|LI, JINBIN - Yunnan Academy Of Agriculture Sciences|
|LI, LIN - Yunnan Academy Of Agriculture Sciences|
|WANG, QUN - Yunnan Academy Of Agriculture Sciences|
|FUKUTA, YOSHIMICHI - Japanese International Research Center For Agricultural Sciences (JIRCAS) - Japan|
|LI, CHENGYUN - Yunnan Agricultural University|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2015
Publication Date: 2/17/2016
Publication URL: http://handle.nal.usda.gov/10113/61850
Citation: Li, J., Li, L., Jia, Y., Wang, Q., Fukuta, Y., Li, C. 2016. Characterization of field isolates of Magnaporthe oryzae with mating type, DNA fingerprinting, and pathogenicity assays. Plant Disease. 100(2):298-303. doi.org/10.1094/PDIS-06-15-0660-RE.
Interpretive Summary: The rice blast fungus known as Magnaporthe oryzae causes pervasive disease on rice and is one of the main contributors of rice yield losses. The sexuality of the rice blast pathogen is controlled by the MAT gene and has two mating types, MAT1-1 and MAT1-2. Sexual reproduction may occur when two opposite mating types meet, and this can lead to an increase in genetic diversity of the fungus making it more difficult to control the disease in rice. In this study, rice blast was collected from two large rice growing regions in Yunnan Province of China to examine the genetic diversity, mating type, and pathogenicity. We demonstrated that there was no evidence of sexual recombination between MAT1-1 and MAT1-2 populations and that they caused a similar amount of disease on a range of rice varieties that carried different blast resistance genes. However, we found that MAT1-2 was more genetically diverse suggesting it has the capability to adapt over a broader range of environments in Yunnan province. This study demonstrated that the rice blast pathogen is highly diverse enabling it to cause disease on all known resistance genes in rice even without sexual recombination.
Technical Abstract: Due to the harmful nature of the rice blast fungus, Magnaporthe oryzae, it is beneficial to characterize field isolates to help aid in the deployment of resistance (R) genes in rice. In the present study, 190 field isolates of M. oryzae, collected from rice fields of Yunnan province in China, were assessed for mating type, DNA fingerprinting, and disease reactions to differential rice lines. Fifty-four isolates (28.4%) were MAT1-1 and 136 (71.6%) were MAT1-2 based on polymerase chain reaction assays, and some of them were verified with the tester isolates. All MAT1-1 and MAT1-2 isolates were virulent to some of the IRRI monogenic lines harboring 22 major resistance genes. Three simple sequence repeat (SSR) markers were used to examine genetic diversity in all isolates. The existence of regional patterns of genetic diversity, sexual reproduction potential, and pathogenicity suggests that M. oryzae populations have been independently adapted asexually in rice fields over centuries of crop cultivation.