Effects of overexpression lycopene beta-cyclase gene on carotenoids metabolism and aroma compounds in tobacco
In order to reveal function of lycopene beta-cyclase (Lcy-b) gene in the growth and development of tobacco plants,especially its influence on aroma substance metabolism,full-length cDNA sequence of Lcy-b was cloned from tobacco variety K326 homology cloning strategy and effects of overexpression of lycopene beta-cyclase gene on carotenoid components and aroma compounds were determined by agrobacterium-mediated transformation.Sequences analysis showed that tobacco Lcy-b contained 1503-bp open reading frame (ORF) and coded 500 amino acid residues,the calculated molecular mass was 56066.12Da with theoretical isoelectric point (pI) of 6.98.Secondary structure prediction results showed that they were mainly made up of alpha helix and random coil.The expression of Lcy-b gene was significantly higher in some of the transgenic positive plants than that of K326 untransformed control.Correspondingly,the proportion of beta-carotene,neoxanthin and violaxanthin increased and the proportion of lutein reduced.Aroma substance in the cured leaves also displayed that the amounts of beta-carotene degradation products were significantly higher in transgenic positive plants than that of K326 untransformed control while the lutein degradation products were equivalent to or lower than that of K326 control.These results showed that Lcy-b could change the proportion of carotenoid components and affect the content of aroma components in cured samples.
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