Identification and fine mapping of qPBR10-1, a novel locus controlling panicle blast resistance in Pigm-containing P/TGMS line

Abstract

BackgroundRice blast is one of the most widespread and devastating diseases in rice production. Tremendous success has been achieved in identi cation and characterization of genes and quantitative trait loci (QTLs) conferring seedling blast resistance, however, genetic studies on panicle blast resistance have lagged far behind. ResultsIn this study, two advanced backcross inbred sister lines (MSJ13 and MSJ18) were obtained in the process of introducing Pigm into C134S, and showed signi cant differences in the panicle blast resistance. One F 2 population derived from the crossing MSJ13/MSJ18 was used to QTL mapping for panicle blast resistance using Genotyping by Sequencing (GBS) method. A total of 7 QTLs were identi ed, including a major QTL qPBR10-1 on chromosome 10 that explaining 24.21% of phenotypic variance with LOD scores of 6.62. Furthermore, qPBR10-1 was veri ed via the BC 1 F 2 and BC 1 F 3 population and narrowed to a 60.6-kb region with six candidate genes predicted, including two genes encoding exonuclease family protein, two genes encoding hypothetical protein, and two genes encoding transposon protein. The nucleotide variations and the expression patterns of the candidate genes were identi ed and analyzed between MSJ13 and MSJ18 through sequence comparison and RT-PCR approach, and results indicated that ORF1 and ORF2 encoding exonuclease family protein might be the causal candidate genes for panicle blast resistance in the qPBR10-1 locus. ConclusionsA total of 7 QTLs conferring panicle blast resistance was identi ed from one F 2 population derived from the crossing between two advanced backcross inbred sister lines MSJ13 and MSJ18, which harbored the broad-spectrum resistance gene Pigm. A major QTL qPBR10-1 was ne mapped in a 60.6-kb region with six candidate genes predicted, and ORF1 and ORF2 encoding exonuclease family protein might be the causal candidate genes for panicle blast resistance in the qPBR10-1 locus through sequence comparison and RT-PCR approach. BackgroundRice blast is one of the most widespread and devastating diseases of rice and causes yield losses between 10 and 30% of rice production worldwide in epidemic years (Skamnioti and Gurr 2009). Domestically, major blast epidemics occurred in China has damaged 5.333 million hectares of paddy rice areas, resulting in more than 1.5 billion kilograms of yield loss in the past decade (He et al. 2014). Development of resistant cultivars by using of resistance (R) genes in rice improvement breeding