Effects Of Green Leave Volatiles Of The Tobacco Nicotiana Tabacum On The Whitefly,Bemisia Tabaci And The Role Of Tobacco HPL Gene

The whitefly,Bemisia tabaci is a species complex including at least 36 cryptic species.Among them,Middle East Asia Minor 1(MEAM1)and Mediterranean(MED)are two invasive species and have been reported to invade many parts of China,causing serious damage to crops such as cotton,vegetables and tobacco.In nature,plants are frequently attacked by diverse herbivores,and they have evolved myriad finely tuned defense responses to pests including direct and indirect plant defenses.Plant can emit green leaf volatiles(GLVs)and they are biosynthesized via the hydroperoxide lyase(HPL)branch of the oxylipin pathway.GLVs refer primarily to C6-aldehydes,C6-alchohols and their acetates.Similar like jasmonic acid(JA),products of another branch(JA branch)of oxylipin pathway,GLVs can act as signal molecules and play an important role in the interaction between plants and insect pests.However,the roles of GLVs in interactions between tobacco and the whitefly Bemisia tabaci are not well studied.In this study,targeting the hydroperoxide lyase gene(HPL)as the research object,combining with the methods of transgene technology,virus-induced gene silencing(VIGS)and behavioral bioassay,we investigate the effects of GLVs of Nicotiana tabacum on the herbivore insect whitefly and the role of tobacco HPL gene in the plant insect interaction system.The main results are as follow:(1)HPL gene participate in the interaction between tobacco and whitefly.We found that tobacco HPL gene was upregulated after feeding by whitefly.Then,we constructed the HPL gene overexpressing tobacco by using transgenic technology.Compared with wild type tobacco,transgenic tobacco could significantly increase the survival rates and fecundity of the whitefly and attract more whitefly individuals.We Obtained silencing HPL and ADH gene tobacco plants by using virus-induced gene silencing(VIGS)methods.The silencing plant significantly decreased survival rates,fecundity and preference of the whitefly.(2)HPL regulate plant GLVs content.We found that the amount of green leaf volatiles in HPL gene overexpression plants increased significantly than wild type tobacco by SPME-GC/MS.At the same time,the down-regulation of HPL gene expression could cause a significant decrease of GLVs content.(3)Application of green leaf volatiles can increase the adaptability of tobacco plants to Bemisia tabaci.We found that application of Trans-2-hexenal and Cis-3-hexenol significantly increased the survival rates and fecundity of the whitefly.The survival rates and fecundity of the whitefly also increased with the application of Cishexenyl acetate,but did not reach the significant level.Applying the above three green leaf volatiles GLVs attract more whitefly significantly.In summary,we found green leaf volatiles synthesized by tobacco HPL pathway increased the survival rates,fecundity and selectivity of the whitefly.The results suggested that the tobacco HPL pathway negatively regulates tobacco defensive response against whitefly.The research brings more insights in understanding the interaction between plant and herbivores and it may be beneficial to further studies on plant defense against insect pests.