Effect Of Elevated CO₂on The Biochemical Substances Of Rice Plant And On The Physiological Metabolism Of Nilaparvata Lugens

Atmospheric carbon dioxide (CO2) concentration is slowly rising which provokes global climate change, and this problem is become serious challenge for human sustainable development. Elevated atmospheric CO2concentration affects the yield, quality and the Distribution of chemical substances of rice which is one of the main cultivated crops.And brown planthopper (Nilaparvata lugens Stal), an important pest on rice, responses to elevated CO2in multiple aspects such as growth and development, physiology and biochemistry. Two levels (375uL/L and750uL/L) of CO2were considered, and the biochemical substances in the stems of3-leaf-stage rice plant were measured in this study. And also, the responses of protein content, enzyme activity, gene expression of fourth instar of N.lugens nymph to elevated CO2including the influence of the time dynamic were studied. The results were as follow:1Response of rice biochemical substances to elevated CO2The results showed that the content of protein and total amino acid in rice stem was decreased along with days, while significantly higher glucose content was observed in elevated CO2relative to ambient CO2treatment. Investigating day significantly affected flavonoid isoschaftoside and contents. Significantly higer flavonoid isoschaftoside was found under elevated CO2than ambient CO2treatment at the7day. Gallic acid was remarkable higher than ambient CO2treatment since the3day, while lower than ambient CO2treatment at the7day. And oxalic acid was significantly higher under elevated CO2than ambient CO2treatment at the5day, while remarkble lower at the7day.2Effect of elevated CO2on nutrient substance and enzyme of N.ugensSignificantly lower protein and significantly higher glucose were found in the body of N.ugens under elevated CO2compared with the ambient CO2treatment. Meanwhile, significantly higher trypsin, total superoxide dismutase and catalase were observed after a period of time in the body of N.ugens nymphs was observed in elevated CO2relative to ambient CO2treatment. However, significantly lower glutathione S-transferase were observed under elevated CO2relative to ambient CO2treatment. There is no significant difference in lipase and acetylcholine esterase between elevated CO2and ambient CO2treatments.3Temporal dynamics of relative gene expression in the body of N.lugens in response to elevated CO2 Glutathione-S transferase gene expression was decrease at4h under elevated CO2. The gene expression of acetylcholine eaterase reached a peak at4h under elevated CO2, then dropped to valley at12h, finally the expression quantity increased along with the time prolonged. The expression of CYP303A1in Cytochrome P450proteins increased significantly at1h and decreased at24h. While the expression of CYP6CS1quantity did not change significantly within24h. Treat for4h with elevated CO2, the expression of hsp90significantly increased at4h under elevated CO2. The expression of hsp70expression was achieved a peak at6h under elevated CO2significantly higher vitellogenin gene expression was observed at4h under elevated CO2relative to ambient CO2treatment. There was no significant difference in ecdysone gene expression in the body of N.lugens during the processing for24h. As well as the juvenile hormone enzymes gene in the body of N.lugens had a no significant difference increase at1h in elevated CO2.This study showed that significantly lower protein and total amino acid contents and significantly higher isoschaftoside, gallic acid and oxalic acid after a period of time or rapidly were observed in rice stems under elevated CO2relative to ambient CO2treatment, which indicated that elevated CO2resulted in lower nutrient quality and higher resistant ability in rice plants Significantly lower protein was found in the body of N. lugens under elevated CO2compared with ambient CO2treatment. Elevated CO2concentration had a significant effect on N. lugens nymphae protective enzymes and the detoxification enzyme activity. Moreover, there was a temporal dynamics response in the specific protein and hormone gene expression in the body of N.lugens under elevated CO2. In addition, elevated CO2affected the gene expression of detoxifying enzymes, endogeny proteins and hormones in N.lugens nymphae body; And there is a temporal dynamics response of the gene expression of glutathione S-transferase, acetylcholine esterase, heat shock protein and vitellogenin to elevated CO2, related to which further study on the physiological metabolism helps to understanding reaction mechanism research in N.lugens body under elevated CO2.