Comparative transcriptome analysis reveals aggravated damage on rice plants by brown planthoppers under elevated CO2.

The increase of atmospheric CO2 concentration will inevitably affect the photosynthesis of C3 plants, thus affecting herbivorous insects. Previous studies have shown that elevated CO2 (eCO2) may aggravate damage of brown planthopper (BPH) Nilaparvata lugens for rice plants. However, the molecular mechanism of this phenomenon is unclear. The comparative transcriptome analysis combined with corresponding phenotypic changes of rice plants and BPHs under ambient CO2 (aCO2) and eCO2 were studied to reveal the molecular mechanism of aggravated damage. The contents of soluble sugar and free fatty acid in rice stems were significantly increased while total amino acid was significantly decreased under eCO2 in contrast to aCO2. Besides, compared with aCO2, eCO2 weakened the secondary defense of rice plants against BPH-damage. More importantly, the contents of trehalose, glucose and triglycerides were increased and total protein and total amino acid were decreased in BPHs fed on rice plants grown under eCO2, resulting in stronger energy metabolism, thus enhancing that feeding behavior to attain sufficient nutrients. Therefore, both the weaken of defense in rice plants and enhancement of piercing and sucking ability of BPHs were presumed to cause the aggravated damage on rice plants by BPHs under eCO2.