Pathotypes of Pyricularia grisea in Rice Fields of Central and Southern China

Abstract

Blast, caused by the fungal pathogen Pyricularia grisea, is the most devastating disease of rice worldwide. Knowledge of the pathotype composition of the pathogen in rice fields is essential for rational deployment of resistance genes in rice breeding programs. In this study, we assayed the pathotypes of the pathogen populations using samples recently collected from 13 major rice-growing provinces of central and southern China. In all, 792 single spore isolates were tested for pathogenicity reactions using 13 host differentials consisting of six indica and seven japonica near-isogenic lines (NILs). The compositions of the pathogen populations were complex; 48 pathotypes were identified with the indica NILs, 82 pathotypes were detected with the japonica NILs, and a total of 344 pathotypes were identified with both indica and japonica NILs. There were large differences in distribution of the pathotypes among the different rice-growing areas. Even neighbor provinces seemed to differ sharply in types and frequencies of the most prevalent pathotypes. There was also a large difference in the frequencies of the isolates producing compatible reactions on the NILs, indicating the difference in frequencies of avirulence genes in the pathogen populations. The data provided very useful information for formulating strategies for improving blast resistance in rice breeding programs.

Comparative analyses of genomic locations and race specificities of loci for quantitative resistance to Pyricularia grisea in rice and barley

“…We used 21 and 11 isolates of P. grisea in testing their infections on the rice and barley parents, respectively. Two Chinese isolates, F1366 and F1814 from our laboratory (25), and a Philippine isolate V86013, were chosen for inoculating the RIL and DHL populations. Each of the isolates produced compatible reactions (LD 4-5) with the rice parent Zhenshan 97 and barley parent Harrington, but incompatible reactions (LD 2-3) with Minghui 63 and TR306 (Table 1).…”

“…The blast inoculation was carried out as described (25). In brief, the blast conidial suspension was adjusted to Ϸ2 ϫ 10 5 per ml with sterilized deionized water.…”

Strategies for developing Green Super Rice

“…Chen et al (72) assayed pathotypes of 792 single-spore isolates of P. grisea using samples collected from 13 major rice-growing provinces of central and southern China. These isolates were tested by inoculation with 13 host differentials consisting of six indica and seven japonica near isogenic lines (NILs), collectively carrying most of the genes for blast resistance identified previously.…”

Use of local rice cultivars as additional differentials to identify pathotypes of Pyricularia oryzae

“…Even though it is desirable to use the recently developed near isogenic lines, the NIL's developed also carry several minor and other major resistance genes (Chen et al, 2001;Fukuta et al, 2009). However, the validity of using additional differential hosts for monitoring virulence changes in the local cultivars with unknown resistance genes is not reduced.…”

“…These cultivars permitted to differentiate agriculturally important virulence in the pathogen population which can be utilized in selecting breeding lines for specific resistance in blast breeding program. Knowledge on the pathotype composition of the pathogen in commercial rice fields is important for rational deployment of resistance genes in breeding programs (Chen et al, 2001).…”