Mapping of QTL Controlling Seed Vitality in Rice under Different Temperature Conditions

To investigate genotype×environmental temperature interactions for seed vitality QTL,a set of 282 F₁₃ recombinant inbred lines(RILs)derived from a japonica/indica rice cross were assessed for four seed vitality traits,i.e.germination rate,radical length,plumule length and plumule dry weight,at three temperatures of 25,20 and 15℃,respectively.Using a linkage map with 198 marker loci,the main-effect QTL for the traits were mapped by composite interval mapping.A total of 34 QTL for the four seed vitality traits were identified.The majority(82%)of these QTL were clustered within five genomic regions designated as QTLqSV-3-1,qSV-3-2,qSV-5,qSV-8-1 and qSV-8-2,respectively.All of these five QTL had small individual effects on the traits,explaining only 3.1% to 15.8% of the phenotypic variation with a mean of 7.3%.QTL qSV-3-1,qSV-3-2 and qSV-8-1 showed almost consistent effects on the traits across all three temperatures while qSV-5 and qSV-8-2 had effects mainly at the normal temperatures of 20 and 25℃.This result indicated that there were significant genotype×environmental temperature interactions controlling seed vitality and these interactions appeared to be QTL-specific.All the five QTL identified showed effects on plumule length,suggesting that plumule length could be used as a good indicator to evaluate the level of seed vitality in rice.