Studies On The Effects Of CYP79B2/83B1 On Indole Glucosinolate Metabolism And Pathogen And Insect Resistance In Transgenic Flowering Chinese Cabbage

Flowering Chinese cabbage（Brassica rapa var.parachinensis）,belonging to Brassicaceae,is rich in important secondary metabolites,indole glucosinolates.Indole glucosinolates（IG）and their hydrolysates play important roles in resistance to diseases and insect pests.The CYP family of cytochrome P450,CYP79B2 and CYP283B1,are two important enzymes in the synthesis of IG.In order to study the effects of CYP79B2 and CYCY3B1 on IG synthesis,infection by Sclerotinia sclerotiorum and feeding by Spodoptera exigua,flowering Chinese cabbage was transformed by Agrobacterium-mediated transformation.Resistance to Sclerotinia sclerotiorum and Spodoptera exigua were studied and transcriptome sequencing analyzed.The results were as follows:1.One CYP79B2/83B1 overexpression transgenic line was obtained.The expression of gene in T₁transgenic plants was significantly higher than that of control by q RT-PCR analysis.The expression levels of CYP79B2 and CYP83B1 were increased about 12 and 2-fold than the control.And the IG content of transgenic plants was significantly higher than the control plants,and the four components were significantly increased,of which 4-hydroxyindole-3-methyl glucosinolates increased the most,5.7-fold as much as control plants.2.The transgenic plants had resistance to Sclerotinia sclerotiorum and Spodoptera exigua.In the Sclerotinia sclerotiorum infection trials,the plaque area of overexpression plants was significantly smaller,which was 0.4-fold compare with control.On the third day,the larvae feeding on leaves of transgenic plants were significantly smaller than the control,and the weight was 0.6-fold of the control.3.Transcriptome analysis revealed that 152 genes were up-regulated and 88 genes were down-regulated in transgenic plants compared with control plants.Functional analysis showed that these DEGs enriched in plant hormone signal transduction and MAPK signaling pathways may leads to enhanced resistance of transgenic plants.The pathway of IG synthesis was constructed.It was found that up-regulated expression of synthetic IG genes and down-regulated expression in IG decomposing genes led to the accumulation of IG and increased disease resistance.4.The content of MDA in transgenic plants was 0.6-fold as much as that of the control and the activity of POD was 1.5-fold higher than the control,indicating that overexpression of CYP79B2/83B1 in flowering Chinese cabbage could alleviate stress and enhance plant resistance.