Rice (Oryza sativa L.) is one of the most important food crops for the people in the world, and it has also developed into a model species for molecular biology study within the monocotyledonous grasses. In recent years, with the completion of rice genome sequencing, the current trend in rice genome biology research has evolved from structural genomics to functional genomics. It is extremely meaningful in theoretical and practical respects to carry out mapping, cloning and functional analysis of genes associated with important agronomic traits in rice. Plant height is an important agronomic trait for morphogenesis and grain yield formation in rice and other crops in grass family. Currently, most understanding of molecular mechanism of plant height in rice attributes to the gene cloning from dwarf or semi-dwarf mutants.In this study, a rice semi-dwarf mutant (sdwrky) was isolated from a collection of Ds-inserted mutant lines. sdwrky mutant showed slow seed germination and growth, early heading, semi-dwarfism, black-green leaf color, large angle of leaf to stem, and its axillary buds showed faster growth and some of them were able to develop into tillers. Most significantly, the mutant was found to be susceptible to gibberellin treatment, and its plant height is about 81% of wild-type plant. Further analysis showed that the differences in plant height between the mutant and wild-type plants derived from both the intermodal length and ear length.The Ds-flanking sequences were cloned from the sdwrky mutant by using TAIL-PCR amplification technique. Analysis of the Ds-flanking sequences indicated that Ds element was inserted into the Os04g0597300 gene (sdwrky) of rice chromosome 4 in the sdwrky mutant. Other databases, such as Pfam (http://pfam.sanger. ac.uk/), GRAMENE (http://gramene. agrinome.org/), RAP-DB (http://rapdb.dna.affrc.go.jp/), and Rice Genome Annotation Project (http://rice.plantbiology.msu.edu/) searched online to find more molecular information, it was showed that the 04g0597300 (sdwrky) gene encoded a WRKY domain-containing SDWRKY protein. There are two possible mechanisms for SDWRKY to regulate seed germination, seedling growth and elongation: (1) SDWRKY may inhibit the functional activities of other WRKY transcription factors (such as OsWRKY71 and OsWRKY51); (2) SDWRKY may have the similar function of OsWRKY24, which is a negative regulator encoded by a rice WRKY gene represses both ABA and GA signaling in aleurone cells.Interestingly, among the 467 lines examined in the T2 generation, 145 lines showed a lethal yellow seeding mutant (lysrcc1) that segregated as a single recessive locus.The Ds-flanking sequences were cloned from the lysrcc1 mutant by using TAIL-PCR amplification technique. Analysis of the Ds-flanking sequences indicated that Ds element was inserted into the Os03g0599600 gene (lysrcc1) of rice chromosome 3 in the lysrcc1 mutant. Other databases, such as Pfam (http://pfam.sanger. ac.uk/), GRAMENE (http://gramene. agrinome.org/), RAP-DB (http://rapdb.dna.affrc.go.jp/), and Rice Genome Annotation Project (http://rice.plantbiology.msu.edu/) searched online to find more molecular information, it was showed that the Os03g0599600 (lysrcc1) gene encoded a RCC1 domain-containing LYSRCC1 protein. LYSRCC1 may be a Ran GEF, involving in regulation of nucleocytoplasmic transport, which regulates chloroplast development. |