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Shiro S, Kuranaga C, Yamamoto A, Sameshima-Saito R, Saeki Y. Temperature-Dependent Expression of NodC and Community Structure of Soybean-Nodulating Bradyrhizobia. Microbes Environ 2016; 31:27-32. [PMID: 26877137 PMCID: PMC4791112 DOI: 10.1264/jsme2.me15114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 11/19/2015] [Indexed: 11/30/2022] Open
Abstract
In order to assess the physiological responses of bradyrhizobia and competition for the nodulation of soybean at different temperatures, we investigated the expression of the nodC gene at 20, 25, and 30°C and the abilities of bacteria to nodulate soybean in microcosms at day/night cultivation temperatures of 23/18°C, 28/23°C, and 33/28°C for 16/8 h. We tested five Bradyrhizobium USDA strains: B. diazoefficiens USDA 110(T) and 122, B. japonicum USDA 123, and B. elkanii USDA 31 and 76(T). The expression of nodC was up-regulated by increasing culture temperatures in USDA 110(T), 122, 31, and 76(T), but was down-regulated in USDA 123. The proportions of USDA 110(T) and 122 within the community were the greatest at 28/23°C. The population of USDA 31 increased, whereas that of USDA 123 decreased with increasing cultivation temperatures. On the other hand, infection by USDA 76(T) was not detected, and low numbers of USDA 76(T) nodules confirmed its poor nodulation ability. These results indicate that the competitiveness of and infection by USDA 110(T), 122, 123, and 31 for soybean nodulation depend on cultivation temperatures, and suggest that the temperature dependence of nodC expression affects the bradyrhizobial community structure.
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Medeot DB, Romina Rivero M, Cendoya E, Contreras-Moreira B, Rossi FA, Fischer SE, Becker A, Jofré E. Sinorhizobium meliloti low molecular mass phosphotyrosine phosphatase SMc02309 modifies activity of the UDP-glucose pyrophosphorylase ExoN involved in succinoglycan biosynthesis. MICROBIOLOGY-SGM 2016; 162:552-563. [PMID: 26813656 DOI: 10.1099/mic.0.000239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In Gram-negative bacteria, tyrosine phosphorylation has been shown to play a role in the control of exopolysaccharide (EPS) production. This study demonstrated that the chromosomal ORF SMc02309 from Sinorhizobium meliloti 2011 encodes a protein with significant sequence similarity to low molecular mass protein-tyrosine phosphatases (LMW-PTPs), such as the Escherichia coli Wzb. Unlike other well-characterized EPS biosynthesis gene clusters, which contain neighbouring LMW-PTPs and kinase, the S. meliloti succinoglycan (EPS I) gene cluster located on megaplasmid pSymB does not encode a phosphatase. Biochemical assays revealed that the SMc02309 protein hydrolyses p-nitrophenyl phosphate (p-NPP) with kinetic parameters similar to other bacterial LMW-PTPs. Furthermore, we show evidence that SMc02309 is not the LMW-PTP of the bacterial tyrosine-kinase (BY-kinase) ExoP. Nevertheless, ExoN, a UDP-glucose pyrophosphorylase involved in the first stages of EPS I biosynthesis, is phosphorylated at tyrosine residues and constitutes an endogenous substrate of the SMc02309 protein. Additionally, we show that the UDP-glucose pyrophosphorylase activity is modulated by SMc02309-mediated tyrosine dephosphorylation. Moreover, a mutation in the SMc02309 gene decreases EPS I production and delays nodulation on Medicago sativa roots.
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Ma HY, Yang B, Wang HW, Yang QY, Dai CC. Application of Serratia marcescens RZ-21 significantly enhances peanut yield and remediates continuously cropped peanut soil. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2016; 96:245-253. [PMID: 25640613 DOI: 10.1002/jsfa.7087] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 10/17/2014] [Accepted: 01/08/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Continuous cropping practices cause a severe decline in peanut yield. The aim of this study was to investigate the remediation effect of Serratia marcescens on continuously cropped peanut soil. A pot experiment was conducted under natural conditions to determine peanut agronomic indices, soil microorganism characteristics, soil enzyme activities and antagonism ability to typical pathogens at different growth stages. Four treatments were applied to red soil as follows: an active fermentation liquor of S. marcescens (RZ-21), an equivalent sterilized fermentation liquor (M), an equivalent fermentation medium (P) and distilled water (CK). RESULTS S. marcescens significantly inhibited the two typical plant pathogens Fusarium oxysporum A1 and Ralstonia solanacearum B1 and reduced their populations in rhizosphere soil. The RZ-21 treatment significantly increased peanut yield, vine dry weight, root nodules and taproot length by 62.3, 33, 72 and 61.4% respectively, followed by the M treatment. The P treatment also increased root nodules and root length slightly. RZ-21 also enhanced the activities of soil urease, sucrase and hydrogen peroxidase at various stages. In addition, RZ-21 and M treatments increased the average population of soil bacteria and decreased the average population of fungi in the three critical peanut growth stages, except for M in the case of the fungal population at flowering, thus balancing the structure of the soil microorganism community. CONCLUSION This is the first report of S. marcescens being applied to continuously cropped peanut soil. The results suggest that S. marcescens RZ-21 has the potential to improve the soil environment and agricultural products and thus allow the development of sustainable management practices.
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Chabaud M, Gherbi H, Pirolles E, Vaissayre V, Fournier J, Moukouanga D, Franche C, Bogusz D, Tisa LS, Barker DG, Svistoonoff S. Chitinase-resistant hydrophilic symbiotic factors secreted by Frankia activate both Ca(2+) spiking and NIN gene expression in the actinorhizal plant Casuarina glauca. THE NEW PHYTOLOGIST 2016; 209:86-93. [PMID: 26484850 DOI: 10.1111/nph.13732] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/27/2015] [Indexed: 05/18/2023]
Abstract
Although it is now well-established that decorated lipo-chitooligosaccharide Nod factors are the key rhizobial signals which initiate infection/nodulation in host legume species, the identity of the equivalent microbial signaling molecules in the Frankia/actinorhizal association remains elusive. With the objective of identifying Frankia symbiotic factors we present a novel approach based on both molecular and cellular pre-infection reporters expressed in the model actinorhizal species Casuarina glauca. By introducing the nuclear-localized cameleon Nup-YC2.1 into Casuarina glauca we show that cell-free culture supernatants of the compatible Frankia CcI3 strain are able to elicit sustained high frequency Ca(2+) spiking in host root hairs. Furthermore, an excellent correlation exists between the triggering of nuclear Ca(2+) spiking and the transcriptional activation of the ProCgNIN:GFP reporter as a function of the Frankia strain tested. These two pre-infection symbiotic responses have been used in combination to show that the signal molecules present in the Frankia CcI3 supernatant are hydrophilic, of low molecular weight and resistant to chitinase degradation. In conclusion, the biologically active symbiotic signals secreted by Frankia appear to be chemically distinct from the currently known chitin-based rhizobial/arbuscular mycorrhizal signaling molecules. Convenient bioassays in Casuarina glauca are now available for their full characterization.
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Zhang W, Wang HW, Wang XX, Xie XG, Siddikee MA, Xu RS, Dai CC. Enhanced nodulation of peanut when co-inoculated with fungal endophyte Phomopsis liquidambari and bradyrhizobium. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 98:1-11. [PMID: 26584395 DOI: 10.1016/j.plaphy.2015.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 10/27/2015] [Accepted: 11/01/2015] [Indexed: 06/05/2023]
Abstract
In peanut continuous cropping soil, the application of fungal endophyte Phomopsis liquidambari B3 showed peanut pod yield promotion and root nodule number increase. P. liquidambari improved soil environment by degrading allelochemicals and thus promoted peanut pod yield. Furthermore, peanut yield promotion is in part due to the root nodule increase since nodular nitrogen fixation provides the largest source of nitrogen for peanut. However, it is unknown whether this nodule number increase is induced by fungal endophyte. We therefore conducted several pot experiments using vermiculite to investigate the effects of P. liquidambari on peanut-bradyrhizobium nodulation. Our results showed that P. liquidambari co-inoculated with bradyrhizobium increased root nodule number and shoot accumulated nitrogen by 28.25% and 29.71%, respectively. Nodulation dynamics analysis showed that P. liquidambari accelerated nodule initiation and subsequent nodule development. Meanwhile, P. liquidambari was able to colonize the peanut root as an endophyte. The dynamics of P. liquidambari and bradyrhizobial root colonization analysis showed that P. liquidambari inoculation significantly increased the rate of bradyrhizobial colonization. Furthermore, P. liquidambari inoculation significantly increased flavonoids synthesis-related enzymes activities, two common types of flavonoid (luteolin and quercetin-peanut rhizobial nod gene inducer) secretion and lateral root (peanut rhizobial infection site) formation, indicating that P. liquidambari altered the peanut nodulation-related physiological and metabolic activities. These obtained results confirmed the direct contribution of P. liquidambari in enhancing peanut-bradyrhizobium interaction, nodulation and yield.
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Liu L, He XY, Xie Q, Wang KL. [Genetic diversity of rhizobia isolated from common legumes in the Karst area. Northwest Guangxi]. YING YONG SHENG TAI XUE BAO = THE JOURNAL OF APPLIED ECOLOGY 2015; 26:3663-3669. [PMID: 27112003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Legumes, with a strong resistance to the adverse environmental conditions, are pioneer plants in degraded habitats, and play an important role in ecosystem restoration. In this study, the nodulation characteristics of 24 legumes were surveyed in the Karst area of Northwest Guangxi. A total of 39 nodule samples were collected from 15 legumes, the DNA was extracted and the 16S rDNA and nifH gene were amplified. A phylogenetic tree was then constructed to analyze the genetic diversity of rhizobia. The results showed that 15 legumes were nodulated, of which 14 belonged to the Papilionoideae, one to the Mimosaceae, and none to the Caesalpinoideae. No nodules were found on some legumes that were reported as nodulated, which might result from soil water stress in Karst. BLAST result and phylogenetic analyse indicated that most of the legumes were associated with rhizobia that belonged to the genus Bradyrhizobium, with the exception of two samples from Callerya nitida that were associated with the genus Mesorhizobium. In the phylogenetic tree, the sequences obtained from the same plot or the sequences from the same host species clustered together in most cases. This finding suggested that host selection and the ecological environment are the major factors that influence the genotype of rhizobia.
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Vernié T, Kim J, Frances L, Ding Y, Sun J, Guan D, Niebel A, Gifford ML, de Carvalho-Niebel F, Oldroyd GED. The NIN Transcription Factor Coordinates Diverse Nodulation Programs in Different Tissues of the Medicago truncatula Root. THE PLANT CELL 2015; 27:3410-24. [PMID: 26672071 PMCID: PMC4707452 DOI: 10.1105/tpc.15.00461] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 11/10/2015] [Accepted: 11/20/2015] [Indexed: 05/18/2023]
Abstract
Biological nitrogen fixation in legumes occurs in nodules that are initiated in the root cortex following Nod factor recognition at the root surface, and this requires coordination of diverse developmental programs in these different tissues. We show that while early Nod factor signaling associated with calcium oscillations is limited to the root surface, the resultant activation of Nodule Inception (NIN) in the root epidermis is sufficient to promote cytokinin signaling and nodule organogenesis in the inner root cortex. NIN or a product of its action must be associated with the transmission of a signal between the root surface and the cortical cells where nodule organogenesis is initiated. NIN appears to have distinct functions in the root epidermis and the root cortex. In the epidermis, NIN restricts the extent of Early Nodulin 11 (ENOD11) expression and does so through competitive inhibition of ERF Required for Nodulation (ERN1). In contrast, NIN is sufficient to promote the expression of the cytokinin receptor Cytokinin Response 1 (CRE1), which is restricted to the root cortex. Our work in Medicago truncatula highlights the complexity of NIN action and places NIN as a central player in the coordination of the symbiotic developmental programs occurring in differing tissues of the root that combined are necessary for a nitrogen-fixing symbiosis.
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Clavijo F, Diedhiou I, Vaissayre V, Brottier L, Acolatse J, Moukouanga D, Crabos A, Auguy F, Franche C, Gherbi H, Champion A, Hocher V, Barker D, Bogusz D, Tisa LS, Svistoonoff S. The Casuarina NIN gene is transcriptionally activated throughout Frankia root infection as well as in response to bacterial diffusible signals. THE NEW PHYTOLOGIST 2015; 208:887-903. [PMID: 26096779 DOI: 10.1111/nph.13506] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/06/2015] [Indexed: 05/26/2023]
Abstract
Root nodule symbioses (RNS) allow plants to acquire atmospheric nitrogen by establishing an intimate relationship with either rhizobia, the symbionts of legumes or Frankia in the case of actinorhizal plants. In legumes, NIN (Nodule INception) genes encode key transcription factors involved in nodulation. Here we report the characterization of CgNIN, a NIN gene from the actinorhizal tree Casuarina glauca using both phylogenetic analysis and transgenic plants expressing either ProCgNIN::reporter gene fusions or CgNIN RNAi constructs. We have found that CgNIN belongs to the same phylogenetic group as other symbiotic NIN genes and CgNIN is able to complement a legume nin mutant for the early steps of nodule development. CgNIN expression is correlated with infection by Frankia, including preinfection stages in developing root hairs, and is induced by culture supernatants. Knockdown mutants were impaired for nodulation and early root hair deformation responses were severely affected. However, no mycorrhizal phenotype was observed and no induction of CgNIN expression was detected in mycorrhizas. Our results indicate that elements specifically required for nodulation include NIN and possibly related gene networks derived from the nitrate signalling pathways.
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Leonova NO. [AUXINS AND CYTOKININES SYNTHESIS BY BRADYRHIZOBIUM JAPONICUM UNDER FLAVONOIDS INFLUENCE]. MIKROBIOLOHICHNYI ZHURNAL (KIEV, UKRAINE : 1993) 2015; 77:95-103. [PMID: 26638490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
AIM Research the ability of different by effectiveness symbiotic nitrogen-fixing soybean bacteria Bradyrhizobium japonicum to the synthesis of phytohormones-stimulators auxins and cytokinins for the actions of plant flavonoids genistein and naringenin. METHODS Extracellular phytohormonal compound isolated from the supernatant culture liquid of the soybean rhizobia by redistribution of phytohormones in two phases solvent immiscible with each other. Auxins and cytokinins were determined by thin layer spectra densitometry chromatography. RESULTS Shown the ability of symbiotic diastrophic soybean strains to synthesize auxins (4-1067 mg/g of absolutely dry biomass) and cytokinins (141-1554 mg/g of absolutely dry biomass). Cultivation soybean rhizobia in the presence of flavonoid compounds genistein and naringenin leads to the narrowing of the range and reducing the number of phytohormones: unchecked synthesis of indole-3-carboxylic acid, indole-3-carbinol, indole-3-acetic acid hydrazide and zeatin. CONCLUSIONS Depressing effect of flavonoids on the phytohormones in soybean rhizobia synthesis is probably due to changes in metabolism microsymbiotic bacteria that are not aimed at the synthesis of secondary metabolites and to launch effective nodulating mechanisms, and also the concentration of flavonoid compounds in the nutrient medium.
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Tsurumaru H, Hashimoto S, Okizaki K, Kanesaki Y, Yoshikawa H, Yamakawa T. A Putative Type III Secretion System Effector Encoded by the MA20_12780 Gene in Bradyrhizobium japonicum Is-34 Causes Incompatibility with Rj4 Genotype Soybeans. Appl Environ Microbiol 2015; 81:5812-9. [PMID: 26092458 PMCID: PMC4551253 DOI: 10.1128/aem.00823-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 06/12/2015] [Indexed: 11/20/2022] Open
Abstract
The nodulation of Bradyrhizobium japonicum Is-34 is restricted by Rj4 genotype soybeans (Glycine max). To identify the genes responsible for this incompatibility, Tn5 mutants of B. japonicum Is-34 that were able to overcome this nodulation restriction were obtained. Analysis of the Tn5 mutants revealed that Tn5 was inserted into a region containing the MA20_12780 gene. In addition, direct disruption of this gene using marker exchange overcame the nodulation restriction by Rj4 genotype soybeans. The MA20_12780 gene has a tts box motif in its upstream region, indicating a possibility that this gene encodes a type III secretion system (T3SS) effector protein. Bioinformatic characterization revealed that the MA20_12780 protein contains the small ubiquitin-like modifier (SUMO) protease domain of the C48 peptidase (ubiquitin-like protease 1 [Ulp1]) family. The results of the present study indicate that a putative T3SS effector encoded by the MA20_12780 gene causes the incompatibility with Rj4 genotype soybeans, and they suggest the possibility that the nodulation restriction of B. japonicum Is-34 may be due to Rj4 genotype soybeans recognizing the putative T3SS effector (MA20_12780 protein) as a virulence factor.
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Granqvist E, Sun J, Op den Camp R, Pujic P, Hill L, Normand P, Morris RJ, Downie JA, Geurts R, Oldroyd GED. Bacterial-induced calcium oscillations are common to nitrogen-fixing associations of nodulating legumes and nonlegumes. THE NEW PHYTOLOGIST 2015; 207:551-8. [PMID: 26010117 PMCID: PMC4736677 DOI: 10.1111/nph.13464] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/25/2015] [Indexed: 05/03/2023]
Abstract
Plants that form root-nodule symbioses are within a monophyletic 'nitrogen-fixing' clade and associated signalling processes are shared with the arbuscular mycorrhizal symbiosis. Central to symbiotic signalling are nuclear-associated oscillations in calcium ions (Ca(2+) ), occurring in the root hairs of several legume species in response to the rhizobial Nod factor signal. In this study we expanded the species analysed for activation of Ca(2+) oscillations, including nonleguminous species within the nitrogen-fixing clade. We showed that Ca(2+) oscillations are a common feature of legumes in their association with rhizobia, while Cercis, a non-nodulating legume, does not show Ca(2+) oscillations in response to Nod factors from Sinorhizobium fredii NGR234. Parasponia andersonii, a nonlegume that can associate with rhizobia, showed Nod factor-induced calcium oscillations to S. fredii NGR234 Nod factors, but its non-nodulating sister species, Trema tomentosa, did not. Also within the nitrogen-fixing clade are actinorhizal species that associate with Frankia bacteria and we showed that Alnus glutinosa induces Ca(2+) oscillations in root hairs in response to exudates from Frankia alni, but not to S. fredii NGR234 Nod factors. We conclude that the ability to mount Ca(2+) oscillations in response to symbiotic bacteria is a common feature of nodulating species within the nitrogen-fixing clade.
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Djordjevic MA, Mohd-Radzman NA, Imin N. Small-peptide signals that control root nodule number, development, and symbiosis. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:5171-81. [PMID: 26249310 DOI: 10.1093/jxb/erv357] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Many legumes have the capacity to enter into a symbiotic association with soil bacteria generically called 'rhizobia' that results in the formation of new lateral organs on roots called nodules within which the rhizobia fix atmospheric nitrogen (N). Up to 200 million tonnes of N per annum is fixed by this association. Therefore, this symbiosis plays an integral role in the N cycle and is exploited in agriculture to support the sustainable fixation of N for cropping and animal production in developing and developed nations. Root nodulation is an expendable developmental process and competency for nodulation is coupled to low-N conditions. Both nodule initiation and development is suppressed under high-N conditions. Although root nodule formation enables sufficient N to be fixed for legumes to grow under N-deficient conditions, the carbon cost is high and nodule number is tightly regulated by local and systemic mechanisms. How legumes co-ordinate nodule formation with the other main organs of nutrient acquisition, lateral roots, is not fully understood. Independent mechanisms appear to regulate lateral roots and nodules under low- and high-N regimes. Recently, several signalling peptides have been implicated in the local and systemic regulation of nodule and lateral root formation. Other peptide classes control the symbiotic interaction of rhizobia with the host. This review focuses on the roles played by signalling peptides during the early stages of root nodule formation, in the control of nodule number, and in the establishment of symbiosis. Here, we highlight the latest findings and the gaps in our understanding of these processes.
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Pancholy A, Jindal SK, Singh SK, Pathak R. Association of growth related seedling traits in Acacia senegal under arid environment of western Rajasthan. JOURNAL OF ENVIRONMENTAL BIOLOGY 2015; 36:941-946. [PMID: 26364473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Climatic models and predictions indicate increase in aridity world over due to global warming. Arid environments occupy about one third land area of the world. A. senegal is the most important dryland resource of western Rajasthan desert ecosystem. The seeds of 13 low and high seed yielding exotic and indigenous provenances were evaluated for diversity and interrelationship among growth related seedling traits targeting establishment and end use of this species. Under the present study most of the growth related seedling traits varied within and amongst provenances. Highly significant correlation of dry biomass per plant of more than 72% with root length (73.3%), collar diameter (72.2%), shoot dryweight (99.7%), root dry weight (95.7%) and seedling length (79.9%) under the present study may be used for early selection. Similarly, highly significant positive correlation of seedling length with seven out of 12 growth related seedling traits validate strong inherent association of these traits under strong genetic control and are amenable for selection. Significant negative correlation in number of nodules per plant with root/shoot length ratio (-57.6%) and no correlation with 10 out of 12 growth related seedling traits tested advocate emphasis on other growth related seedling traits in selection of elite A. senegal genotypes for afforestation. The non significant associations suggest that per cent germination was independent of other characters and could be selected separately.
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Kunert KJ, van Wyk SG, Cullis CA, Vorster BJ, Foyer CH. Potential use of phytocystatins in crop improvement, with a particular focus on legumes. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:3559-70. [PMID: 25944929 DOI: 10.1093/jxb/erv211] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Phytocystatins are a well-characterized class of naturally occurring protease inhibitors that function by preventing the catalysis of papain-like cysteine proteases. The action of cystatins in biotic stress resistance has been studied intensively, but relatively little is known about their functions in plant growth and defence responses to abiotic stresses, such as drought. Extreme weather events, such as drought and flooding, will have negative impacts on the yields of crop plants, particularly grain legumes. The concepts that changes in cellular protein content and composition are required for acclimation to different abiotic stresses, and that these adjustments are achieved through regulation of proteolysis, are widely accepted. However, the nature and regulation of the protein turnover machinery that underpins essential stress-induced cellular restructuring remain poorly characterized. Cysteine proteases are intrinsic to the genetic programmes that underpin plant development and senescence, but their functions in stress-induced senescence are not well defined. Transgenic plants including soybean that have been engineered to constitutively express phytocystatins show enhanced tolerance to a range of different abiotic stresses including drought, suggesting that manipulation of cysteine protease activities by altered phytocystatin expression in crop plants might be used to improve resilience and quality in the face of climate change.
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Kang H, Xiao A, Huang X, Gao X, Yu H, He X, Zhu H, Hong Z, Zhang Z. A Lotus japonicus Cochaperone Protein Interacts With the Ubiquitin-Like Domain Protein CIP73 and Plays a Negative Regulatory Role in Nodulation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:534-45. [PMID: 25761207 DOI: 10.1094/mpmi-11-14-0354-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The calcium/calmodulin-dependent protein kinase CCaMK forms a complex with its phosphorylation target CIP73 (CCaMK-interacting protein of 73 kDa). In this work, a homolog of the animal HSC/HSP70 interacting protein (HIP) was identified as an interacting partner of CIP73 in Lotus japonicus. L. japonicus HIP contains all functional domains characteristic of animal HIP proteins. The C-terminal STI1-like domain of L. japonicus HIP was found to be necessary and sufficient for interaction with CIP73. The interaction between CIP73 and HIP occurred in both the nuclei and cytoplasm in Nicotiana benthamiana leaf cells. The interactions between CIP73 and HIP and between CIP73 and CCaMK could take place simultaneously in the same nuclei. HIP transcripts were detected in all plant tissues tested. As nodule primordia developed into young nodules, the expression of HIP was down-regulated and the HIP transcript level became very low in mature nodules. More nodules were formed in transgenic hairy roots of L. japonicus expressing HIP RNA interference at 16 days postinoculation as compared with the control hairy roots expressing the empty vector. It appears that HIP may play a role as a negative regulator for nodulation.
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Delgadillo J, Lafuente A, Doukkali B, Redondo-Gómez S, Mateos-Naranjo E, Caviedes MA, Pajuelo E, Rodríguez-Llorente ID. Improving legume nodulation and Cu rhizostabilization using a genetically modified rhizobia. ENVIRONMENTAL TECHNOLOGY 2015; 36:1237-1245. [PMID: 25377353 DOI: 10.1080/09593330.2014.983990] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The rhizobia-legume interaction has been proposed as an interesting and appropriate tool for rhizostabilization of soils contaminated with heavy metals. One of the main requirements to use this symbiosis is the availability of tolerant and symbiotically effective rhizobia. The aim of this work was to improve the symbiotic properties of the arsenic-resistant wild-type strain Ensifer medicae MA11 in Cu-contaminated substrates. The copAB genes from a Cu-resistant Pseudomonas fluorescens strain were expressed in E. medicae MA11 under the control of the nifH promoter. The resulting strain E. medicae MA11-copAB was able to alleviate the toxic effect of Cu in Medicago truncatula. At 300 µM Cu, root and shoot dry matter production, nitrogen content, number of nodules and photosynthetic rate were significantly reduced in plants inoculated with the wild-type strain. However, these parameters were not altered in plants inoculated with the genetically modified strain. Moreover, nodules elicited by this strain were able to accumulate twofold the Cu measured in nodules formed by the wild-type strain. In addition, the engineered E. medicae strain increased Cu accumulation in roots and decreased the content in shoots. Thus, E. medicae MA11-copAB increased the capacity of M. truncatula to rhizostabilize Cu, decreasing the translocation factor and avoiding metal entry into the food chain. The plasmid containing the nifH promoter-copAB construct could be a useful biotool for Cu rhizostabilization using legumes, since it can be transferred to different rhizobia microsymbionts of authoctonous legumes growing in Cu-contaminated soils.
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Wang C, Zhu M, Duan L, Yu H, Chang X, Li L, Kang H, Feng Y, Zhu H, Hong Z, Zhang Z. Lotus japonicus clathrin heavy Chain1 is associated with Rho-Like GTPase ROP6 and involved in nodule formation. PLANT PHYSIOLOGY 2015; 167:1497-510. [PMID: 25717037 PMCID: PMC4378172 DOI: 10.1104/pp.114.256107] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 02/23/2015] [Indexed: 05/02/2023]
Abstract
Mechanisms underlying nodulation factor signaling downstream of the nodulation factor receptors (NFRs) have not been fully characterized. In this study, clathrin heavy chain1 (CHC1) was shown to interact with the Rho-Like GTPase ROP6, an interaction partner of NFR5 in Lotus japonicus. The CHC1 gene was found to be expressed constitutively in all plant tissues and induced in Mesorhizobium loti-infected root hairs and nodule primordia. When expressed in leaves of Nicotiana benthamiana, CHC1 and ROP6 were colocalized at the cell circumference and within cytoplasmic punctate structures. In M. loti-infected root hairs, the CHC protein was detected in cytoplasmic punctate structures near the infection pocket along the infection thread membrane and the plasma membrane of the host cells. Transgenic plants expressing the CHC1-Hub domain, a dominant negative effector of clathrin-mediated endocytosis, were found to suppress early nodulation gene expression and impair M. loti infection, resulting in reduced nodulation. Treatment with tyrphostin A23, an inhibitor of clathrin-mediated endocytosis of plasma membrane cargoes, had a similar effect on down-regulation of early nodulation genes. These findings show an important role of clathrin in the leguminous symbiosis with rhizobia.
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143
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Tkacz A, Poole P. Role of root microbiota in plant productivity. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:2167-75. [PMID: 25908654 PMCID: PMC4986727 DOI: 10.1093/jxb/erv157] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/09/2015] [Accepted: 03/12/2015] [Indexed: 05/19/2023]
Abstract
The growing human population requires increasing amounts of food, but modern agriculture has limited possibilities for increasing yields. New crop varieties may be bred to have increased yields and be more resistant to environmental stress and pests. However, they still require fertilization to supplement essential nutrients that are normally limited in the soil. Soil microorganisms present an opportunity to reduce the requirement for inorganic fertilization in agriculture. Microorganisms, due to their enormous genetic pool, are also a potential source of biochemical reactions that recycle essential nutrients for plant growth. Microbes that associate with plants can be considered to be part of the plant's pan-genome. Therefore, it is essential for us to understand microbial community structure and their 'metagenome' and how it is influenced by different soil types and crop varieties. In the future we may be able to modify and better utilize the soil microbiota potential for promoting plant growth.
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144
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Lei MJ, Wang Q, Li X, Chen A, Luo L, Xie Y, Li G, Luo D, Mysore KS, Wen J, Xie ZP, Staehelin C, Wang YZ. The small GTPase ROP10 of Medicago truncatula is required for both tip growth of root hairs and nod factor-induced root hair deformation. THE PLANT CELL 2015; 27:806-22. [PMID: 25794934 PMCID: PMC4558664 DOI: 10.1105/tpc.114.135210] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 02/06/2015] [Accepted: 03/02/2015] [Indexed: 05/18/2023]
Abstract
Rhizobia preferentially enter legume root hairs via infection threads, after which root hairs undergo tip swelling, branching, and curling. However, the mechanisms underlying such root hair deformation are poorly understood. Here, we showed that a type II small GTPase, ROP10, of Medicago truncatula is localized at the plasma membrane (PM) of root hair tips to regulate root hair tip growth. Overexpression of ROP10 and a constitutively active mutant (ROP10CA) generated depolarized growth of root hairs, whereas a dominant negative mutant (ROP10DN) inhibited root hair elongation. Inoculated with Sinorhizobium meliloti, the depolarized swollen and ballooning root hairs exhibited extensive root hair deformation and aberrant infection symptoms. Upon treatment with rhizobia-secreted nodulation factors (NFs), ROP10 was transiently upregulated in root hairs, and ROP10 fused to green fluorescent protein was ectopically localized at the PM of NF-induced outgrowths and curls around rhizobia. ROP10 interacted with the kinase domain of the NF receptor NFP in a GTP-dependent manner. Moreover, NF-induced expression of the early nodulin gene ENOD11 was enhanced by the overexpression of ROP10 and ROP10CA. These data suggest that NFs spatiotemporally regulate ROP10 localization and activity at the PM of root hair tips and that interactions between ROP10 and NF receptors are required for root hair deformation and continuous curling during rhizobial infection.
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145
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Okamoto S, Kawaguchi M. Shoot HAR1 mediates nitrate inhibition of nodulation in Lotus japonicus. PLANT SIGNALING & BEHAVIOR 2015; 10:e1000138. [PMID: 26039467 PMCID: PMC4622647 DOI: 10.1080/15592324.2014.1000138] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Nitrate is a major environmental factor in the inhibition of nodulation. In a model legume Lotus japonicus, a CLV1-like receptor kinase, HAR1, mediates nitrate inhibition and autoregulation of nodulation. Autoregulation of nodulation involves root-to-shoot-to-root long-distance communication, and HAR1 functions in shoots. However, it remains elusive where HAR1 functions in the nitrate inhibition of nodulation. We performed grafting experiments with the har1 mutant under various nitrate conditions, and found that shoot HAR1 is critical for the inhibition of nodulation at 10 mM nitrate. Combined with our recent finding that the nitrate-induced CLE-RS2 glycopeptide binds directly to the HAR1 receptor, this result suggests that CLE-RS2/HAR1 long-distance signaling plays an important role in the both nitrate inhibition and the autoregulation of nodulation.
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146
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Saha S, DasGupta M. Does SUNN-SYMRK Crosstalk occur in Medicago truncatula for regulating nodule organogenesis? PLANT SIGNALING & BEHAVIOR 2015; 10:e1028703. [PMID: 25893374 PMCID: PMC4883944 DOI: 10.1080/15592324.2015.1028703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Recently we reported that overexpression of intracellular kinase domain of Symbiosis Receptor Kinase (SYMRK-kd) hyperactivated spontaneous nodulation in Medicago truncatula indicating the importance of SYMRK ectodomain in restricting nodule number. To clarify whether sunn and sickle pathways were overcome by SYMRK-kd for hyperactivation of nodule organogenesis, we overexpressed SYMRK-kd in these mutants and analyzed for spontaneous nodulation in absence of rhizobia. Spontaneous nodulation in skl/SYMRK-kd roots was 2-fold higher than A17/SYMRK-kd roots indicating nodule organogenesis induced by SYMRK-kd to be ethylene sensitive. Intriguingly, sunn/SYMRK-kd roots failed to generate any spontaneous nodule which directly indicate the LRR-RLK SUNN to have a role in SYMRK-kd mediated nodule development under non-symbiotic conditions. We hypothesize a crosstalk between SUNN and SYMRK receptors for activation as well as restriction of nodule development.
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147
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Liu CW, Breakspear A, Roy S, Murray JD. Cytokinin responses counterpoint auxin signaling during rhizobial infection. PLANT SIGNALING & BEHAVIOR 2015; 10:e1019982. [PMID: 26176899 PMCID: PMC4623047 DOI: 10.1080/15592324.2015.1019982] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The transcriptomics approach to study gene expression in root hairs from M. truncatula has shed light on the developmental events during rhizobial infection and the underlying hormone responses. This approach revealed the induction of several cyclins and an aurora kinase which suggests that the cell-division machinery plays a role in rhizobial infection. Changes in the cell cycle in plants are governed by hormones, in particular auxin and cytokinin. Through gene expression and genetic analyses, we have shown auxin plays a role during rhizobial infection. Here we provide further analysis of the data showing the induction of a set of cytokinin signaling components. These include genes encoding 2 cytokinin-activating enzymes, the cytokinin receptor CRE1, and 5 type-A cytokinin response regulators. We discuss the possible interactions between auxin and cytokinin signaling during the infection process. We also consider a potential role for cytokinin signaling in rhizobial attachment.
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148
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De Cuyper C, Fromentin J, Yocgo RE, De Keyser A, Guillotin B, Kunert K, Boyer FD, Goormachtig S. From lateral root density to nodule number, the strigolactone analogue GR24 shapes the root architecture of Medicago truncatula. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:137-46. [PMID: 25371499 DOI: 10.1093/jxb/eru404] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In the rhizosphere, strigolactones not only act as crucial signalling molecules in the communication of plants with parasitic weeds and arbuscular mycorrhiza, but they also play a key role in regulating different aspects of the root system. Here we investigated how strigolactones influence the root architecture of Medicago truncatula. We provide evidence that addition of the synthetic strigolactone analogue GR24 has an inhibitory effect on the lateral root density. Moreover, treatment with GR24 of Sinorhizobium meliloti-inoculated M. truncatula plants affects the nodule number both positively and negatively, depending on the concentration. Plants treated with 0.1 µM GR24 had a slightly increased number of nodules, whereas concentrations of 2 and 5 µM strongly reduced it. This effect was independent of the autoregulation of nodulation mechanism that is controlled by SUPER NUMERIC NODULE. Furthermore, we demonstrate that GR24 controls the nodule number through crosstalk with SICKLE-dependent ethylene signalling. Additionally, because the expression of the nodulation marker EARLY NODULATION11 was strongly reduced in GR24-treated plants, we concluded that strigolactones influence nodulation at a very early stage of the symbiotic interaction.
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Pal'ove-Balang P, García-Calderón M, Pérez-Delgado CM, Pavlovkin J, Betti M, Márquez AJ. A Lotus japonicus mutant defective in nitrate uptake is also affected in the nitrate response to nodulation. PLANT BIOLOGY (STUTTGART, GERMANY) 2015; 17:16-25. [PMID: 24673996 DOI: 10.1111/plb.12169] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 01/27/2014] [Indexed: 06/03/2023]
Abstract
A chlorate-resistant mutant (Ljclo1) of the model legume Lotus japonicus was identified that showed normal levels of nitrate reductase enzyme activity but had decreased uptake of nitrate, as determined from nitrate depletion and electrophysiological measurements. The data suggest that the mutant could be affected specifically in the low-affinity but not in the high-affinity nitrate transport system, and also showed decreased uptake of chlorate. Back-crosses of the mutant plant to the wild type indicated that it is affected in a single Mendelian recessive trait. Thus, the mutation produced in Ljclo1 may be related to some of the low-affinity nitrate transporters or to a regulatory mechanism associated with nitrate/chlorate uptake. Both size and chlorophyll content in young leaves of the mutant plants were significantly reduced compared to the wild type. In addition, nodulation performance of the mutant plants was similar to the wild type in the absence of any exogenous nitrate. However, the nodule:root biomass ratio in mutant plants was considerably reduced in the presence of 1-2 mm nitrate. The levels of several transcripts for nitrate transport and assimilation genes were determined for the wild type and mutant plants and were slightly different. The results suggest interdependence between nitrate uptake, plant growth and nodulation in Ljclo1 mutant plants.
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150
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Wang C, Xu X, Hong Z, Feng Y, Zhang Z. Involvement of ROP6 and clathrin in nodulation factor signaling. PLANT SIGNALING & BEHAVIOR 2015; 10:e1033127. [PMID: 26251877 PMCID: PMC4622583 DOI: 10.1080/15592324.2015.1033127] [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: 03/06/2015] [Revised: 03/13/2015] [Accepted: 03/17/2015] [Indexed: 05/02/2023]
Abstract
The symbiotic association between the legume Lotus japonicus and the nitrogen-fixing bacterium Mesorhizobium loti results in the formation of root nodules. This process begins with the recognition of the rhizobial nodulation factor (NF) by the NF receptors (NFR) at the cell surface of the host roots. The downstream signaling cascades after NFR recognition have not been fully characterized. We recently identified a clathrin heavy chain 1 (CHC1) from L. japonicus as a potential target of the NF signaling cascades. CHC is a known central component in the clathrin-mediated endocytosis (CME) in eukaryotic cells. The CHC1 gene was highly expressed in Rhizobium-infected root hairs and the CHC1 protein was present in cytoplasmic punctate structures near the infection pockets and along the infection thread membrane. Furthermore, expression of a dominant-negative variant of CHC1 or treatment with a chemical inhibitor of CME resulted in impaired phenotypes in the NF signaling, rhizobial infection and nodulation. These findings open a new avenue for future work aiming at understanding the role of endocytosis in NF signaling pathway and rhizobial infection.
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