| Potato(Solanum tuberosum L.)is an important crop with food and vegetable use.Potato tuber is not only rich in nutritious elements,but also has a wide range of health value,playing an important role in people's diet.Potato tubers contain low levels of carotenoids,for example,?-carotene.?-carotene is a precursor of vitamin A that could prevent night blindness and visionloss.LCYb is a gene of branch point in carotenoid biosynthesis pathway,which controls ?-carotene synthesis.This study isolated StLCYb gene from potato.By constructing overexpression-StLCYb transgenic plants,the accumulation of ?-carotene and the expression levels of carotenoid-related genes were studied in the potato tubers.The results are as follows:StLCYb gene was cloned from potato cultivar Desiree by RT-PCR method.The open reading frame of StLCYb gene was 1503bp long,encoding a protein of 500 amino acid residues.Its relative molecular weight was 12.46 kDa,isoelectric point was 5.04.Potato StLCYb shared 78.53%similarity to the Arabidopsis ApLCYb and 51.70%similarity to tomato StLCYb.Hydrophobicity analysis revealed that potato StLCYb was a lipophilic protein.Transient expression in tobacco indicated that StLCYb was located in chloroplasts.By Agrobacterium-mediated transformation method,we obtained five StLCYb transgenic potato lines.Quantitative RT-PCR analysis showed significantly improved StLCYb expression level in transgenic line tubers,compared with wild-type control.While the expression levels of carotenoid synthesis pathway genes were also raised.HPLC analysis revealed that ?-carotene content in the transgenic tubers was significantly increased. |
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