[QTL analysis of low-temperature-sensitive pollen sterility in Indica-japonica hybrid rice (Oryza sativa L.)].

There existed a number of biological constraints in exploiting the heterosis of indica-japonica hybrid rice.The low-temperature-sensitive sterility (LTSS) of indica-japonica hybrid has become one of the major problems in indica-japonica hybrid rice breeding after the solution of poor fertility of the hybrids by the finding of wide-compatibility gene.Previous studies revealed that the LTSS might be caused by low-temperature-sensitive pollen sterility (LTSPS).However,the genetic basis of LTSPS remained unclear.To explore the genetic basis of LTSPS in indica-japonica hybrid rice,an F_2 genetic population derived from 3037 (indica) and 02428 (japonica) was developed.At the booting stage,pollen fertility of F_2 population together with parents were surveyed after the treatment with low temperature daily average of 21~23℃.The linkage map was constructed containing 108 SSR markers distributed throughout the whole 12 chromosomes with average marker interval of 16.26 cM.Using software MapMaker/QTL,two putative QTLs,namely qLTSPS2 and qLTSPS5 on chromosomes 2 and 5 were detected by interval mapping,which could explain the phenotypic variation 15.6% and 11.9% respectively.The additive effects were 0.021 and 0.045,dominant effects were -0.246 and -0.215,and the degrees of dominance were 11.7 and 4.8,respectively for the two QTLs.Therefore,the mode of gene action in response to low-temperature stress was overdominance and LTSPS was mainly the result of interaction between the indica and japonica alleles within each locus.In addition,two-way ANOVA showed that the two QTLs acted essentially independent of each other in conditioning LTSPS.