|Wang, Xueyan - University Of Arkansas|
|Wamishe, Yeshi - University Of Arkansas|
|Valent, Barbara - Kansas State University|
Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/23/2015
Publication Date: 7/2/2017
Citation: Wang, X., Lin, M.J., Bianco, T.A., Wamishe, Y., Valent, B., Jia, Y. 2017. The race shift of Magnaporthe oryzae occurred within 50 years in the U.S.A.. Proc. 36th Rice Technical Working Group Meeting, Galveston, TX. pg. 68. March 1-4, 2016. CDROM.
Technical Abstract: Rice blast disease caused by Magnaporthe oryzae is one of the most destructive diseases of rice. Infection of the races of M. oryzae can be prevented by the corresponding major resistance (R) gene in rice. However, the races of M. oryzae in the commercial fields can rapidly change to overcome resistance maintained by the corresponding R genes in rice. To direct the deployment of R genes in the USA, an international race differential system consisting of 8 rice varieties, Raminad Str. 3, Zenith, NP125, Usen, Dular, Shataotsao, and Caloro was used to determine the race identity of 563 field isolates collected from 1959 to 2014. Based on disease reactions to differential rice varieties a total of 39 different races was identified. Among 39 races, 19 were present once with a frequency of 0.0018 (1/563), 5 were present twice with a frequency of 0.0036 (2/563), 2 were present three times with a frequency of 0.0053 (3/562), 4 were present five times with a frequency of 0.0089(5/563), respectively. The remaining 9 races were present from 6 to 144 times with frequencies ranging from 0.0107 (6/563) to 0.2558 (144/563). Overall, the races IG-1, IH-1 and IB-45 in 1970s; IC-17, IB-1 and IB-49 in 1980s, IC-17, IB-1 and IG-1 in 1990s, IB-1, IC-17 and IA-1 in 2000s, and IB-17, IB-1 and IB-49 in 2010s were most commonly found. To follow up on these findings, rice genomic regions harboring novel R genes to the current most commonly found races, IB-17, IB-1, and IB-49 will be identified using association mapping with the mini and Pita cores.