Abstract
BackgroundRice yield has a complex genetic architecture, which mainly determined by its three component traits: the number of grains per panicle (GPP), kilo-grain weight (KGW) and tillers per plant (TP). Exploring ideotype breeding based on selection for genetically less complex component traits is an alternative route for further improving rice production. Thus, it is important that studying the genetic basis of relationship between rice yield and component traits and clarifying the effects of each component trait on yield. Main textIn this study, we carried out meta-analyses of genome-wide association study (Meta-GWAS) with two population (575 + 1495 F1) in different environment for yield and its three component traits in rice. Totally, 3589 significant loci for three components traits were detected, while only 3 significant loci for yield were detected. It indicated that rice yield is mainly controlled by minor-effect loci and hardly to be identified. Selecting quantitative trait locus (QTL)/gene affected component traits to further enhance yield is recommended. A Mendelian randomization (MR) design was adopted to further estimate the causal relationship between rice yield and its component traits. Both GPP (Beta=0.086, 95% CI: 0.030~0.141, P=0.003) and TP (Beta=1.865, 95% CI: 1.035~2.694, P<0.0001) has a positive causal relationship with yield, but no significant relationship between KGW and yield (Beta=0.456, 95% CI: -0.119~1.031, P=0.120) was observed. Additionally, TP (Beta=1.865) has a greater effect on yield than GPP (Beta=0.086). Four significant loci for TP and GPP with indirect effect on yield were identified. Pyramiding superior alleles of the four loci revealed improved yield. A combination of direct and indirect effects may better contribute to the yield potential of rice.ConclusionsOur results suggested rice production would improve by ideotype breeding based on selection for GPP and TP. By studying the nature and strength of the relationship between yield and its components, provide genetic insights for further improving rice yield potential.