Key Laboratory of Plant Protection Resources & Pest Management of the Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
Key Laboratory of Plant Protection Resources & Pest Management of the Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
J Insect Physiol. 2021 Nov-Dec;135:104324. doi: 10.1016/j.jinsphys.2021.104324. Epub 2021 Oct 30.
Trehalose plays crucial roles in energy metabolism and stress tolerance in various organisms. The orange wheat blossom midge Sitodiplosis mosellana, a serious pest of wheat worldwide, undergoes long obligatory diapause as a larva to survive harsh temperature extremes in summer and winter. To gain an insight into trehalose function and metabolic mechanism in this process, we measured the content of trehalose and glucose, as well as enzymatic activities of trehalose-6-phosphate synthase (TPS), trehalose-6-phosphate phosphatase (TPP) and soluble trehalase (Treh1) at pre-diapause, diapause and post-diapause larvae of S. mosellana. Trehalose levels greatly increased upon entry into diapause, peaked in low-temperature quiescence phase, and significantly dropped after resumption of development, highly consistent with activity changes of trehalose-synthetic enzymes SmTPS and SmTPP. In marked contrast, the activity of trehalose-degrading SmTreh1 exhibited a completely reversed profile. This profile was in agreement with contents of its product i.e. glucose. Furthermore, deduced amino acid sequences of cloned SmTPS, SmTPPB, SmTPPC, SmTreh1-1 and SmTreh1-2 genes contained all conserved functional domains, motifs and active sites. Expression patterns of these genes were closely correlated with their enzyme activities. These results suggested that coordination of trehalose synthetic and degradation pathways is responsible for diapause-related trehalose accumulation, which may serve as an energy reserve for post-diapause development and a cryoprotectant against cold stress in winter.
海藻糖在各种生物的能量代谢和应激耐受中发挥着关键作用。橘小实蝇（Sitodiplosis mosellana）是一种世界性的小麦严重害虫，它作为幼虫经历长时间的强制性滞育，以在夏季和冬季极端温度下生存。为了深入了解海藻糖在这个过程中的功能和代谢机制，我们测量了海藻糖和葡萄糖的含量，以及海藻糖-6-磷酸合酶（TPS）、海藻糖-6-磷酸磷酸酶（TPP）和可溶性海藻糖酶（Treh1）在橘小实蝇预滞育、滞育和后滞育幼虫中的酶活性。进入滞育后，海藻糖水平大幅上升，在低温休眠期达到峰值，发育恢复后显著下降，与海藻糖合成酶 SmTPS 和 SmTPP 的活性变化高度一致。相比之下，海藻糖降解酶 SmTreh1 的活性则呈现出完全相反的模式。这一模式与它的产物葡萄糖的含量一致。此外，克隆的 SmTPS、SmTPPB、SmTPPC、SmTreh1-1 和 SmTreh1-2 基因的推导氨基酸序列包含所有保守的功能域、基序和活性位点。这些基因的表达模式与它们的酶活性密切相关。这些结果表明，海藻糖合成和降解途径的协调作用是滞育相关海藻糖积累的原因，这可能为后滞育发育提供能量储备，并在冬季抵御冷应激提供保护。
