Elevated CO₂ Effect On The Transmission Of TYLCY By Whiteflies To Tomato Plants

Elevation of CO2 concentration may broadly impact the processes of preliminary and secondary metabolism of various plants,and may also influence the interactions among plants-herbivore arthropods-plant virus via cascading effect.Meanwhile,these effects may re-regulate the induced defensive responses of the host plants.Even though there are plenty of reports revealed the impacts of CO2 elevation to both plant and plant-herbivores systems,we could only read few works mentioned the exploration about the influences of multiple-infections by herbivore and plant pathogens to the internal induced defensive metabolism of host plants,and the reactions of interactive pathways of secondary metabolism under elevation of CO2.Thus,we established an Open-Top-Chamber(OTC)system to stimulate the environment as CO2 elevated and a research system which concerned the trophic relationship among “tomato mutants JA and SA,Q biotype tobacco whitefly(Bemisia tabaci),and tomato yellow leaf curl virus(TYLCV).We intensively studied the impacts of CO2 elevation to the acquiring and transmitting TYLCV by B.tabaci among various of tomato mutants SA and JA.We compared the host plant preference,EPG feeding fitness and the replication performance of plant virus within B.tabaci and tomato mutants among different CO2 treatments.Moreover,we also measured and analyzed the important role of the induced defense related hormones(synthesized by SA and JA resistance pathway)and systematic defensive proteins.Accordingly,we revealed the responsive mechanisms of the internal induced defensive system triggered by both TYLCV-free or TYLCV-infected B.tabaci to the elevation of CO2.Specific research results of this study are as follows:1.In this study,we investigated the TYLCV DNA copy number(log)in mm and cm tomato plants transmitted by viruliferous whiteflies and in whiteflies on infected tomato plants,JA and SA –biosynthesis mutants under ambient CO2 and elevated CO2.The result showed that,elevated CO2 significantly inhibited the concentration of TYLCV DNA in tomato plant transmitted by viruliferous whiteflies,however,significantly increased the concentration of TYLCV DNA in whiteflies feeding on the viruliferous tomato plants.According to this result,defense functional genes related the SA and JA signaling pathway in mm and cm tomato plant under ambient and elevated CO2 were determined too.We found that elevated CO2 generally favored the genes in salicylic acid(SA)biosynthesis and signaling but repressed the functional genes in jasmonic acid(JA)pathway.Whether they are some relationship between the up-regulation of SA or down-regulation of JA and the concentration of TYLCV.2.With the question,we quantitatively analyze the concentration of TYLCV using the SA deficient mutant Nah G and JA deficient mutant spr2.We discovered that the TYLCV copy number was lower in spr2 mutant(SA can increase)than that in wild cm plant in elevated CO2.However,the TYLCV was also lower in mm than that in Nah G mutant(JA will not decrease).It proved that the rising of SA and decreasing of JA can significant suppressed the TYLCV of tomato plant infested by virulieferous whitefly.The same method,we found that virus-free whitefly acquired the virus from viruliferous tomato plant was improved by elevated CO2 is not simple affected by the SA activated and JA suppressed.3.There is no significant influence of elevated CO2 on the preference of viruliferous whitefly and virus-free whitefly to the mm and cm tomato.But the preference of whiteflies was suppressed in Nah G mutant,and it is highest in Nah G mutant plants under the ambient CO2.Conversely,the lowest preference of whiteflies exists on the spr2 tomato plant under the elevated CO2.The whiteflies prefer the plant which is benefit for the transmission of the virus.Much more viruliferous whiteflies will choose the Nah G mutant with the time over,however,Separately,subsequent virus free whiteflies will leave the Nah G mutant with the time over.The preference of whiteflies sharp increased after 24 h on the spr2 biotype under the ambient CO2.During the early feeding,The whiteflies prefer the plant with higher concentration virus for the transmission of the virus,but over time,the whiteflies infected by the virus,they will prefer the one benefit for the development of offspring.It is the trade-off strategy operating by whiteflies between transmission and fecundity.Observation time significantly affect the preference of whiteflies to the virus-infected tomato plants.