Chito-Oligosaccharides Induced Resistance In Tobacco To TMV And Its Inhibitory Effects In Vitro

Chito-oligosaccharide is a linear polymers, in which 2-10 D-glucosamine residues are connected byβ-1, 4 linkages. It has many biological functions to regulate important physiological processes such as growth, development and defence in plant and animal. It was demonstrated that chito-oligosaccharides strongly inhibited the growth of fungal and bacterial pathogens and elicited systemic acquired resistance (SAR) to them in plants, but lacking information about induced resistance or inactivation effects in vitro to plant virus. This research project was revealed comprehensively the induced resistance of tobacco (Nicotiana tabacum) to TMV (Tobacco mosaic virus) elicited by chito-oligosaccharides derived from marine animal and their inactivating effects in vitro to TMV using methods and procedures involving biology, biochemistry, cytology and molecular biology. The main results were as follows.(1) It was evident that treatments of chito-oligosaccharide elicited systemic induced resistance of tobacco to TMV infection. In treated plants, systemic symptoms of TMV infection were strongly reduced, incubation periods were 3-7days delayed, infection sites were remarkably decreased, the average disease severities were more tnan 80% lowered, and chlorophyll contents increased by 34% and more. The most effective dose in eliciting resistance was 50μg/ mL. The effectiveness was decreased with both lower and higher doses. The resistance was expressed following 24h eliciting and lasted more than 9 d. The treated plants were resistant to both TMV and CMV.(2) Multiplication and long distance movement of TMV in tobacco plants was inhibited by chito-oligosaccharide elicited defense response,the experimental molecular weights and degrees of polymerization (DP) of chito-oligosaccharides had no visible influences on eliciting results. The results of ELISA-DSM assay and the assay of local lesions in Nicotiana glutinosa showed that chito-oligosaccharide treatments apparently reduced concentrations of virus particles in inoculated leaves or in new leaves at different days after challenge inoculation with TMV.The OD value in inoculated leaves in treated plants with chito-oligosaccharide was only...