QTL mapping for Q-enzyme activity during grain development in rice

Abstract

Q-enzyme is important for the synthesis of rice grain starch and vital for grain filling. In this study, QTL (Quantitative trait locus) analysis for Q-enzyme activity during grain filling was carried out using recombinant inbred line population derived from the super rice Xieyou 9308. The activity of Qenzyme was greatest at 15 days after heading. In addition, the Q-enzyme activity in early stage (Q10 and Q15) showed significant correlation with the grain filling rate of each stage as well as the average grain filling rate. Nine maineffect QTLs for grain Q-enzyme activity were identified through QTL analysis, they were distributed on chromosome 2, 3, 5, 6 and 7, and the proportion of phenotypic variation explained (R 2 ) by individual QTLs ranged from 5.68% to 11.59%. Among them, qQ10-3 and qQ15-3-2 are located in the same region of RM282-RM6283 on chromosome 3. qQ10-7-1 was detected in two years with an average R 2 of 8.86%, and significant epistasis effect with environment was also identified. These results enhance our understanding of the genetic bases of Q-enzyme activity in rice grain.