Identification and Functional Characterization of the Promoter of a Phytoene Synthase from Sweet Orange (Citrus sinensis Osbeck)
The phytoene synthase (PSY) gene product is involved in the carotenoid biosynthesis pathway. In this study, the promoter of the sweet orange gene CsPSY of sweet orange ‘Cara Cara’ (Citrus sinensis Osbeck [Cs]) was isolated and characterized. Its sequence included a number of regulatory elements predicted to be responsive to light and other environmental cues. The 926-bp region upstream of CsPSY was fused to the β-glucuronidase (GUS) reporter gene, and introduced as a transgene into Arabidopsis thaliana. The pattern of GUS expression in the transgenic plants showed that the CsPSY promoter drove expression in the young seedlings, the leaves, the roots and in parts of the flower, in a developmentally regulated fashion. A promoter deletion analysis revealed that the region −479 to −306 nt positively regulated expression, the region −306 to −93 nt was associated with negative regulation of expression and the region −46 to +21 nt maintained basal promoter activity. In the presence of sucrose, gene expression was regulated via a cis-acting promoter element(s). Two highly repetitive sequences (Sp1 and A-box), located in the region from −479 to −306 nt, may act as light-responsive elements regulating CsPSY transcription during photomorphogenesis.
KeywordsCarotenoid Citrus sinensis GUS activity Phytoene synthase Promoter
Age-related macular degeneration
Rapid amplification of cDNA ends
Transcription start site
The research was financially supported by the National Basic research program of China (973 program; No. 2011CB100601), and National Natural Science Foundation of China (Nos. 30921002 and 30830078).
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