| The contents in this thesis are consisted with two parts:Fine mapping of PSD3, a gene involved in controlling floral organ development in rice; and functional analysis of ZOS2-01, a zinc-finger gene in rice.Rice is the grass model plant and is very important food crops as well. The status of floral organ development has directly impact on the yield and the quality of rice. Therefore, it is a great significance to make some in-depth researches on the floral organ development in rice. A rice mutant named psd3(pistil-stamen degeneration) was found from breeding material Minghui63, which has normal vegetative growth as well as the inflorescence and the flower bud development, but its floral organs is obvious abnormalities. In this study, morphology and genetics analysis and gene mapping of the psd3mutant was carried out. The lodicule, pistil and stamen in the typical psd3mutant spikelets are completely degenerated, compared a few of additional spikelets emerged in the center. Genetic analysis indicated that the psd3mutation was caused by a recessive gene, which was named as PSD3temporarily. In order to map this gene, an F2population was developed by a cross-fertilizing between psd3heterozygote and Acc8558. The result indicated that the gene PSD3was flanked by two markers, InDe14and InDel5on chromosome8, with a distance of about33kb. By searching NCBI databases, eight genes were annoted in the33kb region where PSD3was located. One of them encodes DHHC zinc-finger protein. Sequencing analysis of the zinc-finger gene between psd3and wild type, two SNP differences in coding region were found. One of which located in the fourth exon resulted in an amino change from His in wild type to Arg in psd3. At present, many zinc-finger protein genes were found in Arabidopsis and rice, which are involved in regulating the floral organ development. Therefore, the DHHC zinc-finger protein may be the candidate gene of PSD3, and further analyses are going on.More and more molecular evidence indicated that the zinc-finger transcription factor genes play the crucial roles in regulating the floral organ morphogenesis. According to the conservative domain sequence of SUPERMAN protein in Arabidopsis thaliana, a gene named ZOS2-01, which has similar sequence with SUP-like structure, was found in rice. RT-PCR analysis indicated that the expression of ZOS2-01was weak in leaves and roots, while the expression was strong in the young panicle of1～5cm. These results indicated that ZOS2-01may involve in the floral organ development. On this basis, An GUS expression vector pZOS2-01:GUS and an RNA interference vector pTCK303-ZOS2-01were constructed to transform zhonghua15, and26and18transgenic plants were obtained, respectively. GUS staining results showed that ZOS2-01mRNA was detected in the vegetative organs, including root, leaf, shoot apex, upper node and internode, but no tiller. ZOS2-01mRNA was also detected in reproductive organs. In the early reproductive growth stages, the expression of ZOS2-01was found throughout the panicle. The expression in the branches was gradually increased as the development proceeding. When the flowers were immature, the expression of ZOS2-01was found in the palea and lemma. However the expression was found only in the base part of the mature flowers, and disappeared in the floral organ. The phenotype of the RNAi transgenic plants was similar with that of the wild, which indicated that function of the gene ZOS2-01maybe different from SUPERMAN, and further validation is going on. |
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