Effect of carotenoid composition on expression of carotenoid biosynthesis genes

DAVID E. KACHANOVSKY; JOSEPH HIRSCHBERG

Eilat

Congreso; The 4th Congress of the Federation of the Israel Societies for Experimental Biology; 2005

Federation of the Israel Societies for Experimental Biology

The biosynthetic pathway of carotenoids in plants is tightlycontrolled at the transcriptional regulation of gene expression.Accumulation of the red pigment lycopene in the mature tomato fruitis caused by the up-regulation of transcription of genes for earlyenzymes in the pathway and down-regulation of both lycopene epsilon-and beta-cyclase. These changes in gene expression are mainlydevelopmentally regulated. To study whether expression of carotenoidgenes is affected by the composition of downstream productcarotenoids in the cells we examined gene expression in mutants thatare impaired in synthesis of fruit carotenoids. The tomato mutanttangerine accumulates in fruits prolycopene (7 ,9 ,7',9'-cis-lycopene) instead of all-trans lycopene due to amutation in the gene CrtISO. No significant changes in geneexpression were observed between tangerine and wild type inripe fruits. However, in the green stages of fruit development upregulation of the gene for lycopene epsilon-cyclase (Lcy-e) wasdetected in tangerine compared to wild type. Since carotenoidcomposition in green fruits of tangerine is shifted towardsbeta-carotenoids this change in gene expression may be caused by therelative low content of the epsilon-branch product lutein. Thisresult demonstrates that, in addition to developmental regulation,the level of specific carotenoids in the tissue feedback regulatescarotenoid biosynthesis genes.p { margin-bottom: 0.1in; line-height: 115%; background: transparent }