Effects Of Feeding On Different Mouthpartsinsects On The Signal Molecules And Secondary Metabolites Contents In Tobacco

The relationship between plants and insects is extremely complex,and the herbivorous insects promote the evolution of plants' defense.In turn,the defense of plants also promote the evolution of insects.In this paper,the experiments took the burley tobacco and flue-cured as model plants,feeding the sucking and chewing mouthparts insects with tobacco.Then the experiments showed that not only the contents of nitric oxide and jasmonic acid changed significantly,but also the defensive substances changed in different times.In order to investigate the effects of feeding different mouthparts insects with the same tobacco and feeding the same mouthpart insect with different tobaccos on the signal molecules and the secondary metabolites,the experiments choose the flue-cured and burley tobacco as the experimental object.Then,the experiments analyzed and measured the alkaloids and sucrose ester changing in leaves at 3,6,10,and 15 days after feeding,and the contents of the nitric oxide and jasmine acid at 3,6,9,and 12 hours in leaves and roots as well.The results showed that after feeding M.persicae with the burley tobacco,the defense system of tobacco was activated.The contents of nornicotine,nicotine and total alkaloid increased significantly,reaching the peak at the 6th day and increased 27.92%?89.80%and 82.20%higher than the control after feeding M.persicae.They were increased at first and then decreased after feeding S.litura,reaching the peak at the 6th day.The nornicotine,nicotine and total alkaloids were increased by 34.31%,90.50%and 84.91%than the control.Then the other defensive substance SE also had a similar effect at different times.Another defensive substance of sucrose ester had a similar trend in 15 days.The contents of SE reached the maxium at the 10th day and increased by 60.14%after feeding M.persicae and 65.90%after feeding S.litura.Similarly,to the flue-cured tobacco,the contents of normicotine,nicotine and total alkaloids increased 77.80%,89.83%and 82.12%after feeding S.litura than the control respectively.And after feeding S.litura with burley tobacco,the contents of SE increased by 133.33%.While the control group did not change significantly.To flue-cured tobacco,after feeding M.persicae and S.litura,the signal molecules were fluctuated in 12 hours.NO showed an increase first and then a decrease trend in leaves and roots,peaking the maximum at the 9th hour.JA increased significantly in leaves and roots than the control.It increased first and then decreased in leaves,while the contents of JA in roots showed an rising trend within 12 hours.The signal molecules also showed a similar trend after feeding S.litura with the burley tobacco.The experiments also indirectly showed that the contents of alkaloids and SE were also increased to a certain extent in the control;the signal molecules fluctuating in different parts of the tobacco that indicated insect herbivores can stimulate neighboring plants' defense reaction.It is indirectly suggested that using the exogenous volatile signal molecules such as methyl jasmonate which can enhance the plants' defension and then reduce using the chemical pesticides.