Characterization of a rice chlorophyll-deficient mutant using the T-DNA gene-trap system
Jung, K.H. (Pohang Univ. of Science and Technology, Kyungbuk (Korea R.)) | Hur, J. | Ryu, C.H. | Choi, Y. | Chung, Y.Y. | Miyao, A. | Hirochika, H. | An, G.
We have previously generated a large pool of T-DNA insertional lines in rice. In this study, we screened those T-DNA pools for rice mutants that had defective chloro-phylls. Among the 1,995 lines examined in the T2 generation, 189 showed a chlorophyll-deficient phenotype that segregated as a single recessive locus. Among the mutants, 10 lines were v-glucuronidase (GUS)-positive in the leaves. Line 9-07117 has a T-DNA insertion into the gene that is highly homologous to XANTHA-F in barley and CHLH in Arabidopsis. This OsCHLH gene encodes the largest subunit of the rice Mg-chelatase, a key enzyme in the chloro-phyll branch of the tetrapyrrole biosynthetic pathway. In the T2 and T3 generations, the chlorina mutant phenotypes are co-segregated with the T-DNA. We have identified two additional chlorina mutants that have a Tos17 insertion in the OsCHLH gene. Those phenotypes were co-segregated with Tos17 in the progeny. GUS assays and RNA blot analysis showed that expression of the OsCHLH gene is light inducible, while TEM analysis revealed that the thyla-koid membrane of the mutant chloroplasts is underdeveloped. The chlorophyll content was very low in the OschlH mutants. This is the first report that T-DNA insertional mutagenesis can be used for functional analysis of rice genes.
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