背景回顾：Invertase (INV)-mediated sucrose (Suc) hydrolysis, leading to the irreversible production of glucose (Glc) and fructose (Frc), plays an essential role in abiotic stress tolerance of plants. 

提出问题：However, the regulatory network associated with the Suc catabolism in response to cold environment remains largely elusive. 

结果1-PtrA/NINV7-蔗糖水解-低温抗性：Herein, a cold-induced alkaline/neutral INV gene (PtrA/NINV7) of trifoliate orange (Poncirus trifoliata (L.) Raf.) was shown to function in cold tolerance via mediating the Suc hydrolysis. Meanwhile, a nuclear matrix-associated region (MAR) containing A/T-rich sequences within its promoter was indispensable for the cold induction of PtrA/NINV7. 

结果2-PtrAHL14/17-PtrA/NINV7-蔗糖水解-低温抗性：Two AT-Hook Motif Containing Nuclear Localized (AHL) proteins, PtrAHL14 and PtrAHL17, were identified as upstream transcriptional activators of PtrA/NINV7 by interacting with the A/T-rich motifs. PtrAHL14 and PtrAHL17 function positively in the cold tolerance by modulating PtrA/NINV7-mediated Suc catabolism. 

结果3-PtrAHL14/17-组蛋白乙酰化：Furthermore, both PtrAHL14 and PtrAHL17 could form homo- and hetero-dimers between each other, and interacted with two histone acetyltransferases (HATs), GCN5 and TAF1, leading to elevated histone3 acetylation level under the cold stress. 

结论：Taken together, our findings unraveled a new cold-responsive signaling module (AHL14/17-HATs-A/NINV7) for orchestration of Suc catabolism and cold tolerance, which shed light on the molecular mechanisms underlying Suc catabolism catalyzed by A/NINVs under cold stress.

 背 景 

蔗糖酶INV介导的蔗糖水解会不可逆生成葡萄糖和果糖，在植物的非生物胁迫耐受性中发挥重要作用。然而，响应低温环境时蔗糖分解代谢相关的调控网络仍不清楚。本文中，作者发现三叶橙中一个受到低温诱导的基因PtrA/NINV7能够通过介导蔗糖的水解促进低温耐受性。同时，该基因启动子区一段富含A/T序列的核基质结合区（MAR）对于其低温诱导表达模式必不可少。两个含有AT-Hook基序的AHL蛋白PtrAHL14和PtrAHL17作为PtrA/NINV7基因的上游调控因子，通过与其启动子区域富含A/T基序互作而作用于PtrA/NINV7基因的低温诱导。PtrAHL14和PtrAHL17通过PtrA/NINV7介导的蔗糖水解，正调控三叶橙的低温耐受性。此外，PtrAHL14和PtrAHL17均可以形成同源二聚体，亦或相互之间形成异源二聚体，与两个组蛋白乙酰转移酶GCN5和TAF1互作，从而导致低温胁迫下组蛋白3乙酰化水平升高。综上，本文的研究揭示了一个新的低温响应信号转导模块AHL14/17-HATs-A/NINV7，该模块通过对蔗糖代谢的调控接到植株的低温耐受性，从而为低温胁迫下由A/NINVs催化的蔗糖代谢潜在分子调控机制提供了新的视野。

 刘继红