Project description:Plant Elicitor Peptides (Peps) are conserved regulators of defense responses across diverse plant species and are multigene families in most species. However, the functional relevance of Peps as multigene families remains largely undefined. While Arabidopsis Peps appear largely redundant in function, previous work examining Pep-induced responses in maize implied specificity of function. To better define function of individual ZmPeps, activities of each peptide were examined by assessing changes in defense-associated phytohormones, specialized metabolites and global gene expression patterns. In addition to delineating individual ZmPep and ZmPEPR activities, these experiments led to a number of new insights into Pep signaling. ZmPROPEP precursors were found to harbor multiple ZmPeps, a phenomenon not previously observed. In all, seven new ZmPeps were identified and together the family members were found to have specific activities defined by relative magnitude of response output rather than uniqueness. A striking correlation between ZmPep-elicited changes in levels of jasmonic acid and ethylene and the magnitude of induced defense responses was observed, indicating that ZmPeps regulate immune output through rheostat-like regulation of phytohormone levels. Peptide structure-function studies and ligand-receptor modeling revealed structural features critical to ZmPep signaling function. Structural analysis also led to identification of ZmPep5a as a potential antagonist peptide able to competitively inhibit activity of other ZmPeps, a regulatory mechanism not previously observed for this family. Using heterologous expression assays, endogenous gene expression patterns and analysis of CRISPR/Cas9 generated knockout plants, ZmPEPR1 was found to be the dominant receptor regulating ZmPep-mediated anti-herbivore defenses in planta.
Project description:Rice is a staple food crop worldwide, and its production is severely threatened by phloem-feeding insect herbivores, particularly the brown planthopper (BPH, Nilaparvata lugens), and destructive pathogens. Despite the identification of many BPH resistance genes, the molecular basis of rice resistance to BPH remains largely unclear. Here, we report that the plant elicitor peptide (Pep) signalling confers rice resistance to BPH. Both rice PEP RECEPTORs (PEPRs) and PRECURSORs of PEP (PROPEPs), particularly OsPROPEP3, were transcriptionally induced in leaf sheaths upon BPH infestation. Knockout of OsPEPRs impaired rice resistance to BPH, whereas exogenous application of OsPep3 improved the resistance. Hormone measurement and co-profiling of transcriptomics and metabolomics in OsPep3-treated rice leaf sheaths suggested potential contributions of jasmonic acid biosynthesis, lipid metabolism and phenylpropanoid metabolism to OsPep3-induced rice immunity. Moreover, OsPep3 elicitation also strengthened rice resistance to the fungal pathogen Magnaporthe oryzae and bacterial pathogen Xanthamonas oryzae pv. oryzae and provoked immune responses in wheat. Collectively, this work demonstrates a previously unappreciated importance of the Pep signalling in plants for combating piercing-sucking insect herbivores and promises exogenous application of OsPep3 as an eco-friendly immune stimulator in agriculture for crop protection against a broad spectrum of insect pests and pathogens.
Project description:We identified a leucine-rich repeat receptor kinase (IbLRR-RK1) that is induced upon wounding and herbivory, and related to peptide-elicitor receptors (PEPRs) from tomato and Arabidopsis. We also identified a gene encoding a precursor protein comprising a peptide ligand (IbPep1) for IbLRR-RK1. RNAseq of I. batatas reveals differentially expressed genes (DEGs) upon IbPep1 and IbHypSysIV treatment
Project description:To characterize the differentially expressed genes between adding fungal elicitor and without fungal elicitor on Streptomyces natalensis HW-2
Project description:Xylella fastidiosa is a plant pathogenic bacterium that has been introduced in the European Union (EU), threatening the agricultural economy of relevant Mediterranean crops such as almond (Prunus dulcis). Plant defense elicitor peptides would be promising to manage diseases such as almond leaf scorch but their effect on the host has not been fully studied. In this work, the response of almond plants to the defense elicitor peptide flg22-NH2 was studied in-depth using RNA-seq, confirming the activation of the salicylic acid and abscisic acid pathways. Marker genes related to the response triggered by flg22-NH2 were used to study the effect of the application strategy of the peptide on almond plants and to depict its time course. The application of flg22-NH2 by endotherapy triggered the highest number of upregulated genes, especially at 6 hours after the treatment. A library of peptides that include BP100-flg15, HpaG23, FV7, RIJK2, PIP-1, Pep13, BP16-Pep13, flg15-BP100 and BP16 triggered a stronger defense response in almond plants than flg22-NH2. The best candidate, FV7, when applied by endotherapy on almond plants inoculated with X. fastidiosa, significantly reduced levels of the pathogen and decreased disease symptoms. Therefore, these novel plant defense elicitors are suitable candidates to manage diseases caused by X. fastidiosa, in particular almond leaf scorch.
Project description:Transcriptional overlap between transgenic Arabidopsis plants expressing C4G2A from the Tomato yellow leaf curl virus (TYLCV) and a cas-1 mutant upon activation of plant immunity by treatment with the bacterial peptide elicitor flg22 (1 µM, 12 h).
Project description:DNA methylation is a ubiquitous chromatin feature — in maize, more than 25% of cytosines in the genome are methylated. Recently, major progress has been made in describing the molecular mechanisms driving methylation, yet variation and evolution of the methylation landscape during maize domestication remain largely unknown. Here we leveraged whole-genome sequencing (WGS) and whole-genome bisulfite sequencing (WGBS) on populations of modern maize, landrace, and teosinte (Zea mays ssp. parviglumis) to investigate the adaptive and phenotypic consequences of methylation variations in maize. By using a novel estimation approach, we inferred the methylome site frequency spectrum (mSFS) to estimate forward and backward methylation mutation rates and selection coefficients. We only found weak evidence for direct selection on DNA methylation in any context, but thousands of differentially methylated regions (DMRs) were identified in population-wide that are correlated with recent selection. Further investigation revealed that DMRs are enriched in 5’ untranslated regions, and that maize hypomethylated DMRs likely helped rewire distal gene regulation. For two trait-associated DMRs, vgt1-DMR and tb1DMR, our HiChIP data indicated that the interactive loops between DMRs and respective downstream genes were present in B73, a modern maize line, but absent in teosinte. Functional analyses suggested that these DMRs likely served as cis-acting elements that modulated gene regulation after domestication. Our results enable a better understanding of the evolutionary forces acting on patterns of DNA methylation and suggest a role of methylation variation in adaptive evolution.
Project description:The goal of the experiment was to perform a large scale study of circadian regulation of gene expression in maize. To identify maize genes with expression regulated by the circadian clock, transcript levels in the aerial tissues of young maize seedlings were determined by transcriptional profiling with the Affymetrix GeneChip Maize Genome Array. Maize inbred B73 seedlings were grown inside Conviron growth chamber. B73 seedlings were grown for 7 days under 12 h light:12 h dark (LD) photocycles, 26° C temperature and 70% humidity. At the 8th day, seedlings were transferred to continuous light (LL) and were allowed to entrain completely for 24 h prior to tissue harvest following which tissue was harvested every 4 hours under LL conditions for a period of 48h. Therefore, for the circadian LL time course 12 time points were collected as follows (also defined as factors in the treatment section): ZT0 - 8:00 am/ subjective dawn/ Day1 ZT4 - 12:00 pm/ subjective mid-day/ Day1 ZT8 - 4:00 pm/ subjective late-day/ Day1 ZT12 - 8:00 pm/ subjective dusk/ Day1 ZT16 - 12:00 am/ subjective mid-night/ Day1 ZT20 - 4:00 am/ subjective pre-dawn/ Day1 ZT24- 8:00 am/ subjective dawn/ Day2 ZT28 - 12:00 pm/ subjective mid-day/ Day2 ZT32 - 4:00 pm/ subjective late-day/ Day2 ZT36 - 8:00 pm/ subjective dusk/ Day2 ZT40 - 12:00 am/ subjective mid-night/ Day2 ZT44 - 4:00 am/ subjective pre-dawn/ Day2 Tissue comprised of aerial portion of the seedlings (corresponding to tissue from the prop roots and up) for RNA isolation. Total RNA was isolated from the entire aerial portion of 7 day-old seedlings (corresponding to tissue from the prop roots and up) by Trizol extraction followed by Qiagen RNeasy columns and treatment with RNase-free DNase I (Qiagen; qiagen.com). RNA was isolated from 3 independent biological replicates was pooled. cRNA was generated from pooled total RNA from 3 biological replicates with the GeneChip One-Cycle Target Labeling kit according to the manufacturer’s recommendations (Affymetrix, affymetrix.com). The University of California, Berkeley Functional Genomics Laboratory hybridized samples to Affymetrix GeneChip Maize Genome Arrays and scanned the washed arrays as suggested by manufacturer. Probe sets called “Not Present” or “Marginal” on one or more microarrays were removed from the downstream analysis, as is common practice with circadian studies. Raw hybridization intensities were normalized across all twelve arrays using RMA express in Perfect Match mode. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, Frank G. Harmon. The equivalent experiment is ZM28 at PLEXdb.]
Project description:<p><strong>BACKGROUND:</strong> The coevolution and interaction between plants and microorganisms have long been a subject of significant research interest. Dark septate endophytes (DSE) have garnered great attention in contemporary research due to their functional diversity, in vitro cultivation ability, and ability to establish symbiotic associations with host plants. In the present study, three DSE strains, namely <em>Acrocalymma vagum</em>, <em>Zopfiella marina</em>, and <em>Phoma herbarum</em>, which were obtained from the roots of <em>Astragalus membranaceus</em>, were introduced into maize plants through inoculation. We evaluated the effects of DSE inoculation on maize growth and root secretion activity through a multi omics methods, and proposed mechanisms for 'internal pathways' and 'external pathways'.</p><p><strong>RESULTS:</strong> The findings indicated that A. vagum exhibited superior growth-promoting ability on maize compared to <em>Z. marina</em> and <em>P. herbarum</em>.GO and KEGG enrichment analysis found that <em>A. vagum</em> inoculation resulted in significant enrichment of differentially expressed genes in annotation functions related to hormone regulation and lipid metabolism. A. vagum inoculation revealed that the gene pathways involved in plant hormone signaling and plant pathogen interactions play a crucial role in promoting host growth, and <em>A. vagum</em> inoculation group exhibited the highest number of differentially expressed genes, the most intricate protein-protein interaction (PPI) model, and the most pronounced relationship between differentially expressed genes. After the inoculation of <em>A.vagum</em>, the levels of salicylic acid, zeatin, and IAA in maize plants significantly increased. Additionally, the diversity and abundance of endophytic fungi, as well as the proportion of harmful bacteria and beneficial fungi, had significantly increased. Compared with <em>Z. marina</em> and <em>P. herbarum</em>, the net photosynthetic rate (Pn) and stomatal conductance (Gs) of <em>A.vagum</em> inoculated plants significantly increased. Inoculation with <em>A.vagum</em> could enhance the ability of corn roots to secrete lipids, sugars, and amino acids, resulted in a notable augmentation of beneficial bacteria and fungi, accompanied by a significant reduction in the proportion of harmful bacteria in the rhizosphere soil, such as <em>Fusarium solani</em> and <em>Fusarium lacertarum</em>, exhibited significant inhibition, whereas <em>Bacillus niabensis</em> and <em>Bacillus nealsonii</em> demonstrated enrichment trends. Soil pH, organic matter, available potassium content, acid phosphatase, alkaline phosphatase and urease activity exhibited significant increases following the inoculation of <em>A. vagum</em>. Variance decomposition and structural equation modeling (SEM) analysis indicated that the 'internal pathway', maize growth is mainly influenced by the interaction of endogenous hormones, endophytic microorganisms, and photosynthetic parameters, whereas within the 'external pathway', the interaction between soil microorganisms and soil physicochemical properties exerted a dominant influence. Compared with the <em>Z. marina</em> and <em>P. herbarum</em> inoculation, <em>A. vagum</em> inoculation showed a more significant impact on maize growth, both in terms of 'internal pathway' and 'external pathway', in terms of pathway level and quantity.</p><p><strong>CONCLUSIONS:</strong> These findings provide a new perspective for understanding the potential mechanisms of 'microbe-plant' interactions and also contribute to the exploration of targeted functional microorganisms that promote growth and stress resistance.</p>
Project description:The goal of the experiment was to perform a large scale study of circadian regulation of gene expression in maize. To identify maize genes with expression regulated by the circadian clock, transcript levels in the aerial tissues of young maize seedlings were determined by transcriptional profiling with the Affymetrix GeneChip Maize Genome Array. Maize inbred B73 seedlings were grown inside Conviron growth chamber. B73 seedlings were grown for 7 days under 12 h light:12 h dark (LD) photocycles, 26° C temperature and 70% humidity. At the 8th day, seedlings were transferred to continuous light (LL) and were allowed to entrain completely for 24 h prior to tissue harvest following which tissue was harvested every 4 hours under LL conditions for a period of 48h. Therefore, for the circadian LL time course 12 time points were collected as follows (also defined as factors in the treatment section): ZT0 - 8:00 am/ subjective dawn/ Day1 ZT4 - 12:00 pm/ subjective mid-day/ Day1 ZT8 - 4:00 pm/ subjective late-day/ Day1 ZT12 - 8:00 pm/ subjective dusk/ Day1 ZT16 - 12:00 am/ subjective mid-night/ Day1 ZT20 - 4:00 am/ subjective pre-dawn/ Day1 ZT24- 8:00 am/ subjective dawn/ Day2 ZT28 - 12:00 pm/ subjective mid-day/ Day2 ZT32 - 4:00 pm/ subjective late-day/ Day2 ZT36 - 8:00 pm/ subjective dusk/ Day2 ZT40 - 12:00 am/ subjective mid-night/ Day2 ZT44 - 4:00 am/ subjective pre-dawn/ Day2 Tissue comprised of aerial portion of the seedlings (corresponding to tissue from the prop roots and up) for RNA isolation. Total RNA was isolated from the entire aerial portion of 7 day-old seedlings (corresponding to tissue from the prop roots and up) by Trizol extraction followed by Qiagen RNeasy columns and treatment with RNase-free DNase I (Qiagen; qiagen.com). RNA was isolated from 3 independent biological replicates was pooled. cRNA was generated from pooled total RNA from 3 biological replicates with the GeneChip One-Cycle Target Labeling kit according to the manufacturer’s recommendations (Affymetrix, affymetrix.com). The University of California, Berkeley Functional Genomics Laboratory hybridized samples to Affymetrix GeneChip Maize Genome Arrays and scanned the washed arrays as suggested by manufacturer. Probe sets called “Not Present” or “Marginal” on one or more microarrays were removed from the downstream analysis, as is common practice with circadian studies. Raw hybridization intensities were normalized across all twelve arrays using RMA express in Perfect Match mode. ****[PLEXdb(http://www.plexdb.org) has submitted this series at GEO on behalf of the original contributor, Frank G. Harmon. The equivalent experiment is ZM28 at PLEXdb.] Continuous Light: ZT0(1-replications); Continuous Light: ZT4(1-replications); Continuous Light: ZT8(1-replications); Continuous Light: ZT12(1-replications); Continuous Light: ZT16(1-replications); Continuous Light: ZT20(1-replications); Continuous Light: ZT24(1-replications); Continuous Light: ZT28(1-replications); Continuous Light: ZT32(1-replications); Continuous Light: ZT36(1-replications); Continuous Light: ZT40(1-replications); Continuous Light: ZT44(1-replications)