Poster: Metabolic Engineering

Abs # 1023: Transcriptional analysis of carotenoid-related genes in leaves and fruits of transgenic tomato overexpressing the lycopene b-cyclase gene (tlcy-b) .

Presenter:	Stigliani, Lucia Adriana , lstigliani@agrobios.it
Authors	Stigliani, Lucia Adriana  (A)   Giorio, Giovanni  (A)   Cellini, Francesco  (A)   D'Ambrosio, Caterina  (A)
Affiliations:	(A): Metapontum Agrobios

Transgenic tomato plants (HighCaro) carrying the tlcy-b cDNA under the control of the 35S promoter produce fruits accumulating b-carotene instead of lycopene as a consequence of the complete deregulation of the carotenoid biochemical pathway. Steady state levels of phytoene synthase, phytoene desaturase, z-carotene desaturase and lycopene cyclase RNAs were estimated by Quantitative RT-PCR technique using 18S rRNA as reference endogenous control. Total RNAs were extracted from leaves and fruits collected at two different stages (mature green and 15 days after breaker) from transgenic HighCaro tomato plant and azygous control plant. According to the expectations lycopene cyclase gene was shown to be overexpressed in all analyzed organs of the transgenic plant. Surprisingly the other analyzed genes, with the exception of phytoene synthase, also manifested a higher expression level in the HighCaro genotype across all organs. The increase levels of transcripts varied among organs and genes. These results would indicate that the accumulation of b-carotene in HighCaro genotypes is due to the higher lcy-b gene transcription that presumably caused an increase of the transcripts of the other genes involved in the carotenoid metabolic flux.