Glucosinolate Content and Expression of Related Genes in Chinese Cabbage (Brassica campestris sub. pekinensis) Mutants Resistance to Diamondback Moth (Plutella xylostella L.)
Abstract：Glucosinolates(GS) is important secondary metabolites in cruciferous plant. Ethyl methylsulfonate (EMS) mutants of Chinese cabbage (Brassica campestris sub. pekinensis) were used as materials in this research, aiming to obtain resistance genotypes to diamondback moth (Plutella xylostella L.) and to identify relationships between resistance level and glucosinaolate (GS) contents. In this study 5 Chinese cabbage mutants with 1st grade resistance to diamondback moth were selected using two methods: In vitro and under net condition. Through analyzing content of GS in leaf, the levels of progoitrin (PRO), glucobrassicanapin (GBN) and 4-hydroxyglucobrassicin (4-OH) in mutants were higher than that in wild type. The main reason caused the resistance to DBM could be the high level of PRO. Expression levels of GS related genes between wild type and mutants were compared with qRT-PCR. Expression of myb family transcription factor 28(MYB28), MYB29, 2-oxoglutarate-dependent dioxygenase (AOP2) and 2-oxoacid-dependent dioxygenase (GSL-OH) in five mutants were higher than that in wild type, increasing folds of 1.41~4.85, 1.76~6.99, 1.16~4.60, 1.86~8.06 and 0.46~7.85, respectively. This result indicated that GS related genes MYB28, MYB29, AOP2 and GSL-OH were positive regulation to synthesis pathway of aliphatic, and uridine diphosphate (UDP)-glucosyl transferase 74B1 (UGT74B1) was positive regulation to synthesis pathway of indolyl. Analyzing the expression of above genes along with feeding time, the expression peak in mutants was earlier for 16~20 h than that in wild type, which suggested to be the sensitive performance to DBM resistance. This study can be useful for researching regulatory relations of DBM resistance and GS, and developing new varieties with resistance to insect and valuable GS component in Chinese cabbage.
