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Shahid M, Khan MS, Singh UB. Pesticide-tolerant microbial consortia: Potential candidates for remediation/clean-up of pesticide-contaminated agricultural soil. ENVIRONMENTAL RESEARCH 2023; 236:116724. [PMID: 37500042 DOI: 10.1016/j.envres.2023.116724] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 07/16/2023] [Accepted: 07/21/2023] [Indexed: 07/29/2023]
Abstract
Reclamation of pesticide-polluted lands has long been a difficult endeavour. The use of synthetic pesticides could not be restricted due to rising agricultural demand. Pesticide toxicity has become a pressing agronomic problem due to its adverse impact on agroecosystems, agricultural output, and consequently food security and safety. Among different techniques used for the reclamation of pesticide-polluted sites, microbial bioremediation is an eco-friendly approach, which focuses on the application of resilient plant growth promoting rhizobacteria (PGPR) that may transform or degrade chemical pesticides to innocuous forms. Such pesticide-resilient PGPR has demonstrated favourable effects on soil-plant systems, even in pesticide-contaminated environments, by degrading pesticides, providing macro-and micronutrients, and secreting active but variable secondary metabolites like-phytohormones, siderophores, ACC deaminase, etc. This review critically aims to advance mechanistic understanding related to the reduction of phytotoxicity of pesticides via the use of microbe-mediated remediation techniques leading to crop optimization in pesticide-stressed soils. The literature surveyed and data presented herein are extremely useful, offering agronomists-and crop protectionists microbes-assisted remedial strategies for affordably enhancing crop productivity in pesticide-stressed soils.
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Affiliation(s)
- Mohammad Shahid
- Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Kushmaur, Mau Nath Bhanjan, 275103, UP, India; Department of Agricultural Microbiology, Faculty of Agriculture Science, Aligarh Muslim University (A.M.U.), Aligarh, 202001, UP, India.
| | - Mohammad Saghir Khan
- Department of Agricultural Microbiology, Faculty of Agriculture Science, Aligarh Muslim University (A.M.U.), Aligarh, 202001, UP, India
| | - Udai B Singh
- Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Kushmaur, Mau Nath Bhanjan, 275103, UP, India
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2
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Rutten J, van den Berg T, Tusscher KT. Modeling Auxin Signaling in Roots: Auxin Computations. Cold Spring Harb Perspect Biol 2022; 14:a040089. [PMID: 34001532 PMCID: PMC8805645 DOI: 10.1101/cshperspect.a040089] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Auxin signaling and patterning is an inherently complex process, involving polarized auxin transport, metabolism, and signaling, its effect on developmental zones, as well as growth rates, and the feedback between all these different aspects. This complexity has led to an important role for computational modeling in unraveling the multifactorial roles of auxin in plant developmental and adaptive processes. Here we discuss the basic ingredients of auxin signaling and patterning models for root development as well as a series of key modeling studies in this area. These modeling studies have helped elucidate how plants use auxin signaling to compute the size of their root meristem, the direction in which to grow, and when and where to form lateral roots. Importantly, these models highlight how auxin, through patterning of and collaborating with other factors, can fulfill all these roles simultaneously.
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Affiliation(s)
- Jaap Rutten
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Thea van den Berg
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Kirsten Ten Tusscher
- Computational Developmental Biology Group, Utrecht University, Utrecht 3584 CH, The Netherlands
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3
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Ahmed B, Shahid M, Syed A, Rajput VD, Elgorban AM, Minkina T, Bahkali AH, Lee J. Drought Tolerant Enterobacter sp./ Leclercia adecarboxylata Secretes Indole-3-acetic Acid and Other Biomolecules and Enhances the Biological Attributes of Vigna radiata (L.) R. Wilczek in Water Deficit Conditions. BIOLOGY 2021; 10:1149. [PMID: 34827142 PMCID: PMC8614786 DOI: 10.3390/biology10111149] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/31/2021] [Accepted: 11/01/2021] [Indexed: 12/17/2022]
Abstract
Drought or water stress is a limiting factor that hampers the growth and yield of edible crops. Drought-tolerant plant growth-promoting rhizobacteria (PGPR) can mitigate water stress in crops by synthesizing multiple bioactive molecules. Here, strain PAB19 recovered from rhizospheric soil was biochemically and molecularly characterized, and identified as Enterobacter sp./Leclercia adecarboxylata (MT672579.1). Strain PAB19 tolerated an exceptionally high level of drought (18% PEG-6000) and produced indole-3-acetic acid (176.2 ± 5.6 µg mL-1), ACC deaminase (56.6 ± 5.0 µg mL-1), salicylic acid (42.5 ± 3.0 µg mL-1), 2,3-dihydroxy benzoic acid (DHBA) (44.3 ± 2.3 µg mL-1), exopolysaccharide (204 ± 14.7 µg mL-1), alginate (82.3 ± 6.5 µg mL-1), and solubilized tricalcium phosphate (98.3 ± 3.5 µg mL-1), in the presence of 15% polyethylene glycol. Furthermore, strain PAB19 alleviated water stress and significantly (p ≤ 0.05) improved the overall growth and biochemical attributes of Vigna radiata (L.) R. Wilczek. For instance, at 2% PEG stress, PAB19 inoculation maximally increased germination, root dry biomass, leaf carotenoid content, nodule biomass, leghaemoglobin (LHb) content, leaf water potential (ΨL), membrane stability index (MSI), and pod yield by 10%, 7%, 14%, 38%, 9%, 17%, 11%, and 11%, respectively, over un-inoculated plants. Additionally, PAB19 inoculation reduced two stressor metabolites, proline and malondialdehyde, and antioxidant enzymes (POD, SOD, CAT, and GR) levels in V. radiata foliage in water stress conditions. Following inoculation of strain PAB19 with 15% PEG in soil, stomatal conductance, intercellular CO2 concentration, transpiration rate, water vapor deficit, intrinsic water use efficiency, and photosynthetic rate were significantly improved by 12%, 8%, 42%, 10%, 9% and 16%, respectively. Rhizospheric CFU counts of PAB19 were 2.33 and 2.11 log CFU g-1 after treatment with 15% PEG solution and 8.46 and 6.67 log CFU g-1 for untreated controls at 40 and 80 DAS, respectively. Conclusively, this study suggests the potential of Enterobacter sp./L. adecarboxylata PAB19 to alleviate water stress by improving the biological and biochemical features and of V. radiata under water-deficit conditions.
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Affiliation(s)
- Bilal Ahmed
- School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea
| | - Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India;
| | - Asad Syed
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (A.S.); (A.M.E.); (A.H.B.)
| | - Vishnu D. Rajput
- Academy of Biology and Biotechnology, Southern Federal University, 344090 Rostov-on-Don, Russia; (V.D.R.); (T.M.)
| | - Abdallah M. Elgorban
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (A.S.); (A.M.E.); (A.H.B.)
| | - Tatiana Minkina
- Academy of Biology and Biotechnology, Southern Federal University, 344090 Rostov-on-Don, Russia; (V.D.R.); (T.M.)
| | - Ali H. Bahkali
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (A.S.); (A.M.E.); (A.H.B.)
| | - Jintae Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan 38541, Korea
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Khan S, Shahid M, Khan MS, Syed A, Bahkali AH, Elgorban AM, Pichtel J. Fungicide-Tolerant Plant Growth-Promoting Rhizobacteria Mitigate Physiological Disruption of White Radish Caused by Fungicides Used in the Field Cultivation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E7251. [PMID: 33020389 PMCID: PMC7579310 DOI: 10.3390/ijerph17197251] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/29/2020] [Accepted: 09/30/2020] [Indexed: 12/20/2022]
Abstract
Excessive use of fungicides in agriculture may result in substantial accumulation of active residues in soil, which affect crop health and yield. We investigated the response of Raphanus sativus (white radish) to fungicides in soil and potential beneficial interactions of radish plants with fungicide-tolerant plant growth-promoting rhizobacteria (PGPR). The PGPR were isolated from cabbage and mustard rhizospheres. Morphological and biochemical characteristics measured using standard methods, together with analysis of partial 16S rRNA gene sequences, revealed that fungicide-tolerant PGPR, isolates PS3 and AZ2, were closely related to Pseudomonas spp. These PGPR survived in the presence of high fungicide concentrations i.e., up to 2400 μg mL-1 carbendazim (CBZM) and 3200 μg mL-1 hexaconazole (HEXA). Bacterial isolates produced plant growth stimulants even under fungicide stress, though fungicides induced surface morphological distortion and alteration in membrane permeability of these bacteria, which was proved by a set of microscopic observations. Fungicides considerably affected the germination efficiency, growth, and physiological development of R. sativus, but these effects were relieved when inoculated with PGPR isolates. For instance, CBZM at 1500 mg kg-1 decreased whole dry biomass by 71%, whole plant length by 54%, total chlorophyll by 50%, protein content by 61%, and carotenoid production by 29%. After applying isolate AZ2 for white radish grown in CBZM (10 mg kg-1)-amended soil, it could improve plant growth and development with increased whole plant dry weight (10%), entire plant length (13%) and total chlorophyll content (18%). Similarly, isolate PS3 enhanced plant survival by relieving plant stress with declined biomarkers, i.e., proline (12%), malondialdehyde (3%), ascorbate peroxidase (6.5%), catalase (18%), and glutathione reductase (4%). Application of isolates AZ2 and PS3 could be effective for remediation of fungicide-contaminated soil and for improving the cultivation of radish plants while minimizing inputs of fungicides.
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Affiliation(s)
- Sadaf Khan
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India; (S.K.); (M.S.K.)
| | - Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India; (S.K.); (M.S.K.)
| | - Mohammad Saghir Khan
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India; (S.K.); (M.S.K.)
| | - Asad Syed
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. 2455, Riyadh 11451, Saudi Arabia; (A.S.); (A.H.B.); (A.M.E.)
| | - Ali H. Bahkali
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. 2455, Riyadh 11451, Saudi Arabia; (A.S.); (A.H.B.); (A.M.E.)
| | - Abdallah M. Elgorban
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. 2455, Riyadh 11451, Saudi Arabia; (A.S.); (A.H.B.); (A.M.E.)
| | - John Pichtel
- Natural Resources and Environmental Management, Ball State University, Muncie, IN 47306, USA;
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5
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Ng JLP, Welvaert A, Wen J, Chen R, Mathesius U. The Medicago truncatula PIN2 auxin transporter mediates basipetal auxin transport but is not necessary for nodulation. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:1562-1573. [PMID: 31738415 DOI: 10.1093/jxb/erz510] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
The development of root nodules leads to an increased auxin response in early nodule primordia, which is mediated by changes in acropetal auxin transport in some legumes. Here, we investigated the role of root basipetal auxin transport during nodulation. Rhizobia inoculation significantly increased basipetal auxin transport in both Medicago truncatula and Lotus japonicus. In M. truncatula, this increase was dependent on functional Nod factor signalling through NFP, NIN, and NSP2, as well as ethylene signalling through SKL. To test whether increased basipetal auxin transport is required for nodulation, we examined a loss-of-function mutant of the M. truncatula PIN2 gene. The Mtpin2 mutant exhibited a reduction in basipetal auxin transport and an agravitropic phenotype. Inoculation of Mtpin2 roots with rhizobia still led to a moderate increase in basipetal auxin transport, but the mutant nodulated normally. No clear differences in auxin response were observed during nodule development. Interestingly, inoculation of wild-type roots increased lateral root numbers, whereas inoculation of Mtpin2 mutants resulted in reduced lateral root numbers compared with uninoculated roots. We conclude that the MtPIN2 auxin transporter is involved in basipetal auxin transport, that its function is not essential for nodulation, but that it plays an important role in the control of lateral root development.
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Affiliation(s)
- Jason L P Ng
- Division of Plant Science, Research School of Biology, Australian National University, Canberra, Australia
| | - Astrid Welvaert
- Division of Plant Science, Research School of Biology, Australian National University, Canberra, Australia
| | - Jiangqi Wen
- Noble Research Institute LLC, Ardmore, OK, USA
| | - Rujin Chen
- School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Ulrike Mathesius
- Division of Plant Science, Research School of Biology, Australian National University, Canberra, Australia
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6
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Huisman R, Geurts R. A Roadmap toward Engineered Nitrogen-Fixing Nodule Symbiosis. PLANT COMMUNICATIONS 2020; 1:100019. [PMID: 33404552 PMCID: PMC7748023 DOI: 10.1016/j.xplc.2019.100019] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/06/2019] [Accepted: 12/27/2019] [Indexed: 05/26/2023]
Abstract
In the late 19th century, it was discovered that legumes can establish a root nodule endosymbiosis with nitrogen-fixing rhizobia. Soon after, the question was raised whether it is possible to transfer this trait to non-leguminous crops. In the past century, an ever-increasing amount of knowledge provided unique insights into the cellular, molecular, and genetic processes controlling this endosymbiosis. In addition, recent phylogenomic studies uncovered several genes that evolved to function specifically to control nodule formation and bacterial infection. However, despite this massive body of knowledge, the long-standing objective to engineer the nitrogen-fixing nodulation trait on non-leguminous crop plants has not been achieved yet. In this review, the unsolved questions and engineering strategies toward nitrogen-fixing nodulation in non-legume plants are discussed and highlighted.
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Affiliation(s)
- Rik Huisman
- Wageningen University, Department of Plant Sciences, Laboratory of Molecular Biology, Droevendaalsesteeg 1, Wageningen 6708PB, The Netherlands
| | - Rene Geurts
- Wageningen University, Department of Plant Sciences, Laboratory of Molecular Biology, Droevendaalsesteeg 1, Wageningen 6708PB, The Netherlands
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7
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Schiessl K, Lilley JLS, Lee T, Tamvakis I, Kohlen W, Bailey PC, Thomas A, Luptak J, Ramakrishnan K, Carpenter MD, Mysore KS, Wen J, Ahnert S, Grieneisen VA, Oldroyd GED. NODULE INCEPTION Recruits the Lateral Root Developmental Program for Symbiotic Nodule Organogenesis in Medicago truncatula. Curr Biol 2019; 29:3657-3668.e5. [PMID: 31543454 PMCID: PMC6839406 DOI: 10.1016/j.cub.2019.09.005] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 07/02/2019] [Accepted: 09/02/2019] [Indexed: 01/18/2023]
Abstract
To overcome nitrogen deficiencies in the soil, legumes enter symbioses with rhizobial bacteria that convert atmospheric nitrogen into ammonium. Rhizobia are accommodated as endosymbionts within lateral root organs called nodules that initiate from the inner layers of Medicago truncatula roots in response to rhizobial perception. In contrast, lateral roots emerge from predefined founder cells as an adaptive response to environmental stimuli, including water and nutrient availability. CYTOKININ RESPONSE 1 (CRE1)-mediated signaling in the pericycle and in the cortex is necessary and sufficient for nodulation, whereas cytokinin is antagonistic to lateral root development, with cre1 showing increased lateral root emergence and decreased nodulation. To better understand the relatedness between nodule and lateral root development, we undertook a comparative analysis of these two root developmental programs. Here, we demonstrate that despite differential induction, lateral roots and nodules share overlapping developmental programs, with mutants in LOB-DOMAIN PROTEIN 16 (LBD16) showing equivalent defects in nodule and lateral root initiation. The cytokinin-inducible transcription factor NODULE INCEPTION (NIN) allows induction of this program during nodulation through activation of LBD16 that promotes auxin biosynthesis via transcriptional induction of STYLISH (STY) and YUCCAs (YUC). We conclude that cytokinin facilitates local auxin accumulation through NIN promotion of LBD16, which activates a nodule developmental program overlapping with that induced during lateral root initiation.
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Affiliation(s)
- Katharina Schiessl
- Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK; Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Jodi L S Lilley
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Tak Lee
- Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK
| | - Ioannis Tamvakis
- Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK; Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Wouter Kohlen
- Laboratory for Molecular Biology, Wageningen University & Research, Droevendaalsesteeg 1, 6708 PB Wageningen, the Netherlands
| | - Paul C Bailey
- Earlham Institute, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Aaron Thomas
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Jakub Luptak
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Karunakaran Ramakrishnan
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Matthew D Carpenter
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | | | - Jiangqi Wen
- Noble Research Institute, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
| | - Sebastian Ahnert
- Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK
| | - Veronica A Grieneisen
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK
| | - Giles E D Oldroyd
- Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK; Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, UK.
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Shahid M, Khan MS. Fungicide tolerant Bradyrhizobium japonicum mitigate toxicity and enhance greengram production under hexaconazole stress. J Environ Sci (China) 2019; 78:92-108. [PMID: 30665660 DOI: 10.1016/j.jes.2018.07.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 06/24/2018] [Accepted: 07/18/2018] [Indexed: 05/28/2023]
Abstract
Bacterial strain RV9 recovered from greengram nodules tolerated 2400μg/mL of hexaconazole and was identified by 16S rDNA sequence analysis as Bradyrhizobium japonicum (KY940048). Strain RV9 produced IAA (61.6μg/mL), ACC deaminase (51.7mg/(protein·hr)), solubilized TCP (105μg/mL), secreted 337.6μg/mL EPS, and produced SA (52.2μg/mL) and 2,3-DHBA (28.3μg/mL). Exopolysaccharides produced by strain RV9 was quantified and characterized by SEM, AFM, EDX and FTIR. Beyond tolerance limit, hexaconazole caused cellular impairment and reduced the viability of strain RV9 revealed by SEM and CLSM. Hexaconazole distorted the root tips and altered nodule structure leading thereby to reduction in the performance of greengram. Also, the level of antioxidant enzymes, proline, TBARS, ROS and cell death was increased in hexaconazole treated plants. CLSM images revealed a concentration dependent increase in the characteristic green and blue fluorescence of hexaconazole treated roots. The application of B. japonicum strain RV9 alleviated the fungicide toxicity and improved the measured plant characteristics. Also, rhizobial cells were localized inside tissues as revealed by CLSM. Colonization of B. japonicum strain RV9 decreased the levels of CAT, POD, APX, GPX and TBARS by 80%, 5%, 13%, 13% and 19%, respectively over plants grown at 80μg/(hexaconazole·kg) soil. The ability to detoxify hexaconazole, colonize plant tissues, secrete PGP bioactive molecules even under fungicide pressure and its unique ability to diminish oxidative stress make B. japonicum an attractive choice for remediation of fungicide polluted soils and to concurrently enhance greengram production under stressed environment.
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Affiliation(s)
- Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India.
| | - Mohd Saghir Khan
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India
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9
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Gaudioso-Pedraza R, Beck M, Frances L, Kirk P, Ripodas C, Niebel A, Oldroyd GED, Benitez-Alfonso Y, de Carvalho-Niebel F. Callose-Regulated Symplastic Communication Coordinates Symbiotic Root Nodule Development. Curr Biol 2018; 28:3562-3577.e6. [PMID: 30416059 DOI: 10.1016/j.cub.2018.09.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 07/27/2018] [Accepted: 09/13/2018] [Indexed: 01/08/2023]
Abstract
The formation of nitrogen-fixing nodules in legumes involves the initiation of synchronized programs in the root epidermis and cortex to allow rhizobial infection and nodule development. In this study, we provide evidence that symplastic communication, regulated by callose turnover at plasmodesmata (PD), is important for coordinating nodule development and infection in Medicago truncatula. Here, we show that rhizobia promote a reduction in callose levels in inner tissues where nodules initiate. This downregulation coincides with the localized expression of M. truncatula β-1,3-glucanase 2 (MtBG2), encoding a novel PD-associated callose-degrading enzyme. Spatiotemporal analyses revealed that MtBG2 expression expands from dividing nodule initials to rhizobia-colonized cortical and epidermal tissues. As shown by the transport of fluorescent molecules in vivo, symplastic-connected domains are created in rhizobia-colonized tissues and enhanced in roots constitutively expressing MtBG2. MtBG2-overexpressing roots additionally displayed reduced levels of PD-associated callose. Together, these findings suggest an active role for MtBG2 in callose degradation and in the formation of symplastic domains during sequential nodule developmental stages. Interfering with symplastic connectivity led to drastic nodulation phenotypes. Roots ectopically expressing β-1,3-glucanases (including MtBG2) exhibited increased nodule number, and those expressing MtBG2 RNAi constructs or a hyperactive callose synthase (under symbiotic promoters) showed defective nodulation phenotypes. Obstructing symplastic connectivity appears to block a signaling pathway required for the expression of NODULE INCEPTION (NIN) and its target NUCLEAR FACTOR-YA1 (NF-YA1) in the cortex. We conclude that symplastic intercellular communication is proactively enhanced by rhizobia, and this is necessary for appropriate coordination of bacterial infection and nodule development.
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Affiliation(s)
| | - Martina Beck
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Lisa Frances
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Philip Kirk
- Centre for Plant Sciences, School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Carolina Ripodas
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Andreas Niebel
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Giles E D Oldroyd
- Sainsbury Laboratory, Cambridge University, Bateman Street, Cambridge CB2 1LR, UK
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10
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Shahid M, Khan MS. Cellular destruction, phytohormones and growth modulating enzymes production by Bacillus subtilis strain BC8 impacted by fungicides. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2018; 149:8-19. [PMID: 30033020 DOI: 10.1016/j.pestbp.2018.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 04/22/2018] [Accepted: 05/01/2018] [Indexed: 05/24/2023]
Abstract
In vitro experiments were performed to ascertain the impact of kitazin, hexaconazole, metalaxyl and carbendazim on growth behaviour, enzymatic profile, ultrastructure, cell permeability and bioactive molecules of phosphate-solubilizing bacterium. Strain BC8 isolated from Brassica oleracea rhizosphere was characterized and identified as Bacillus subtilis by 16S rDNA sequencing (Accession no. MG028650) technique. Strain BC8 was unambiguously chosen due to its high tolerance capability to various fungicides and substantial production of plant growth regulators. The biomarker enzymatic assays (lipid peroxidation, lactate dehydrogenase) and oxidative stress (catalase) induced by fungicides exhibited significant (p < 0.05) toxicity of fungicides toward strain BC8. Fungicides caused the cellular/ultrastructural damage and reduced the viability of strain BC8 as clearly revealed under scanning (SEM), high resolution transmission (HR-TEM) and confocal laser scanning (CLSM) microscopy. As the concentration of fungicides increased, a gradual drop in the plant growth promoting traits of B. subtilis strain BC8 was observed. Kitazin at 2400 μg mL-1, hexaconazole at 1500 μg mL-1, metalaxyl at 1200 μg mL-1 and carbendazim at 1200 μg mL-1decreased the IAA production by 35 (48.3 μg mL-1), 27 (51.5 μg mL-1), 39 (43.6 μg mL-1) and 47% (37.3 μg mL-1), respectively, over control (71.3 μg mL-1), while, α-ketobutyrate was declined by 51 (29.6), 56 (26.2), 61 (22.8) and 68 (19)%, respectively, over untreated control (59.9 mg protein-1 h-1). Also, with increase in the concentration of fungicides there was a significant decrease in plant nutrient (P); the maximum being (19.6 μg mL-1) observed at 1500 μg mL-1 hexaconazole with consequent drop in pH (from pH 6.4 to 4.2). The current findings clearly suggest that despite injury, B. subtilis maintained secreting active biomolecules and this property makes this organism truly indispensable for enhancing crop production under fungicide stressed conditions.
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MESH Headings
- Bacillus subtilis/drug effects
- Bacillus subtilis/genetics
- Bacillus subtilis/growth & development
- Bacillus subtilis/ultrastructure
- Brassica/microbiology
- Cell Membrane Permeability/drug effects
- Cell Survival
- DNA, Ribosomal/genetics
- Enzymes/metabolism
- Fungicides, Industrial/pharmacology
- Microbial Sensitivity Tests
- Microscopy, Confocal
- Microscopy, Electron, Scanning
- Microscopy, Electron, Transmission
- Microscopy, Fluorescence
- Oxidative Stress
- Plant Growth Regulators/metabolism
- RNA, Bacterial/genetics
- RNA, Ribosomal, 16S/genetics
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Affiliation(s)
- Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India.
| | - Mohammad Saghir Khan
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, Uttar Pradesh, India
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11
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Ng JLP, Mathesius U. Acropetal Auxin Transport Inhibition Is Involved in Indeterminate But Not Determinate Nodule Formation. FRONTIERS IN PLANT SCIENCE 2018; 9:169. [PMID: 29497432 PMCID: PMC5818462 DOI: 10.3389/fpls.2018.00169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 01/30/2018] [Indexed: 05/23/2023]
Abstract
Legumes enter into a symbiotic relationship with nitrogen-fixing rhizobia, leading to nodule development. Two main types of nodules have been widely studied, indeterminate and determinate, which differ in the location of the first cell division in the root cortex, and persistency of the nodule meristem. Here, we compared the control of auxin transport, content, and response during the early stages of indeterminate and determinate nodule development in the model legumes Medicago truncatula and Lotus japonicus, respectively, to investigate whether differences in auxin transport control could explain the differences in the location of cortical cell divisions. While auxin responses were activated in dividing cortical cells during nodulation of both nodule types, auxin (indole-3-acetic acid) content at the nodule initiation site was transiently increased in M. truncatula, but transiently reduced in L. japonicus. Root acropetal auxin transport was reduced in M. truncatula at the very start of nodule initiation, in contrast to a prolonged increase in acropetal auxin transport in L. japonicus. The auxin transport inhibitors 2,3,5-triiodobenzoic acid and 1-N-naphthylphthalamic acid (NPA) only induced pseudonodules in legume species forming indeterminate nodules, but failed to elicit such structures in a range of species forming determinate nodules. The development of these pseudonodules in M. truncatula exhibited increased auxin responses in a small primordium formed from the pericycle, endodermis, and inner cortex, similar to rhizobia-induced nodule primordia. In contrast, a diffuse cortical auxin response and no associated cortical cell divisions were found in L. japonicus. Collectively, we hypothesize that a step of acropetal auxin transport inhibition is unique to the process of indeterminate nodule development, leading to auxin responses in pericycle, endodermis, and inner cortex cells, while increased auxin responses in outer cortex cells likely require a different mechanism during the formation of determinate nodules.
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Affiliation(s)
- Jason L. P. Ng
- Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, Australia
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12
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Shahid M, Khan MS. Glyphosate induced toxicity to chickpea plants and stress alleviation by herbicide tolerant phosphate solubilizing Burkholderia cepacia PSBB1 carrying multifarious plant growth promoting activities. 3 Biotech 2018; 8:131. [PMID: 29450121 PMCID: PMC5812922 DOI: 10.1007/s13205-018-1145-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 01/31/2018] [Indexed: 12/17/2022] Open
Abstract
In this study, strain PSBB1 isolated from Vicia faba rhizosphere was identified as Burkholderia cepacia, by 16S rDNA sequence analysis and characterized. Strain PSBB1 tolerated glyphosate up to 3200 μg ml-1 and produced IAA (81.6 μg ml-1), ACC deaminase (69.3 mg-1 protein h-1), SA (39.3 μg ml-1) and 2,3-DHBA (26.6 μg ml-1), solubilized insoluble P (50.8 μg ml-1) and secreted 29.4 μg ml-1 exopolysaccharides, which decreased with increasing concentrations of glyphosate. Cell damage following glyphosate application was visible under SEM and CLSM. The phytotoxicity of glyphosate on chickpea was variable but significant. B. cepacia mitigated toxicity and enhanced the size, dry matter, symbiosis, seed attributes and nutritional contents of chickpea. Further, B. cepacia strain PSBB1 declined the levels of CAT, POD, APX and GPX and MDA contents at 4332 μg kg-1 soil glyphosate. Proline also increased under glyphosate stress but declined in B. cepacia inoculated plants. The ability to tolerate higher concentration of glyphosate, the capacity to secrete plant growth regulators even under herbicide stress and potential to reduce the level of proline and antioxidant enzymes makes B. cepacia as an interesting choice for enhancing chickpea production in soils contaminated even with herbicides.
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Affiliation(s)
- Mohammad Shahid
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, Uttar Pradesh 202002 India
| | - Mohd. Saghir Khan
- Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh, Uttar Pradesh 202002 India
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13
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Kohlen W, Ng JLP, Deinum EE, Mathesius U. Auxin transport, metabolism, and signalling during nodule initiation: indeterminate and determinate nodules. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:229-244. [PMID: 28992078 DOI: 10.1093/jxb/erx308] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Most legumes can form a unique type of lateral organ on their roots: root nodules. These structures host symbiotic nitrogen-fixing bacteria called rhizobia. Several different types of nodules can be found in nature, but the two best-studied types are called indeterminate and determinate nodules. These two types differ with respect to the presence or absence of a persistent nodule meristem, which consistently correlates with the cortical cell layers giving rise to the nodule primordia. Similar to other plant developmental processes, auxin signalling overlaps with the site of organ initiation and meristem activity. Here, we review how auxin contributes to early nodule development. We focus on changes in auxin transport, signalling, and metabolism during nodule initiation, describing both experimental evidence and computer modelling. We discuss how indeterminate and determinate nodules may differ in their mechanisms for generating localized auxin response maxima and highlight outstanding questions for future research.
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Affiliation(s)
- Wouter Kohlen
- Laboratory for Molecular Biology, Wageningen University & Research, The Netherlands
| | - Jason Liang Pin Ng
- Division of Plant Science, Research School of Biology, The Australian National University, Australia
| | - Eva E Deinum
- Mathematical and Statistical Methods, Wageningen University & Research, The Netherlands
| | - Ulrike Mathesius
- Division of Plant Science, Research School of Biology, The Australian National University, Australia
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14
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Abstract
The luxurious vegetation at Sanya, the most southern location in China on the island of Hainan, provided a perfect environment for the 'Auxin 2016' meeting in October. As we review here, participants from all around the world discussed the latest advances in auxin transport, metabolism and signaling pathways, highlighting how auxin acts during plant development and in response to the environment in combination with other hormones. The meeting also provided a rich perspective on the evolution of the role of auxin, from algae to higher plants.
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Affiliation(s)
- Teva Vernoux
- Laboratoire Reproduction et Développement des Plantes, University of Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon F-69342, France
| | - Stéphanie Robert
- Swedish University of Agricultural Sciences, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Umeå 90183, Sweden
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15
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Gamas P, Brault M, Jardinaud MF, Frugier F. Cytokinins in Symbiotic Nodulation: When, Where, What For? TRENDS IN PLANT SCIENCE 2017; 22:792-802. [PMID: 28739135 DOI: 10.1016/j.tplants.2017.06.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/12/2017] [Accepted: 06/19/2017] [Indexed: 05/21/2023]
Abstract
Substantial progress has been made in the understanding of early stages of the symbiotic interaction between legume plants and rhizobium bacteria. Those include the specific recognition of symbiotic partners, the initiation of bacterial infection in root hair cells, and the inception of a specific organ in the root cortex, the nodule. Increasingly complex regulatory networks have been uncovered in which cytokinin (CK) phytohormones play essential roles in different aspects of early symbiotic stages. Intriguingly, these roles can be either positive or negative, cell autonomous or non-cell autonomous, and vary, depending on time, root tissues, and possibly legume species. Recent developments on CK symbiotic functions and interconnections with other signaling pathways during nodule initiation are the focus of this review.
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Affiliation(s)
- Pascal Gamas
- LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France
| | - Mathias Brault
- IPS2 (Institute of Plant Sciences - Paris Saclay), CNRS, INRA, Université Paris-Sud, Université Paris-Diderot, Université d'Evry, Université Paris-Saclay, Bâtiment 630, Gif-sur-Yvette, France
| | - Marie-Françoise Jardinaud
- LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France; INPT-Université de Toulouse, ENSAT, Castanet-Tolosan, France
| | - Florian Frugier
- IPS2 (Institute of Plant Sciences - Paris Saclay), CNRS, INRA, Université Paris-Sud, Université Paris-Diderot, Université d'Evry, Université Paris-Saclay, Bâtiment 630, Gif-sur-Yvette, France.
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