[A new rice dwarf1 mutant caused by a frame-shift mutation]

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.