Appraisal And Preliminary Gene Location Of A White Leaf Sheath Mutant In Maize

Color mutation material is one of the basic material for molecular breeding and function research, color change could be used as morphological markers to guide the breeding of special traits, such as the selection of associated traits and genetic research. Therefore, exploring the related mutant of plants color, and using normal mutant to locate the related normal regulation genes are of great theoretical significance and application value.And it is the ideal material to carry out basic theory studies such as genetic and development of plant chloroplast, chlorophyll synthetic and regulation approach, and the molecular mechanism of photosynthesis. In-depth study is of important theoretical significance to elucidate the mechanism of photosynthesis regulation and use of genetic engineering to improve the photosynthetic efficiency of crops, and thus to increase crop yields and improve crop varieties.In this study, we chose maize white leaf sheath mutant K10under natural conditions as research object, and use forward genetic approach to the phenotypic characteristics, light and pigment, and anthocyanin content, chloroplast ultrastructure, genetic methods to systematic study. We have finished the gene positioning of white sheath mutant trait and found SSR molecular markers adjacent to the target trait gene, which is designed to lay the foundation for further fine mapping and cloning of the gene, as well as explore the genetic development of chloroplast and biosynthetic pathway of anthocyanin. The main findings are as follows1.The phenotypes characteristics of maize with white leaf sheath mutant K10The material is inbred line with light green seedling and ivory leaf sheath. The average height is172cm, adult plant has18-19leaves. The male has3-5branches, yellow filaments. Less pollen, male and female panicle are physical coordination. When the color of leaf sheath mutate into white, photosynthetic efficiency and production reduces, and the growth period is shortened to10d, as well as the seriously premature aging phenomenon of plant emerges2. The genetic feature of white leaf sheathWe hybridize mutant K10and nine normal varieties, then observe the leaf color and do genetic analysis, the results show that all the combination Fl generation are normal green color phenotype, the separation ratio of normal green and white leaf in F2generation does not accord with mendel’ s law, and it did not appear in certain separation ratio. The results show that the traits of mutant K10is controled by several recessive nuclear genes.3. Determination of photosynthetic pigments contentThe seedling25days, the jointing stage, the silking shedding of the chlorophyll content of K10are lower than the same period of wild-type. After jointing stage, the differences are significant narrowing, and have little to do with the content of pollen-shedding. The content changes of photosynthetic pigment show that the dynamic change of photosynthetic pigment content in various components of mutant in the process of the maize plant growth is the same with the green leaves plant. The content determination of anthocyanins show that the flavonoid content in different parts from the same the growing period of mutant K10, normal green plants and purple plant is different.4. The ultrastructural changes of mutants chloroplasts K10We use the transmission electron microscopy to observe the chloroplast ultrastructure of the maize in normal green and white leaf sheath in F2generation, the results show that there is little complete chloroplasts structure in the jointing stage white sheath cells. And most of them do not have thylakoid slice layer and grana. Normal green leaf cells have more chloroplast, apparent thylakoid grana slice layer structure, tidy and compact thylakoids, as well as complete chloroplasts double membrane and grana thylakoids with internal mutual connection which could be observed.5. Positioning the leaf color mutant gene of mutants K10Using the SSR molecular marker combined with the BSA method to do the gene mapping of white leaf traits, we choose540SSR primers on10chromosomes of maize, obtain17parents and DNA pool polymorphism between primer, preliminary position the gene on8and9chromosome.