J Integr Plant Biol. ›› 2009, Vol. 51 ›› Issue (4): 393-408.DOI: 10.1111/j.1744-7909.2008.00807.x

• Molecular Physiology • Previous Articles     Next Articles

Additive and Over-dominant Effects Resulting from Epistatic Loci Are the Primary Genetic Basis of Heterosis in Rice

Xiaojin Luo1,2,3,4, Yongcai Fu1,2,3, Peijiang Zhang5, Shuang Wu1,2,3, Feng Tian1,2,3,Jiayong Liu1,2,3, Zuofeng Zhu1,2,3, Jinshui Yang 4and Chuanqing Sun1,2,3*   

  1. 1Department of Plant Genetics and Breeding and State Key Laboratory of Plant Physiology and Biochemistry, China Agricultural University, Beijing 100193, China
    2National Centre for Evaluation of Agricultural Wild Plant (Rice), Beijing 100193, China
    3Beijing Key Laboratory of Crop Genetic Improvement and Genome of Ministry of Agriculture, Beijing 100193, China
    4State Key Laboratory of Genetic Engineering, Morgan-Tan International Center for Life Sciences, School of Life Sciences, Fudan University, Shanghai 200433, China
    5Institute of Rice Research, Anhui Academy of Agricultural Sciences, Hefei 230031, China
  • Received:2008-07-04 Accepted:2008-10-20 Published:2009-03-31
  • About author:*Author for correspondence Tel/Fax: +86 10 6273 1811; E-mail: suncq@cau.edu.cn

Abstract:

A set of 148 F9 recombinant inbred lines (RILs) was developed from the cross of an indica cultivar 93-11 and japonica cultivar DT713, showing strong F1 heterosis. Subsequently, two backcross F1 (BCF1) populations were constructed by backcrossing these 148 RILs to two parents, 93-11 and DT713. These three related populations (281BCF1 lines, 148 RILs) were phenotyped for six yield-related traits in two locations. Significant inbreeding depression was detected in the population of RILS and a high level of heterosis was observed in the two BCF1 populations. A total of 42 main-effect quantitative trait loci (M-QTLs) and 109 epistatic effect QTL pairs (E-QTLs) were detected in the three related populations using the mixed model approach. By comparing the genetic effects of these QTLs detected in the RILs, BCF1 performance and mid parental heterosis (HMP), we found that, in both BCF1 populations, the QTLs detected could be classified into two predominant types: additive and over dominant loci, which indicated that the additive and over-dominant effect were more important than complete or partially dominance for M-QTLs and E-QTLs. Further, we found that the E-QTLs detected collectively explained a larger portion of the total phenotypic variation than the M-QTLs in both RILs and BCF1 populations. All of these results suggest that additive and over dominance resulting from epistatic loci might be the primary genetic basis of heterosis in rice.

Luo XJ, Fu YC, Zhang PJ, Wu S, Tian F, Liu JY, Zhu ZF, Yang JS, Sun CQ (2009) Additive and over-dominant effects resulting from epistatic loci are the primary genetic basis of heterosis in rice. J. Integr. Plant Biol. 51(4), 393–408.

Key words: additivity, epistasis, heterosis, over-dominance, quantitative trait locus.

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