Characterization And Gene Mapping Of Rolled Leaf Mutant 28 (rl28) In Rice (Oryza Sativa L.)

Leaves are vital organs for photosynthesis, which play an irreplaceable role in growth of plants. Plants provide the material energy and energy sources for almost all organisms, including humans, throughout photosynthesis. Multicellular organisms in the long process of evolution, leaves formed many unique structures, and some organ or tissue formed collaboration growth pattern form accepting the transformation of energy into consumption of energy. As a model plant, the development mechanism of rice leaf has been a hot research in genetics, and leaf is an important aspect in plant morphogenesis, which is closely related with plant type and yield. Therefore, the research on rice leaves not only for us to get a deep understanding of leaf morphogenesis, but also for increasing rice yield and quality via biodesign.This study reported a new rolled leaf 28 (rl28), which was derived from EMS-treated restorer line Jinhui10. In this study, using Jinhui10 as wild type control, the morphological analysis, agronomical characters analysis, cytological analysis, genetic analysis and molecular mapping of rl28 was reported. The results as follows:1. Morphological AnalysisCompared with the wild type, rl28 had no significant difference in the seedling stage, while the leaves of rl28 began to curl along the medial axis pulse from jointing stage, which lasted until the plants matured. From the fall to the third, leaf rolling index of wild type were below 10%, however, that of rl28 were more than 70%, all were significantly higher than those of the wild-type, and leaf angles were less than those of wild-type, decreased by 3.1%,5.2%,4.5%.2. Agronomical Characters Analysisrl28 mutant demonstrated rolled leaf traits in the jointing stage. Agronomical characters analysis displayed, the plant height,1000-grain weight, panicle length, effective panicles, leaf length and width of the flag, the second, the third of rl28 had no difference with wild type, but seed setting rate account for about 40.2% of the wild type.3. Histological AnalysisIn order to find the main reason responsible to the formation of rolled leaf, we took the fresh leaves of the rl28 and the control in the period of the rolled leaf trait fully performance expressed, and made them into paraffin sections. The results showed that, compared to the wild type, midrib of rl28 was much larger, and the number of the two adjacent vesicular cells decreased. DL (DROOPING LEAF) is a key gene for regulating midrib development in rice, the area of rl28’midrib increased significantly, thus using QPCR detected the expression of DL in the wild type and rl28, but the results show no significant difference between them. Scanning electron microscopy indicated that stomata number per 10-5 m2 and stomatal conductance were significantly higher than that of the wild-type, transpiration rate was significantly higher than that of wild-type.4. Genetic Analysis of the rolled leaf traitIn this study, reciprocal hybrid between the rolled leaf mutant rl28 and Xinong 1A was done for genetic analysis. In F1 population, all leaves showed exactly the same phenotype as the rl28, which indicated that the mutational trait was controlled by a single recessive nuclear gene. While there is a clear separation in F2 generations, which performance characters of both parents, smooth leaves (2280):rolled leaves (752) full compliance with 3:1 segregation ratio (X2=0.05<X2 0.05=3.84), which suggested that the traits of rl28 were controlled by a single recessive nuclear gene. 5. Molecular Mapping of the Rolled Leaf GeneRL28 gene was located between primers RM3664 and RM19160 preliminary on fifth chromosome by bulked segregation analysis, with the genetic distance 8.57 cM and 10.24 cM. RL28 was finally mapped on chromosome 5 between SSR maker 5-43 and 5-34 with an interval of 90 kb, containing 12 ORFs, during which,3 are expressed protein,2 encodes retrotransposon protein,2 encodes fasciclin domain containing protein,1 encodes glutaredoxin,1 encodes auxin response factor 15,1 encodes splicing factor U2AF,1 encodes zinc finger, and 1 encodes ras-related protein. These results provide a foundation for cloning and function analysis of RL28.