their leguminous host plants.IMPORTANCE While production of phytohormones by plant-associated microbes has long been appreciated, identification of the gibberellin (GA) biosynthetic operon in plant-associated bacteria has revealed surprising genetic heterogeneity. Notably, this heterogeneity seems to be associated with the lifestyle of the microbe; while the GA operon in phytopathogenic bacteria does not seem to vary to any significant degree, thus enabling production of bioactive GA, symbiotic rhizobia exhibit a number of GA operon gene loss and gain events. This suggests that a unique set of selective pressures are exerted on this biosynthetic gene cluster in rhizobia. Through analysis of the evolutionary history of the GA operon in alphaproteobacterial rhizobia, which display substantial diversity in their GA operon structure and gene content, we provide insight into the effect of lifestyle and host interactions on the production of this phytohormone by plant-associated bacteria.
Collapse
|
16
|
Unay J, Perret X. A Minimal Genetic Passkey to Unlock Many Legume Doors to Root Nodulation by Rhizobia. Genes (Basel) 2020; 11:genes11050521. [PMID: 32392829 PMCID: PMC7290934 DOI: 10.3390/genes11050521] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 12/31/2022] Open
Abstract
In legume crops, formation of developmentally mature nodules is a prerequisite for efficient nitrogen fixation by populations of rhizobial bacteroids established inside nodule cells. Development of root nodules, and concomitant microbial colonization of plant cells, are constrained by sets of recognition signals exchanged by infecting rhizobia and their legume hosts, with much of the specificity of symbiotic interactions being determined by the flavonoid cocktails released by legume roots and the strain-specific nodulation factors (NFs) secreted by rhizobia. Hence, much of Sinorhizobium fredii strain NGR234 symbiotic promiscuity was thought to stem from a family of >80 structurally diverse NFs and associated nodulation keys in the form of secreted effector proteins and rhamnose-rich surface polysaccharides. Here, we show instead that a mini-symbiotic plasmid (pMiniSym2) carrying only the nodABCIJ, nodS and nodD1 genes of NGR234 conferred promiscuous nodulation to ANU265, a derivative strain cured of the large symbiotic plasmid pNGR234a. The ANU265::pMiniSym2 transconjugant triggered nodulation responses on 12 of the 22 legumes we tested. On roots of Macroptilium atropurpureum, Leucaena leucocephala and Vigna unguiculata, ANU265::pMiniSym2 formed mature-like nodule and successfully infected nodule cells. While cowpea and siratro responded to nodule colonization with defense responses that eventually eliminated bacteria, L. leucocephala formed leghemoglobin-containing mature-like nodules inside which the pMiniSym2 transconjugant established persistent intracellular colonies. These data show seven nodulation genes of NGR234 suffice to trigger nodule formation on roots of many hosts and to establish chronic infections in Leucaena cells.
Collapse
|
17
|
Tang L, Hamid Y, Zehra A, Sahito ZA, He Z, Khan MB, Feng Y, Yang X. Mechanisms of water regime effects on uptake of cadmium and nitrate by two ecotypes of water spinach (Ipomoea aquatica Forsk.) in contaminated soil. CHEMOSPHERE 2020; 246:125798. [PMID: 31927376 DOI: 10.1016/j.chemosphere.2019.125798] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/20/2019] [Accepted: 12/29/2019] [Indexed: 06/10/2023]
Abstract
Availability of cadmium (Cd) and nitrate and their transfer to green leafy vegetables is highly dependent on physical, chemical and biochemical conditions of the soil. The phenotypic characteristics, accumulation of hazardous materials and rhizosphere properties of two ecotypes of water spinach in response to water stress were investigated. Flooding significantly enhanced plant growth and decreased Cd and nitrate concentrations in the shoot and root of both ecotypes of water spinach. Flooding extensively changed the physicochemical properties and biological processes in the rhizosphere, including increased pH and activities of urease and acid phosphatase, and decreased availability of Cd and nitrate and activity of nitrate reductase. Furthermore, flooding increased rhizosphere bacteria community diversity (including richness and evenness) and changed their community structure. Denitrifying bacteria (Clostridiales, Azoarcus and Pseudomonas), toxic metal resistant microorganisms (Rhodosporillaceae, Rhizobiales and Geobacter) were enriched in the rhizosphere under flooding conditions, and the plant growth-promoting taxa (Sphingomonadaceae) were preferentially colonized in the high accumulator (HA) rhizosphere region. These results indicated that flooding treatments result in biochemical and microbiological changes in soil, especially in the rhizosphere and reduced the availability of Cd and nitrate to plants, thus decreasing their uptake by water spinach. It is, therefore, possible to promote crop growth and reduce the accumulation of hazardous materials in vegetable crops like water spinach by controlling soil moisture conditions.
Collapse
Affiliation(s)
- Lin Tang
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Yasir Hamid
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Afsheen Zehra
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, PR China; Department of Botany, Federal Urdu University of Arts, Science and Technology, Karachi, Pakistan
| | - Zulfiqar Ali Sahito
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Zhenli He
- University of Florida, Institute of Food and Agricultural Sciences, Indian River Research and Education Center, Fort Pierce, Florida, 34945, United States
| | - Muhammad Bilal Khan
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Ying Feng
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Xiaoe Yang
- Ministry of Education Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, PR China.
| |
Collapse
|
18
|
Kusakabe S, Higasitani N, Kaneko T, Yasuda M, Miwa H, Okazaki S, Saeki K, Higashitani A, Sato S. Lotus Accessions Possess Multiple Checkpoints Triggered by Different Type III Secretion System Effectors of the Wide-Host-Range Symbiont Bradyrhizobium elkanii USDA61. Microbes Environ 2020; 35. [PMID: 32074548 PMCID: PMC7104275 DOI: 10.1264/jsme2.me19141] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Bradyrhizobium elkanii, a rhizobium with a relatively wide host range, possesses a functional type III secretion system (T3SS) that is involved in symbiotic incompatibility against Rj4-genotype soybean (Glycine max) and some accessions of mung bean (Vigna radiata). To expand our knowledge on the T3SS-mediated partner selection mechanism in the symbiotic legume-rhizobia association, we inoculated three Lotus experimental accessions with wild-type and T3SS-mutant strains of B. elkanii USDA61. Different responses were induced by T3SS in a host genotype-dependent manner. Lotus japonicus Gifu inhibited infection; L. burttii allowed infection, but inhibited nodule maturation at the post-infection stage; and L. burttii and L. japonicus MG-20 both displayed a nodule early senescence-like response. By conducting inoculation tests with mutants of previously reported and newly identified effector protein genes of B. elkanii USDA61, we identified NopF as the effector protein triggering the inhibition of infection, and NopM as the effector protein triggering the nodule early senescence–like response. Consistent with these results, the B. elkanii USDA61 gene for NopF introduced into the Lotus symbiont Mesorhizobium japonicum induced infection inhibition in L. japonicus Gifu, but did not induce any response in L. burttii or L. japonicus MG-20. These results suggest that Lotus accessions possess at least three checkpoints to eliminate unfavorable symbionts, including the post-infection stage, by recognizing different T3SS effector proteins at each checkpoint.
Collapse
Affiliation(s)
| | | | | | - Michiko Yasuda
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology
| | - Hiroki Miwa
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology
| | - Shin Okazaki
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology
| | - Kazuhiko Saeki
- Department of Biological Sciences and Kyousei Science Center for Life and Nature, Nara Women's University
| | | | - Shusei Sato
- Graduate School of Life Sciences, Tohoku University
| |
Collapse
|
19
|
Harris MO, Pitzschke A. Plants make galls to accommodate foreigners: some are friends, most are foes. THE NEW PHYTOLOGIST 2020; 225:1852-1872. [PMID: 31774564 DOI: 10.1111/nph.16340] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 07/24/2019] [Indexed: 06/10/2023]
Abstract
At the colonization site of a foreign entity, plant cells alter their trajectory of growth and development. The resulting structure - a plant gall - accommodates various needs of the foreigner, which are phylogenetically diverse: viruses, bacteria, protozoa, oomycetes, true fungi, parasitic plants, and many types of animals, including rotifers, nematodes, insects, and mites. The plant species that make galls also are diverse. We assume gall production costs the plant. All is well if the foreigner provides a gift that makes up for the cost. Nitrogen-fixing nodule-inducing bacteria provide nutritional services. Gall wasps pollinate fig trees. Unfortunately for plants, most galls are made for foes, some of which are deeply studied pathogens and pests: Agrobacterium tumefaciens, Rhodococcus fascians, Xanthomonas citri, Pseudomonas savastanoi, Pantoea agglomerans, 'Candidatus' phytoplasma, rust fungi, Ustilago smuts, root knot and cyst nematodes, and gall midges. Galls are an understudied phenomenon in plant developmental biology. We propose gall inception for discovering unifying features of the galls that plants make for friends and foes, talk about molecules that plants and gall-inducers use to get what they want from each other, raise the question of whether plants colonized by arbuscular mycorrhizal fungi respond in a gall-like manner, and present a research agenda.
Collapse
Affiliation(s)
- Marion O Harris
- Department of Entomology, North Dakota State University, Fargo, ND, 58014, USA
| | - Andrea Pitzschke
- Department of Biosciences, Salzburg University, Hellbrunner Strasse 34, A-5020, Salzburg, Austria
| |
Collapse
|
20
|
Trněný O, Vlk D, Macková E, Matoušková M, Řepková J, Nedělník J, Hofbauer J, Vejražka K, Jakešová H, Jansa J, Piálek L, Knotová D. Allelic Variants for Candidate Nitrogen Fixation Genes Revealed by Sequencing in Red Clover ( Trifolium pratense L.). Int J Mol Sci 2019; 20:E5470. [PMID: 31684086 PMCID: PMC6862357 DOI: 10.3390/ijms20215470] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/25/2019] [Accepted: 10/30/2019] [Indexed: 02/06/2023] Open
Abstract
Plant-rhizobia symbiosis can activate key genes involved in regulating nodulation associated with biological nitrogen fixation (BNF). Although the general molecular basis of the BNF process is frequently studied, little is known about its intraspecific variability and the characteristics of its allelic variants. This study's main goals were to describe phenotypic and genotypic variation in the context of nitrogen fixation in red clover (Trifolium pretense L.) and identify variants in BNF candidate genes associated with BNF efficiency. Acetylene reduction assay validation was the criterion for selecting individual plants with particular BNF rates. Sequences in 86 key candidate genes were obtained by hybridization-based sequence capture target enrichment of plants with alternative phenotypes for nitrogen fixation. Two genes associated with BNF were identified: ethylene response factor required for nodule differentiation (EFD) and molybdate transporter 1 (MOT1). In addition, whole-genome population genotyping by double-digest restriction-site-associated sequencing (ddRADseq) was performed, and BNF was evaluated by the natural 15N abundance method. Polymorphisms associated with BNF and reflecting phenotype variability were identified. The genetic structure of plant accessions was not linked to BNF rate of measured plants. Knowledge of the genetic variation within BNF candidate genes and the characteristics of genetic variants will be beneficial in molecular diagnostics and breeding of red clover.
Collapse
Affiliation(s)
- Oldřich Trněný
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - David Vlk
- Department of Experimental Biology, Masaryk University, 625 00 Brno, Czech Republic.
| | - Eliška Macková
- Department of Experimental Biology, Masaryk University, 625 00 Brno, Czech Republic.
| | | | - Jana Řepková
- Department of Experimental Biology, Masaryk University, 625 00 Brno, Czech Republic.
| | - Jan Nedělník
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - Jan Hofbauer
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - Karel Vejražka
- Agricultural Research, Ltd., Zahradní 1, 664 41 Troubsko, Czech Republic.
| | - Hana Jakešová
- Red Clover and Grass Breeding, 724 47 Hladké Životice, Czech Republic.
| | - Jan Jansa
- Institute of Microbiology of the Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic.
| | - Lubomír Piálek
- Department of Zoology, Faculty of Science, University of South Bohemia, 370 05 České Budějovice, Czech Republic.
| | - Daniela Knotová
- Research Institute for Fodder Crops, Ltd., 664 41 Troubsko, Czech Republic.
| |
Collapse
|
21
|
Miller DL, Parish AJ, Newton IL. Transitions and transmission: behavior and physiology as drivers of honey bee-associated microbial communities. Curr Opin Microbiol 2019; 50:1-7. [PMID: 31563000 DOI: 10.1016/j.mib.2019.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/13/2019] [Accepted: 08/15/2019] [Indexed: 12/14/2022]
Abstract
Microbial communities have considerable impacts on animal health. However, only in recent years have the host factors impacting microbiome composition been explored. An increasing wealth of microbiome data in combination with decades of research on behavior, physiology, and development have resulted in the European honey bee (Apis mellifera) as a burgeoning model system for studying the influence of host behavior on the microbiota. Honey bees are eusocial insects which exhibit striking behavioral and physiological differences between castes and life stages. These include changes in social contact, environmental exposure, diet, and physiology: all factors which can affect microbial composition and function. The honey bee system offers an opportunity to tease apart the interactive effects of all these factors on microbiota composition, abundance, and diversity.
Collapse
Affiliation(s)
- Delaney L Miller
- Department of Biology, Indiana University, Bloomington, IN, 47405, United States
| | - Audrey J Parish
- Department of Biology, Indiana University, Bloomington, IN, 47405, United States
| | - Irene Lg Newton
- Department of Biology, Indiana University, Bloomington, IN, 47405, United States.
| |
Collapse
|
22
|
Wang R, Wei S, Jia P, Liu T, Hou D, Xie R, Lin Z, Ge J, Qiao Y, Chang X, Lu L, Tian S. Biochar significantly alters rhizobacterial communities and reduces Cd concentration in rice grains grown on Cd-contaminated soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 676:627-638. [PMID: 31051368 DOI: 10.1016/j.scitotenv.2019.04.133] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 04/07/2019] [Accepted: 04/09/2019] [Indexed: 05/27/2023]
Abstract
Cadmium (Cd) contamination poses a serious problem in paddy soils. Biochar is frequently reported to deactivate Cd in soils and reduce Cd accumulation in rice plants, but few studies have addressed whether and how biochar affected the microbial communities in rice rhizosphere, which was an important factor determining the metal bioavailability and plant growth. In this study, biochar was pyrolyzed from bamboo (Phyllostachys heterocycla) chips at 350 °C. By using ICP-MS analysis and 16S rRNA gene sequencing, the impact of the biochar on Cd uptake by rice and on rhizospheric bacterial communities was investigated in both high-accumulating (HA) and low-accumulating (LA) rice cultivars grown in soils artificially contaminated with different Cd levels. Applied biochar significantly reduced Cd contents in rice plants of both cultivars, with substantially lower grain Cd contents for LA grown in highly contaminated soil. Soil pH was slightly increased by the applied biochar. Cd bioavailability was somehow reduced in soils, but not as significant as the reduction of Cd contents in rice plants. More interestingly, biochar application significantly altered the rhizobacterial community: it stimulated growth-promoting bacteria, such as Kaistobacter, Sphingobium (order Sphingomonadales), and Rhizobiaceae (order Rhizobiales); improved natural barrier formation and the transformation of metal mobilization around the rhizosphere mediated by, e.g., Rhodocyclaceae (class Betaproteobacteria) and Geobacter (class Deltaproteobacteria); and enhanced colonization of the LA rhizosphere possibly by taxa involved in Cd immobilization (Desulfovibrionales and Desulfobacterales). These results indicate that biochar application significantly reduces Cd uptake and accumulation by altering the rhizosphere bacterial community in rice grown on Cd-contaminated soils. The baseline data generated in this study provide insights that pave the way toward safer rice production.
Collapse
Affiliation(s)
- Runze Wang
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Shuai Wei
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Peihan Jia
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ting Liu
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Dandi Hou
- School of Marine Sciences, Ningbo University, Ningbo 315211, China
| | - Ruohan Xie
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Zhi Lin
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jun Ge
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yabei Qiao
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiaoyan Chang
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Lingli Lu
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Shengke Tian
- MOE Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
| |
Collapse
|
23
|
Li X, Wang H, Tong W, Feng L, Wang L, Rahman SU, Wei G, Tao S. Exploring the evolutionary dynamics of Rhizobium plasmids through bipartite network analysis. Environ Microbiol 2019; 22:934-951. [PMID: 31361937 DOI: 10.1111/1462-2920.14762] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 06/24/2019] [Accepted: 07/25/2019] [Indexed: 10/26/2022]
Abstract
The genus Rhizobium usually has a multipartite genome architecture with a chromosome and several plasmids, making these bacteria a perfect candidate for plasmid biology studies. As there are no universally shared genes among typical plasmids, network analyses can complement traditional phylogenetics in a broad-scale study of plasmid evolution. Here, we present an exhaustive analysis of 216 plasmids from 49 complete genomes of Rhizobium by constructing a bipartite network that consists of two classes of nodes, the plasmids and homologous protein families that connect them. Dissection of the network using a hierarchical clustering strategy reveals extensive variety, with 34 homologous plasmid clusters. Four large clusters including one cluster of symbiotic plasmids and two clusters of chromids carrying some truly essential genes are widely distributed among Rhizobium. In contrast, the other clusters are quite small and rare. Symbiotic clusters and rare accessory clusters are exogenetic and do not appear to have co-evolved with the common accessory clusters; the latter ones have a large coding potential and functional complementarity for different lifestyles in Rhizobium. The bipartite network also provides preliminary evidence of Rhizobium plasmid variation and formation including genetic exchange, plasmid fusion and fission, exogenetic plasmid transfer, host plant selection, and environmental adaptation.
Collapse
Affiliation(s)
- Xiangchen Li
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.,Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Hao Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.,Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Wenjun Tong
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Li Feng
- College of Enology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Lina Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.,Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Siddiq Ur Rahman
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.,Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, 712100, China.,Department of Computer Science and Bioinformatics, Khushal Khan Khattak University, Karak, Khyber Pakhtunkhwa, 27200, Pakistan
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Shiheng Tao
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.,Bioinformatics Center, Northwest A&F University, Yangling, Shaanxi, 712100, China
| |
Collapse
|
24
|
Lan Q, Liu C, Ling S. Research on Measurement of Symbiosis Degree Between National Fitness and the Sports Industry from the Perspective of Collaborative Development. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:E2191. [PMID: 31234272 PMCID: PMC6617403 DOI: 10.3390/ijerph16122191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 06/15/2019] [Accepted: 06/18/2019] [Indexed: 11/17/2022]
Abstract
Clarifying the symbiotic relationship between national fitness and the sports industry has important theoretical and practical significance for the collaborative development of the two. In order to measure and verify the symbiotic relationship between national fitness and the sports industry, we introduce a "symbiosis degree" model test method for the measurement of the symbiotic relationship during 2000-2017 between the two. Our results show that national fitness and the sports industry have symbiotic sufficient and necessary conditions, for both of which there is a symbiotic relationship, and a non-symmetric reciprocal symbiotic mode long-term. Overall, the impact of national fitness on the sports industry is greater than the impact of the sports industry on national fitness. From a structural perspective, there is a certain difference in the mutual influence of national fitness and the sports industry in the field of sports goods and sports services. In a dynamic forecast, we found that national fitness and the sports industry have the development trend of a symmetric reciprocal symbiotic state. Through theoretical studies, data measured and simulated projections, we believe that the symbiosis degree of the measurement model for the detection and prediction of the symbiotic unit of the symbiotic relationship between them to be of practical value.
Collapse
Affiliation(s)
- Qing Lan
- School of Public Administration, Central South University, Changsha 410083, China.
- College of Physical Education, Yichun University, Yichun 336000, China.
| | - Chunxiang Liu
- School of Public Administration, Central South University, Changsha 410083, China.
| | - Shuang Ling
- School of Public Administration, Central South University, Changsha 410083, China.
| |
Collapse
|
25
|
Barros-Carvalho GA, Hungria M, Lopes FM, Van Sluys MA. Brazilian-adapted soybean Bradyrhizobium strains uncover IS elements with potential impact on biological nitrogen fixation. FEMS Microbiol Lett 2019; 366:fnz046. [PMID: 30860585 DOI: 10.1093/femsle/fnz046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 05/15/2019] [Indexed: 11/14/2022] Open
Abstract
Bradyrhizobium diazoefficiens CPAC 7 and Bradyrhizobium japonicum CPAC 15 are broadly used in commercial inoculants in Brazil, contributing to most of the nitrogen required by the soybean crop. These strains differ in their symbiotic properties: CPAC 7 is more efficient in fixing nitrogen, whereas CPAC 15 is more competitive. Comparative genomics revealed many transposases close to genes associated with symbiosis in the symbiotic island of these strains. Given the importance that insertion sequences (IS) elements have to bacterial genomes, we focused on identifying the local impact of these elements in the genomes of these and other related Bradyrhizobium strains to further understand their phenotypic differences. Analyses were performed using bioinformatics approaches. We found IS elements disrupting and inserted at regulatory regions of genes involved in symbiosis. Further comparative analyses with 21 Bradyrhizobium genomes revealed insertional polymorphism with distinguishing patterns between B. diazoefficiens and B. japonicum lineages. Finally, 13 of these potentially impacted genes are differentially expressed under symbiotic conditions in B. diazoefficiens USDA 110. Thus, IS elements are associated with the diversity of Bradyrhizobium, possibly by providing mechanisms for natural variation of symbiotic effectiveness.
Collapse
Affiliation(s)
- Gesiele Almeida Barros-Carvalho
- GaTE Lab; Departamento de Botânica - Instituto de Biociências, Universidade de São Paulo, 277 Matão Street, 05508-090, São Paulo, SP, Brazil
- Instituto de Matemática e Estatística, Universidade de São Paulo, 1010 Matão Street, 05508-090, São Paulo, SP, Brazil
| | | | - Fabrício Martins Lopes
- Universidade Tecnológica Federal do Paraná, 1640 Alberto Carazzai Avenue, 86300-000, Cornélio Procópio, Pr, Brazil
| | - Marie-Anne Van Sluys
- GaTE Lab; Departamento de Botânica - Instituto de Biociências, Universidade de São Paulo, 277 Matão Street, 05508-090, São Paulo, SP, Brazil
| |
Collapse
|
26
|
Cherni AE, Perret X. Deletion of rRNA Operons of Sinorhizobium fredii Strain NGR234 and Impact on Symbiosis With Legumes. Front Microbiol 2019; 10:154. [PMID: 30814981 PMCID: PMC6381291 DOI: 10.3389/fmicb.2019.00154] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 01/22/2019] [Indexed: 01/08/2023] Open
Abstract
During their lifecycle, from free-living soil bacteria to endosymbiotic nitrogen-fixing bacteroids of legumes, rhizobia must colonize, and cope with environments where nutrient concentrations and compositions vary greatly. Bacterial colonization of legume rhizospheres and of root surfaces is subject to a fierce competition for plant exudates. By contrast root nodules offer to rhizobia sheltered nutrient-rich environments within which the cells that successfully propagated via infection threads can rapidly multiply. To explore the effects on symbiosis of a slower rhizobia growth and metabolism, we deleted one or two copies of the three functional rRNA operons of the promiscuous Sinorhizobium fredii strain NGR234 and examined the impact of these mutations on free-living and symbiotic lifestyles. Strains with two functional rRNA operons (NGRΔrRNA1 and NGRΔrRNA3) grew almost as rapidly as NGR234, and NGRΔrRNA1 was as proficient as the parent strain on all of the five legume species tested. By contrast, the NGRΔrRNA1,3 double mutant, which carried a single rRNA operon and grew significantly slower than NGR234, had a reduced symbiotic proficiency on Cajanus cajan, Macroptilium atropurpureum, Tephrosia vogelii, and Vigna unguiculata. In addition, while NGRΔrRNA1 and NGR234 equally competed for nodulation of V. unguiculata, strain NGRΔrRNA1,3 was clearly outcompeted by wild-type. Surprisingly, on Leucaena leucocephala, NGRΔrRNA1,3 was the most proficient strain and competed equally NGR234 for nodule occupation. Together, these results indicate that for strains with otherwise identical repertoires of symbiotic genes, a faster growth on roots and/or inside plant tissues may contribute to secure access to nodules of some hosts. By contrast, other legumes such as L. leucocephala appear as less selective and capable of providing symbiotic environments susceptible to accommodate strains with a broader spectrum of competences.
Collapse
Affiliation(s)
- Ala Eddine Cherni
- Microbiology Unit, Department of Botany and Plant Biology, Sciences III, University of Geneva, Geneva, Switzerland
| | - Xavier Perret
- Microbiology Unit, Department of Botany and Plant Biology, Sciences III, University of Geneva, Geneva, Switzerland
| |
Collapse
|
27
|
Saad MM, Michalet S, Fossou R, Putnik-Delić M, Crèvecoeur M, Meyer J, de Malézieux C, Hopfgartner G, Maksimović I, Perret X. Loss of NifQ Leads to Accumulation of Porphyrins and Altered Metal-Homeostasis in Nitrogen-Fixing Symbioses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:208-216. [PMID: 30070615 DOI: 10.1094/mpmi-07-18-0188-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Symbiotic nitrogen fixation between legumes and rhizobia involves a coordinated expression of many plant and bacterial genes as well as finely tuned metabolic activities of micro- and macrosymbionts. In spite of such complex interactions, symbiotic proficiency remains a resilient process, with host plants apparently capable of compensating for some deficiencies in rhizobia. What controls nodule homeostasis is still poorly understood and probably varies between plant species. In this respect, the promiscuous Sinorhizobium (Ensifer) fredii strain NGR234 has become a model to assess the relative contribution of single gene products to many symbioses. Here, we describe how a deletion in nifQ of NGR234 (strain NGRΔnifQ) makes nodules of Vigna unguiculata, V. radiata, and Macroptilium atropurpureum but not of the mimisoid tree Leucaena leucocephala, purple-red. This peculiar dark-nodule phenotype did not necessarily correlate with a decreased proficiency of NGRΔnifQ but coincided with a 20-fold or more accumulation of coproporphyrin III and uroporphyrin III in V. unguiculata nodules. Porphyrin accumulation was not restricted to plant cells infected with bacteroids but also extended to the nodule cortex. Nodule metal-homeostasis was altered but not sufficiently to prevent assembly and functioning of nitrogenase. Although the role of NifQ in donating molybdenum during assembly of nitrogenase cofactor FeMo-co makes it essential in free-living diazotrophs, our results highlight the dispensability of NifQ in many legume species.
Collapse
Affiliation(s)
- Maged M Saad
- 1 University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
- 2 King Abdullah University of Science and Technology (KAUST), Biological and Environmental Sciences and Engineering Division (BESE), Thuwal 6900-2355, Kingdom of Saudi Arabia
| | - Sophie Michalet
- 3 University of Geneva, Mass Spectrometry Core Facility (MZ 2.0), Faculty of Sciences, Bd d'Yvoy 11, CH-1211 Geneva 4, Switzerland
| | - Romain Fossou
- 1 University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | | | - Michèle Crèvecoeur
- 1 University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Julien Meyer
- 3 University of Geneva, Mass Spectrometry Core Facility (MZ 2.0), Faculty of Sciences, Bd d'Yvoy 11, CH-1211 Geneva 4, Switzerland
| | - Chloé de Malézieux
- 1 University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Gérard Hopfgartner
- 5 University of Geneva, Department of Inorganic and Analytical Chemistry, Faculty of Sciences, 26 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| | - Ivana Maksimović
- 4 University of Novi Sad, Faculty of Agriculture, Novi Sad, Serbia; and
| | - Xavier Perret
- 1 University of Geneva, Sciences III, Department of Botany and Plant Biology, Microbiology Unit, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
| |
Collapse
|
28
|
Piromyou P, Songwattana P, Teamtisong K, Tittabutr P, Boonkerd N, Tantasawat PA, Giraud E, Göttfert M, Teaumroong N. Mutualistic co-evolution of T3SSs during the establishment of symbiotic relationships between Vigna radiata and Bradyrhizobia. Microbiologyopen 2019; 8:e00781. [PMID: 30628192 PMCID: PMC6612562 DOI: 10.1002/mbo3.781] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/04/2018] [Accepted: 11/06/2018] [Indexed: 02/06/2023] Open
Abstract
This study supports the idea that the evolution of type III secretion system (T3SS) is one of the factors that controls Vigna radiata-bradyrhizobia symbiosis. Based on phylogenetic tree data and gene arrangements, it seems that the T3SSs of the Thai bradyrhizobial strains SUTN9-2, DOA1, and DOA9 and the Senegalese strain ORS3257 may share the same origin. Therefore, strains SUTN9-2, DOA1, DOA9, and ORS3257 may have evolved their T3SSs independently from other bradyrhizobia, depending on biological and/or geological events. For functional analyses, the rhcJ genes of ORS3257, SUTN9-2, DOA9, and USDA110 were disrupted. These mutations had cultivar-specific effects on nodulation properties. The T3SSs of ORS3257 and DOA9 showed negative effects on V. radiata nodulation, while the T3SS of SUTN9-2 showed no effect on V. radiata symbiosis. In the roots of V. radiata CN72, the expression levels of the PR1 gene after inoculation with ORS3257 and DOA9 were significantly higher than those after inoculation with ORS3257 ΩT3SS, DOA9 ΩT3SS, and SUTN9-2. The T3Es from ORS3257 and DOA9 could trigger PR1 expression, which ultimately leads to abort nodulation. In contrast, the T3E from SUTN9-2 reduced PR1 expression. It seems that the mutualistic relationship between SUTN9-2 and V. radiata may have led to the selection of the most well-adapted combination of T3SS and symbiotic bradyrhizobial genotype.
Collapse
Affiliation(s)
- Pongdet Piromyou
- School of Biotechnology, Institute of Agricultural TechnologySuranaree University of TechnologyNakhon RatchasimaThailand
| | - Pongpan Songwattana
- School of Biotechnology, Institute of Agricultural TechnologySuranaree University of TechnologyNakhon RatchasimaThailand
| | - Kamonluck Teamtisong
- The Center for Scientific and Technological EquipmentSuranaree University of TechnologyNakhon RatchasimaThailand
| | - Panlada Tittabutr
- School of Biotechnology, Institute of Agricultural TechnologySuranaree University of TechnologyNakhon RatchasimaThailand
| | - Nantakorn Boonkerd
- School of Biotechnology, Institute of Agricultural TechnologySuranaree University of TechnologyNakhon RatchasimaThailand
| | - Piyada Alisha Tantasawat
- School of Crop Production Technology, Institute of Agricultural TechnologySuranaree University of TechnologyNakhon RatchasimaThailand
| | - Eric Giraud
- IRD, Laboratory of Tropical and Mediterranean SymbiosesUMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de BaillarguetMontpellierFrance
| | | | - Neung Teaumroong
- School of Biotechnology, Institute of Agricultural TechnologySuranaree University of TechnologyNakhon RatchasimaThailand
| |
Collapse
|
29
|
Wang D, Couderc F, Tian CF, Gu W, Liu LX, Poinsot V. Conserved Composition of Nod Factors and Exopolysaccharides Produced by Different Phylogenetic Lineage Sinorhizobium Strains Nodulating Soybean. Front Microbiol 2018; 9:2852. [PMID: 30534119 PMCID: PMC6275314 DOI: 10.3389/fmicb.2018.02852] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 11/06/2018] [Indexed: 12/31/2022] Open
Abstract
The structural variation of symbiotic signals released by rhizobia determines the specificity of their interaction with legume plants. Previous studies showed that Sinorhizobium strains from different phylogenetic lineages had different symbiotic performance on certain cultivated soybeans. Whether they released similar or different symbiotic signals remained unclear. In this study, we compared their nod and exo gene clusters and made a detailed structural analysis of Nod factors and EPS by ESI-MS/MS and two dimensions NMR. Even if there are some differences among nod or exo gene clusters; they produced much conserved Nod factor and EPS compositions. The Nod factors consist of a cocktail of β-(1, 4)-linked tri-, tetra-, and pentamers of N-acetyl-D-glucosamine (GlcNAc). The C2 position on the non-reducing terminal end is modified by a lipid chain that contains 16 or 18 atoms of carbon–with or without unsaturations-, and the C6 position on the reducing residue is decorated by a fucose or a 2-O-methylfucose. Their EPS are composed of glucose, galactose, glucuronic acid, pyruvic acid in the ratios 5:1:2:1 or 6:1:2:1. These findings indicate that soybean cultivar compatibility of Sinorhizobium strains does not result from Nod factor or EPS structure variations. The structure comparison of the soybean microbionts with other Sinorhizobium strains showed that Nod factor structures of soybean microbionts are much conserved, although there are no specific genes shared by the soybean microsymbionts. EPS produced by Sinorhizobium strains are different from those of Bradyrhizobium. All above is consistent with the previous deduction that Nod factor structures are related to host range, while those of EPS are connected with phylogeny.
Collapse
Affiliation(s)
- Dan Wang
- Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou, China.,Laboratoire des IMRCP, UMR5623 Université Paul Sabatier, CNRS, Toulouse, France.,State Key Laboratory of Agrobiotechnology, and College of Biological Sciences, China Agricultural University, Beijing, China
| | - François Couderc
- Laboratoire des IMRCP, UMR5623 Université Paul Sabatier, CNRS, Toulouse, France
| | - Chang Fu Tian
- State Key Laboratory of Agrobiotechnology, and College of Biological Sciences, China Agricultural University, Beijing, China
| | - Wenjie Gu
- Institute of Agricultural Resources and Environment, Guangdong Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer in South Region, Ministry of Agriculture, Guangdong Key Laboratory of Nutrient Cycling and Farmland Conservation, Guangzhou, China
| | - Li Xue Liu
- State Key Laboratory of Agrobiotechnology, and College of Biological Sciences, China Agricultural University, Beijing, China
| | - Verena Poinsot
- Laboratoire des IMRCP, UMR5623 Université Paul Sabatier, CNRS, Toulouse, France
| |
Collapse
|
30
|
Lebre PH, Aliyu H, De Maayer P, Cowan DA. In silico characterization of the global Geobacillus and Parageobacillus secretome. Microb Cell Fact 2018; 17:156. [PMID: 30285747 PMCID: PMC6171300 DOI: 10.1186/s12934-018-1005-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 09/26/2018] [Indexed: 11/17/2022] Open
Abstract
Background Geobacillus and Parageobacillus are two ecologically diverse thermophilic genera within the phylum Firmicutes. These taxa have long been of biotechnological interest due to their ability to secrete thermostable enzymes and other biomolecules that have direct applications in various industrial and clinical fields. Despite the commercial and industrial interest in these microorganisms, the full scope of the secreted protein, i.e. the secretome, of Geobacillus and Parageobacillus species remains largely unexplored, with most studies focusing on single enzymes. A genome-wide exploration of the global secretome can provide a platform for understanding the extracellular functional “protein cloud” and the roles that secreted proteins play in the survival and adaptation of these biotechnologically relevant organisms. Results In the present study, the global secretion profile of 64 Geobacillus and Parageobacillus strains, comprising 772 distinct proteins, was predicted using comparative genomic approaches. Thirty-one of these proteins are shared across all strains used in this study and function in cell-wall/membrane biogenesis as well as transport and metabolism of carbohydrates, amino acids and inorganic ions. An analysis of the clustering patterns of the secretomes of the 64 strains according to shared functional orthology revealed a correlation between the secreted profiles of different strains and their phylogeny, with Geobacillus and Parageobacillus species forming two distinct functional clades. Conclusions The in silico characterization of the global secretome revealed a metabolically diverse set of secreted proteins, which include proteases, glycoside hydrolases, nutrient binding proteins and toxins. Electronic supplementary material The online version of this article (10.1186/s12934-018-1005-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Pedro H Lebre
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Habibu Aliyu
- Technical Biology, Institute of Process Engineering in Life Science, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Pieter De Maayer
- School of Molecular and Cell Biology, University of Witwatersrand, Johannesburg, South Africa
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa.
| |
Collapse
|
31
|
Mabrouk Y, Hemissi I, Salem IB, Mejri S, Saidi M, Belhadj O. Potential of Rhizobia in Improving Nitrogen Fixation and Yields of Legumes. Symbiosis 2018. [DOI: 10.5772/intechopen.73495] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
32
|
Salazar-Cerezo S, Martínez-Montiel N, García-Sánchez J, Pérez-Y-Terrón R, Martínez-Contreras RD. Gibberellin biosynthesis and metabolism: A convergent route for plants, fungi and bacteria. Microbiol Res 2018; 208:85-98. [PMID: 29551215 DOI: 10.1016/j.micres.2018.01.010] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/24/2018] [Accepted: 01/27/2018] [Indexed: 11/26/2022]
Abstract
Gibberellins (GAs) are natural complex biomolecules initially identified as secondary metabolites in the fungus Gibberella fujikuroi with strong implications in plant physiology. GAs have been identified in different fungal and bacterial species, in some cases related to virulence, but the full understanding of the role of these metabolites in the different organisms would need additional investigation. In this review, we summarize the current evidence regarding a common pathway for GA synthesis in fungi, bacteria and plant from the genes depicted as part of the GA production cluster to the enzymes responsible for the catalytic transformations and the biosynthetical routes involved. Moreover, we present the relationship between these observations and the biotechnological applications of GAs in plants, which has shown an enormous commercial impact.
Collapse
Affiliation(s)
- Sonia Salazar-Cerezo
- Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif 103J, Ciudad Universitaria, Col. San Manuel, CP 72570, Puebla, Mexico
| | - Nancy Martínez-Montiel
- Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif 103J, Ciudad Universitaria, Col. San Manuel, CP 72570, Puebla, Mexico
| | - Jenny García-Sánchez
- Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif 103J, Ciudad Universitaria, Col. San Manuel, CP 72570, Puebla, Mexico
| | | | - Rebeca D Martínez-Contreras
- Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif 103J, Ciudad Universitaria, Col. San Manuel, CP 72570, Puebla, Mexico.
| |
Collapse
|
33
|
Abstract
Beneficial microbes such as rhizobia possess effector proteins that are secreted into the host cytoplasm where they modulate host-signaling pathways. Among these effectors, type 3 secreted effectors (T3Es) of rhizobia play roles in promoting nitrogen-fixing nodule symbiosis, suppressing host defenses and directly activating symbiosis-related processes. Rhizobia use the same strategy as pathogenic bacteria to suppress host defenses such as targeting the MAPK cascade. In addition, rhizobial T3E can promote root nodule symbiosis by directly activating Nod factor signaling, which bypasses Nod factor perception. The various strategies employed by beneficial microbes to promote infection and maintain viability in the host are therefore crucial for plant endosymbiosis.
Collapse
Affiliation(s)
- Hiroki Miwa
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan
| | - Shin Okazaki
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu, Tokyo 183-8509, Japan.
| |
Collapse
|
34
|
Stopka SA, Agtuca BJ, Koppenaal DW, Paša-Tolić L, Stacey G, Vertes A, Anderton CR. Laser-ablation electrospray ionization mass spectrometry with ion mobility separation reveals metabolites in the symbiotic interactions of soybean roots and rhizobia. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 91:340-354. [PMID: 28394446 DOI: 10.1111/tpj.13569] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 05/18/2023]
Abstract
Technologies enabling in situ metabolic profiling of living plant systems are invaluable for understanding physiological processes and could be used for rapid phenotypic screening (e.g., to produce plants with superior biological nitrogen-fixing ability). The symbiotic interaction between legumes and nitrogen-fixing soil bacteria results in a specialized plant organ (i.e., root nodule) where the exchange of nutrients between host and endosymbiont occurs. Laser-ablation electrospray ionization mass spectrometry (LAESI-MS) is a method that can be performed under ambient conditions requiring minimal sample preparation. Here, we employed LAESI-MS to explore the well characterized symbiosis between soybean (Glycine max L. Merr.) and its compatible symbiont, Bradyrhizobium japonicum. The utilization of ion mobility separation (IMS) improved the molecular coverage, selectivity, and identification of the detected biomolecules. Specifically, incorporation of IMS resulted in an increase of 153 differentially abundant spectral features in the nodule samples. The data presented demonstrate the advantages of using LAESI-IMS-MS for the rapid analysis of intact root nodules, uninfected root segments, and free-living rhizobia. Untargeted pathway analysis revealed several metabolic processes within the nodule (e.g., zeatin, riboflavin, and purine synthesis). Compounds specific to the uninfected root and bacteria were also detected. Lastly, we performed depth profiling of intact nodules to reveal the location of metabolites to the cortex and inside the infected region, and lateral profiling of sectioned nodules confirmed these molecular distributions. Our results established the feasibility of LAESI-IMS-MS for the analysis and spatial mapping of plant tissues, with its specific demonstration to improve our understanding of the soybean-rhizobial symbiosis.
Collapse
Affiliation(s)
- Sylwia A Stopka
- Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, DC, 20052, USA
| | - Beverly J Agtuca
- Divisions of Plant Sciences and Biochemistry, C. S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - David W Koppenaal
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99354, USA
| | - Ljiljana Paša-Tolić
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99354, USA
| | - Gary Stacey
- Divisions of Plant Sciences and Biochemistry, C. S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65211, USA
| | - Akos Vertes
- Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, DC, 20052, USA
| | - Christopher R Anderton
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99354, USA
| |
Collapse
|
35
|
Mitter EK, de Freitas JR, Germida JJ. Bacterial Root Microbiome of Plants Growing in Oil Sands Reclamation Covers. Front Microbiol 2017; 8:849. [PMID: 28559882 PMCID: PMC5432656 DOI: 10.3389/fmicb.2017.00849] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/25/2017] [Indexed: 12/22/2022] Open
Abstract
Oil sands mining in northern Alberta impacts a large footprint, but the industry is committed to reclaim all disturbed land to an ecologically healthy state in response to environmental regulations. However, these newly reconstructed landscapes may be limited by several factors that include low soil nutrient levels and reduced microbial activity. Rhizosphere microorganisms colonize plant roots providing hosts with nutrients, stimulating growth, suppressing disease and increasing tolerance to abiotic stress. High-throughput sequencing techniques can be used to provide a detailed characterization of microbial community structure. This study used 16S rRNA amplicon sequencing to characterize the bacterial root microbiome associated with annual barley (Hordeum vulgare) and sweet clover (Melilotus albus) growing in an oil sands reclamation area. Our results indicate that Proteobacteria dominated the endosphere, whereas other phyla such as Acidobacteria and Gemmatimonadetes were restricted to the rhizosphere, suggesting that plants have the ability to select for certain soil bacterial consortia. The bacterial community in the endosphere compartments were less rich and diverse compared to the rhizosphere. Furthermore, it was apparent that sweet clover plants were more selective, as the community exhibited a lower richness and diversity compared to barley. Members of the family Rhizobiaceae, such as Sinorhizobium and Rhizobium were mainly associated with clover, whereas Acholeplasma (wall-less bacteria transmitted by insects) was unique to barley. Genera from the Enterobacteriaceae family, such as Yersinia and Lentzea were also mostly detected in barley, while other genera such Pseudomonas and Pantoea were able to successfully colonize both plants. Endophytic bacterial profiles varied within the same plant species at different sampling locations; however, these differences were driven by factors other than slope positions or cover management. Our results suggest that bacterial endophytic communities of plants growing in land reclamation systems are a subset of the rhizosphere community and selection is driven by plant factors.
Collapse
Affiliation(s)
- Eduardo K Mitter
- Department of Food and Bioproduct Sciences, University of Saskatchewan, SaskatoonSK, Canada
| | | | - James J Germida
- Department of Soil Science, University of Saskatchewan, SaskatoonSK, Canada
| |
Collapse
|
36
|
Brouwer P, Bräutigam A, Buijs VA, Tazelaar AOE, van der Werf A, Schlüter U, Reichart GJ, Bolger A, Usadel B, Weber APM, Schluepmann H. Metabolic Adaptation, a Specialized Leaf Organ Structure and Vascular Responses to Diurnal N 2 Fixation by Nostoc azollae Sustain the Astonishing Productivity of Azolla Ferns without Nitrogen Fertilizer. FRONTIERS IN PLANT SCIENCE 2017; 8:442. [PMID: 28408911 PMCID: PMC5374210 DOI: 10.3389/fpls.2017.00442] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/14/2017] [Indexed: 05/02/2023]
Abstract
Sustainable agriculture demands reduced input of man-made nitrogen (N) fertilizer, yet N2 fixation limits the productivity of crops with heterotrophic diazotrophic bacterial symbionts. We investigated floating ferns from the genus Azolla that host phototrophic diazotrophic Nostoc azollae in leaf pockets and belong to the fastest growing plants. Experimental production reported here demonstrated N-fertilizer independent production of nitrogen-rich biomass with an annual yield potential per ha of 1200 kg-1 N fixed and 35 t dry biomass. 15N2 fixation peaked at noon, reaching 0.4 mg N g-1 dry weight h-1. Azolla ferns therefore merit consideration as protein crops in spite of the fact that little is known about the fern's physiology to enable domestication. To gain an understanding of their nitrogen physiology, analyses of fern diel transcript profiles under differing nitrogen fertilizer regimes were combined with microscopic observations. Results established that the ferns adapted to the phototrophic N2-fixing symbionts N. azollae by (1) adjusting metabolically to nightly absence of N supply using responses ancestral to ferns and seed plants; (2) developing a specialized xylem-rich vasculature surrounding the leaf-pocket organ; (3) responding to N-supply by controlling transcripts of genes mediating nutrient transport, allocation and vasculature development. Unlike other non-seed plants, the Azolla fern clock is shown to contain both the morning and evening loops; the evening loop is known to control rhythmic gene expression in the vasculature of seed plants and therefore may have evolved along with the vasculature in the ancestor of ferns and seed plants.
Collapse
Affiliation(s)
- Paul Brouwer
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht UniversityUtrecht, Netherlands
| | - Andrea Bräutigam
- Institute for Plant Biochemistry, Cluster of Excellence on Plant Sciences, Heinrich Heine UniversityDüsseldorf, Germany
| | - Valerie A. Buijs
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht UniversityUtrecht, Netherlands
| | - Anne O. E. Tazelaar
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht UniversityUtrecht, Netherlands
| | | | - Urte Schlüter
- Institute for Plant Biochemistry, Cluster of Excellence on Plant Sciences, Heinrich Heine UniversityDüsseldorf, Germany
| | | | - Anthony Bolger
- Institute for Botany and Molecular Genetics, Bioeconomy Science Center, RWTH Aachen UniversityAachen, Germany
| | - Björn Usadel
- Institute for Botany and Molecular Genetics, Bioeconomy Science Center, RWTH Aachen UniversityAachen, Germany
| | - Andreas P. M. Weber
- Institute for Plant Biochemistry, Cluster of Excellence on Plant Sciences, Heinrich Heine UniversityDüsseldorf, Germany
| | - Henriette Schluepmann
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht UniversityUtrecht, Netherlands
| |
Collapse
|
37
|
Burkhart BJ, Schwalen CJ, Mann G, Naismith JH, Mitchell DA. YcaO-Dependent Posttranslational Amide Activation: Biosynthesis, Structure, and Function. Chem Rev 2017; 117:5389-5456. [PMID: 28256131 DOI: 10.1021/acs.chemrev.6b00623] [Citation(s) in RCA: 138] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
With advances in sequencing technology, uncharacterized proteins and domains of unknown function (DUFs) are rapidly accumulating in sequence databases and offer an opportunity to discover new protein chemistry and reaction mechanisms. The focus of this review, the formerly enigmatic YcaO superfamily (DUF181), has been found to catalyze a unique phosphorylation of a ribosomal peptide backbone amide upon attack by different nucleophiles. Established nucleophiles are the side chains of Cys, Ser, and Thr which gives rise to azoline/azole biosynthesis in ribosomally synthesized and posttranslationally modified peptide (RiPP) natural products. However, much remains unknown about the potential for YcaO proteins to collaborate with other nucleophiles. Recent work suggests potential in forming thioamides, macroamidines, and possibly additional post-translational modifications. This review covers all knowledge through mid-2016 regarding the biosynthetic gene clusters (BGCs), natural products, functions, mechanisms, and applications of YcaO proteins and outlines likely future research directions for this protein superfamily.
Collapse
Affiliation(s)
| | | | - Greg Mann
- Biomedical Science Research Complex, University of St Andrews , BSRC North Haugh, St Andrews KY16 9ST, United Kingdom
| | - James H Naismith
- Biomedical Science Research Complex, University of St Andrews , BSRC North Haugh, St Andrews KY16 9ST, United Kingdom.,State Key Laboratory of Biotherapy, Sichuan University , Sichuan, China
| | | |
Collapse
|
38
|
|
39
|
Improvement of Faba Bean Yield Using Rhizobium/Agrobacterium Inoculant in Low-Fertility Sandy Soil. AGRONOMY-BASEL 2017. [DOI: 10.3390/agronomy7010002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
40
|
Fossou RK, Ziegler D, Zézé A, Barja F, Perret X. Two Major Clades of Bradyrhizobia Dominate Symbiotic Interactions with Pigeonpea in Fields of Côte d'Ivoire. Front Microbiol 2016; 7:1793. [PMID: 27891120 PMCID: PMC5104742 DOI: 10.3389/fmicb.2016.01793] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 10/25/2016] [Indexed: 12/03/2022] Open
Abstract
In smallholder farms of Côte d'Ivoire, particularly in the northeast of the country, Cajanus cajan (pigeonpea) has become an important crop because of its multiple beneficial facets. Pigeonpea seeds provide food to make ends meet, are sold on local markets, and aerial parts serve as forage for animals. Since it fixes atmospheric nitrogen in symbiosis with soil bacteria collectively known as rhizobia, C. cajan also improves soil fertility and reduces fallow time. Yet, seed yields remain low mostly because farmers cannot afford chemical fertilizers. To identify local rhizobial strains susceptible to be used as bio-inoculants to foster pigeonpea growth, root nodules were collected in six fields of three geographically distant regions of Côte d'Ivoire. Nodule bacteria were isolated and characterized using various molecular techniques including matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) and DNA sequencing. These molecular analyses showed that 63 out of 85 nodule isolates belonged to two major clades of bradyrhizobia, one of which is known as the Bradyrhizobium elkanii super clade. Phylogenies of housekeeping (16S-ITS-23S, rpoB) and symbiotic (nifH) genes were not always congruent suggesting that lateral transfer of nitrogen fixation genes also contributed to define the genome of these bradyrhizobial isolates. Interestingly, no field-, plant-, or cultivar-specific effect was found to shape the profiles of symbiotic strains. In addition, nodule isolates CI-1B, CI-36E, and CI-41A that belong to distinct species, showed similar symbiotic efficiencies suggesting that any of these strains might serve as a proficient inoculant for C. cajan.
Collapse
Affiliation(s)
- Romain K Fossou
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva Geneva, Switzerland
| | - Dominik Ziegler
- Microbiology Unit, Department of Botany and Plant Biology, University of GenevaGeneva, Switzerland; Mabritec AGRiehen, Switzerland
| | - Adolphe Zézé
- Laboratoire de Biotechnologies Végétale et Microbienne, Unité Mixte de Recherche et d'Innovation en Sciences Agronomiques et Génie Rural, Institut National Polytechnique Félix Houphouët-Boigny (INPHB) Yamoussoukro, Côte d'Ivoire
| | - François Barja
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva Geneva, Switzerland
| | - Xavier Perret
- Microbiology Unit, Department of Botany and Plant Biology, University of Geneva Geneva, Switzerland
| |
Collapse
|
41
|
Iyer B, Rajput MS, Jog R, Joshi E, Bharwad K, Rajkumar S. Organic acid mediated repression of sugar utilization in rhizobia. Microbiol Res 2016; 192:211-220. [PMID: 27664739 DOI: 10.1016/j.micres.2016.07.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 07/20/2016] [Accepted: 07/25/2016] [Indexed: 01/17/2023]
Abstract
Rhizobia are a class of symbiotic diazotrophic bacteria which utilize C4 acids in preference to sugars and the sugar utilization is repressed as long as C4 acids are present. This can be manifested as a diauxie when rhizobia are grown in the presence of a sugar and a C4 acid together. Succinate, a C4 acid is known to repress utilization of sugars, sugar alcohols, hydrocarbons, etc by a mechanism termed as Succinate Mediated Catabolite Repression (SMCR). Mechanism of catabolite repression determines the hierarchy of carbon source utilization in bacteria. Though the mechanism of catabolite repression has been well studied in model organisms like E. coli, B. subtilis and Pseudomonas sp., mechanism of SMCR in rhizobia has not been well elucidated. C4 acid uptake is important for effective symbioses while mutation in the sugar transport and utilization genes does not affect symbioses. Deletion of hpr and sma0113 resulted in the partial relief of SMCR of utilization of galactosides like lactose, raffinose and maltose in the presence of succinate. However, no such regulators governing SMCR of glucoside utilization have been identified till date. Though rhizobia can utilize multitude of sugars, high affinity transporters for many sugars are yet to be identified. Identifying high affinity sugar transporters and studying the mechanism of catabolite repression in rhizobia is important to understand the level of regulation of SMCR and the key regulators involved in SMCR.
Collapse
Affiliation(s)
- Bhagya Iyer
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | | | - Rahul Jog
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India; Environmental Molecular Biology Laboratory, Division of Biosphere, Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Ekta Joshi
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | - Krishna Bharwad
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | - Shalini Rajkumar
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India.
| |
Collapse
|
42
|
Tatsukami Y, Ueda M. Rhizobial gibberellin negatively regulates host nodule number. Sci Rep 2016; 6:27998. [PMID: 27307029 PMCID: PMC4910070 DOI: 10.1038/srep27998] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 05/23/2016] [Indexed: 12/12/2022] Open
Abstract
In legume-rhizobia symbiosis, the nodule number is controlled to ensure optimal growth of the host. In Lotus japonicus, the nodule number has been considered to be tightly regulated by host-derived phytohormones and glycopeptides. However, we have discovered a symbiont-derived phytohormonal regulation of nodule number in Mesorhizobium loti. In this study, we found that M. loti synthesized gibberellic acid (GA) under symbiosis. Hosts inoculated with a GA-synthesis-deficient M. loti mutant formed more nodules than those inoculated with the wild-type form at four weeks post inoculation, indicating that GA from already-incorporated rhizobia prevents new nodule formation. Interestingly, the genes for GA synthesis are only found in rhizobial species that inhabit determinate nodules. Our findings suggest that the already-incorporated rhizobia perform GA-associated negative regulation of nodule number to prevent delayed infection by other rhizobia.
Collapse
Affiliation(s)
- Yohei Tatsukami
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
- Japan Society for the Promotion of Science, Sakyo-ku, Kyoto, Japan
| | - Mitsuyoshi Ueda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| |
Collapse
|
43
|
Symbiotic Efficiency of Native and Exotic Rhizobium Strains Nodulating Lentil (Lens culinaris Medik.) in Soils of Southern Ethiopia. AGRONOMY-BASEL 2016. [DOI: 10.3390/agronomy6010011] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
44
|
Baymiev AK, Ivanova ES, Gumenko RS, Chubukova OV, Baymiev AK. Analysis of symbiotic genes of leguminous root nodule bacteria grown in the southern urals. RUSS J GENET+ 2015. [DOI: 10.1134/s1022795415110034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
45
|
Abstract
Rhizobia are nitrogen-fixing bacteria that establish a nodule symbiosis with legumes. Nodule formation depends on signals and surface determinants produced by both symbiotic partners. Among them, rhizobial Nops (nodulation outer proteins) play a crucial symbiotic role in many strain-host combinations. Nops are defined as proteins secreted via a rhizobial T3SS (type III secretion system). Functional T3SSs have been characterized in many rhizobial strains. Nops have been identified using various genetic, biochemical, proteomic, genomic and experimental approaches. Certain Nops represent extracellular components of the T3SS, which are visible in electron micrographs as bacterial surface appendages called T3 (type III) pili. Other Nops are T3 effector proteins that can be translocated into plant cells. Rhizobial T3 effectors manipulate cellular processes in host cells to suppress plant defence responses against rhizobia and to promote symbiosis-related processes. Accordingly, mutant strains deficient in synthesis or secretion of T3 effectors show reduced symbiotic properties on certain host plants. On the other hand, direct or indirect recognition of T3 effectors by plant cells expressing specific R (resistance) proteins can result in effector triggered defence responses that negatively affect rhizobial infection. Hence Nops are double-edged swords that may promote establishment of symbiosis with one legume (symbiotic factors) and impair symbiotic processes when bacteria are inoculated on another legume species (asymbiotic factors). In the present review, we provide an overview of our current understanding of Nops. We summarize their symbiotic effects, their biochemical properties and their possible modes of action. Finally, we discuss future perspectives in the field of T3 effector research.
Collapse
|
46
|
Malgieri G, Palmieri M, Russo L, Fattorusso R, Pedone PV, Isernia C. The prokaryotic zinc-finger: structure, function and comparison with the eukaryotic counterpart. FEBS J 2015; 282:4480-96. [PMID: 26365095 DOI: 10.1111/febs.13503] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/23/2015] [Accepted: 08/24/2015] [Indexed: 01/18/2023]
Abstract
Classical zinc finger (ZF) domains were thought to be confined to the eukaryotic kingdom until the transcriptional regulator Ros protein was identified in Agrobacterium tumefaciens. The Ros Cys2 His2 ZF binds DNA in a peculiar mode and folds in a domain significantly larger than its eukaryotic counterpart consisting of 58 amino acids (the 9-66 region) arranged in a βββαα topology, and stabilized by a conserved, extensive, 15-residue hydrophobic core. The prokaryotic ZF domain, then, shows some intriguing new features that make it interestingly different from its eukaryotic counterpart. This review will focus on the prokaryotic ZFs, summarizing and discussing differences and analogies with the eukaryotic domains and providing important insights into their structure/function relationships.
Collapse
Affiliation(s)
- Gaetano Malgieri
- Department of Environmental, Biological and Pharmaceutical Science and Technology, II University of Naples, Caserta, Italy
| | - Maddalena Palmieri
- Department of Environmental, Biological and Pharmaceutical Science and Technology, II University of Naples, Caserta, Italy
| | - Luigi Russo
- Department of Environmental, Biological and Pharmaceutical Science and Technology, II University of Naples, Caserta, Italy
| | - Roberto Fattorusso
- Department of Environmental, Biological and Pharmaceutical Science and Technology, II University of Naples, Caserta, Italy.,Interuniversity Research Centre on Bioactive Peptides, University of Naples 'Federico II', Naples, Italy
| | - Paolo V Pedone
- Department of Environmental, Biological and Pharmaceutical Science and Technology, II University of Naples, Caserta, Italy.,Interuniversity Research Centre on Bioactive Peptides, University of Naples 'Federico II', Naples, Italy
| | - Carla Isernia
- Department of Environmental, Biological and Pharmaceutical Science and Technology, II University of Naples, Caserta, Italy.,Interuniversity Research Centre on Bioactive Peptides, University of Naples 'Federico II', Naples, Italy
| |
Collapse
|
47
|
Faruque OM, Miwa H, Yasuda M, Fujii Y, Kaneko T, Sato S, Okazaki S. Identification of Bradyrhizobium elkanii Genes Involved in Incompatibility with Soybean Plants Carrying the Rj4 Allele. Appl Environ Microbiol 2015; 81:6710-7. [PMID: 26187957 PMCID: PMC4561682 DOI: 10.1128/aem.01942-15] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 07/13/2015] [Indexed: 11/20/2022] Open
Abstract
Symbioses between leguminous plants and soil bacteria known as rhizobia are of great importance to agricultural production and nitrogen cycling. While these mutualistic symbioses can involve a wide range of rhizobia, some legumes exhibit incompatibility with specific strains, resulting in ineffective nodulation. The formation of nodules in soybean plants (Glycine max) is controlled by several host genes, which are referred to as Rj genes. The soybean cultivar BARC2 carries the Rj4 gene, which restricts nodulation by specific strains, including Bradyrhizobium elkanii USDA61. Here we employed transposon mutagenesis to identify the genetic locus in USDA61 that determines incompatibility with soybean varieties carrying the Rj4 allele. Introduction of the Tn5 transposon into USDA61 resulted in the formation of nitrogen fixation nodules on the roots of soybean cultivar BARC2 (Rj4 Rj4). Sequencing analysis of the sequence flanking the Tn5 insertion revealed that six genes encoding a putative histidine kinase, transcriptional regulator, DNA-binding transcriptional activator, helix-turn-helix-type transcriptional regulator, phage shock protein, and cysteine protease were disrupted. The cysteine protease mutant had a high degree of similarity with the type 3 effector protein XopD of Xanthomonas campestris. Our findings shed light on the diverse and complicated mechanisms that underlie these highly host-specific interactions and indicate the involvement of a type 3 effector in Rj4 nodulation restriction, suggesting that Rj4 incompatibility is partly mediated by effector-triggered immunity.
Collapse
Affiliation(s)
- Omar M Faruque
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Hiroki Miwa
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Michiko Yasuda
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Yoshiharu Fujii
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Takakazu Kaneko
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Shusei Sato
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Shin Okazaki
- Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| |
Collapse
|
48
|
Ziegler D, Pothier JF, Ardley J, Fossou RK, Pflüger V, de Meyer S, Vogel G, Tonolla M, Howieson J, Reeve W, Perret X. Ribosomal protein biomarkers provide root nodule bacterial identification by MALDI-TOF MS. Appl Microbiol Biotechnol 2015; 99:5547-62. [PMID: 25776061 DOI: 10.1007/s00253-015-6515-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 02/19/2015] [Accepted: 02/28/2015] [Indexed: 01/25/2023]
Abstract
Accurate identification of soil bacteria that form nitrogen-fixing associations with legume crops is challenging given the phylogenetic diversity of root nodule bacteria (RNB). The labor-intensive and time-consuming 16S ribosomal RNA (rRNA) sequencing and/or multilocus sequence analysis (MLSA) of conserved genes so far remain the favored molecular tools to characterize symbiotic bacteria. With the development of mass spectrometry (MS) as an alternative method to rapidly identify bacterial isolates, we recently showed that matrix-assisted laser desorption ionization (MALDI) time-of-flight (TOF) can accurately characterize RNB found inside plant nodules or grown in cultures. Here, we report on the development of a MALDI-TOF RNB-specific spectral database built on whole cell MS fingerprints of 116 strains representing the major rhizobial genera. In addition to this RNB-specific module, which was successfully tested on unknown field isolates, a subset of 13 ribosomal proteins extracted from genome data was found to be sufficient for the reliable identification of nodule isolates to rhizobial species as shown in the putatively ascribed ribosomal protein masses (PARPM) database. These results reveal that data gathered from genome sequences can be used to expand spectral libraries to aid the accurate identification of bacterial species by MALDI-TOF MS.
Collapse
Affiliation(s)
- Dominik Ziegler
- Department of Botany and Plant Biology, Microbiology Unit, Sciences III, University of Geneva, 30 quai Ernest-Ansermet, CH-1211, Geneva 4, Switzerland
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
The Sinorhizobium meliloti SyrM regulon: effects on global gene expression are mediated by syrA and nodD3. J Bacteriol 2015; 197:1792-806. [PMID: 25777671 DOI: 10.1128/jb.02626-14] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 03/06/2015] [Indexed: 01/27/2023] Open
Abstract
UNLABELLED In Sinorhizobium meliloti, three NodD transcriptional regulators activate bacterial nodulation (nod) gene expression. NodD1 and NodD2 require plant compounds to activate nod genes. The NodD3 protein does not require exogenous compounds to activate nod gene expression; instead, another transcriptional regulator, SyrM, activates nodD3 expression. In addition, NodD3 can activate syrM expression. SyrM also activates expression of another gene, syrA, which when overexpressed causes a dramatic increase in exopolysaccharide production. In a previous study, we identified more than 200 genes with altered expression in a strain overexpressing nodD3. In this work, we define the transcriptomes of strains overexpressing syrM or syrA. The syrM, nodD3, and syrA overexpression transcriptomes share similar gene expression changes; analyses imply that nodD3 and syrA are the only targets directly activated by SyrM. We propose that most of the gene expression changes observed when nodD3 is overexpressed are due to NodD3 activation of syrM expression, which in turn stimulates SyrM activation of syrA expression. The subsequent increase in SyrA abundance results in broad changes in gene expression, most likely mediated by the ChvI-ExoS-ExoR regulatory circuit. IMPORTANCE Symbioses with bacteria are prevalent across the animal and plant kingdoms. Our system of study, the rhizobium-legume symbiosis (Sinorhizobium meliloti and Medicago spp.), involves specific host-microbe signaling, differentiation in both partners, and metabolic exchange of bacterial fixed nitrogen for host photosynthate. During this complex developmental process, both bacteria and plants undergo profound changes in gene expression. The S. meliloti SyrM-NodD3-SyrA and ChvI-ExoS-ExoR regulatory circuits affect gene expression and are important for optimal symbiosis. In this study, we defined the transcriptomes of S. meliloti overexpressing SyrM or SyrA. In addition to identifying new targets of the SyrM-NodD3-SyrA regulatory circuit, our work further suggests how it is linked to the ChvI-ExoS-ExoR regulatory circuit.
Collapse
|
50
|
The enhancer binding protein Nla6 regulates developmental genes that are important for Myxococcus xanthus sporulation. J Bacteriol 2015; 197:1276-87. [PMID: 25645554 DOI: 10.1128/jb.02408-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED In the bacterium Myxococcus xanthus, starvation triggers the formation of multicellular fruiting bodies containing thousands of stress-resistant spores. Recent work showed that fruiting body development is regulated by a cascade of transcriptional activators called enhancer binding proteins (EBPs). The EBP Nla6 is a key component of this cascade; it regulates the promoters of other EBP genes, including a downstream-functioning EBP gene that is crucial for sporulation. In recent expression studies, hundreds of Nla6-dependent genes were identified, suggesting that the EBP gene targets of Nla6 may be part of a much larger regulon. The goal of this study was to identify and characterize genes that belong to the Nla6 regulon. Accordingly, a direct repeat [consensus, C(C/A)ACGNNGNC] binding site for Nla6 was identified using in vitro and in vivo mutational analyses, and the sequence was subsequently used to find 40 potential developmental promoter (88 gene) targets. We showed that Nla6 binds to the promoter region of four new targets (asgE, exo, MXAN2688, and MXAN3259) in vitro and that Nla6 is important for their normal expression in vivo. Phenotypic studies indicate that all of the experimentally confirmed targets of Nla6 are primarily involved in sporulation. These targets include genes involved in transcriptional regulation, cell-cell signal production, and spore differentiation and maturation. Although sporulation occurs late in development, all of the developmental loci analyzed here show an Nla6-dependent burst in expression soon after starvation is induced. This finding suggests that Nla6 starts preparing cells for sporulation very early in the developmental process. IMPORTANCE Bacterial development yields a remarkable array of complex multicellular forms. One such form, which is commonly found in nature, is a surface-associated aggregate of cells known as a biofilm. Mature biofilms are structurally complex and contain cells that are highly resistant to antibacterial agents. When starving, the model bacterium Myxococcus xanthus forms a biofilm containing a thin mat of cells and multicellular structures that house a highly resistant cell type called a myxospore. Here, we identify the promoter binding site of the transcriptional activator Nla6, identify genes in the Nla6 regulon, and show that several of the genes in the Nla6 regulon are important for production of stress-resistant spores in starvation-induced M. xanthus biofilms.
Collapse
|