Dissection of gene regulation mechanism for avirulence gene in rice blast fungus

Name: Katanyutita Damchuay

ThaSH: Kasetsart University -- Dissertations. Ph.D. (Genetics) 2021

ThaSH: Kasetsart University. Department of Genetics -- Dissertations

Abstract: Rice blast is one of the most destructive disease of rice and is caused by the fungus Magnaporthe oryzae. The disease causes enormous yield losses in rice production worldwide. Rice blast fungus delivers effector proteins into rice cells. The effector proteins play an essential role in fungal virulence by manipulating and controlling host cellular pathways and inhibiting host immune responses to enhance pathogenicity. In rice blast disease, the most important class of intracellular immune receptors are the nucleotide-binding domain leucine-rich repeat containing (NLR) family proteins. The NLR proteins act as immune receptors and recognize specific virulence effectors of the fungus inside the host cell. AvrPi9, a M. oryzae effector protein is recognized by the NLR protein, Pi9 in certain rice varieties. The virulent function of AvrPi9 has not been determined. In my studies, I analyzed the genetic variation of the effector gene, AvrPi9 of the rice blast fungus, characterized its promoter, and searched for AvrPi9-interacting proteins in rice. The results showed that the frequency of AvrPi9 in Thailand blast population is 96.55% (56/58) that there is no sequence variation of the AvrPi9 gene among 58 Thai rice blast isolates collected from different rice production areas in Thailand. And only -900 bp upstream of AvrPi9 ORF is the minimum promoter that regulates the AvrPi9 expression. The 200 bp located between -900 to -700 upstream of the translation initiation sites is essential for the transcription regulation of AvrPi9. This region was designed as a biotinylated probe for protein-DNA pull-down assay to discover transcription factors that regulate the expression of AvrPi9. The Mass spectrometry (MS) was used to identify a Homeobox domain-containing protein accession G4MRM6 as a candidate transcription factor. The protein-protein pull-down assay showed about 62 interacting proteins of AvrPi9 effector from healthy and inoculated rice. Interestingly, one rice protein that could be a good partner for AvrPi9 effector is NB-ARC domain-containing protein, encoded by LOC_Os10g03670 gene. This protein has been reported as a disease resistance protein in plants. The results from this study provided the first insight into the regulation of the transcription of AvrPi9 in M. oryzae and its role in the virulence of the fungus.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Chatchawan Jantasuriyarat

Role: Thesis Advisor

Name: Pattavipha Songkumarn

Role: Thesis Co-Advisor

Created: 2021

Modified: 2025-07-09

Issued: 2025-07-09

วิทยานิพนธ์/Thesis

application/pdf

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degree

Descipline: Genetics

Grantor: Kasetsart University

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