Abiotic Stress and Hormonal Responses of a Promoter of Citrus Carotenoid Isomerase Gene in Transgenic Arabidopsis

A genomic DNA clone encoding carotenoid isomerase (CRTISO) was isolated from Citrus unshiu. It has 12 introns, 13 exons, and 2501 bp of flanking region 5’ of the translational start codon. To identify(X) regulatory elements in the citrus CRTISO (citCRTISO) gene, 2501 bp, 1603 bp and 1037 bp of presumptive promoter DNA sequences and the β-glucuronidase (GUS) coding sequence were fused in pCAMBIA2300. The promoter-GUS constructs were inserted in Arabidopsis thaliana (L.) Col-0 (Columbia) by Agrobacterium-mediated transformation. The transgenic Arabidopsis plants were detected GUS activity in cotyledon, young leaf, mature leaf, flower, and silique. Especially, transgenic plants showed high expression levels of GUS in silique, and the promoter-GUS constructs drove GUS expression in the green stage of silique development. In various treatment experiments, constructs with the 2501 bp promoter indicating the presence of HSE prove GUS expression by heat treatment, but not by other condition. On the other hand, 1603 bp promoter has not shown GUS expression, but 1037 bp promoter demonstrated responsiveness to cold stress and ethylene (This research was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2010-0007627 and 2009-0094059), and by Golden Seed Project, Ministry of Agriculture, Food and Rural Affairs (MAFRA), Ministry of Oceans and Fisheries (MOF), Rural Development Administration (RDA) and Korea Forest Service (KFS), Republic of Korea).