Project description:Identification of molecular determinants underlying the firming effect and protection gainst senescence of high CO2 using diploid strawberries: One of the greatest threats to strawberries is rapid softening, however firmness increases during or following high CO2 levels. Firmness at consumption is an obvious target for preventing fruit loss and to gain eating quality. Therefore, we performed RNA-seq analysis, construcing a weighted gene co-expression network analysis (WGCNA) to identify which molecular determinants play a role in cell wall integrity , using strawberries under storage conditions. Differential gene expression (DEG) analysis showed that cell wall structural architecture of firmer CO2 -treated strawberries is characterised by xyloglucans stabilisation attributed mainly to a down-regulation of Csl-like E1, β-glc, XTH15 and maintenance of expression levels of FUT and GMP as well as improved lamella integrity linked to a down-regulation of RG-lyase and PL-like. The preservation of cell wall elasticity together with the up-regulation of LEA, EXPA4, and MATE transporters required to maintain cell turgor, are the mechanisms controlled by high CO2. In stressed air-cold stored strawberries, in addition to an acute softening, there is a preferential transcript accumulation of genes involved in lignin and raffinose pathways. The oxidative stress involving jasmonate and H2O 2 is characteristic of senescent non-cold stored samples. The results are fundamental and practical for breeding in strawberry industry.
Project description:Diversification of effector function, driven by a co-evolutionary arms race, enables pathogens to establish compatible interactions with their hosts. Structurally conserved plant pathogenesis-related PR-1 and PR-1-like (PR-1L) proteins are involved in plant defense and fungal virulence, respectively. It is unclear how fungal PR-1L counteracts plant defense. Here, we show that Ustilago maydis UmPR-1La and yeast ScPRY1 with conserved phenolic detoxification functions are Ser/Thr-rich region-mediated cell-surface localization proteins. However, UmPR-1La has gained additional specialized activity in eliciting hyphal-like formation, suggesting that U. maydis deploys UmPR-1La to sense phenolics and direct their growth in plants. U. maydis also hijacks plant cathepsin B-like 3 (CatB3) to release functional CAPE-like peptides after cleaving a conserved CNYD motif of UmPR-1La to subvert plant immunity for promoting fungal virulence. Surprisingly, CatB3 avoids cleavage of plant PR-1s, despite the presence of the same conserved CNYD motif. Our work highlights that UmPR-1La has acquired additional dual roles to suppress plant defense and sustain the infection process of fungal pathogens.
Project description:Report of an RNA-Seq analysis done with strawberries taken from MYB123 RNAi silenced and stable transgenic plants vs control plants transformed with the pFRN empty vector
Project description:A LysM Receptor-like Kinase Mediates Chitin Perception and Fungal Resistance in Arabidopsis; Jinrong Wan,1 Xuecheng Zhang,1 David Neece,2 Katrina M. Ramonell,3 Steve Clough,2,4 Sung-yong Kim,1 Minviluz Stacey,1 and Gary Stacey1*; 1Division of Plant Sciences, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA; 2Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; 3Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA; 4US Department of Agriculture, Soybean/Maize Germplasm, Pathology and Genetics Research, Urbana, IL 61801, USA; *To whom correspondence should be addressed. E-mail: staceyg@missouri.edu; Abstract: Chitin, a polymer of N-acetyl-D-glucosamine, is found in fungal cell walls, but not in plants. Plant cells are capable of perceiving chitin fragments (chitooligosaccharides) to trigger various defense responses. We identified a LysM receptor-like protein (AtLysM RLK1) that is required for the perception of chitooligosaccharides in Arabidopsis. Mutation of this gene blocked the induction of almost all chitooligosaccharide-responsive genes (CRGs) and led to more susceptibility to fungal pathogens, but not to a bacterial pathogen. In addition, exogenously applied chitooligosaccharides enhanced resistance against both fungal and bacterial pathogens in the wild-type plants, but not in the mutant. Together, our data strongly suggest AtLysM RLK1 is the chitin receptor or a key part of the receptor complex and chitin is a PAMP (pathogen-associated molecular pattern) in fungi recognized by the receptor leading to the induction of plant innate immunity against fungal pathogens. Since LysM RLKs were also recently shown to be critical for the perception of the rhizobial lipo-chitin Nod signals, our data suggest that LysM RLKs not just recognize friendly symbiotic rhizobia (via their lipo-chitin Nod signals), but also hostile fungal pathogens (via their cell wall chitin). These data suggest a possible evolutionary relationship between the perception mechanisms of Nod signals and chitin by plants. Experiment Overall Design: wild type Col-0 and chitin receptor mutants treated with or without chitooctaose
Project description:Dynamic regulation of silencing histone marks, specifically H3K9me3 and H3K27me3, provide effector gene expression plasticity, which enables adaptative responses to environmental fluctuations in plant fungal pathogens. It remains an unanswered question whether the epigenetic regulatory mechanisms governing gene expression during infection stages in Phytophthora are the same as in fungal pathogens. We performed chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) of three histone modifications, H3K4me3, H3K36me3, and H3K27me3 in P. sojae and P. infestans, encompassing both the mycelium stage, and infection stages (12h post-inoculation (hpi), and 24hpi in soybean, as well as 3dpi in potato respectively).Integrative analysis of ChIP-seq and RNA-seq data of mycelium and infection stages was performed.Overall, our work provides a comprehensive and detailed view of distinctive chromatin dynamic patterns during the infection stages of Phytophthora.
Project description:Worldwide, 20-25% of all harvested fruit and vegetables are lost annually in the field and throughout the postharvest supply handling chain due to spoilage by fungal pathogens. Most impactful postharvest pathogens exhibit necrotrophic lifestyles, resulting in rotting of the host tissues and complete loss of marketable commodities. Necrotrophic fungi can readily infect ripe fruit leading to the rapid establishment of disease symptoms. However, these pathogens generally fail to infect unripe fruit, or remain quiescent until host and environmental conditions stimulate a successful infection. Current research on necrotrophic infections of fruit was mainly focused on the host by characterizing genetic and physicochemical factors that inhibit or promote the disease. However, the pathogenicity and virulence strategies employed by necrotrophic pathogens in ripe and unripe fruit are mostly understudied. Here, we provide a first comparative transcriptomics study of fungal postharvest pathogens: Botrytis cinerea, Rhizopus stolonifer and Fusarium acuminatum, all of which display necrotrophic behavior when infecting fruit. We de novo assembled and annotated the transcriptomes of R. stolonifer, and F. acuminatum and performed a differential gene expression analysis comparing the three fungal transcriptomes during fruit infection with that of fungal in-vitro growth. Analysis of the differentially expressed genes for enrichment of functional annotations revealed shared strategies of the three fungi during infection of compatible (ripe fruit) and incompatible (unripe fruit) hosts. We furthermore selected candidate genes that are involved in these strategies to characterize their expression during infection of unripe and ripe-like fruit of the non-ripening (nor) tomato mutant, both of which are physiologically and biochemically similar to unripe wildtype fruit. By enabling a better understanding of fungal necrotrophic infection strategies, we move closer to generating accurate models of fruit diseases and development of early detection tools and effective management strategies.
Project description:Lysine acetylation is critical in regulating important biological processes in many organisms, yet little is known about acetylome evolution and its contribution to phenotypic diversity. Here, we compare the acetylomes of baker’s yeast and the three deadliest human fungal pathogens, Cryptococcus neoformans, Candida albicans, and Aspergillus fumigatus. Using mass spectrometry enriched for acetylated peptides together with public data from Saccharomyces cerevisiae, we show that fungal acetylomes are characterized by dramatic evolutionary dynamics and limited conservation in core biological processes. Notably, the levels of protein acetylation in pathogenic fungi correlate with their pathogenicity. Using gene knockouts and pathogenity assays in mice, we identify deacetylases with critical roles in virulence and protein translation elongation. Finally, through mutational analysis of deactylation motifs we find evidence of positive selection at specific acetylation motifs in fungal pathogens. These results shed new light on the pathogenicity regulation mechanisms underlying the evolution of fungal acetylomes.
Project description:The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve virulence potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we performed a multi-condition sRNA-seq analysis comparing expression of several RNAi double knockout mutants with the wild-type strain in conidia and mycelium grown for 24 or 48 hours.
Project description:By searching for new drugs against fungal pathogens, we found that miltefosine is active against Aspergillus fumigatus clinical isolates. A library of transcription factors (TF) null mutants was then challenged with this drug and we discovered a novel TF that confers resistance to miltefonise, named here SmiA. By using ChIP-seq, we searched for SmiA targets upon miltefosine treatment.