The Effect Of Exogenous Methyl Jasmonate, Kynurenine And Aminoxyacetic Acid On Expression Of BrCYP79B2/B3 And The Related Physiological And Biochemical Factors In Chinese Cabbage

Chinese cabbage(Brassica rapa ssp. pekinensis) is one of the most widely cultivated leafy Cruciferous vegetables, playing an important role in vegetables supply in China. Glucosinolates are a kind of important secondary metabolites mainly found in cruciferous plants, and its hydrolates play a key role in anticarcinogennesis, insect and microbe resistance, so more and more investigators focused on glucosinolates research. Indolyl glucosinolates and IAA metabolic pathways have a common precursor, indole-3-acetaldoxime, catalyzed by BrCYP79B2/B3. Thus, it is useful to clone those genes and analyze their function for indole glucosinolates and IAA metabolism. In order to analyze their catalyzation ability in indole-3-acetaldoxime formation, we cloned BrCYP79B2/B3 genes, and analyzed the correlation between indolyl glucosinolates and IAA contents, and the expression levels of target genes by treating plants with inducer or inhibitors. The main results of the study are as follows:1) We cloned BrCYP79B2-1 from Chinese cabbage and constructed the over-expression vector. It will be useful in study on the neofunctionalization or subfunctioanlization of BrCYP79B2/B3 genes and modification of glucosinolates profiles by metabolic engineering.2) We analyzed the expression level change of indolyl glucosinolates and IAA synthesis genes on indole-pyruvate pathway by qReal-Time PCR after the materials were treated with inducer(methyl jasmonate) or inhibitors(kynurenine and aminoxyacetic acid). The result indicated that the expression levess of the biosynthetic genes and transcription factor MYB122 for indolyl glucosinolates synthesis were higher than those of control after methyl jasmonate treatment. With aminoxyacetic acid treatment, the expression levels of indolyl glucosinolates biosynthetic genes decreased in leaves, while the levels of BrCYP79B2-1, BrCYP79B3, BrCYP83B1 and some transcription factors in roots increased. The biosynthetic genes of indolyl glucosinolates and IAA, transcription factor MYB122 mainly expressed in roots after kynurenine treatment.3) We studied the effect of foliar methyl jasmonate, kynurenine and aminoxyacetic acid treatment on plant growth, physiological and biochemical change, and found that aminoxyacetic acid affected the growth of Chinese cabbage obviously. It reduced root length and photosythesis ability, while enhanced the levels of MDA, glucosinolates, and the antioxidant enzyme activity. 200 μM methyl jasmonate inhibited the growth of both aerial and underground parts. Methyl jasmonate treatment enhanced the levels of MDA and indolyl glucosinolates while decreased the IAA content and Fv/Fm in leaves. Kynurenine treatment also inhibited Chinese cabbage growth which was less than methyl jasmonate treatment. Kynurenine enhanced glucosinolates levels without affecting the IAA content in leaves.