Effect of allelic combinations of grain-size regulating genes and rice grain size predicting

Abstract Rice is one of the most important crops in the world. Increasing rice yield can help alleviate the current global food shortage. Rice grain size directly affects rice grain yield and is an important target quantitative trait. Many genes regulating grain size have been mapped and cloned in recent years. However, there are few studies on the effect of different allele combinations of grain-size regulating genes. Here we studied the effect of different allele combinations of seven major grain size-regulating genes ( GS3 , GS5 , GW8/OsSPL16 , BG2 , GS6 , GS2 and TGW3 ) on grain size-related traits (grain length, grain width, grain length width ratio, thousand grain weight). We found that different allele combinations displayed significant variation in effect on rice grain size, and specific allele combinations such as GS3 -A, GS6 -Ⅰ, BG2 -Nipponbare and TGW3 -CW23 can improve grain weight. In addition, among seven genes, GS3 gene played the most important effect in regulating grain size, pyramiding GS3 alleles with other genes which have insignificant effect on grain size could significantly enhance grain size and weight. We also established multiple regression equations to predict rice grain size, which contributed to developing rice varieties with ideal traits and high yield.