Treh1-3 And Treh1-4 Genes Cloned From Harmonia Axyridis And The Metabolism Of Trehalose Under Cold Induction

Trehalose, which is main ingredients in insect blood sugar, acts as a source of energy and as an agent for protecting insect upon exposure to environmental extremes. Trehalase(Treh), which is present in many insect tissues, can catalyze 1 mol trehalose into 2 mol glucose. A large number of studies have shown that when insects in the face of environmental stresses, trehalose will be accumulation in the body, help them to resist the bad environment. In order to expore how trehalose metabolism to control cold tolerance in Harmonia axyridis, we cloned two novel trehalase genes from the H. axyridis by transcriptome sequencing and rapid amplification of c DNA ends. Meanwhile, we tested the expression analysis of 4 Treh1 genes. Then, we designed two different cold stresses: short-time and long-time cold stress and a comparison of trehalose and glycogen levels and trehalase activities in these treatments were carried out. The main results are listed as follows:1. Two novel soluble trehalase genes—Treh1-3 and Treh1-4—were cloned from H.axyridis, the NCBI accession number: JX514372 and KP318742, respectively. The whole Treh1-3 c DNA consisted of 2336 bp, including a 1644 bp open reading frame(ORF) encoding a 547-aa protein with a predicted mass of 65.02 k Da. And the whole Treh1-4 c DNA consisted of 2084 bp, including an ORF of 1677 bp and a 558 predicted aa protein with an estimated molecular mass of 64.93 k Da.2. During short-time cold stress, the comparison of trehalose and glycogen content in cooling and warming treatments shown that, an increase in the absolute concentration of trehalose occurred at low temperature, and the inducing temperature is 5°C. We found a transforming relationship between glycogen and trehalose, so glycogen could be converted into trehalose when exposed to a low temperature environment.3. During long-time storage, we compared the trehalose, glycogen content and trehalase activity in yellow and black adults, which come from overwintering or indoor populatin, and found that there was no significant difference between theyellow and the black from indoor population. For overwintering population, the yellow’s trehalose and glycogen levels significantly lower at 20 d saved at 5℃, while the black mainly happened at 40 d. However, the survival rate of them was no significantly different.