| The molecular genetic basis related to plant vegetative growth and reproductive development has been deeply studied, but few studies have been reported on pleiotropic genes, which that simultaneously regulate vegetative growth and reproductive development in plants, ddf1(dwarf and deformed flower1) is a dwarf mutant of rice with deformed floral organs. The DDF1gene was previously mapped into a60-kb region on chromosome6. SUPERMAN-like (SUPL) genes are a kind of single C2H2zinc finger genes, which play important roles in plant growth and development. By homolog search, we cloned a SUPL gene ZOS11-11in rice. Based on the above results, the functions and expressions of DDF1and ZOS11-11were analysised. The main results are as follows:1. Functional and expressional analysis of DDF1(1) Morphological characteristics of the mutant:The vegetative growth and floral organ development of ddfl were obviously abnormal. During the vegetative growth period, its vegetative organs were significantly thinner and smaller, and the cell size and cell number all decreased in internodes and leaves. During the reproductive development period, the branch number, spikelet number and the length of panicles of ddfl all decreased; the lemma and palea could not close; two lodicules were transformed into glumes, stamens were all or partly transformed into pistils and the carpal is deformed in ddfl floret. SEM analysis of ddfl floral development indicated that all floral organ primordia could form but could not develop normally.(2) Cloning and functional validation of the target gene:DDF1was further fine mapped into a smaller (45-kb) region. Sequence and expression analysis indicated that a single base mutation occurred in an F-box gene, resulting in a change from Arg251to Tyr251-So, this F-box gene was taken as the candidate of DDFL and its function was confirmed by genetic complementation and antisense RNA experiments. In addition, overexpression of DDF1in wild type rice had no effect on the vegetative growth, but altered the floral development. (3) Gene expression analysis:Quantitative PCR analysis showed that DDF1was expressed in all tissues. It was expressed most strongly in young panicles of0.5-1cm in length; less strongly in roots, stems and leaves; and weakly in internodes. The expression levels of some floral identity genes were significantly upregulated or downregulated in ddf1. The results of in situ hybridization are similar to Quantitative PCR analysis and the expression region of some floral identity genes expanded, suggesting that DDF1might regulate the floral development by affecting the expression of floral identity genes. In addition, the expression levels of some genes related to cell elongation and division were significantly downregulated in ddf1, implying that DDF1might also play an important role in cell elongation and division.2. Functional and expressional analysis of ZOS11-11ZOS11-11is located on chromosome11, encoding a protein of245amino acids. Phylogenetic and conservative sequence analysis showed that ZOS11-11has the same functional domains as other SUPL proteins. Quantiative PCR and GUS analyses indicated that ZOS11-11was expressed in almost all tissues of rice. So, it was deduced that ZOS11-11might be involved in the regulation of vegetative growth and reproductive development in rice. However, overexpression of ZOS11-11in wild type rice did not affect the vegetative and reproductive growth. These results will facilitate further functional research of ZOS11-11. |
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