Genetic Analysis for Mapping of Physiological Traits Related to Seed Vigour in Rice Through Association Mapping

Abstract Background:Good quality seed is an important factor for a good crop. Vigor is the key performing trait of quality seed. Genomic regions controlling the physiological traits related to seed vigour are not fully reported.Results: A panel was prepared by including genotypes from all the groups of the fifteen physiological traits representing a population of 250 germplasm lines. Wide variations were observed for the 15 physiological traits in the population. The population was classified into 6 genetic groups. Presence of linkage disequilibrium (LD) was detected in the panel population based on the fixation indices of the subpopulations. Moderate values of gene diversity, polymorphic information content (PIC) and other diversity parameters were estimated from the population by genotyping with 109 SSR markers. The population was classified into subpopulations and sub-clusters showed relation with the genotypes for their physiological traits. Ten physiological traits were detected to be significantly associated with SSR markers analyzed by both the General linear model (GLM) and Mixed linear model (MLM). A total of 19 novel QTLs controlling different physiological traits namely qGP 6.2 and qGP 8.2 for germination % (GP); qGR 9.1 for germination rate (GR); qGI 1.2, qGI 6.1, qGI 8.1, qGI 11.1 and qGI 12.1 for germination index (GI); qRPE1.1 and qRPE8.1 for rate of plumule elongation (RPE); qAGR 8.1 for AGR; qRSG1.2 and qRSG12.2 for rate of shoot growth (RSG); qRGR3.1 and qRGR11.1 for relative growth rate (RGR); qSVI 1.1 for seed vigour index I (SVI I); qSVII 1.1, qSVII3.1, and qSVII12.1 for seed vigour index II (SVI II), and qRRG8.1 for relative root growth rate were identified. The reported QTL for root length, qRL11.1 was validated in this mapping population. Additionally, QTLs, qRPE8.1 and qAGR8.1 of traits, RPE and AGR; qGI 6.1 and qGP6.2 of GI and GP; qGI 11.1 and qRL11.1 of GI and RL; qAGR8.1 and qRRG8.1 of AGR and RRG, and qRSG3.1 and qRGR3.1of traits RSG and RGR were detected for co-localization or co-inheritance. Conclusion: The traits identified and markers detected in the association analysis will be useful for improvement of seed vigour trait through marker-assisted selection in rice.