|WANG, XUEYAN - University Of Arkansas|
|WAMISHE, YESHI - University Of Arkansas|
|VALENT, BARBARA - Kansas State University|
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/3/2020
Publication Date: 1/10/2020
Citation: Jia, Y., Wang, X., Jia, M.H., Wamishe, Y., Valent, B. 2020. Co-evolutionary mechanisms of Oryza sativa and Magnaporthe oryzae pathosystem [abstract]. Plant and Animal Genome Conference, San Diego, California, January 11-15, 2020.
Technical Abstract: Blast disease caused by the filamentous fungus Magnaporthe oryzae (M. oryzae) is a serious threat for rice production worldwide. Major resistance (R) genes are effective in preventing blast disease when both the rice variety and M. oryzae contain the matched pair of R gene and avirulence (AVR) gene. In the USA, 8 blast R genes Pi-a, Pi-i, Pi-ks, Pi-km, Pi-z, Pi-d, Pi-ta/Pi-ta2(Ptr), and Pi-b have been deployed in different commercial varieties from 1964 to 2015. To determine if the deployed R genes influence DNA sequence changes of AVR genes, we analyzed AVR genes, AVR-Pii, AVR-Pia, AVR-Pib, ACE1, AVR-Pita1 and AVR-Pik in selected blast isolates from 1964-2015 and evaluated pathogenicity with rice monogenic lines carrying these major blast R genes in the japonica rice variety Lijianxintuanheigu (LTH), YT14 with Pi-ta, and Katy with Pita/Ptr and Piks. LTH and M202 without these R genes were used as controls. We found deletions at AVR-Pii and AVR-Pia, point mutations at AVR-Pik resulting in different AVR-Pik variants, and transposon insertion and deletion at AVR-Pita1 in isolates of M. oryzae several years after their cognate R genes were deployed in rice varieties. In contrast, few or no changes at AVR-Pi9, ACE1 (AVR of Pi-33), AVR-Pib were detected indicating the changes of these AVR genes have not been influenced by their cognate R genes. In fact, Pi-9, Pi-33, Pi-b have not been widely deployed from 1964 to 2015 in the USA which supports that there was no selection pressure from these R genes. Together these findings suggest that host R genes may have influenced genomic changes of AVR genes in M. oryzae. A model of co-evolution of host R genes and pathogen AVR genes at the Host-pathogen interface will be presented.