Suppression of carotenoid synthesis in transgenic Arabidopsis cultured cells over-expressing the AHL29/SOB3 gene

Abstract

Up-regulation of the Arabidopsis gene AHL29/SOB3 (At1g76500), encoding a protein with an AT-hook DNA-binding protein motif, is known to function as a suppressor of the phyB phenotype and to cause delayed senescence. We over-expressed the full-length cDNA of AHL29/SOB3 under the cauliflower mosaic virus 35S promoter in Arabidopsis suspension-cultured T87 cells. Preliminary DNA array experiments suggested down-regulation of many genes of the carotenoid synthesis pathway in the transgenic cells. Metabolite analysis with a liquid chromatography-coupled mass spectrometer demonstrated that the accumulation of the carotenoids lycopene, α-carotene, β-carotene, lutein, zeaxanthin, antheraxanthin, violaxanthin and neoxanthin was suppressed in the transgenic cells. These results suggest that up-regulation of AHL29/SOB3 down-regulates the mechanism of carotenoid biosynthesis at the transcriptional level.