Diversity and symbiotic divergence of endophytic and non-endophytic rhizobia of Medicago sativa

Kang, Wenjuan; Shi, She‐Po; Xu, Lin

doi:10.1007/s13213-018-1333-3

Cited by 7 publications

(6 citation statements)

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“…In accordance with our previous conclusion, alfalfa cultivars differ in their sensitivity to infections by different rhizobial strains [45,46]. However, it remains unclear if the extent of the transcriptomic variation is correlated with the phylogenetic distance among the rhizobial symbionts.…”

Section: Biotype Identification On the Basis Of Symbiotic Performancesupporting

confidence: 90%

“…Alfalfa seeds and plants with rhizosphere soil were collected in May and August 2014 from three pasture experimental stations administrated by Gansu Agricultural University, Gansu, China (Additional file 1) using standard methods as previously described [45,46]. For phylogenetic analysis, genomic DNAs were extracted from leaf samples and subsequently used for PCR amplification of four housekeeping genes matK1, matK2, matK3, and rbcL as previously described [54].…”

Section: Plant Sampling and Genetic Identificationmentioning

confidence: 99%

“…Rhizobia were isolated from various types of samples such as nodule, leaf, stem, flower, root epidermis, root stele, rhizosphere soil, field soil and seed [45]. All the 32 isolates were subjected to identification by 16S rRNA gene sequencing and subsequent phylogenetic analysis using the standard methods [46].…”

Section: Symbiotic Performance Analysis Of E Meliloti Isolatesmentioning

confidence: 99%

“…The daily consumption of water in the basin was supplemented with sterile distilled water. At 45 days after inoculation ten seedlings were randomly selected from each pot and symbiotic properties were assayed using standard methods [45]: nodule number, effective nodule weight (the weight of pink nodules), nodule diameter, compound leaf number, shoot height, root length, nodule nitrogenase activity, chlorophyll content and crude protein content. Fresh and dry weights were measured separately for the shoot and root of a plant.…”

Section: Symbiotic Performance Analysis Of E Meliloti Isolatesmentioning

confidence: 99%

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Plant transcriptome analysis reveals specific molecular interactions between alfalfa and its rhizobial symbionts below the species level

et al. 2020

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Background: Leguminous plants alter patterns of gene expression in response to symbiotic colonization and infection by their cognate rhizobial bacteria, but the extent of the transcriptomic response has rarely been examined below the species level. Here we describe the identification of 12 rhizobial biotypes of Ensifer meliloti, which form nitrogen-fixing nodules in the roots of alfalfa (Medicago sativa L.), followed by a comparative RNA-seq analysis of four alfalfa cultivars each inoculated with two E. meliloti strains varying in symbiotic performance and phylogenetic relatedness. Results: Rhizobial biotypes were identified on the basis of their symbiotic performance, particularly shoot dry weight. Differentially expressed genes (DEGs) and metabolic pathways were determined by comparing the RNA-seq data with that of the uninoculated control plant. Significant differences were found between DEGs generated in each cultivar with the inoculation of two rhizobial strains in comparison (P < 0.01). A total of 8111 genes was differentially expressed, representing~17.1% of the M. sativa genome. The proportion of DEGs ranges from 0.5 to 12.2% for each alfalfa cultivar. Interestingly, genes with predicted roles in flavonoid biosynthesis and plant-pathogen interaction (NBS-LRR) were identified as the most significant DEGs. Other DEGs include Medsa002106 and genes encoding nodulins and NCR peptides whose expression is specifically induced during the development of nitrogenfixing nodules. More importantly, strong significant positive correlations were observed between plant transcriptomes (DEGs and KEGG pathways) and phylogenetic distances between the two rhizobial inoculants. Conclusions: Alfalfa expresses significantly distinct sets of genes in response to infection by different rhizobial strains at the below-species levels (i.e. biotype or strain). Candidate genes underlying the specific interactions include Medsa002106 and those encoding nodulins and NCR peptides and proteins in the NBS-LRR family.

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Section: Biotype Identification On the Basis Of Symbiotic Performancesupporting

confidence: 90%

Section: Plant Sampling and Genetic Identificationmentioning

confidence: 99%

Section: Symbiotic Performance Analysis Of E Meliloti Isolatesmentioning

confidence: 99%

Section: Symbiotic Performance Analysis Of E Meliloti Isolatesmentioning

confidence: 99%

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Plant transcriptome analysis reveals specific molecular interactions between alfalfa and its rhizobial symbionts below the species level

et al. 2020

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“…The Hoagland N-free nutrient solution (500 mL, once a week) and sterile distilled water were supplemented duly for seedlings growth. At 45 days post inoculation (dpi), the nodule number, effective nodule weight (the weight of pink nodules), nodule diameter, nodule nitrogenase activity, compound leaf number, shoot height, root length, shoot and root dry/fresh weight, and crude protein content were measured using standard methods (Kang et al, 2018). Nodules were graded as previously described (Li et al, 2009).…”

Section: Symbiotic Performance Of Two Alfalfa Cultivarsmentioning

confidence: 99%

Plant Peptides (NCRs) and Plant Immunity Play Vital Roles in Determining Specificity Between Alfalfa Cultivars and Sinorhizobium Meliloti Strain

Kang

Zhang

et al. 2021

Preprint

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Alfalfa expresses significantly distinct sets of genes in response to infection by different rhizobia strains at the below-species level (i.e., biotype or strain). However, differences in the transcriptomic profiles of two alfalfa cultivars nodulated by a single rhizobium strain have been largely unexamined. In this study, the comparative RNA-seq analysis of two alfalfa cultivars, Medicago sativa cv. Gannong No. 3 and Gannong No. 9 inoculated with one Sinorhizobium meliloti strain LL2, with varying in symbiotic performance, was conducted, followed by a hub gene interaction network construction based on weighted gene co-expression network analysis (WGCNA). The G9-LL2 symbiotic system showed better nodule-formation, nitrogen-fixing, and growth characteristics than the G3-LL2 system. Compared with the uninoculated control (CK), the LL2-inoculated G9 plants (10053) produced more differentially expressed genes (DEGs) than the LL2-inoculated G3 plants (7112). A group of 227 (2623 shared) genes displayed completely distinguished expression in G9 (6.63 < log2(FC) < 15.45) and G3 (‒3.05 < log2(FC) < 12.05), which are primarily involved in encoding nodule-specific cysteine-rich peptides (NCRs), nodulin, and leghemoglobin. Although genes with predicted roles in nitrogen metabolism were primarily upregulated, and almost all of those in ubiquitin-mediated proteolysis and plant-pathogen interaction were suppressed, interestingly, a consistently higher expression level measured by log2(FC) was observed in G9 plants. Hub gene interaction networks showed that the NCRs, late nodulin, and genes related to plant immunity (TIR-NBS-LRR, defensin, thioredoxin, thionine, and polygalacturonase) regulated other genes at the source node positions. After the successful initiation of nodulation in both alfalfa cultivars G3 and G9 by S. meliloti strain LL2, G9 achieved preferable outcomes of rhizobia-alfalfa symbiosis by equilibrating the antagonism and compatibility of plant immunity. It elevated PTI and suppressed defense and ETI, as well as enhancing nitrogen fixation and utilization efficiency by inducing the expression of genes encoding NCRs, nodulin, and leghemoglobin. Hub genes predominantly underlying the highly specific rhizobia-alfalfa symbiosis, positively governed by NCRs and fine-tuned immune antagonism, comprise NCRs, late nodulin, and TIR-NBS-LRR. These findings provide insights into the genetic mechanisms underlying the modification and efficient utilization of semi-compatible and incompatible rhizobia resources.

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Role of Plant Growth-Promoting Rhizobacteria (PGPR) for Crop Stress Management

Kabiraj

Majhi

Halder

et al. 2020

Sustainable Agriculture in the Era of Climate Change

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Diversity and symbiotic divergence of endophytic and non-endophytic rhizobia of Medicago sativa

Cited by 7 publications

References 57 publications

Plant transcriptome analysis reveals specific molecular interactions between alfalfa and its rhizobial symbionts below the species level

Plant transcriptome analysis reveals specific molecular interactions between alfalfa and its rhizobial symbionts below the species level

Plant Peptides (NCRs) and Plant Immunity Play Vital Roles in Determining Specificity Between Alfalfa Cultivars and Sinorhizobium Meliloti Strain

Role of Plant Growth-Promoting Rhizobacteria (PGPR) for Crop Stress Management

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