A Rice Leaf Mutant Of Genetic Analysis And Gene Location

Rice is one of the most important crops in the world. So increasing the yield of rice is great significance to survival of human. Leaf is a main organization for its photosynthesis and transpiration. Moderate leaf rolling can remarkably improve the base of the rice receiving light and have enough air. Therefore rice with moderate leaf rolling is ideal plant type for high yield.In this study,we made cross combination using the rolled leaf mutant and indica variety Longtepu (Oryza sativa L.ssp.Indica cv.Longtepu). F2generation as mapping population was used to map target gene which is control the rolled leaf trait. In addition, we identified and analyzed the phenotype and genetic principles in detail. The results are as follows:1. Agronomic trait and morphological analysisThe leaf of mutant curled inward along the veins into a semi-cylinder-shaped in all life cycle of rice. Under the same external conditions, the average plant height of mutant was49cm is lower than the average of wild-type that is99cm.Compared with the wild-type, the length of the every internode length of mutants were shorter. The average panicle length of mutant and wild-type were13.8cm and20.1cm. The panicle length were shaply reduced than the wild-type.In addition, the leaves of mutant were narrow, the average width of flag leaf and the leaf near flag-leaf in mutant were0.8cm and0.6cm, while those were1.4cm and1.2cm in wild-type. The width of leaves were shaply reduced than that in the wild-type.2. Chlorophyll content analysisThe color of leaves in mutant was lighter than that in wild-type.So we measured the chlorophyll content of mutant and the wild type in the early of heading.And the results showed that the contents of chlorophyll a and chlorophyll b were significantly reduced in the mutant.3. The histological observation and analysisTo explain the reason of rolled leaf on the morphology,we took the fresh leaf of the wild-type and mutant, and then made them into paraffin seetions. The results showed that, the number of the large and small vaseular bundles of mutant leaf were reduced compared with the wild-type.These difference may lead to the mutant leaves curled inward along the veins.4. Genetic analysis of the rolled leaf traitTo analyze the genetic principle of mutated trait, we investigated the numbers of the mutant and wild type plants in F2segregated population. The result showed that the wild type plants and the mutant plant were844and274plants respectively in total1118F2plants. The segregation ratio is conformed with3:1by the χ2test. The results confirmed that the mutant trait is controlled by a single recessive gene.5. The mapping of the rolled leaf geneTo map target gene related to rolled leaf trait,after mading the DNA mixed pool of F2,we choosed selected72pairs of SSR markers, which uniformly coverdcoverage the whole rice genome and showed polymorphisms between the parent to carry out primary mapping.These SSR markers were used to PCR for screening,and found that, two SSR markers. The result showed that ML1and ML2on the chromosome12showed strains linkagelinked with the target gene trait on the chromosome12. And Five and eight combinants in the ML1and ML2position were found in80F2target individuals respectively. And then, we carried out fine mapping of the target gene. And at last, the target gene was narrowed110.006kb region,between SSR markers ML6and ML7.