Subfunctionalization of D27 Isomerase Genes in Saffron.
Int J Mol Sci 2022;
23:ijms231810543. [PMID:
36142456 PMCID:
PMC9504799 DOI:
10.3390/ijms231810543]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
Chromoplasts and chloroplasts contain carotenoid pigments as all-trans- and cis-isomers, which function as accessory light-harvesting pigments, antioxidant and photoprotective agents, and precursors of signaling molecules and plant hormones. The carotenoid pathway involves the participation of different carotenoid isomerases. Among them, D27 is a β-carotene isomerase showing high specificity for the C9-C10 double bond catalyzing the interconversion of all-trans- into 9-cis-β-carotene, the precursor of strigolactones. We have identified one D27 (CsD27-1) and two D27-like (CsD27-2 and CsD27-3) genes in saffron, with CsD27-1 and CsD27-3, clearly differing in their expression patterns; specifically, CsD27-1 was mainly expressed in the undeveloped stigma and roots, where it is induced by Rhizobium colonization. On the contrary, CsD27-2 and CsD27-3 were mainly expressed in leaves, with a preferential expression of CsD27-3 in this tissue. In vivo assays show that CsD27-1 catalyzes the isomerization of all-trans- to 9-cis-β-carotene, and could be involved in the isomerization of zeaxanthin, while CsD27-3 catalyzes the isomerization of all-trans- to cis-ζ-carotene and all-trans- to cis-neurosporene. Our data show that CsD27-1 and CsD27-3 enzymes are both involved in carotenoid isomerization, with CsD27-1 being specific to chromoplast/amyloplast-containing tissue, and CsD27-3 more specific to chloroplast-containing tissues. Additionally, we show that CsD27-1 is co-expressed with CCD7 and CCD8 mycorrhized roots, whereas CsD27-3 is expressed at higher levels than CRTISO and Z-ISO and showed circadian regulation in leaves. Overall, our data extend the knowledge about carotenoid isomerization and their implications in several physiological and ecological processes.
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