METABOLISM OF PLANT OSMOLYTES

长期以来，我们一直参与阐明代谢途径。 用于几种无环糖的生物合成和降解 酒精，例如山梨醇和甘露醇，并测定 这些细胞的特征和组织、细胞和亚细胞位置 参与这些途径的酶。酶的鉴定和鉴定 表征目前包括对监管机制的研究 无论是蛋白质水平还是基因水平。例如，我们已经克隆了 对甘露糖6-磷酸还原酶基因进行了测序，这是 甘露醇的生物合成，目前正在研究这些因素 参与其监管。我们对甘露醇新陈代谢的研究 我们最初使用MALDI-MS来验证不太准确的分子 甘露糖6-磷酸还原酶的重量测定 (M6PR)。在基因克隆之后，MALDI-MS也证实了克隆 通过允许比较两个分子的分子量来确定身份 克隆表达的细菌和天然植物酶。这个 这项工作的重要性与植物逆境生理学有关。我们是 非常有兴趣通过以下方式发展对机制的理解 哪些植物能耐受非生物胁迫、极端环境，如 盐度、干旱和温度，特别是因为其中几个 机制可能与某些植物的合成能力有关。 相容的溶质，如无环糖醇。因此，我们 一直在研究某些非生物胁迫是如何调节糖的 酒精的代谢、储存和运输，以及这些化合物是如何 可能会因应对压力而积累。M6PR与 其他植物中的几种类似的酶是无环糖的关键步骤。 酒精生物合成。携带M6PR基因的工程植物可以 对培育抗逆性改善的植物具有重要意义 宽容。

We have long been involved in elucidating the metabolic pathways for both biosynthesis and degradation of several acyclic sugar alcohols, e.g., sorbitol and mannitol, and determining the characteristics and tissue, cell, and subcellular locations of those enzymes involved in these pathways. Enzyme identification and characterization currently includes study of regulatory mechanisms at both the protein and gene level. We have, for example, cloned and sequenced the gene for mannose 6-phosphate reductase, a key step in mannitol biosynthesis, and are now investigating those factors involved in its regulation. For our work on mannitol metabolism in plants we initially used MALDI-MS to verify less accurate molecular weight determinations of the enzyme mannose 6-phosphate reductase (M6PR). Following gene cloning, MALDI-MS also confirmed clonal identity by allowing a comparison of the molecular weights of the clonally expressed bacterial and the native plant enzymes. The importance of this work relates to plant stress physiology. We are very interested in developing an understanding of the mechanisms by which plants tolerate abiotic stress, environmental extremes such as salinity, drought, and temperature, especially since several of these mechanisms may be related to the capacity of some plants to synthesize compatible solutes like the acyclic sugar alcohols. Accordingly, we have been looking at how certain abiotic stresses regulate sugar alcohol metabolism, storage, and transport, and how these compounds may accumulate in response to exposure to stress. M6PR along with several similar enzymes in other plants is a key step in acyclic sugar alcohol biosynthesis. Engineering plants with a gene for M6PR can have important implications for developing plants with improved stress tolerance.