Development of hybrid rice with high yield and grain quality is a goal of rice breeding. To investigate the genetic mechanism of heterosis for rice milling and appearance quality in indica/xian rice, QTL mapping was conducted using 1061 recombinant inbred lines (RILs) derived from a cross of the xian rice cultivars Quan9311B (Q9311B) and Wu-shan-si-miao (WSSM), and a backcross F1 (BC1F1) population developed by crossing the RILs with Quan9311A (Q9311A), combined with phenotyping in two environments. The F1 hybrid (Q9311A × WSSM) showed various degrees of heterosis for milling and appearance quality. A total of 142 main-effect QTL (M-QTL) and 407 pairs of epistatic QTL (E-QTL) were identified for five milling and appearance quality traits and grain yield per plant (GYP) in the RIL, BC1F1 and mid-parental heterosis (HMP) populations. Differential detection of QTL in three populations revealed that most additive loci detected in the RILs did not show heterotic effects, but some of them did contribute to BC1F1 trait perfor-mance. Unlike heterosis of GYP, single-locus overdominance and epistasis were the main contributors to heterosis for milling and appearance quality. Epistasis contributed more to the heterosis for milling qual-ity than to that for appearance quality. Three (four) QTL regions harboring opposite (consistent) direc-tions of favorable allele effects for GYP and grain quality were identified, indicating the presence of partial genetic overlaps between GYP and grain quality. Three strategies are proposed to develop hybrid rice with high yield and good grain quality:1) pyramiding favorable alleles with consistent directions of gene effects for GYP and grain quality at the M-QTL on different chromosomes;2) introgressing favorable alleles for GYP and grain quality into the parents and then pyramiding and fixing these additive effects in hybrids;and 3) pyramiding overdominant and dominant loci and minimizing or eliminating underdom-inant loci from the parents.

Hui You;Sundus Zafar;Fan Zhang;Shuangbing Zhu;Kai Chen;Congcong Shen;Xiuqin Zhao;Wenzhong Zhang;Jianlong Xu

Rice Research Institute,Shenyang Agricultural University,Shenyang 110866,Liaoning,China;The National Key Facility for Crop Gene Resources and Genetic Improvement,Institute of Crop Sciences,Chinese Academy of Agricultural Sciences,Beijing 100081,China;Shenzhen Branch,Guangdong Laboratory for Lingnan Modern Agriculture,Agricultural Genomics Institute at Shenzhen,Chinese Academy of Agricultural Sciences,Shenzhen 518120,Guangdong,China;Hainan Yazhou Bay Seed Lab/National Nanfan Research Institute(Sanya),Chinese Academy of Agricultural Sciences,Sanya 572024,Hainan,China

作物学报（英文版）

[1]Hui You;Sundus Zafar;Fan Zhang;Shuangbing Zhu;Kai Chen;Congcong Shen;Xiuqin Zhao;Wenzhong Zhang;Jianlong Xu-.Genetic mechanism of heterosis for rice milling and appearance quality in an elite rice hybrid)[J].作物学报（英文版）,2022(06):1705-1716

Quan9311B,Q9311B,miao,WSSM,backcross,Quan9311A,Q9311A,GYP,heterotic,Epistasis,pyramiding,introgressing,overdominant,underdom

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