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Research Project: Gene Discovery and Crop Design for Current and New Rice Management Practices and Market Opportunities

Location: Dale Bumpers National Rice Research Center

Title: Toward understanding of rice innate immunity to rice blast fungus

item Jia, Yulin
item WANG, XUEYAN - University Of Arkansas
item WAMISHE, YESHI - University Of Arkansas
item VALENT, BARBARA - Kansas State University

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/4/2020
Publication Date: 1/6/2021
Citation: Jia, Y., Wang, X., Wamishe, Y., Valent, B. 2021. Toward understanding of rice innate immunity to rice blast fungus. Proceedings of 38th Rice Technical Working Group Meeting, February 24-27, 2020, Orange Beach, Alabama. p 114. Electronic Publication.

Interpretive Summary:

Technical Abstract: The fungus Magnaporthe oryzae causes rice and wheat blast diseases and both diseases are major threats to global food security. Understanding rice innate immunity to M. oryzae can help to prevent rice and wheat crop losses. Major resistance (R) genes in rice are known to be useful to prevent damage caused by M. oryzae strains carrying the corresponding avirulence (AVR) genes. In this study, we conducted marker and sequence analysis of R genes Pi-ta/Ptr and Pi-k in US rice varieties and AVR genes AVR-Pita1and AVR-Pik isolated from blast strains found in rice fields over a period of 6 decades where known cultivars were grown. We found that Pi-ks and Pikm/h deployed in varieties tracing back to 1966 and Pi-ta/(Pi-ta2/Ptr) was deployed in varieties grown since 1991 in different areas in the Southern USA. We analyzed over 1000 historical blast strains using PCR with AVR gene specific markers and found that most blast strains carry AVR-Pita1 and one third of which carry AVR-Pik. Sequence analysis of PCR amplicons demonstrated that there were 32 different AVR-Pita variants of which variant 24 is the most abundant from the 70s to 2010s, and 10 AVR-Pik variants of which variant 2 is the most abundant from the 80s to 2010s. Regression analysis of these two pairs of R and AVR showed the same trend of papulation shifts, and diversification of AVR genes in pathogen approximately 5 years after R gene deployment suggesting that host R genes influenced genetic changes of pathogen. Implications of this for crop protection will be presented.