Journal: Molecular Plant-Microbe Interactions

Abbreviation

Mol. Plant-Microb. Interact.

Publisher

American Phytopathological Society

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ISSN

0894-0282

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Publications 1 - 10 of 39
  • Field Trial and Molecular Characterization of RNAi-Transgenic Tomato Plants That Exhibit Resistance to Tomato Yellow Leaf Curl Geminivirus
    Item type: Journal Article
    Fuentes, Alejandro; Carlos, Natacha; Ruiz, Yoslaine; et al. (2016)
    Molecular Plant-Microbe Interactions
    RNA interference (RNAi) is a widely used approach to generate virus-resistant transgenic crops. However, issues of agricultural importance like the long-term durability of RNAi-mediated resistance under field conditions and the potential side effects provoked in the plant by the stable RNAi expression remain poorly investigated. Here, we performed field trials and molecular characterization studies of two homozygous transgenic tomato lines, with different selection markers, expressing an intron-hairpin RNA cognate to the Tomato yellow leaf curl virus (TYLCV) C1 gene. The tested F6 and F4 progenies of the respective kanamycin- and basta-resistant plants exhibited unchanged field resistance to TYLCV and stably expressed the transgene-derived short interfering RNA (siRNAs) to represent 6 to 8% of the total plant small RNAs. This value outnumbered the average percentage of viral siRNAs in the nontransformed plants exposed to TYLCV-infested whiteflies. As a result of the RNAi transgene expression, a common set of up- and downregulated genes was revealed in the transcriptome profile of the plants selected from either of the two transgenic events. A previously unidentified geminivirus causing no symptoms of viral disease was detected in some of the transgenic plants. The novel virus acquired V1 and V2 genes from TYLCV and C1, C2, C3, and C4 genes from a distantly related geminivirus and, thereby, it could evade the repressive sequence-specific action of transgene-derived siRNAs. Our findings shed light on the mechanisms of siRNA-directed antiviral silencing in transgenic plants and highlight the applicability limitations of this technology as it may alter the transcriptional pattern of nontarget genes.
  • Widely Conserved Attenuation of Plant MAMP-Induced Calcium Influx by Bacteria Depends on Multiple Virulence Factors and May Involve Desensitization of Host Pattern Recognition Receptors
    Item type: Journal Article
    Lammertz, Meltem; Kuhn, Hannah; Pfeilmeier, Jonas Sebastian; et al. (2019)
    Molecular Plant-Microbe Interactions
  • The Molecular Dialogue Between Zymoseptoria tritici and Wheat
    Item type: Journal Article
    Meile, Lukas; Carrasco-López, Cristian; Lorrain, Cécile; et al. (2025)
    Molecular Plant-Microbe Interactions
    Zymoseptoria tritici is a highly damaging pathogen that causes high wheat yield losses in temperate climates. Z. tritici emerged during the domestication of wheat in the Fertile Crescent and has been extensively used as a model system for population genetic and genomic studies. New genetic tools and resources have provided a better understanding of the molecular components involved in the wheat-Z. tritici interaction, which is highlighted by the cloning of three wheat resistance genes and four Z. tritici avirulence genes. Despite the considerable progress made in the last few years, the mechanisms that mediate Z. tritici colonization remain largely unknown. In this review, we summarize the latest advances in understanding the molecular components mediating wheat-Z. tritici interactions, and we discuss future research lines to close current knowledge gaps.Copyright (c) 2025 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
  • Quantitative Variation in Effector Activity of ToxA Isoforms from Stagonospora nodorum and Pyrenophora tritici-repentis
    Item type: Journal Article
    Tan, Kar-Chun; Ferguson-Hunt, Margo; Rybak, Kasia; et al. (2012)
    Molecular Plant-Microbe Interactions
    ToxA is a proteinaceous necrotrophic effector produced by Stagonospora nodorum and Pyrenophora tritici-repentis. In this study, all eight mature isoforms of the ToxA protein were purified and compared. Circular dichroism spectra indicated that all isoforms were structurally intact and had indistinguishable secondary structural features. ToxA isoforms were infiltrated into wheat lines that carry the sensitivity gene Tsn1. It was observed that different wheat lines carrying identical Tsn1 alleles varied in sensitivity to ToxA. All ToxA isoforms induced necrosis when introduced into any Tsn1 wheat line but we observed quantitative variation in effector activity, with the least-active version found in isolates of P. tritici-repentis. Pathogen sporulation increased with higher doses of ToxA. The isoforms that induced the most rapid necrosis also induced the most sporulation, indicating that pathogen fitness is affected by differences in ToxA activity. We show that differences in toxin activity encoded by a single gene can contribute to the quantitative inheritance of necrotrophic virulence. Our findings support the hypothesis that the variation at ToxA results from selection that favors increased toxin activity.
  • Expression Pattern Suggests a Role of MiR399 in the Regulation of the Cellular Response to Local Pi Increase During Arbuscular Mycorrhizal Symbiosis
    Item type: Journal Article
    Branscheid, Anja; Sieh, Daniela; Pant, Bikram D.; et al. (2010)
    Molecular Plant-Microbe Interactions
    Many plants improve their phosphate (Pi) availability by forming mutualistic associations with arbuscular mycorrhizal (AM) fungi. Pi-repleted plants are much less colonized by AM fungi than Pi-depleted plants. This indicates a link between plant Pi signaling and AM development. MicroRNAs (miR) of the 399 family are systemic Pi-starvation signals important for maintenance of Pi homeostasis in Arabidopsis thaliana and might also qualify as signals regulating AM development in response to Pi availability. MiR399 could either represent the systemic low-Pi signal promoting or required for AM formation or they could act as counter players of systemic Pi-availability signals that suppress AM symbiosis. To test either of these assumptions, we analyzed the miR399 family in the AM-capable plant model Medicago truncatula and could experimentally confirm 10 novel MIR399 genes in this species. Pi-depleted plants showed increased expression of mature miR399 and multiple pri-miR399, and unexpectedly, levels of five of the 15 pri-miR399 species were higher in leaves of mycorrhizal plants than in leaves of nonmycorrhizal plants. Compared with nonmycorrhizal Pi-depleted roots, mycorrhizal roots of Pi-depleted M. truncatula and tobacco plants had increased Pi contents due to symbiotic Pi uptake but displayed higher mature miR399 levels. Expression levels of MtPho2 remained low and PHO2-dependent Pi-stress marker transcript levels remained high in these mycorrhizal roots. Hence, an AM symbiosis-related signal appears to increase miR399 expression and decrease PHO2 activity. MiR399 overexpression in tobacco suggested that miR399 alone is not sufficient to improve mycorrhizal colonization supporting the assumption that, in mycorrhizal roots, increased miR399 are necessary to keep the MtPho2 expression and activity low, which would otherwise increase in response to symbiotic Pi uptake. (© 2010 The American Phytopathological Society).
  • Comparative Transcriptome Analyses in Zymoseptoria tritici Reveal Significant Differences in Gene Expression Among Strains During Plant Infection
    Item type: Journal Article
    Palma-Guerrero, Javier; Ma, Xin; Torriani, Stefano F.F.; et al. (2017)
    Molecular Plant-Microbe Interactions
    Zymoseptoria tritici is an ascomycete fungus that causes Septoria tritici blotch, a globally distributed foliar disease on wheat. Z. tritici populations are highly polymorphic and exhibit significant quantitative variation for virulence. Despite its importance, the genes responsible for quantitative virulence in this pathogen remain largely unknown. We investigated the expression profiles of four Z. tritici strains differing in virulence in an experiment conducted under uniform environmental conditions. Transcriptomes were compared at four different infection stages to characterize the regulation of gene families thought to be involved in virulence and to identify new virulence factors. The major components of the fungal infection transcriptome showed consistent expression profiles across strains. However, strain-specific regulation was observed for many genes, including some encoding putative virulence factors. We postulate that strain-specific regulation of virulence factors can determine the outcome of Z. tritici infections. We show that differences in gene expression may be major determinants of virulence variation among Z. tritici strains, adding to the already known contributions to virulence variation based on differences in gene sequence and gene presence/absence polymorphisms.
  • A Community-Curated DokuWiki Resource on Diagnostics, Diversity, Pathogenicity and Genetic Control of Xanthomonads
    Item type: Journal Article
    Costa, Joana; Pothier, Joël F.; Bosis, Eran; et al. (2024)
    Molecular Plant-Microbe Interactions
    Xanthomonads, including Xanthomonas and Xylella species, constitute a large and significant group of economically and ecologically important plant pathogens. Up-to-date knowledge of these pathogens and their hosts is essential for the development of suitable control measures. Traditional review articles or book chapters have inherent limitations, including static content and rapid obsolescence. To address these challenges, we have developed a web-based knowledge platform dedicated to xanthomonads, inspired by the concept of living systematic reviews. This platform offers a dynamic resource that encompasses bacterial virulence factors, plant resistance genes, and tools for diagnostics and genetic diversity studies. Our goal is to facilitate access for newcomers to the field, provide continuing education opportunities for students, assist plant protection services with diagnostics, provide valuable information to breeders on sources of resistance and breeding targets, and offer comprehensive expert knowledge to other stakeholders interested in plant-pathogenic xanthomonads.
  • Stable Fluorescent and Enzymatic Tagging of Bradyrhizobium diazoefficiens to Analyze Host-Plant Infection and Colonization
    Item type: Journal Article
    Ledermann, Raphael; Bartsch, Ilka; Remus-Emsermann, Mitja N.; et al. (2015)
    Molecular Plant-Microbe Interactions
    MBradyrhizobium diazoefficiens USDA 110 (formerly named Bradyrhizobium japonicum) can fix dinitrogen when living as an endosymbiont in root nodules of soybean and some other legumes. Formation of a functional symbiosis relies on a defined developmental program mediated by controlled gene expression in both symbiotic partners. In contrast to other well-studied Rhizobium-legume model systems that have been thoroughly examined by means of genetically tagged strains, analysis of B. diazoefficiens host infection has been impaired due to the lack of suitable tagging systems. Here, we describe the construction of B. diazoefficiens strains constitutively expressing single-copy genes for fluorescent proteins (eBFP2, mTurquoise2, GFP+, sYFP2, mCherry, HcRed) and enzymes (GusA, LacZ). For stable inheritance, the constructs were recombined into the chromosome. Effectiveness and versatility of the tagged strains was demonstrated in plant infection assays. (i) The infection process was followed from root-hair attachment to colonization of nodule cells with epifluorescent microscopy. (ii) Monitoring mixed infections with two strains producing different fluorescent proteins allowed rapid analysis of nodule occupancy and revealed that the majority of nodules contained clonal populations. (iii) Microscopic analysis of nodules induced by fluorescent strains provided evidence for host-dependent control of B. diazoefficiens bacteroid morphology in nodules of Aeschynomene afraspera and Arachis hypogaea (peanut), as deduced from their altered morphology compared with bacteroids in soybean nodules.
  • Comparative transcriptomics reveals how wheat responds to infection by Zymoseptoria tritici
    Item type: Journal Article
    Ma, Xin; Keller, Beat; McDonald, Bruce; et al. (2018)
    Molecular Plant-Microbe Interactions
    The fungus Zymoseptoria tritici causes septoria tritici blotch (STB) on wheat, an important disease globally and the most damaging wheat disease in Europe. Despite the global significance of STB, the molecular basis of wheat defense against Z. tritici is poorly understood. Here, we use a comparative transcriptomic study to investigate how wheat responds to infection by four distinct strains of Z. tritici. We examined the response of wheat across the entire infection cycle, identifying both shared responses to the four strains and strain-specific responses. We found that the early asymptomatic phase is characterized by strong upregulation of genes encoding receptor-like kinases and pathogenesis-related proteins, indicating the onset of a defense response. We also identified genes that were differentially expressed among the four fungal strains, including genes related to defense. Genes involved in senescence were induced during both the asymptomatic phase and at late stages of infection, suggesting manipulation of senescence processes by both the plant and the pathogen. Our findings illustrate the need, when identifying important genes affecting disease resistance in plants, to include multiple pathogen strains.
  • A Gall-Inducing Caterpillar Species Increases Essential Fatty Acid Content of Its Host Plant Without Concomitant Increases in Phytohormone Levels
    Item type: Journal Article
    Tooker, John F.; De Moraes, Consuelo M. (2009)
    Molecular Plant-Microbe Interactions
    Gall-inducing insects are accomplished plant parasites that can profoundly influence host-plant physiology. We recently reported that the caterpillar Gnorimoschema gallaesolidaginis failed to significantly alter emissions of host-plant volatiles that often recruit natural enemies of insect herbivores, and demonstrated that a caterpillar species feeding on linolenate-deficient plant tissues avoids inducing some of the indirect defenses of its host plant. Here, we investigate whether absence of volatile responses to the galler G. gallaesolidaginis could similarly be explained by a lack of linolenate in galls. We screened interior and exterior tissue of galls and control stems of Solidago altissima for free linolenate, linoleate, 12-oxo-phytodienoate, jasmonate, and salicylate. We found, unexpectedly, that G. gallaesolidaginis strongly increased amounts of linolenic and linoleic acids inside galls without associated increases in two downstream products, 12-oxo-phytodienoic or jasmonic acid. In contrast, the generalist caterpillar Heliothis virescens induced elevated levels of linolenic, linoleic, 12-oxo-phytodienoic, and jasmonic acids in S. altissima. Moreover, these two fatty acids and 12-oxo-phytodienoate were significantly and positively associated with jasmonic acid, suggesting that increased levels of these precursors can lead directly to greater amounts of jasmonic acid. Taken together, these findings suggest that gall insects may be able to nutritionally enhance their food source without inducing concomitant increases in phytohormones and associated defense responses.
Publications 1 - 10 of 39