The Studies On Fine-mapping And Molecular Ecology Of Stem Gravitropism Response Mutant Gene In Rice

The responses to plant gravitropism can be divided into three stages: gravity perception. signal transduction and asymmetric growth. Some gravitropism genes have been mapped or cloned in Arabidopsis.tomato and maze. Great progress has been made in cognition to plant gravitropism mechanism. A geotropism mutant was isolated from indica type rice 9311 treated with 0.15% EMS (ethylmethane sulphonate), named stem gravitropism response mutant,for the gravitropism research. Classical genetic studies, morphological observation, the construction of mapping population, first-pass mapping and fine-scale mapping were done in the dissertation. The main results are summarized as follows:1 The roots of mutant is ablity to sense the gravity and has positive gravitropism, the upperground of mutant grows groundlingly. The nodes in the stem bend suddenly as heading time. The base of vagina can not sense gravity completely, the phenotype of wildtype and sgrm mutant has no change in Agarose with gibberellin and 2, 4-D or in the dark compared with normal conditions, showed that the phenotype of the mutant have no relations with the three exterior condotions.2 The mutant crossed with its wild type Japonica rice zhonghua11, taijing14, taijing19, taijing20, jinggao and RBQ respectively, the phenotype of F1 was similar with the wild type, the result of genetic analysis for F2 population indicated that the mutant is controlled by a single recessive gene.3 Through the fine-scale mapping, the target gene was mapped between two SSR markers, RM26668 and RM26686,which belong to PAC/BAC clones AC137586 and AC135398, with genetic distance 0.4cM and 0.8cM respectively on chromosome 11 near the centromere.