| Mutants of rice leaf color are powerful materials for the dissection of photosynthesis, genetic characteristics, differentiation, development, and the chloroplast internal biochemical process. Because the phenotype of most of the leaf color mutant can be observed during seedling stage, gene mapping work can be finished within one year, while most other traits have to wait until the plants mature. Leaf color mutant also can be used in breeding and basic research. Therefore, the research of the leaf color mutant has the very vital significance, has been loved by researchers.In this study, a new rice green-white-stripe mutant was obtained from the M2 progeny of a 60Co-irradiated population of the indica cultivar 9311. This mutant was designated as B38. The phenotype in seedling stage and the matured stage are described, and we still investigated the agronomic traits, the chloroplast ultrastructure and thermosensitivity. Then through its phenotypic analysis of F1, F2 generations, the genetic control of the mutant is determined. Further, we used molecular markers for mapping. The main results were as follows:1. The green-white-stripe mutant B38 showed a white-stripe phenotype in seedling stage in the field. The phenotype of the second leaf is the most obvious. This mutant phenotype gradually turn normal as the rice development. There was almost no difference between the mutant and the wild type. The agricultural traits such as the plant height, the panicle length, the tillers number and the seed setting rate, etc. were nearly the same.2. Mutant B38 were observed at various temperatures. In 30℃ incubator (the condition of high temperature), the first, second and third leaf of B38 were all showed the white stripe characteristic, especially the second leaf which is the most obvious. In 26 ℃ incubator, the first, third leaves do not show mutant phenotype except the second leaf. Mutants in 23 ℃ incubator, leaves show nearly no white stripes.3. The inner structure of chloroplast of the green-white-stripe mutant B38 had obvious difference from the wild type 9311 under the transmission electron microscope. There is not chloroplast in the albino part cells, while normal in wild type 9311.4. The population of B38 crossed with wild type indica varieties 9311 was used in genetic analysis. The result showed that leaf color of F1 progenies showed normal green, and segregation ratio of normal green to virescent fitted the expected ratio of 3:1 in F2 population, suggesting that the green-white-stripe trait of B38 was controlled by one pair of recessive nuclear gene.5. The F2 population of B38 and Hdl was used as the preliminary mapping population. The preliminary mapping of B38 using 10 recessive plants from F2 progeny showed that it was located at the long arm of chromosome 1, between RM129 and RM11307. The F2 and F23 populations of B38 and Hdl for precise positioning with the F2 population of B38 and NJ45. The gene was further restricted between b-12 and b-44 at an interval of 34kb on the physical map.6. We got six candidate ORFs through http://rice.plantbiology.msu.edu and http://www.gramene.org. According to http://wolfpsort.org, two of these proteins was predicted to be localized in the chloroplasts. Sequecing analysis found that there is a 6 bp deletion in one of gene, leading to the termination of translation in advance. |
PDF Full Text Request