Inhibitory effects of esterified whey protein fractions by inducing chemical defense against tobacco mosaic virus (TMV) in tobacco seedlings

The inhibitory effects of methylated alpha-lactalbumin (Met-ALA), methylated p-lactoglobulin (Met-BLG), methylated lactoferrin (Met-LF) against tobacco mosaic virus (TMV) in tobacco seedlings and the underlying mechanism were investigated. The results indicated that plants treated with Met-ALA and Met-LF showed an increase in height of 24%, 49% and an increase in weight of fresh tissue of 27% and 43% over the controls, respectively. Plants treated with Met-BLG, Met-ALA and Met-LF had a decrease in the number of necrotic lesions of 9%, 21% and 75%. The levels of the antioxidant enzyme, including ascorbate peroxidase (AP), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GP), guaiacol-dependent peroxidases (GPDX) and defense-related enzymes phenylalanine ammonia lyase (PAL), and lipooxygenase (LOX) were increased systemically by esterified whey protein fractions (EWPF) treatment, in correlation with the induction of resistance against TMV. The antiviral water-soluble phenolic compounds (PHC) showed an increase by 1.7, 2.3, 2.9-fold higher than the controls. Collected data shows that EWPF could stimulate the development of treated tobacco seedlings and increase resistance against TMV and the mechanism might attribute to activate the expression of a number of defense-related enzymes. (C) 2011 Elsevier B.V. All rights reserved.