Distribution of bacterial blight resistance genes in the main cultivars and application of Xa23 in rice breeding
Shiguang Wang1,2†, Wei Liu 1,2†, Dongbai Lu1,2, Zhanhua Lu1,2, Xiaofei Wang1,2,Jiao Xue1,2 and Xiuying He1,2*
Frontiers in Plant Science
Abstract
Bacterial blight (BB) is an important constraint on achieving a high and stable rice grainyield. An increasing number of BB resistance (R) genes have been identified and cloned toincrease the available options for rice disease resistance breeding. However, it isnecessary to understand the distribution of R genes in rice varieties for rationaldistribution and breeding. Here, we genotyped five R genes, i.e. Xa4, Xa7, Xa21, Xa23,and Xa27, in seventy main cultivars from Guangdong Province, South China using thecorresponding specific markers. Our results showed that 61 varieties carried Xa4, onlythree varieties carried Xa27, and Xa7, Xa21, or Xa23 was not detected in all testedvarieties. Notably, only 33 varieties exhibited resistance to pathotype IV Xoo strains. Theseresults indicate that Xa4 is no longer suitable for widespread use in rice breeding, althoughXa4 is widely present in tested varieties. Remarkably, the strongly virulent BB strains ofpathotype IX evolved quickly in southern China, and Xa23 was found to effectively conferresistance against the pathotype IX strains. Subsequently, we successfully bred two novelinbred rice varieties as also being restorer lines and two photoperiod- and thermosensitivegenic male sterility (P/TGMS) lines using the broad-spectrum resistance geneXa23 through marker-assisted selection (MAS) combined with phenotypic selection. All ofthe developed lines and derived hybrids exhibited enhanced resistance to BB withexcellent yield performance. Our research may potentially facilitate both of the inbredand hybrid rice disease resistance breeding.
Keywords:rice, bacterial blight, distribution, Xa23, marker-assisted selection
