Cloning And Functional Analysis Of STCDC20-1and Sttsf Genes From Potato

The development of the potato tuber is a highly coordinated, morphological and physiological process which is happened in underground stolon. It is related to the expression of series genes and regulated collectively by the internal factors and the external environment factors. The formation of stolon, the development and expansion of the potato tubers are directly related to the cell division. At the same time, the accumulation of dry matter in potato is directly related to the synthesis and transportation of the sucrose. This study cloned a cell-division cycle protein20gene CDC20-1and a tuber-specific and sucrose-responsive element binding factor gene TS and then analyzed the role of these genes in the regulaution of potato tuber formation. The results are as follows:1. The StCDC20-1gene contained five introns and six exons and an ORF of1368bp which start codon is ATG and stop coden is TGA. The ORF encoded a50kDa protein which contained455amino acids and the isoelectric point is8.1. Sequence alignment showed that StCDC20-1shared92.3%and91%identity with homologues from tomato and Arabidopsis. Semi-quantitative RT-PCR analysis showed that the StCDC20-1mRNA is expressed in foliage, root and tuber of potato and the expression in foliage is the highest. In order to analyze the function of the StCDC20-1, StCDC20-1transgenic potato plants were constructed by Agrobacterium-mediated method. In total9independent transgenic potato lines were identified by PCR. The RT-PCR showed that the StCDC20-1gene could express normally in the transgenic potato plants. Yield analysis indicated that the average weight of tuber for the StCDC20-1transgenic potato plants was lower than the wild type control plants.2. The StTSF cDNA sequence of potato was cloned by PCR method. The ORF of the StTSF was753bp long which start codon was ATG and stop coden was TGA. The ORF encoded a28kDa protein which contained251amino acids and the isoelectric point was8.7. Sequence alignment showed that StCDC20-1shared97%identify with its homologue from tomato. The analysis of tissue expression indicated that StCDC20-1mRNA is expressed in foliage, root, stem and young tuber of potato and expression in stem is the highest. At the same time, transgenic potato plants expressing StTSF were constructed. The PCR and RT-PCR results showed that the StTSF gene were integrated into the potato genome and expressed normally. The tuber number per plant of the StTSF transgenic potato plants was lower than the wild type control. But the average weight of the tuber for the StTSF transgenic potato plants was heavier than the wild type control.