Assessment of the Virulence Spectrum and Its Association with Genetic Diversity in Magnaporthe oryzae Populations from Sub-Saharan Africa

作者：Mutiga S K^*; Rotich F; Ganeshan V Devi; Mwongera D T; Mgonja E M; Were V M; Harvey J W; Zhou B; Wasilwa L; Feng C; Ouedraogo I; Wang G L; Mitchell T K; Talbot N J; Correll J C

来源：Phytopathology, 2017, 107(7): 852-863.

DOI：10.1094/PHYTO-08-16-0319-R

• resistance breeding
• rice blast
• virulence spectrum

A collection of 122 isolates of Magnaporthe oryzae, from nine sub-Saharan African countries, was assessed for virulence diversity and genetic relatedness. The virulence spectrum was assessed by pathotype analysis with a panel of 43 rice genotypes consisting of differential lines carrying 24 blast resistance genes (R-genes), contemporary African rice cultivars, and susceptible checks. The virulence spectrum among isolates ranged from 5 to 80%. Five isolates were avirulent to the entire rice panel, while two isolates were virulent to similar to 75% of the panel. Overall, cultivar 75-1-127, the Pi9 R-gene donor, was resistant to all isolates (100%), followed by four African rice cultivars (AR105, NERICA 15, 96%; NERICA 4, 91%; and F6-36, 90%). Genetic relatedness of isolates was assessed by single nucleotide polymorphisms derived from genotyping-by-sequencing and by vegetative compatibility tests. Phylogenetic analysis of SNPs of a subset of isolates (n = 78) revealed seven distinct clades that differed in virulence. Principal component analysis showed isolates from East Africa were genetically distinct from those from West Africa. Vegetative compatibility tests of a subset of isolates (n = 65) showed no common groups among countries. This study shows that blast disease could be controlled by pyramiding of Pi9 together with other promising R-genes into rice cultivars that are adapted to East and West African regions.

• 出版日期2017-7