从一批水稻品种“中花11” 组织培养苗里分离到一个矮化突变株“C6PS”, 它的T2代群体株高呈现3:1分离。利用该群体矮化单株与“珍汕97”、“牡丹江8”构建2个F2群体F2(CZ)、F2(CM), 两个群体中高株与矮株均呈现3:1分离, 证明该性状变异为单基因控制。“C6PS” 表现型与已经报道的Dwarf1隐性突变体“d1”相似, 以D1附近标记RM430检测F2(CZ) 群体基因型, 结果显示群体表型与RM430基因型呈极显著相关(P=0.0001), 将该基因初步定位于Dwarf1附近。对“C6PS”及“中花11”进行D1序列分析显示, 突变株中D1基因在其第九个外显子与第九个内含子的剪接位点上发生6个碱基的缺失, 根据缺失两侧序列设计C6PS-D1L/R标记, 在T2代群体该标记与表型呈现共分离, 表明“C6PS”是一种新的Dwarf1突变体。cDNA测序显示突变体d1基因转录产物发生26个碱基的缺失, 导致移码产生终止突变, 从而无法翻译出有功能的Gα蛋白, 因此, 它是一个Gα功能缺失突变体。叶倾斜度检测显示“C6PS”对油菜素内酯响应比野生型“中花11”弱。
A dwarf mutant C6PS, which has the similar phenotype as the recessive mutant Dwarf1 (d1), was produced from tissue-cultured plants of Zhonghua 11. In its progeny (T2), the ratio of tall to dwarf plants was in agreement with the expected segregation ratio (3:1) of a single Mendelian inheritance gene, which indicated that the variation of plant height is caused by a single gene. To locate the mutation, C6PS was crossed with Zhenshan 97 and Mudanjiang 8 for producing two F2 populations of F2 (CM) and F2 (CZ), respectively. The plant height in each F2 population also showed the same segregation pattern as that in T2 generation. SSR marker RM430 closely linked to Dwarf1 was preferentially used to genotype the F2 (CZ) population because C6PS showed the similar phenotype to d1 mutant. RM430 was significantly associated with plant height, which indicated that the mutant gene might be D1. Comparative sequencing of D1 between C6PS and Zhonghua 11 showed a 6 bp deletion occurred in the splice site of its ninth exon. The marker C6PS-D1L/R designed on the 6 bp deletion was co-segregated with plant height in T2 generation. The results indicated that C6PS was a new mutant of D1. This mutation led to a 26 bp deletion of the transcript and resulted in a frame-shift mutation and a premature stop codon in C6PS, which could not translate the functional Gα protein. C6PS was weakly sensitive to Brassinolide based on the leaf inclination angle test.
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