Cloning Of StFT And StAP1 From Solanum Tuberosum And Analysis Of Tuberization In Constans-Antisense Transgenic Potato Plants

Potato(Solarium tuberosum L.), as one of the main cultivated crops, plays a vital role in agricultural production. As yield improvement is one of main targets in potato breeding, studies on the regulation mechanism of tuberization are of great significance. There is good evidence that flowering and tuberizing signals might be similar and AtCO could negatively regulate tuber formation. However, there was little known about the role of endogene StCOL in potato tuberization. FT and API are the targets of CO and function as an integrator of the different flowering regulatory pathways. Whether they are also involved in tuberization regulation? In this thesis, we analyzed the consequence of StCOL silence on transgenic potato plants and cloned StFT and StAPl gene from potato. The main results are as follows:1. A gene named StFT(Solarium tuberosum FT, GU223211) was isolated from potato by RT-PCR and PCR, the full length of the DNA contains four exons and three introns. The open reading frame of the gene was 522 bp long and encoded a putative protein of 173 amino acids with a molecular weight of 19.75 kDa and a theoretical pI of 7.76. StFT protein had a conserved PBP domain and a higher degree of identity with FT homologous members from Arabidopsis. Analysis on the mRNA levels of StFT showed that it was highly expressed in leaves, apical buds, flowers and swelling stolons.2. A homologue of APETALA1 gene, designated StAP1(Solarium tuberosum APETALA1, GU220568), was isolated from potato by RT-PCR. The ORF of the StAP1 was 735 bp long and encoded a putative protein of 244 amino acids with a molecular weight of 28.57 kDa and a theoretical p1 of 8.32. StAP1 protein contained a conserved MADS domain and had a high degree of identity with AP1 homologous member from tobacco. Analysis on the mRNA level of StAPl showed that it was highly expressed in leaves, apical buds and flowers, and little in tubers.3. Southern blot analysis on 5 PCR positive lines indicated the presence of antisene StCOL sequences in 3 lines. This confirmed that the StCOL-antisense gene fragment has been integrated into the genome of the transgenic lines. Being compared with the non-tranformed line, the StCOL-antisense transgenic potato lines had better tuberization, no matter in long-day conditions or short-day conditions. This demonstrated a negative effect of StCOL in the photoperiodic control of tuberization. Analysis of StFT and StAPl mRNA level indicated that their expressions were regulated by CONSTANS gene in StCOL-antisense transgenic potato plants, suggesting that StFT and StAPl could be involved in the regulation of potato tuberization as downstream of StCOL gene.