The effect of elevated CO₂ on TYLCV-enhanced attractiveness to Bemisia tabaci in tomato plants

Raising atmospheric CO₂ could modify plant defenses against herbivorous insects and pathogenic microbial, by which shapes the outcomes of biotic interaction. Relative few studies, however, evaluates the effects of elevated CO₂ on the attractiveness of plant with and without virus infection to the virus-vector insects. Here, the effects of elevated CO₂ (750 ppm vs. 400 ppm), plant genotypes (a jasmonate-deficient mutant spr2 vs. its wild-type Castlemart) and TYLCV infection on the attractiveness of tomato plants to whitefly were determined in field open-top chambers. We found that elevated CO₂ increased plant photosynthetic rate and facilitated TYLCV infection on tomato plants. TYLCV infection and plant genotypes, rather than CO₂ levels, significantly affected plant attractiveness to whitefly, in that JA signaling pathway is required for virus-enhanced attractiveness to whitefly. Furthermore, TYLCV infection reduced the emission of five monoterpene volatiles, and three of them were repellent against whitefly. TYLCV infection downregulated the gene expression of JA signaling pathway and decreased JA content. The emission of monoterpenes in spr2 plants was lower than that in wild-type plants. These results suggested that TYLCV infection could reduce JA-dependent monoterpenes emission of tomato plants, thereby increasing plant attractiveness to whitefly. Our results revealed that TYLCV-enhanced olfactory attractiveness of tomato plants to whitefly was unaffected by elevated CO₂, indicating the evolutionarily chemical associations among plant-virus-insect vector remain robust and still effective under the context of climate change.