Genetic Analysis And Gene Mapping Of Two Leaf-color Mutants In Rice

The plant of which the leaf color is changed and stably inherited is so called plant leaf color mutant.Rice leaf color mutants are usually used for studying the development of chloroplasts and the molecular mechanisms of photosynthesis.In addition,these mutants can also be utilized as early marker to remove off-Type seedlings in the industry of hybrid seed production.In this study,we characterized two leaf color mutants and mapped the mutated genes responsible for the abnormal leaf color.The main results are listed below.The white stripe leaf mutant stll was obtained from tissue-cultured rice Kitaake(Oryza saliva spp Japonica).This mutant exhibited its white stripe leaf phenotype from tillering through mature stages.Compared with the wild type Kitaake,the mutant stll did not show any obvious changes in agricultural traits,including tiller numbers,plant height,seeds-setting rate,and grain weight.The pigment content in stll was obviously reduced compared to that in Kitaake.Genetic analyses showed that the white stripe leaf phenotype in the mutant stll was controlled by a single recessive gene.By using two F2 segregating populations derived from the crosses,sill×Jodan and stll×02428,respectively,we mapped stll on the interval between the marker RM151 and RM10080 on chromosome 1.We then used more molecular markers to perform mapping and finally delimited the gene Stll on the region of about 270kb between the Indel markers,114 and 126.Our study provided a strong base for cloning and utilizing of stll.The other mutant yl-k2 which showed yellow leaf mutant was also obtained from tissue-cultured rice Kitaake(Oryza sativa spp Japonica).This mutant exhibited its yellow leaf phenotype obviously from germination through three-leaf stages.At the mature stage,we found that the tiller number of yl-k2 was clearly reduced when compared to the wild type Kitaake.Genetic analyses revealed that the yellow leaf phenotype in the mutant yl-k2 was controlled by a single recessive gene.Further analysis indicated that the yellow leaf phenotype in yl-k2 was co-segregated with the hygromycin gene,suggesting that the mutation might be resulted from T-DNA insertion during tissue culturing.However,we failed to clone the gene yl-k2 through isolation the T-DNA flanked rice genomic DNA sequence.We then developed two F2 segregating populations from the crosses,yl-k2×Jodan and yl-k2×02428,respectively,and performed mapping of the gene yl-k2.We found that yl-k2 was located on the interval between the marker RM25898 and RM25811 on chromosome 10.Using additional molecular markers nearby,we finally mapped the gene yl-k2 on the region of about 250 kb between the two markers,RM333and RM25898.These results made a solid base for cloning of yl-k2.