Enhanced accumulation of indole glucosinolate and resistance to insect and pathogen in flowering Chinese cabbage by overexpression of Arabidopsis CYP79B2 and CYP83B1.

Abstract

BACKGROUND Indole glucosinolates (IGs) are a group of phytochemicals that are derived from tryptophan and mainly found in Brassicaceae. The breakdown products play an important role in insect and disease resistance. To metabolically engineer the IG pathway flux in flowering Chinese cabbage (Brassica rapa L. ssp. chinensis var. utilis Tsen et Lee), binary constructs comprising two Arabidopsis cytochrome P450 complementary DNAs (cDNAs), AtCYP79B2 and AtCYP83B1, under the control of a cauliflower mosaic virus 35S promoter were tandemly introduced into flowering Chinese cabbage via Agrobacterium-mediated genetic transformation. RESULTS The results showed that overexpression of AtCYP79B2 and AtCYP83B1 was accompanied by higher accumulation levels of IG in the transformed plants compared to the wild-type control. Glucobrassicin was the main component of IG that accumulated at approximately 2 μmol/g dry weight (DW) indole-3-acetic acid. 4-Hydroxy glucobrassicin and glucobrassicin were the most affected components in transgenic plants, exhibiting an approximately 5- and 4-fold, respectively, when compared to wild-type control. In both trials of the Sclerotinia sclerotiorum infection and Spodoptera exigua feeding, the transformants significantly inhibited the growth of S. sclerotiorum and S. exigua. Transcriptomic analysis indicated that overexpression of AtCYP79B2/83B1 cDNAs led to the up-regulation of 152 genes and down-regulation of 88 genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis suggested that the genes involved in plant-pathogen interaction, plant hormone signal transduction, and MAPK signaling pathways are primarily responsible for enhanced resistance to S. sclerotiorum and S. exigua. CONCLUSION Our study illustrates a successful use of the genes encoding IG pathway enzymes to increase IG content and resistance to insect and fungal pathogens via regulated expression of a broad spectrum of the genes associated with the innate immune responses in flowering Chinese cabbage. © 2025 Society of Chemical Industry.