Effect of Induction by Burdock Oligosaccharide on Powdery Mildew Resistance in Wheat

Powdery mildew is one of the most important disease on wheat.Different concentrations of Burdock Oligosaccharide(BOS)(0.5,2.0,5.0,10.0 and 20.0 g/L)were sprayed to wheat seedlings at one-leaf stage,water was sprayed as control,the wheat seedlings were inoculated with powdery mildew at three-leaf stage.Seriousness of powdery mildew in different treatments were scored on classes of 0~4 when the control were heavily infected,illness index(Ind %) of wheat seedlings were calculated.Activities of phenylalanin ammo-nialyase(PAL)、Peroxidase(POD) and Catalase(CAT) in wheat with different treatments were investigated.According to the the difference of illness index and the activity changes of enzymes,powdery mildew resistance in wheat induced by BOS was analysed.Results showed that powdery mildew resistance in wheat gradually improved along with the increase of concentration of BOS.The resistance were the best when the BOS concentration was 10 g/L.Activities of PAL,POD and CAT were higher than that of control and gradually increased along with the increase of concentration of BOS.Activitie of PAL was the highest when the BOS concentration was 5.0 g/L.When BOS concentration was higher than 5.0 g/L,the activity of PAL decreased.Activities of POD and CAT achieved their peaks when the BOS concentration was 10.0 g/L.It was concluded that BOS induction at appropriate concentration can improve the activites of defensive enzymes and evidently enhance the powdery mildew resistance in wheat.