Genome-Wide Classification and Abiotic Stress-Responsive Expression Profiling of Carotenoid Oxygenase Genes in Brassica rapa and Brassica oleracea

Abstract

Carotenoid oxygenase is a key enzyme involved in the metabolism of carotenoids, which are important quality factors affecting the pigmentation and aroma of flowers and fruits, as well as main regulators of plant phytohormones, such as abscisic acid (ABA) and strigolactone (SL). To investigate the regulation of carotenoid metabolism, including ABA and SL biosynthesis by carotenoid oxygenase genes, in B. rapa and B. oleracea, we studied the expression of these genes in response to salt, drought, cold, ABA, and SL treatments. In the Brassica database, we identified genes related to carotenoid cleavage dioxygenase (CCD) 1, CCD4, CCC7, CCD8, NCED (9-cis-epoxycarotenoid dioxygenase) 2, NCED3, NCED5, NCED 6, and NCED9. We classified 15 and 14 carotenoid oxygenase candidate genes in B. rapa and B. oleracea, respectively. CCD1 and CCD4 showed similar transcription trends under abiotic stress treatment conditions in both B. rapa and B. oleracea, with expression peaking at 3-6 h post treatment before decreasing at 12 h. NCED2, NCED6, and NCED9 were responsive to ABA and SL treatments. Our results show that the phytohormone biosynthetic enzymes involved in carotenoid oxygenase pathways may be activated as multifunctional stress signaling factors with a variety of transcriptional responses via their interactions under abiotic stress treatment conditions in B. rapa and B. oleracea.

Dynamic changes in methylome and transcriptome patterns in response to methyltransferase inhibitor 5-azacytidine treatment in citrus

“…51 Moreover, transcripts of CCD1 were activated by hormonal treatments including ABA and strigolactone, and abiotic stresses including salt, drought and cold in Brassica rapa and Brassica oleracea . 52 In this study, the RNA-seq data show that 5azaC treatment as a stimulant induced callus stress reactions ( Fig. 5 ) and activated peroxidase gene expression and enzyme activities ( Supplementary Fig.…”

Genome-wide identification and expression profiling of the carotenoid cleavage dioxygenase (CCD) gene family in Brassica napus L

“…The genome-wide alignment was verified by the MEGABLAST program [45], and the following screening standards were used: the consistency of aligned sequences with the reference sequence was �80% and gene sequences <700 bp were discarded. Because enzymes involved in carotenoid cleavage contain a retinal pigment epithelial membrane protein (RPE65) domain [16,17], gene sequences from the Pfam database [46] that did not contain this domain were excluded.…”

“…Moreover, CCDs are also a class of non-heme oxygenases, whose catalytic activity requires Fe 2+ as a cofactor [14,15]. CCD proteins contain four highly conserved histidine residues bound to Fe 2+ and all contain a retinal pigment epithelial membrane protein (RPE65) domain that is characteristic of enzymes involved in carotenoid cleavage [16,17].…”

A Functional Genomic Perspective on Drought Signalling and its Crosstalk with Phytohormone-mediated Signalling Pathways in Plants

“…In Arabidopsis exogenous application of GR24 (synthetic SL analogue) rescued drought sensitive effect of the SL-deficient mutant ( max3 and max4 ) but not of the SL-response mutant ( max2 ) and in wild type SL treatments enhanced drought tolerance of plants [ 140 ]. Genome - wide expression analysis of carotenoid oxygenase genes in response to salt, drought, cold, ABA, and SL treatments in Brassica rapa and Brassica oleracea led to the identification of various genes related to carotenoid metabolism such as carotenoid cleavage dioxygenase (CCD)1, CCD4, CCC7, CCD8, NCED (9-cis-epoxycarotenoid dioxygenase) 2, NCED3, NCED5, NCED 6, and NCED9 [ 141 ]. Further NCED2, NCED 6 and NCED9 were found to be responsive to both ABA and SL treatments indicating their important role in abiotic stress signalling.…”