Characterization Of Three Plant-type Related Mutants In Rice

With accomplish of the rice genome sequence project, elucidating the molecular basis of gene biological functions was the next challenge in post genomic era. Plant-type was the main factor in rice yield. Elucidated the molecular mechanisms of plant-type development will provide the theoretical fundament for rice breeding. Three mutants related to plant-type, i.e. Brush-like panicle2 (Bp2), large leaf angles(lla) and twisted-stem and tiller angle(ts-ta) , were isolated from our T-DNA insertion mutant populations. The morphology , genetic and physiology of three mutants involved were analyzed. Mainly results were as follows:1. Bp2 showed semi-dwarf, short and dense panicle, narrow leaf, late heading and low fertility.Compared with the wild type, the floral organ number was increased in Bp2. Interestingly, Bp2 mutant showed thermo-sensitive. Genetic analysis of Bp2 mutant showed that Bp2 was stably inherited and the phenotype was regulated by a nuclear incomplete dominant gene. Bp2 and wild-type were treated with exogenous GA₃ at internodes elongation stages. The results demonstrated that Bp2 plants were insensitive to exogenous GA₃.2. The Basta reactions suggested that Bp2 mutant was co-segregated with the T-DNA insertion. PCR and Southern blotting confirmed the results. The sequence flanking T-DNA indicated that T-DNA inserted in a putative homebox transcription gene in rice chromosome 5. The cDNA of OsBp2 gene was amplified by RT-PCR. The OsBp2 transcriptions were detected in all organs which been tested.3. The OsBp2 ORF was fused in pGBKT7 DNA-BD sequence and transformed into yeast. The pGBKT7-Bp2 can successfully active the expression of report gene. The OsBp2 genes homologous were investigated in grass family. RNA interference vector and over-expressing vector were constructed.4. lla show semi-dwarf, large angles, rolled leaf and late heading. Bp2 and wild-type were treated by exogenous GA₃ at seedling and heading stage. Although the lla mutant sensitive to exogenous GA₃ at different concentrations, GA₃ tested plant height and leaf angles in lla couldn't restore to the corresponding wild type. Genetic analysis of lla showed that lla can stable inherits and the lla mutant was regulated by a recessive nuclear gene. Basta reactions suggested that lla mutant was co-segregated with T-DNA insertion. PCR experiment confirmed the results. The sequence flanking T-DNA indicated that T-DNA inserted in a rice WRKY transcription gene in rice chromosome 1. The cDNA of LLA was amplified used by RT-PCR. The homologous proteins were also identified. The transcripts of OsWRKYll were detected in all organs which been tested. Subcellar location analysis showed that OsWRKY11 actives in nucleus.5. ts-ta showed twisted sheath at seedling stages and large tiller angles at adults, ts-ta also showed semi-dwarf, late heading and low fertility. The sections of sheath at seeding in ts-ta exhibits epidermis cells in twisted part was small, as a result the epidermis cells was arranged dense.