GS3, a major QTL for grain length and weight and minor QTL for grain width and thickness in rice, encodes a putative transmembrane protein

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Chuchuan Fan, Yongzhong Xing, Hailiang Mao, Tingting Lu, Bin Han, Caiguo Xu, Xianghua Li, Qifa Zhang
Theoretical and Applied Genetics, 2006, 112(6): 1164-1171  DOI: 10.1007/s00122-006-0218-1     追溯原文......本站官方QQ群:62473826

The GS3 locus located in the pericentromeric region of rice chromosome 3 has been frequently identified as a major QTL for both grain weight (a yield trait) and grain length (a quality trait) in the literature. Near isogenic lines of GS3 were developed by successive crossing and backcrossing Minghui 63 (large grain) with Chuan 7 (small grain), using Minghui 63 as the recurrent parent. Analysis of a random subpopulation of 201 individuals from the BC3F2 progeny confirmed that the GS3 locus explained 80–90% of the variation for grain weight and length in this population. In addition, this locus was resolved as a minor QTL for grain width and thickness. Using 1,384 individuals with recessive phenotype (large grain) from a total of 5,740 BC3F2 plants and 11 molecular markers based on sequence information, GS3 was mapped to a DNA fragment approximately 7.9 kb in length. A full-length cDNA corresponding to the target region was identified, which provided complete sequence information for the GS3 candidate. This gene consists of five exons and encodes 232 amino acids with a putative PEBP-like domain, a transmembrane region, a putative TNFR/NGFR family cysteine-rich domain and a VWFC module. Comparative sequencing analysis identified a nonsense mutation, shared among all the large-grain varieties tested in comparison with the small grain varieties, in the second exon of the putative GS3 gene. This mutation causes a 178-aa truncation in the C-terminus of the predicted protein, suggesting that GS3 may function as a negative regulator for grain size. Cloning of such a gene provided the opportunity for fully characterizing the regulatory mechanism and related processes during grain development.

水稻粒长和粒重主效QTL和粒宽和籽粒厚度微效QTL GS3编码一个可能的跨膜蛋白

位于水稻3号染色体着丝粒附件区域的GS3位点在文献中经常被鉴定为粒重(产量性状)和粒长(品质性状)的主效QTL。以明恢63(大粒)为轮回亲本与川7(小粒)进行连续杂交和回交,构建了GS3的近等基因系。对BC3F2后代的201个随机个体进行分析表明了GS3解释了该群体80%-90%的粒重和粒长的变异。另外,该位点还被确定为粒宽和籽粒厚度的微效QTL。从总共5740个BC3F2个体中挑出1384个隐性个体,利用11个分子标记将GS3定位在大约长7.9kb的DNA片段。从该目标区域内鉴定出了一个全长cDNA,为GS3的候选基因提供了完整的序列信息。该基因含有5个外显子,编码一个232个氨基酸的蛋白,含有类PEBP结构域,跨膜区,TNFR/NGFR家族富含半胱氨酸结构域和VWFC模块。对GS3基因进行序列比较分析,在第二个外显子中鉴定出了一个无义突变,与小粒品种相比该突变在所检测的所有大粒品种中都存在。该突变导致GS3蛋白C端缺失了178个氨基酸,这表明GS3可能是籽粒大小的负调节因子。
结果:GS3是粒长和粒重的主效QTL和粒宽和籽粒厚度的微效QTL;将GS3定位在7.9kb的DNA片段;GS3编码一个可能的跨膜蛋白;蛋白翻译提前终止导致了长粒的表型。


基因列表
  粒长粒重主效控制基因 GS3