Isolation And Functional Analysis Of TaDWARF27 In Triticum Aestivum L.

Wheat(Triticum aestivum L.) is an important crop in our country. The grain yield is directly reflected by spike numbers, grain number per spike and 1000-grain weight. To a certain extent, the spike number is determined by the number of effective tiller. Little is known about the molecular mechanism of tillering regulation in wheat. Strigolactones(SLs) is a type of novel plant hormone which can inhibit plant branching in rice and Arabidopsis. DWARF27(D27) encodes a ?-carotene isomerase with iron and is required for SLs biosynthesis. d27 mutants exhibited reduced plant height, increased tillers and compact plant architecture. To study the molecular mechanism of SLs regulating tiller in wheat, we isolated TaDWARF27(TaD27), and studied its expression pattern and function. The results were as follows:There were three homoeologs of TaD27, which were assigned to wheat chromosome 7A, 7B and 7D, respectively. Three homoeolgs were highly similar(about 97.71%) to each other and all harbored seven exons and six introns. The full length of TaD27 gDNA were 4675bp(TaD27-7A), 4896bp(TaD27-7B) and 4703bp(TaD27-7D) and they had the encoding region of 837bp(TaD27-7A), 840bp(TaD27-7B) and 840bp(TaD27-7D).The deduced amino acid sequence of TaD27 respectively contained 278(TaD27-7A), 280(Ta D27-7B) and 280(TaD27-7D) amino acid residues. The phylogenetic analysis revealed that the TaD27 protein was closer to Aegliops tauschii, Hordeum vulgare and Brachypodium distachyon. TaD27 protein was located in the chloroplast by protoplast extraction technology. We found that TaD27 was mainly expressed in leaf. The tissue-specific expression pattern of TaD27 was further examined using mRNA in situ hybridization. TaD27 was predominantly expressed in leaf, the axil of axillary buds and spike promodia. To explore the function of TaD27, the gene was transferred to Arabidopsis d27 mutants. The results showed that the overexpression of TaD27 can complement d27 mutant phenotype, which suggested that TaD27 may have conserved function in wheat and Arabidopsis. To confirm the function of TaD27 in wheat, the TaD27 RNA interference and overexpression vectors were transfected into wheat(cultivated variety KN199). We have obtained 295 RNAi resistant plants and 255 overexpression resistant plants. Further analysis showed that there are 16 positive RNAi transgenic plants and 10 positive overexpression transgenic plants. The positive plants were planted and their phenotypes will be analysised in further study.In conclusion, TaD27 is likely to play an important role in regulating tillering. This study will provide new molecular basis for yield improvement in wheat.