French Associates Institute for Biotechnology and Agriculture of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben Gurion 84990, Israel.
Plant Physiol. 2013 Jul;162(3):1583-98. doi: 10.1104/pp.113.217844. Epub 2013 Jun 4.
Comparative studies of the stress-tolerant Arabidopsis (Arabidopsis thaliana) halophytic relative, Eutrema salsugineum, have proven a fruitful approach to understanding natural stress tolerance. Here, we performed comparative phenotyping of Arabidopsis and E. salsugineum vegetative development under control and salt-stress conditions, and then compared the metabolic responses of the two species on different growth platforms in a defined leaf developmental stage. Our results reveal both growth platform-dependent and -independent phenotypes and metabolic responses. Leaf emergence was affected in a similar way in both species grown in vitro but the effects observed in Arabidopsis occurred at higher salt concentrations in E. salsugineum. No differences in leaf emergence were observed on soil. A new effect of a salt-mediated reduction in E. salsugineum leaf area was unmasked. On soil, leaf area reduction in E. salsugineum was mainly due to a fall in cell number, whereas both cell number and cell size contributed to the decrease in Arabidopsis leaf area. Common growth platform-independent leaf metabolic signatures such as high raffinose and malate, and low fumarate contents that could reflect core stress tolerance mechanisms, as well as growth platform-dependent metabolic responses were identified. In particular, the in vitro growth platform led to repression of accumulation of many metabolites including sugars, sugar phosphates, and amino acids in E. salsugineum compared with the soil system where these same metabolites accumulated to higher levels in E. salsugineum than in Arabidopsis. The observation that E. salsugineum maintains salt tolerance despite growth platform-specific phenotypes and metabolic responses suggests a considerable degree of phenotypic and metabolic adaptive plasticity in this extremophile.
对具有耐盐性的拟南芥（Arabidopsis thaliana）盐生近缘植物盐芥（Eutrema salsugineum）的比较研究已被证明是一种了解自然耐盐性的有效方法。在这里，我们对拟南芥和盐芥的营养生长在对照和盐胁迫条件下的表型进行了比较研究，然后在不同的生长平台上比较了两个物种在特定叶片发育阶段的代谢反应。我们的研究结果揭示了两种生长平台依赖和不依赖的表型和代谢反应。在体外培养的两种物种中，叶片出现的情况相似，但在盐芥中观察到的影响出现在更高的盐浓度下。在土壤中没有观察到叶片出现的差异。发现盐介导的盐芥叶片面积减少的新效应。在土壤中，盐芥叶片面积减少主要是由于细胞数量减少，而细胞数量和细胞大小都导致了拟南芥叶片面积的减少。确定了一些共同的生长平台独立的叶片代谢特征，如高水平的棉子糖和苹果酸，以及低富马酸含量，这可能反映了核心耐盐机制，以及生长平台依赖的代谢反应。特别是，与土壤系统相比，体外生长平台导致盐芥中许多代谢物（包括糖、糖磷酸和氨基酸）的积累受到抑制，而在土壤系统中，这些相同的代谢物在盐芥中的积累水平高于拟南芥。尽管盐芥表现出特定于生长平台的表型和代谢反应，但仍能保持耐盐性，这表明该极端微生物具有相当程度的表型和代谢适应性。
