Genetic Analysis And Gene Mapping Of A Tillering Angle Mutant In Rice

Tiller is a special branch which in the formation of rice growth and development, is an important indicator of plant type and is closely related to grain yield.Tillering and leaf morphology is an important part of the study on plant type, tiller angle control the gap between the tiller and the blade profile, which directly change the photosynthesis and disease resistance of rice, thereby affecting the growth and yield of rice. With the published of rice genome information and the rapid development of disciplines relate to molecular biology, laid the foundation for the understanding of the nature of the growth and development of rice in molecular level. Plant type-related genes in rice, especially genes related to tiller angle, play important role in ideal plant type breeding, high-yield breeding as well as improved varieties in rice. Through the observation and analysis of the field materials,we obtained a rice large tiller angle mutant X32, then associated genetic analysis, morphological observation, gene mapping and preliminary functional analysis were studies in this paper.The main results are as follows:1. A mutant X32exhibited large tiller angle from the first tiller to heading tillers, then in the late heading stage, stems experienced some degree of recovery upright.Compared with the wild-type, the angle between leaf and stem increases and plant type dispersed in mutant X32.2.Crossing the mutant X32 with indica variety Xieqingzao B, F1 plants showed compact plant. Among F2 segregation progeny, compact plants and large plants tiller angle matched with the 3:1 segregation ratio, indicating that the large tiller angle mutant trait was caused by a recessive mutation.3. The wild-type and mutant seedlings grown for three days in normal and then given the stimulus of gravity, both the wild-type and mutant were able to feel the change in the direction of gravity, and gradually restored to the growth of negative gravity. But in comparison to the wild-type recovery from a horizontal state to a growth direction of gravity at the same rate more slowly, the roots were no significant difference in response to gravity.4.Treated with different light conditions, we observed that the mutant showed maximum tiller angle under 16 h light/8 hours dark, however minimum tiller angle under 8 h light/16 h dark. The results indicated that the tiller angle of mutants was regulated by light duration. By reprocessing plant seedlings under different lengths of light, then to gravity stimulate,we observed that the tiller angle of mutants changed to 24.52 °by 16 h light/8 h dark treatment, changed to 26.59 "after 12 h light/12 h dark treatment, and changed to 33.52° after 8 h light/16 h darkness treatment. Compared to the other two treatments,8 h light/16 h dark treatments were highly significant. Thus, the length of light exposure has effect on the gravitational reaction of mutants.5. F2 populations were generated from crosses between the mutant X32 and indica cultivar Xieqingzao B, and a total of 813 large tiller angle F2 plants were choose as F2 separation plants in Lingshui, Hainan.Among 80 F2 individuals for gene mapping, the single recessive large tiller angle locus was initially located on chromosome 11 between RM26652 and InD151, two markers 20-cM apart. By using more individual genotypes, we mapped the locus between L-3 and M265, at a physical interval of 62.5-kb.These results provide the basis for large tiller angle gene cloning and explaining the role of light in plant type built.