Abstract: S.L belongs to Chenopodiaceae,its polysaccharide extract can induce the resistance of plant against tobacco mosaic virus (TMV).A preliminary research was made on the mechanism about the S.L_induced resistance to viral infection in tobacco.It was investigated that how long the S.L_induced resistance will take in the plant which were treated by the polysaccharide extract at different time before inoculation.It is showed that the disease incidence index of the plant treated by S.L extract was much lower than the control,and the disease incidence was reduced by 4.31% to 45.75%.The best inducing effect was in 5 days later after the tobacco was treated by the polysaccharide.So,it can be inferred that S.L _induced resistance reaches to the top in about 5 days.5 days later after the treatment,the resistance induced by S.L polysaccharide becomes lower as time goes by.In further experiment,there were four groups of tobacco.Three of the groups are treated by the extract respectively 5,3,1 days before inoculation,while the control was sprayed just with water.Then,the total protein content,peroxidase act ivity and isoenzyme genealogy was compared between the different treatments.The results showed there was no much difference among all groups of tobacco about the total protein content.But the peroxidase of the three treated groups and the control went to a peak in different time after virus inoculation.The peroxidase of all the treated groups peaked 9 days later after inoculation,and the peak a litt le later and lower than the control.Another,the isoenzyme genealogies analysis of different treatments indicated that S.L polysaccharide can induce more isoenzyme expression much more earlier than the control.

Key words: Tobacco mosaic virus, Induce resistance, Protein content, Peroxidase, Isoenzyme

CLC Number: 

• S476