PJB-2018-1051
IDENTIFICATION AND CHARACTERIZATION OF GLUCOSINOLATE BIOSYNTHETIC GENES IN BRASSICA NIGRA
YANG LI
Abstract
Glucosinolates (GSs) are secondary metabolites that are mainly found in plants of the order Brassicales. The breakdown products of GSs play important roles in insect and disease resistance, flavor formation of plants, and human health. In the present study, 99 GS biosynthetic genes were identified in Brassica nigra by genome-wide search as the homologs of GS genes in Arabidopsis thaliana, B. rapa and B. oleracea. Whole genome duplication and tandem duplication were found to be the main mechanisms accounting for the expansion of the BniGS genes. High-performance liquid chromatography (HPLC) analysis revealed the presence of seven different types of GSs in five aboveground organs of B. nigra, and significant differences in GS concentrations were found among the different organs. Sinigrin was found to be the predominant GS. Phylogenetic and evolutionary analyses suggested that GS biosynthesis-related CYPs, FMOGS-OXs, and AOPs genes could be classified into nine, two, and two main clades, respectively. In addition, more CYP79B2s, CYP79A2s, CYP83A1s, FMOGS-OX5s, and AOP2s were preserved than other paralogs. CYP83B1s and CYP79B2s were highly conserved over the course of evolution, and AOP1s and AOP2s exhibited the largest sequence changes. Expression profile analysis by quantitative real-time polymerase chain reaction demonstrated that the expression of 13 BniGS genes was detected in at least two of the five aboveground organs, and most of them exhibited organ-/tissue-specific or high expression pattern in B. nigra. Our comparative analysis provided some basic information on BniGS genes, which will be valuable for further functional analysis of BniGS genes and genetic improvement of GSs in B. nigra and other Brassica species.
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