Molecular dissection of genetic basis of significant correlation among five morphological traits in rice (Oryza sativa L.)

To enhance understanding of the genetic basis of trait correlation in rice, a recombinant inbred line (RIL) population (F₆ and F₇) from a cross between Zhenshan97 and HR5 was employed to identify main quantitative trait loci (QTLs) and epistatic QTL (E-QTL). Highly significant positive correlations were detected among five traits of heading date (HD), plant height (PH), panicle length (PL), flag leaf length (FLL) and flag leaf width (FLW) in 2 environments. Four to 8 main QTLs were detected for an individual trait. No E-QTL was detected for PH. One, 4, 4 and 5 E-QTLs were detected for FLL, HD, FLW and PL, respectively. Each E-QTL individually explained less than 3% of trait variation except E-QFll1. Comparison of QTL results was made in order to dissect the genetic basis of trait correlation. We found that main QTLs with pleiotropic effects and QTL clusters were the main genetic basis of trait correlation. No E-QTL had pleiotropic effects. E-QTL played an important role in the genetic basis of individual trait, but it made a little contribution to trait correlation.