Fine Mapping Of Major QTL QSSL1b For Rice Seedling Vigor And QGC10 For Rice Quality

Rice is an important cereal crop that provides food for more than half of the world's population.Seedling vigor is an important agricultural trait as direct-seeded rice technology becomes widely applied.With the improvement of people's living standards,improving grain quality is essential to rice consumers.In order to investigate the genetic mechanisms underlying seedling vigor and cooking and eating quality in rice,seeds of 132 recombinant inbred lines?RILs?derived from 93-11 and PA64S,a high-resolution genetic map generated from sequencing of the RILs.Seeds of 132 RILs harvested from Lingshui and Hangzhou were cultivated in the nutrient solution,and four indices for seedling vigor were measured including seedling shoot length?SSL?,seedling root length?SRL?,seedling wet weight?SWW?and seedling dry weight?SDW?.Significant correlations were observed among the indices,and also between 1000-seed weight?TSW?and SWW or SDW.Combined with a high-resolution genetic map generated from sequencing of the RILs,65 quantitative trait loci?QTLs?were detected on all chromosomes.Among 57 QTLs for seedling vigor,28 were detected from seeds harvested in both sites and 33 were first identified.With BC₃F₂ derived from 93-11and a CSSL harboring segments from PA64S in 93-11 background,a major QTL for SSL,qSSL1b was fine mapped within 80.5 kb between two InDel markers on chromosome 1.Amylose content?AC?,gel consistency?GC?and gelatinization temperature?GT?are three main properties that determine rice cooking and eating quality.Using linkage genetic map with high-density SNPs,we detected 4 QTLs for AC,3 QTLs for GT and 5 QTLs for GC on chromosomes 2,3,4,5,6,10and 12,which included 1 QTL cluster for AC and GC.Combining the phenotype and genotype analysis,qGC-10 was further delimited in 355 kb region between two InDel markers on chromosome 10.Our study provides a platform for cloning of these QTLs and dissecting the molecular basis for seedling vigor at early seedling stage and the cooking and eating quality in rice.