Molecular Plant-microbe Interactions最新文献

{"title":"Improved Gene Annotation of the Fungal Wheat Pathogen <i>Zymoseptoria tritici</i> Based on Combined Iso-Seq and RNA-Seq Evidence.","authors":"Nicolas Lapalu, Lucie Lamothe, Yohann Petit, Anne Genissel, Camille Delude, Alice Feurtey, Leen N Abraham, Dan Smith, Robert King, Alison Renwick, Melanie Appertet, Justine Sucher, Andrei S Steindorff, Stephen B Goodwin, Gert H J Kema, Igor V Grigoriev, James Hane, Jason Rudd, Eva Stukenbrock, Daniel Croll, Gabriel Scalliet, Marc-Henri Lebrun","doi":"10.1094/MPMI-07-25-0077-TA","DOIUrl":"https://doi.org/10.1094/MPMI-07-25-0077-TA","url":null,"abstract":"<p><p>Despite large omics datasets, the prediction of eukaryotic genes is still challenging. We have developed a new method to improve the prediction of eukaryotic genes and demonstrate its utility using the genome of the fungal wheat pathogen <i>Zymoseptoria tritici</i>. From 10,933 to 13,260 genes were predicted by four previous annotations, but only one third were identical. A novel bioinformatics suite, InGenAnnot, was developed to improve <i>Z. tritici</i> gene annotation using Iso-Seq full-length transcript sequences. The best gene models were selected among different <i>ab initio</i> gene predictions, according to transcript and protein evidence. Overall, 13,414 re-annotated gene models (RGMs) were predicted, improving previous annotations. Iso-Seq transcripts outlined 5' and 3' UTRs for 73% of the RGMs, and alternative transcripts mainly due to intron retention. Our results showed that the combination of different <i>ab initio</i> gene predictions and evidence-driven curation improved gene annotation of a eukaryotic genome. It also provided new insights into the transcriptional landscape of this fungus.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145092301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Salivary Effector of the Pea Aphid Interacts with Pea Proteins and Enhances Its Performance on the Host Plant.","authors":"Po-Yuan Shih, Stéphanie Le Bras, Rémi Ollivier, Hélène Boulain, Stéphanie Morlière, Yannick Outreman, Jean-Christophe Simon, Akiko Sugio","doi":"10.1094/MPMI-08-24-0089-R","DOIUrl":"10.1094/MPMI-08-24-0089-R","url":null,"abstract":"<p><p>Aphids have intricate interactions with their host plants, but the molecular mechanisms behind these interactions remain largely unknown. The pea aphid, <i>Acyrthosiphon pisum</i>, is a legume specialist that forms a complex of several biotypes, each specialized in feeding on a few legume species. Aphids inject a cocktail of salivary effector proteins into plants to suppress plant immunity and promote their performance, such as fecundity. Previous studies showed that subsets of salivary effector genes of <i>A. pisum</i> are differentially expressed between the pea- and alfalfa-adapted biotypes. We hypothesized that the salivary effector genes that are important for <i>A. pisum</i> to feed on pea (<i>Pisum sativum</i>) are highly expressed in the pea-adapted biotype compared with non-adapted ones and selected such genes for functional characterization. We examined 10 candidate genes and found that expression of the salivary gene <i>LOC100159932</i> (<i>Ap4</i>) in pea leaves increased the fecundity of the <i>A. pisum</i> pea biotype. A yeast two-hybrid screening using Ap4 as a bait identified two pea proteins named PsBPL1 and PsBPL2 that showed high homology with Arabidopsis BPL (Binding Partner of ACD11-Like) proteins, which are conserved in plants and fungi and known to be involved in plant immunity. GFP-tagged Ap4 proteins produced puncta in <i>Nicotiana benthamiana</i> cytoplasm, and a bimolecular fluorescence complementation experiment confirmed the interaction of Ap4 and PsBPL1 and PSBPL2 in planta. These results highlight Ap4's role as an effector and suggest the involvement of BPL proteins in pea-aphid interactions. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":"MPMI08240089R"},"PeriodicalIF":3.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144564983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Population Genomics Approach to Understand the Diversity, Migration, and Reproduction of the Rice Pathogen <i>Cercospora janseana</i>.","authors":"Jacob Searight, Vinson P Doyle, Adam N Famoso, Xin-Gen Zhou, Jonathan K Richards","doi":"10.1094/MPMI-03-25-0031-R","DOIUrl":"https://doi.org/10.1094/MPMI-03-25-0031-R","url":null,"abstract":"<p><p><i>Cercospora janseana</i> is the causal agent of narrow brown leaf spot (NBLS) on rice, an increasingly problematic disease in the southern United States. Historically, this disease was considered sporadic and a minor nuisance, however, recent NBLS epidemics and the resulting detrimental impacts on yield underscore the need for a deeper understanding of the pathogen population biology. In this study, we used whole-genome sequencing of 136 <i>C. janseana</i> isolates collected from Louisiana and Texas to investigate genetic diversity, population structure, and possible reproductive strategies. Our results revealed a high level of genetic diversity across sampling years and locations. Population structure and phylogenetic analyses identified two distinct lineages with most isolates belonging to a dominant lineage found in both states. Despite the disparity in observed lineage frequencies, overall population differentiation was minimal, indicating ongoing gene flow across regional boundaries. Linkage disequilibrium decay and index of association analyses revealed evidence for a population that predominately reproduces clonally with infrequent sexual reproduction. However, nearly equal frequencies of mating type idiomorphs in most sampled populations indicate ongoing or past sexual reproduction to some extent. Taken together, these results suggest that <i>C. janseana</i> populations are diverse, migrate between production regions, and exhibit a mixed mode of reproduction. These findings have important implications for the development of integrated disease management and pathogen monitoring practices to ultimately mitigate the impacts of this resurgent disease.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145040951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cellular Responses in the Pigeonpea Wild Relative <i>Cajanus platycarpus</i> to <i>Helicoverpa armigera</i> Herbivory: The Role of Methionine Sulfoxide Reductase B1 (<i>CpMSRB1</i>) in Enhanced Defense.","authors":"Maniraj Rathinam, Narasimham Dokka, Kameshwaran Senthil, Shivangi Mahawar, Shaily Tyagi, Dineshkumar Rengarajan, Preethi Vijayaraghavareddy, Yuvaraj Iyyappan, Basavaraj Y B, Sandeep Reddy, Vinutha T, Rama Prashat G, Subodh Kumar Sinha, Prasanta K Dash, Sheshshayee Sreeman, Manoj Majee, Rohini Sreevathsa","doi":"10.1094/MPMI-11-24-0149-R","DOIUrl":"10.1094/MPMI-11-24-0149-R","url":null,"abstract":"<p><p>Understanding key cellular mechanisms leading to improved defense against various stressors is essential for cultivating robust nutritious crops capable of flourishing in diverse environments. We present an in-depth characterization of the defense response in the pigeonpea wild relative <i>Cajanus platycarpus</i> to herbivory by pod borer <i>Helicoverpa armigera.</i> To fight the attacking pest, <i>C. platycarpus</i> strategically activated non-enzymatic reactive oxygen species (ROS) scavengers and unleashed methionine sulfoxide reductases to safeguard the integrity of methionine residues. We unveiled for the first time physical interaction between <i>Cp</i>MSRB1 and chorismate mutase (<i>Cp</i>CM1.1), a pivotal player in the phenylpropanoid pathway. This association fueled the synthesis of phenylpropanoids and enhanced ROS scavenging crucial for repelling herbivores. Repairing <i>Cp</i>CM1.1 also boosted salicylic acid production, coordinating defense signaling with jasmonic acid. Additionally, heterologous expression of <i>CpMSRB1</i> in tomato improved defense against herbivory by enhanced ROS scavenging and polyphenol production. This study demonstrates the role of <i>Cp</i>MSRB1 in protecting a major enzyme in the shikimate pathway, reinforcing defense against <i>H. armigera</i>. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":"MPMI11240149R"},"PeriodicalIF":3.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144033188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cowpea Lipid Transfer Protein LTP1 Mediates Plant Resistance to <i>Botrytis cinerea</i>.","authors":"Jie Ji, Shanwei Zhao, Ziyan Qi, Shengli Du, Hongyi Zhang, Tao Tian, Deqiang Duanmu, Qiuling Fan","doi":"10.1094/MPMI-04-25-0041-SC","DOIUrl":"https://doi.org/10.1094/MPMI-04-25-0041-SC","url":null,"abstract":"<p><p>Plant lipid transfer proteins (LTPs), belonging to pathogenesis-related protein 14 family, participate in plant immune response to biotic stress. LTP1 from <i>Vigna unguiculata</i> was previously shown to be able to suppress infection by cowpea mosaic virus and soybean mosaic virus. However, whether cowpea LTP1 participates in the plant resistance to other plant pathogens remains unclear. The present study analyzed the role of LTP1 in plant resistance to eukaryotic pathogens. We observed that LTP1 overexpression in cowpea and tobacco significantly reduced lesion areas and biomass of the fungus <i>Botrytis cinerea</i> and oomycete <i>Phytophthora capsici</i>. Protein lipid overlay assay showed that LTP1 bound phosphatidic acid (PA) and phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P₂), but LTP1^3A, with three amino acids in the lipid binding domain being mutated to alanine, lost the lipid binding ability. Consistently, overexpression of LTP1^3A did not influence lesion areas and pathogen biomass in cowpea and tobacco plants after inoculation with <i>B. cinerea</i> at 48 hpi. LTP1 heterologous expression in tobacco induced significant increase in intracellular calcium, inositol 1,4,5-trisphosphate (IP₃) levels and abscisic acid (ABA) contents, leading to a more significant stomatal closure after <i>B. cinerea</i> infection. Overall, our findings suggest that cowpea LTP1 participates in the plant defense response through interacting with specific phospholipids, thereby interfering with pathological processes such as IP₃-mediated calcium signaling and stomatal movement.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145001007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interactions of Wheat Powdery Mildew Effectors Involved in Recognition by the Wheat NLR PM3.","authors":"Jonatan Isaksson, Matthias Heuberger, Milena Amhof, Lukas Kunz, Salim Bourras, Beat Keller","doi":"10.1094/MPMI-05-25-0050-SC","DOIUrl":"https://doi.org/10.1094/MPMI-05-25-0050-SC","url":null,"abstract":"<p><p>To successfully colonize the living tissue of its host, the fungal wheat powdery mildew pathogen produces diverse effector proteins that are suggested to reprogram host defense responses and physiology. When recognized by host immune receptors, these proteins become avirulence (AVR) effectors. Several sequence-diverse AVRPM3 effectors and the suppressor of AVRPM3-PM3 recognition (SVRPM3^a1/f1) are involved in triggering allele-specific, <i>Pm3</i>-mediated resistance, but the molecular mechanisms controlling their function in the host cell remain unknown. Here, we describe that AVRPM3^b2/c2, AVRPM3^a2/f2 and SVRPM3^a1/f1 form homo- and heteromeric complexes with each other, suggesting they are present as dimers in the host cell. Alphafold2 modelling substantiated previous predictions that AVRPM3^b2/c2, AVRPM3^a2/f2 and SVRPM3^a1/f1 all adopt a core RNase-like fold. We found that a single amino acid mutation in a predicted surface exposed region of AVRPM3^a2/f2 enables it to trigger the PM3b immune receptor, which does not recognize wildtype AVRPM3^a2/f2. This indicates that differential AVRPM3 recognition by variants of the highly related PM3 immune receptors is due to subtle differences in similar protein surfaces of sequence-diverse AVRs. Our study reveals complex molecular interactions between powdery mildew effectors. These findings suggest that structural similarity, rather than sequence conservation, underlies both the promiscuous dimerization of these effectors and their recognition by specific PM3 immune receptors.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144962140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Lipopolysaccharide Lipid A Acyltransferase Gene <i>msbB</i> Is Involved in Soybean Rhizobial Intracellular Colonization and Symbiotic Nitrogen Fixation.","authors":"Ziqi Li, Yao Lu, Puxuan Du, Mengting Zhang, Dongzhi Li, Fuli Xie, Dasong Chen, Hui Lin, Youguo Li","doi":"10.1094/MPMI-02-25-0018-R","DOIUrl":"https://doi.org/10.1094/MPMI-02-25-0018-R","url":null,"abstract":"<p><p>Three major components of lipopolysaccharide (LPS) in rhizobia, namely core polysaccharide, o-antigen, and lipid A, act as microbe-associated molecular patterns (MAMPs) to participate in the symbiosis between rhizobia and legume. Rhizobia have a different lipid A structure from other Gram-negative bacteria. The 3-hydroxy group on the 2' or 3' myristate acyl chain of its lipid A is substituted by a unique very long chain fatty acid (VLCFA). VLCFAs are transferred to lipid A by an acyltransferase MsbB. In this research, we constructed the <i>msbB</i> deletion mutant, complementary, and overexpression strains of <i>Sinorhizobium fredii</i> HH103, and investigated their free-living and symbiotic phenotypes. The findings revealed that deletion of <i>msbB</i> had no impact on the autonomous growth of HH103, yet significantly reduced the resistance of rhizobia to abiotic stresses. The promoter-GUS assays revealed that <i>msbB</i> was mainly expressed at the early stage of nodulation. Quantitative analysis of early infection revealed that the mutation of <i>msbB</i> significantly reduced root hair curling, infection threads, and nodule primordia, suggesting impairment of the symbiotic infection process. The nodulation assay and transmission electron microscopy analysis of nodule ultrastructure showed that <i>msbB</i> deletion led to the formation of ineffective root nodules without colonization of rhizobia, thereby causing a loss of nitrogen fixation capacity. RNA-seq analysis indicated that HH103Ω<i>msbB</i> inoculation trigger a localized defense response in the soybean root to result in symbiotic deficiencies. Taken together, these results reveal the important role of VLCFAs in soybean rhizobia in the establishment of effective symbiosis and nodule nitrogen fixation.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144962125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transcriptional Dynamics of Nitrogen Fixation and Senescence in Soybean Nodules: A Dual Perspective on Host and <i>Bradyrhizobium</i> Regulation.","authors":"Ryan DelPercio, Madison McGregor, Stewart Morley, Nazhin Nikaeen, Blake Meyers, Patricia Baldrich","doi":"10.1094/MPMI-04-25-0037-R","DOIUrl":"https://doi.org/10.1094/MPMI-04-25-0037-R","url":null,"abstract":"<p><p>The Soybean-<i>Bradyrhizobium</i> symbiosis enables symbiotic nitrogen fixation (SNF) within root nodules, reducing reliance on synthetic N-fertilizers. However, nitrogen fixation is transient, peaking several weeks after <i>Bradyrhizobium</i> colonization and declining as nodules senesce in coordination with host development. To investigate the regulatory mechanisms governing SNF and senescence, we conducted a temporal transcriptomic analysis of soybean nodules colonized with <i>Bradyrhizobium diazoefficiens</i> USDA110. Weekly nodule samples (2-10 weeks post-inoculation, wpi) were analyzed using RNA and small RNA sequencing, while acetylene reduction assays assessed nitrogenase activity from 4 to 7 wpi. We identified three major nodule developmental phases: early development (2-3 wpi), nitrogen fixation (3-8 wpi), and senescence (8-10 wpi). Soybean showed extensive transcriptional reprogramming during senescence, whereas <i>Bradyrhizobium</i> underwent major transcriptional shifts early in development before stabilizing during nitrogen fixation. We identified seven soybean genes and several microRNAs as candidate biomarkers of nitrogen fixation, including <i>lipoxygenases</i> (<i>Lox</i>), suggesting roles for oxylipin metabolism. Soy <i>hemoglobin-2</i> (<i>Hb2</i>), previously classified as non-symbiotic, was upregulated during senescence, implicating oxidative stress responses within aging nodules. Upregulation of the <i>Bradyrhizobium paa</i> operon and <i>rpoH</i> during senescence suggested metabolic adaptation for survival beyond symbiosis. Additionally, <i>Bradyrhizobium NIF</i> gene expression showed stage-specific regulation, with <i>nifK</i> peaking at 2 wpi, <i>nifD</i> and <i>nifA</i> at 2 and 10 wpi, and <i>nifH</i>, <i>nifW</i>, and <i>nifS</i> at 10 wpi. These findings provide insights into SNF regulation and nodule aging, revealing temporal gene expression patterns that could inform breeding or genetic engineering strategies to enhance nitrogen fixation in soybeans and other legume crops.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144855852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FERONIA Kinase Interacting Cell Wall Sensors LRX1/2 Regulate the Plant Rhizosphere Microbiome.","authors":"Siyu Song, Keegan J McDonald, Aditi Bhat, Melissa Y Chen, Zayda Morales Moreira, Cara H Haney","doi":"10.1094/MPMI-05-25-0064-R","DOIUrl":"https://doi.org/10.1094/MPMI-05-25-0064-R","url":null,"abstract":"<p><p>Plants establish beneficial associations with microbiota, enhancing their resilience to environmental challenges. FERONIA (FER) kinase shapes the microbiome; despite extensive knowledge on FER interactors that regulate development and immunity against pathogens, the specific partners involved in microbiome modulation remain underexplored. Through a reverse genetic screen of <i>Arabidopsis leucine-rich repeat extensin</i> (<i>LRX</i>) genes, which encode FER-interacting cell wall sensors, we found that loss-of-function of <i>lrx1/2</i> leads to enriched rhizosphere <i>Pseudomonas</i>, similar to <i>fer</i> mutants. When grown in natural soil, 16S rRNA sequencing revealed that <i>lrx1/2</i> and <i>fer-4</i> have similarly altered rhizosphere microbiomes with decreased bacterial diversity. Notably, <i>lrx1/2</i> and <i>fer-4</i> mutants both exhibit growth defects in high pH natural soil that could be rescued by lowering soil pH and increasing phosphate. Microbiome sequencing under conditions that rescued <i>fer-4</i> and <i>lrx1/2</i> stunting showed that the altered microbiome of <i>lrx1/2</i> and <i>fer-4</i> persists independently of changes in plant growth. This indicates that FER and LRX1/2 play an integral role in shaping the rhizosphere microbiome.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144835847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stachydrine Catabolism Contributes to an Optimal Root Nodule Symbiosis Between <i>Sinorhizobium meliloti</i> and <i>Medicago sativa</i>.","authors":"Garrett J Levin, Jason V S Kearsley, Turlough M Finan, Barney A Geddes","doi":"10.1094/MPMI-02-25-0021-SC","DOIUrl":"https://doi.org/10.1094/MPMI-02-25-0021-SC","url":null,"abstract":"<p><p><i>Sinorhizobium meliloti</i> forms a robust N₂-fixing root-nodule symbiosis with <i>Medicago sativa</i>. We are interested in identifying the minimal symbiotic genome of the model strain <i>S. meliloti</i> Rm1021. This gene set refers to the minimal genetic determinants required to form a robust N₂-fixing symbiosis. Many symbiotic genes are located on the 1,354 kb pSymA megaplasmid of <i>S. meliloti</i> Rm1021. We recently constructed a minimalized pSymA, minSymA2.1, that lacked over 90% of the pSymA genes. Relative to the wild-type, minSymA2.1 showed a reduction in <i>M. sativa</i> shoot biomass production and nodule size with an increase in total nodule number. Here we show that the addition of either the stachydrine (<i>stc</i>) or trigonelline (<i>trc</i>) catabolism genes from pSymA to minSymA2.1 restores nodule size and total nodule number to levels indistinguishable from the wild-type but does not restore reduced shoot biomass production. In the context of the complete Rm1021 genome, removing the <i>stc</i> genes reduced nodule size and increased total nodule number while removal of the <i>trc</i> genes alone had no apparent effect. Together, these observations implicate stachydrine catabolism as an important determinant of root nodule symbiosis between <i>S. meliloti</i> and <i>M. sativa</i> while trigonelline catabolism seems to contribute in a more conditional manner, in the context of the minimized genome. These findings highlight the minimal symbiotic genome as a tool for investigating the impact individual genetic determinants have in conferring an optimal symbiosis. Factors whose impact, in the context of a complete genome, may be hidden or dampened due to redundancies.</p>","PeriodicalId":19009,"journal":{"name":"Molecular Plant-microbe Interactions","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144817187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}