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http://10.1.7.192:80/jspui/handle/123456789/10506| Title: | Transcriptional Dynamics Study of Resistant Host Peanut Plant against Foliar Disease to Reveal Molecular Insights Involved in Resistance |
| Authors: | Rathod, Visha |
| Keywords: | Science Theses Theses 2021 15EXTPHDS63 Foliar Disease Transcriptional Dynamics RNA-Seq Plant-fungus interaction |
| Issue Date: | Mar-2021 |
| Publisher: | Institute of Science, Nirma University |
| Series/Report no.: | ;ST000082 |
| Abstract: | Among biotic stresses, several diseases, including rust caused by Puccinia arachidis and early leaf spot (ELS) caused by Cercospora arachidicola are global constraints leading to 50% yield losses for peanut production. The use of a fungicide is not a viable option economically and it is unsafe for human health as well as the environment. The development and characterization of naturally-resistant host-plant species is the most effective approach. To understand the plantpathogen interaction comprehensively, it is valuable to monitor the gene expression profiles of both the interacting organisms simultaneously in the same infected plant tissue. In this study, we used RNA-Seq to analyse the expression profile of resistant (GPBD-4) and susceptible (JL-24) genotypes of peanut plant against P. arachidis and C. arachidicola infection. Gene Ontology and KEGG analysis of Differentially expressed genes (DEGs) revealed essential genes and their pathways responsible for defense response of peanut plants against fungal pathogens. The majority of the transcripts were assigned to plant-pathogen interaction pathways, metabolic pathways, MAPK signalling pathway, plant hormone signal transduction, phenylalanine metabolism and biosynthesis of secondary metabolites-related pathways. The resistant variety was able to withstand biotic stress due to exclusive upregulation of defense-related genes (pathogenesis-related (PR) proteins, thaumatin, glutathione peroxidase, ethylene-responsive factor and F-box). On the other hand, the susceptible variety was more prone to damage by infection due to down-regulation of genes including (betaglucosidase, cytochrome p450, Leucine-rich repeat protein kinase, transcription factors (WRKY, bZIP, MYB and terpene synthase) associated with a majority of biological function. This finding was also supported by expression data generated by RT-qPCR analysis. RNA-Seq analysis data for both the diseases were validated by RT-qPCR using 15 randomly selected primer sets derived from DEGs. A high correlation (R2= 0.82) was obtained between RNA-Seq analysis data and RT-qPCR data. A total of 4511 and 8591 EST-SSRs were identified from the unigenes of rust and ELS transcriptome data, respectively, which can be useful in evaluating genetic diversity among genotypes, QTL mapping, and plant variety improvement through marker-assisted breeding. Out of all EST-SSRs primers, random 15 primer sets for each disease were validated for PCR iii amplification. These findings will help to understand the molecular defense mechanisms of the peanut plant in response to P. arachidis and C. arachidicola infection. Metabolomic profiling of peanut samples provides insights into the production of different metabolites as components of the plant defense system, which can be used as biomarkers for plant breeding and crop protection. The plant defense mechanism involves production of oxidative enzymes involved in phenylpropanoid and antimicrobial metabolites (flavonoid), interfering with pathogen growth. In the case of rust disease, the metabolic response was assessed in resistant (GPBD-4) and susceptible (JL-24) genotypes at the control stage (0 day without inoculation), 2 DAI (Day after inoculation), 4 DAI and 6 DAI by Gas Chromatography Mass Spectrometry (GC-MS) while for ELS disease, four resistant genotypes (GPBD-4, GPBD-5, KDG-123, KDG-128) and three susceptible genotypes (JL-24, GG-20, TMV-2) were analysed at the control stage (0 day-without inoculation) and at 2 DAI stage. These metabolites were identified by NIST library, comprising sugars, phenols, fatty acids, carboxylic acids and sugar alcohols. Sugars and fatty acids were predominant in leaf extracts compared to other metabolites. The concentration of different metabolites such as salicylic acid, mannitol, flavonoid, 9,12-octadecadienoic acid, linolenic acid, propanoic acid, hexadecenoic acid and glucopyranoside were higher in resistant genotype than in susceptible genotype during infection. Systemic acquired resistance (SAR) and hypersensitive reaction (HR) components such as oxalic acid was recorded more in resistant genotype during pathogen infection. Principle component analysis (PCA) and Partial Least Square-Discriminant Analysis (PLS-DA) were applied to GC-MS data to reveal metabolites profile differences between resistant and susceptible genotype during infection. The phenol content and oxidative enzyme activity, i.e., catalase, peroxidase and polyphenol oxidase were found to be higher in resistant genotype (p value <0.01) over susceptible genotype. This study provides insight into the understanding of molecular interactions between plant and pathogen and may help to generate molecular markers for crop protection and marker-assisted plant breeding of peanut. |
| Description: | ST000082 |
| URI: | http://10.1.7.192:80/jspui/handle/123456789/10506 |
| Appears in Collections: | Theses, IS |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ST000082.pdf | ST000082 | 8.79 MB | Adobe PDF |  View/Open |
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