Genes of carotenoid biosynthesis pathway in the moss Hylocomium splendens: identification and differential expression during abiotic stresses

A promising approach to solve the problem of tolerance of plants in hostile environments is to focus of stress tolerance mechanisms of extremophilic plants, in particular mosses. Along with the universal stress mechanisms, bryophytes exhibit a unique spectrum of secondary metabolites such as carotenoids, a lipophilic metabolite derived from the isoprenoid pathway. The main representatives of carotenoids in mosses are α- and β-carotene, lutein, neo-, viola- and zeaxanthins. Hylocomium splendens is one of the most common and widespread mosses of Northern Hemisphere. The genome of this moss has not been sequenced, and the carotenoid biosynthesis pathway (CBP) genes of this species have not been reported to date. This is the first report to of an attempt to identify and characterize the CBP genes in H. splendens. As a result of cloning, sequencing, and in silico analysis, we identified and characterized ten CBP genes in H. splendens with a full ORF, and prediction of subcellular localization suggests chloroplast localization of CBP proteins. Using multiple alignments and phylogenetic and homology analyses, we demonstrated that the CBP genes of H. splendens share high similarity with the sequences in other bryophytes. Differential expression of CBP transcripts during abiotic stresses was more evident for genes in the middle and downstream steps of CBP. This work provides information on the molecular genetics of CBP in extremophilic bryophytes. Analysis of CBP genes can help to unravel the genetic evolution of carotenoid biosynthesis in plants.