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Dissertation
ROLES OF CHICKPEA POLYGALACTURONASE-INHIBITING PROTEINS IN DEFENSE AGAINST PATHOGENIC FUNGI.
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2022
DOI:
https://doi.org/10.7273/000004459
Handle:
https://hdl.handle.net/2376/123736
Abstract
Chickpeas are a nutritious food crop and the world's third most widely planted legume which are susceptible to many diseases. Pathogens produce polygalacturonases (PGs) during early infection, to break down the plant cell wall. Polygalacturonase-inhibiting proteins (PGIPs) are used by the plant to inhibit PGs. When PGIPs and PGs interact, oligogalacturonides (OGs) are produced, which activate plants immunity by acting as damage-associated molecular patterns. In many legumes, PGIP is shown to be a tool for disease resistance, but little is known in chickpea. Our study identified two new Capgips (Capgip3 and Capgip4) on chromosome 3 in addition two already known Capgip1 and Capgip2 on chromosome 6. PCR amplification, cloning and sanger sequencing of Capgip1, Capgip3, and Capgip4 showed that their sequence matched the NCBI sequence expect for Capgip1 which has a synonymous substitution at 720th position. Bioinformatic analysis revealed that all Capgips except Capgip2 had a signal peptide, and Capgips promoter sequence consisted of several cis acting elements crucial for biotic stress response. Homology modeling of Capgips showed the presence of 10 distinct leucine-rich repeats (LRRs) except for Capgip2. Phylogenetic analysis suggested a close relationship of Capgip1 and Capgip2 with other legume PGIPs and CaPGIP 3 and Capgip4 not related tolegume PGIPs. Immunofluorescence localization carried out using Capgips and GFP reporter fusion indicated that Capgip1, Capgip3 and Capgip4 are located on cell wall and Capgip2 located in the endoplasmic reticulum and cytoplasm. Absolute gene quantification indicated Capgip1, Capgip3and Capgip4 are expressed in all chickpea tissues at varied levels. Relative gene expression analysis conducted during infection from four fungi showed Capgips differentially responded to varied pathogen stress. Relative gene expression analysis conducted by treating chickpeas with phytohormones and wounding revealed that Capgips are differentially triggered. Invitro inhibition assay showed only recombinant Capgip3 and Capgip4 proteins can inhibit S. sclerotiorum PGs and Capgip3 can partially inhibit B. cinerea PGs. Transgenic over expressing Nicotiana tabacum lines for Capgip3 and Capgip4 could reduce S. sclerotiorum infection. These findings demonstrate CaPGIPs ability to inhibit fungal infections. Using PGIPs to boost plant immunity against pathogens is a sustainable solution against fungal diseases.
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Details
- Title
- ROLES OF CHICKPEA POLYGALACTURONASE-INHIBITING PROTEINS IN DEFENSE AGAINST PATHOGENIC FUNGI.
- Creators
- Vishnutej Ellur
- Contributors
- Weidong Chen (Advisor)Hanu Pappu (Committee Member)George Vandemark (Committee Member)Amit Dhingra (Committee Member)Kiwamu Tanaka (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Program in Molecular Plant Sciences
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 207
- Identifiers
- 99900883039301842
- Language
- English
- Resource Type
- Dissertation