J Integr Plant Biol. ›› 2013, Vol. 55 ›› Issue (10): 938-949.DOI: 10.1111/jipb.12062

Special Issue: Rice Genomics and Agriculture

• Molecular Ecology and Evolution • Previous Articles     Next Articles

GS6, A Member of the GRAS Gene Family, Negatively Regulates Grain Size in Rice

Lianjun Sun1,2†, Xiaojiao Li1,2†, Yongcai Fu1,2, Zuofeng Zhu1,2, Lubin Tan1,2, Fengxia Liu1,2, Xianyou Sun1,2, Xuewen Sun1,2 and Chuanqing Sun1*   

  1. 1State Key Laboratory of Plant Physiology and Biochemistry, National Center for Evaluation of Agricultural Wild Plants (Rice), MOE Key Laboratory of Crop Heterosis and Utilization, Beijing, China
    2Key Laboratory of Crop Genetic Improvement, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
  • Received:2013-02-27 Accepted:2013-05-01 Published:2013-08-02
  • About author:These authors contributed equally to this work
    *Corresponding author Tel/Fax: +86 10 6273 1811; E-mail: suncq@cau.edu.cn

Abstract:

Grain size is an important yield‐related trait in rice. Intensive artificial selection for grain size during domestication is evidenced by the larger grains of most of today’s cultivars compared with their wild relatives. However, the molecular genetic control of rice grain size is still not well characterized. Here, we report the identification and cloning of Grain Size 6 (GS6), which plays an important role in reducing grain size in rice. A premature stop at the þ348 position in the coding sequence (CDS) of GS6 increased grain width and weight significantly. Alignment of the CDS regions of GS6 in 90 rice materials revealed three GS6 alleles. Most japonica varieties (95%) harbor the Type I haplotype, and 62.9% of indica varieties harbor the Type II haplotype. Association analysis revealed that the Type I haplotype tends to increase the width and weight of grains more than either of the Type II or Type III haplotypes. Further investigation of genetic diversity and the evolutionary mechanisms of GS6 showed that the GS6 gene was strongly selected in japonica cultivars. In addition, a “ggc” repeat region identified in the region that encodes the GRAS domain of GS6 played an important historic role in the domestication of grain size in rice. Knowledge of the function of GS6 might aid efforts to elucidate the molecular mechanisms that control grain development and evolution in rice plants, and could facilitate the genetic improvement of rice yield.

Sun L, Li X, Fu Y, Zhu Z, Tan L, Liu F, Sun X, Sun X, Sun C(2013) GS6, a member of the GRAS gene family, negatively regulates grain size in rice. J. Integr. Plant Biol. 55(10), 938–949.

Key words: Domestication, GS6, grain size, haplotype, Oryza sativa, rice

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