Sugar-Mediated Acclimation: The Importance of Sucrose Metabolism in Meristems

We have designed an in vitro experimental setup to study the role of sucrose in sugar-mediated acclimation of banana meristems using established highly proliferating meristem cultures. It is a first step toward the systems biology of a meristem and the understanding of how it can survive severe abiotic stress. Using the 2D-DIGE proteomic approach and a meristem-specific EST library, we describe the long-term acclimation response of banana meristems (after 2, 4, 8, and 14 days) and analyze the role of sucrose in this acclimation by setting up a control, a sorbitol, and a sucrose acclimation treatment over time. Sucrose synthase is the dominant enzyme for sucrose breakdown in meristem tissue, which is most likely related to its lower energy consumption. Metabolizing sucrose is of paramount importance to survive, but the uptake of sugar and its metabolism also drive respiration, which may result in limited oxygen levels. According to our data, a successful acclimation is correlated to an initial efficient uptake of sucrose and subsequently a reduced breakdown of sucrose and an induction of fermentation likely by a lack of oxygen.

本研究构建了一套体外（in vitro）实验体系，以已建立的高增殖分生组织培养物为实验材料，探究蔗糖在香蕉分生组织糖介导驯化过程中的作用。本研究是推进分生组织系统生物学研究、解析其耐受严重非生物胁迫机制的首要步骤。本研究采用双向荧光差异凝胶电泳（2D-DIGE）蛋白质组学方法，结合分生组织特异性表达序列标签（EST）文库，对香蕉分生组织在2、4、8及14天处理后的长期驯化响应进行了系统描述；并通过设置不同时间梯度的对照组、山梨醇处理组与蔗糖处理组，分析了蔗糖在该驯化过程中的调控作用。研究表明，蔗糖合酶是分生组织组织中蔗糖分解的主导酶类，这一特征大概率与其较低的能量消耗特性相关。蔗糖代谢对分生组织存活至关重要，但糖类摄取与代谢同时会驱动呼吸作用，进而可能导致局部氧含量不足。结合本研究数据，成功的驯化过程与初始阶段高效的蔗糖摄取、后续蔗糖分解的减弱，以及大概率由缺氧引发的发酵途径诱导显著相关。