Fine Mapping Of A Rolled Leaf Gene Rl_10(t) In Rice

Plant breeding has theoretically and practically improved crop yield by improving the light energy interception and utilization rate. The geometrical configuration and spatial arrangement pattern of plants could be regulated by shaping plant type, which could make individuals of population more flexible to adapt to both natural and artificial environments. Also, the improvement of population structure, leaf area index and dry matters throughput of the population are the most possibility. Leaf traits play an important role in ideal plant type, for example, plant with long rolled and straight leaves is viewed as a model of ideal plant type, because the permeation rate of rolled leaves is higher than that of smooth ones, which improves illumination condition of the basal parts at the mid and later stage, and further increases rice photosynthesis ability. Recently, several key genes regulating leaf development have been identified and cloned via genetic and molecular methods. Understanding leaf development mechanism is helpful to develop ideal plant types and increase rice yield.A rolled leaf mutant was obtained from indica cultivar Yuefeng B treated with 60Co-γray. The mutant was crossed with japonica cultivar Zhonghua 11 to establish F1 and F2 populations. In F1 population, all individuals had smooth leaves, while in F2 generation, there were two kinds of plants, smooth and rolled leaves, and the segregation ratio was fitted to 3: 1 which indicated that the rolled leaf trait was controlled by a recessive gene, which was tentatively designated as rl10(t).It was roughly mapped on chromosome 4 of rice between two SSR makers RM6089 and RM124, with genetic distances of 5.00cM and 7.86cM, respectively. The population was enlarged and 32 markers of SSR and STS were developed for fine mapping. The rl10(t) gene was further mapped between SSR4-25 and STS4-26 with both genetic distances of 0.11cM and the physical distance as 31.6kb. Seven candidate genes were found in this region, and 2 genes out of these 7 have bromodomains relating to leaf development.We observed the transverse section of the rolled leaf and normal leaf, found that mesophyll cell of lower epidermis is more than epicuticula in the mutant. Chamber of the small vascular bundle in the mutant is bigger in the wild type. Also, in the wild type both sides of the mesophyll cell are symmetrical.