Effects of several plants extracts on the activatity of TMV in vitro and ultrastructure of tobacco leaves.

Objective Tobacco mosaic virus (TMV) is a kind of plant disease,it affects the leaf tobacco output and quality.The aim of this study is to provide a theoretical basis for prevention and control of tobacco mosaic virus with agents of plant origin.Method Active substances were extracted from Oldenlandia diffusa Roxb.and Nelumbo nucifera Garetn.and compounds with constitutes of many plants were prepared by water and ethanol.The plant extracts were mixed with equivalent TMV and the inactivation effects of plant extracts on TMV in vitro,and the plant extracts were sprayed on tobacco leaves with TMV for observing the changes of ultrastructure of tobacco leaves.Result The shape of TMV was rigid and rod-shaped,but the destruction and the break or condenses were different after mixing equivalent plant extracts as the difference in action time and the difference in plant extracts from different species of plants.There were many TMV particles and crystalls in cells of tobacco leaves with TMV,and the chloroplast was swell and the ectoplasm of chloroplast ruptured,and the grana lamella was disorderly and disassembled,the cell organ disappeard and the cell was vacuolated.The systemic symptoms were alleviated after treatment.The effects of plant extracts on the inactivation of TMV in vitro were significant:50.77%-60.61% (Oldenlandia diffusa Roxb.),73.39%-85.10% (Nelumbo mucifere Garetn.),and 91.30%-92.13% (compound preparation),respectively.In field the control and curative effects of the compound preparation on TMV were 71.02%-81.9%.Conclusion Plant extracts have obvious damage effects on TMV,so,it can reduce the harm of TMV to tobacco.