The Effects And Mechanism Of Elevated CO₂on Tomato-pathogens Interactions

Vegetable and other crops have to face a variety of environment factors like light, temperature and moisture etc. during their growth and developmental period. Since19th century, the rapid development of human activities such as oil, coal and other industries have greatly challenged the global weather. From the industrial revolution to now, the concentration of CO2in the atmosphere has been observed to increase fast from280μl/L in1900s to almost380μl/L at present, and it is predicted to be reached at730-1020μL/L in the end of this century. To understand all aspects of plant under elevated CO2containing environment will help us to predict the changes of plant in the future and develop the agricultural management strategy to over come those limitations.In this research we used Lycopersicum esculentum as plant material and automatically controlled growth chamber to make elevated CO2environment. We choose TMV, PstDC3000and Botrytis.cinerea as objects of study. We constructed the gene silencing vector carrying the fragment of LeNPR1and LePⅠ Ⅰ and LePⅠ Ⅱ genes to silence the NPRI and PIs. So that we can proof the mechanism of the disease-resistance change in Lycopersicum esculentum under elevated CO2. The following are the major results:1. The changes of elevated CO2on tomato-TMV interactionsControlling the concentration of CO2in the environment, we investigated how tomato showed resistance to TMV under elevated CO2. The result showed that compared to the ambient environment the expression of TMV-CP was obviously lower than elevated CO2. The expression of ICSI and PAL were higher under elevated CO2or TMV inoculation. The free and total SA combined to the down side signal also showed the same tend. However, the signals of JA did not show any differences under elevated CO2and inoculated TMV. So the reason why tomato shows resistance to TMV under elevated CO2may be the SA pathway is enhanced under CO2.2. The changes of elevated CO2on tomato-PstDC3000interactions Tomato showed more resistance to PstDC3000under elevated CO2. The expression of ICS1and PAL were higher under elevated CO2or inoculated by PstDC3000. The free, and total SA were also higher under elevated CO2or inoculated by PstDC3000. Similar to the experiment of TMV, the down side signal of SA, NPR1and PR1were obviously higher. At the same time the JA downside signals PⅠⅠ and PⅠⅡ were also higher when inoculated by PstDC3000but the expression was lower under elevated CO2.3. The changes of elevated CO2on tomato-Botrytis.cinerea interactionsTomato showed more susceptibility to Botrytis.cinerea under elevated CO2. Under Botiytis cinerea inoculation, the expression of NPR1, PR1, PⅠⅠ and PⅠⅡ were higher, however the expression of PⅠ Ⅰ and PⅠ Ⅱ were limited by CO2That may explain why tomato shows more susceptibility to Botrytis.cinerea under elevated CO2.4. The effect of elevated CO2on the silencing of NPR1and PⅠ in tomato with TMV PstDC3000B cinereaWe used VIGS to silence the expression of NPRl and PR1but the expression of PⅠⅠ PⅠ Ⅱ were elevated, that reduced the resistance to TMV and PstDC3000. Silencing the expression of PI did not show any affect on the expression of NPR1and PR1. The TRV-PI tomato showed less resistance to Botrytis cinerea but had not effect on the TMV and PstDC3000. Due to these phenomena, we can draw the conclusion that the effect of elevated CO2on tomato-pathogens interactions may have relation with the SA and JA in tomato.