Promoter Analysis Of An Abiotic-Stress Tolerance TaF-box Gene Cluster, And Cloning Of A New Gene Related To Rice Development In A Mutant

Drought and salinity are two main abiotic stresses that affect the crop growth and production worldwide, as well as in China. Particularly the drought stress dramatically restricts the agricultural productivity, because dried and semi-dried land occupies about 10% of the arable land. Nowadays, scientists have paid more attention to the genetic engineering to improve the drought tolerance in crops. In our previous studies, we found three copies of TaF-box gene tandemly existing in common wheat and ites diploid ancestors (named as TaF-box1, TaF-box2 and TaF-box3, respectively.) and two of them had been identified to be related to salinity and drought tolerance clearly. Three promoters (Pro_TaF-boxl, Pro_TaF-box2 and Pro_TaF-box3) of the TaF-box genes were analyzed in this study, in order to further understand their functional differentiation and the biological significance in wheat. The major progresses were as follows:1. Each promoter of the three TaF-box genes was cloned and fused to vector with the GUS as reporter, and then each constructed expression vector was introduced into rice by Agrobacterium-mediated transformation, respectively. And the T2 generation of transgenic seeds with single copy T-DNA insertion was screened. According to the histochemical staining results, we made a conclusion that all the three promoters can drive the GUS report gene expression in almost all organs examined to some extent, with the exception that only the Pro_TaF-box3 promoter can drive the GUS gene expression in root. High level GUS staining activity driven by Pro_TaF-box2 promoter was detected in the immature seed and the germinating seeds.2. Pro_Del-MITE, in which 163bp MITE sequence has been deleted, still has the ability to drive the GUS report gene expression, but its GUS staining activity level was much lower than that with the Pro_TaF-box2 containing the MITE sequence. So we primarily conclude that the MITE insertion at Pro_TaF-box2 promoter region could enhance the gene expression.3. Different length fragments of each promoter (Pro_TaF-box1,Pro_TaF-box2 and Pro_TaF-box3) have been amplified and fused to expression vector containing GUS gene. The constructed expression vectors of the 5’deletion promoters will be used to further define the functional cis-elements in the promoter sequence.4. During the identification of transgenic plants with ProTaF-box1 promoter, we found a mutant related to the rice development. Plant height, panicle and spiklets are significantly increased, wich are heritable traits proven by two years field examination. The Tail-PCR method was used to isolate the adjacent fragments of T-DNA insertion, and combining with bioinfrmatic analysis of the detected flanking sequences. The candidate gene was acquired and named as Ghdl (Grain number, plant height and heading date). Our results showed that the Ghdl was related to the rice development. However more experiments are needed to further vertify its functions.