Trehalose-6-Phosphate Synthase Contributes to Rapid Cold Hardening in Invasive Insect Lissorhoptrus oryzophilus (Coleoptera: Curculionidae) by Regulating Trehalose Metabolism

Abstract

RCH is known rapidly enhance cold tolerance of insects. Trehalose has been demonstrated to be one of the cryoprotectant in L. oryzophilus, an important invasive pest of rice in China. Trehalose synthesis mainly occurs through the TPS/TPP pathway in insects. In this study, LoTPS gene was cloned and characterized for the first time. Its expression and trehalose content changes elicited by RCH were investigated. Our results revealed that RCH not only increased the survival rate of adults but also upregulated the gene expression level of LoTPS and increased trehalose content under low temperature. We hypothesized upregulated LoTPS promoted trehalose synthesis and accumulation to protect adults from low-temperature damage. To further verify the function of LoTPS gene, we employed RNAi technology. Our findings showed that RCH efficiency disappeared and failed to increase the survival rate when the adults were fed dsRNA of LoTPS. Additionally, inhibiting LoTPS gene expression resulted in no significant difference in trehalose content between RCH and non-RCH treatments. Furthermore, the expression patterns of TRET and TRE were also affected. Collectively, these results indicate the critical role of LoTPS in L. oryzophilus cold resistance after RCH induction. LoTPS can enhance the survival ability by regulating trehalose metabolism. These findings contribute to further understanding of the role of TPS in insect cold resistance and invasiveness of L. oryzophilus. Moreover, RNAi of the LoTPS opens up possibilities for novel control strategies against L. oryzophilus in the future.