The Screening Of Leaf Color Mutants And Primary Mapping Of Two Mutants To Chlorophyll-Deficiency In Rice

Mutant of rice leaf color, a kind of relatively common mutant type, can be used for the dissection of plant chloroplast structure, function, genetic, differentiation and development, chlorophyll biosynthesis and hormone adjustment. Because the phenotype of most of leaf color mutant can be observed during seedling stage, gene cloning work can be finished in a shorter time. Therefore, the related research of rice leaf color mutant on breeding, plant physiology research work has very important significance.In this study,we launched a larger-scale screen in a mutant library with WOI7, NJ11, 12Xinuo, Xia 951, IRAT118, SLG-1, Dongjin varieties as the background material by physical and chemical mutagenesis from professor An and Jiangsu Academy of Agricultural Sciences. We obtained 49 mutants of rice leaf color and investigated the phenotype in seedling and mature stage for the part of these materials. We also measured the part of the agronomic traits and studied the chlorophyll level changes. At the same time, an albino turned green mutant and a xanthan leaf mutant were selected for further study and the main results were as follows:1. The main result of leaf color mutant screening are as follows:In the spring of 2013, we sowed the seeds of M2 generation of the mutant pools with WOI7, NJ11,12Xinuo, Xia 951, IRAT118, SLG-1, Dongjin varieties as the background material by physical and chemical mutagenesis in Nanjing Agricultural University Pailou Breeding Base, each strain seeded 200 strains and repeated observation and identification. We obtained 49 mutants of rice leaf color and investigated the phenotype in seedling and mature stage for 5 materials. We also measured the agronomic traits such as plant height、 flag leaf length、width、panicle length. No of effective panicles per plant, and studied the chlorophyll level changes. The study made actively preparing for the next research.2. The main results of albino green-revertible mutant 2165 were as follows:(1) In this study, the albino green-revertible mutant 2165 was isolated from a spontaneous mutant pool of the hybrid generations from Nipponbare and Kasalath. The mutant showed an albino green-revertible phenotype in seedling stage in the field. In addition,we found agronomic traits such as plant height、flag leaf length、width、panicle length、No of effective panicles per plant showed no significant difference between the mutant and the wild type. This data indicated that the mutation of 2165 impressed the development of pant in rice.(2) The phenotype of mutant 2165 and wild type were surveyed at various temperatures. The leaves of mutant showed completely white in 23℃ incubator; The first and second leave of mutant showed albino in 25℃ incubator; The top and sides of The first and second leave of mutant showed white in 27℃ incubator; The leaves of mutant showed normal green. Compare the wild type, we found the contents of chlorophylls and carotenes were significantly reduced under 23,25 and 27℃ temperatures. But the contents of chlorophylls and carotenes were no significantly changed between the mutant and the wild type.(3) Ultrastructural analysis of chloroplasts showed the size of chloroplast became smaller and the thylakoids were nearly invisible in mutant under 23℃ temperature. Meanwhile, more osmiphilic bodies were observed in 2165 mutant. Furthermore, the inner structure of chloroplast of the albino green-revertible mutant 2165 had no significantly difference from the wild type under 30℃ temperature.(4) We used 50 recessive plants from F2 population of the mutant 2165 and N22 to conduct a preliminary mapping and the result showed that it was located at the long arm of chromosome 5, between RM31 and the end of the long arm of chromosome 5. We did not find related genes were reported in this area, so we think that it is a valuable new gene.3. The main results of a xanthan leaf mutant T113 were as follows:(1) In this study, the xanthan leaf mutant T113 was isolated from a T-DNA mutant pool with Dongjin varieties as the background material. The mutant showed a xanthan leaf phenotype in whole developing stage. Meanwhile, the plant height of the mutant was lower than that of the wild type. The phenotype of mutant was not affected by temperature. We also found that flag leaf length、width、panicle length、No of effective panicles per plant were no significantly difference between the mutant and the wild type.(2) Compare the wild type, we found the contents of chlorophyll a, chlorophyll b and carotenes were significantly reduced in the field. Most interesting is that the variance of these pigment content in maturation stage was noteworthy smaller than seedling period. In summary, the difference of pigment content and phenotype was relatively consistent.(3) Ultrastructural analysis of chloroplasts showed the chloroplast of mutant was brighter than wild type. The result may be associated with the mutant developed loosed thylakoid lamellar structures.