University of Gabes, Arid Regions Institute, LR16IRA03 Laboratory of Rangeland Ecosystems and Valorization of Spontaneous Plants and Associated Microorganisms, El Fjé, Medenine, Tunisia.
University of Gabes, Faculty of Sciences of Gabes, Gabes, Tunisia.
Physiol Plant. 2021 Aug;172(4):2112-2128. doi: 10.1111/ppl.13446. Epub 2021 May 11.
To cope with abiotic stresses, the halophytes use various tolerance mechanisms that are not all known for some species of halophytes. This work aimed to model the responses of two halophytes, Limonium pruinosum and Limonium tunetanum, to changing environmental conditions over a year in Sabkha biotope, Tunisia. Our findings indicated that the model could describe well the seasonal variations of all studied traits over a year in this region (R > 0.80). The pH, electrical conductivity (EC), and mineral composition (i.e., Sodium [Na ], potassium [K ], calcium [Ca ], and magnesium [Mg ] concentrations] in the soil significantly varied during the year (P < 0.01). The highest soil Na concentration was found during the dry period (June-August), which matched with a high Na content in the aerial parts (i.e., 2455.1 and 3366.0 μmol g SDM in August for L. pruinosum and L. tunetanum, respectively). This accumulation is concomitant with a deficit in nutrients, particularly K and Mg and, to a lesser extent, Ca . Following these disturbances, both species decreased their photosynthetic activity, water potential as well as the relative water content to a lesser extent, especially in August. To counteract these harmful effects, these species have accumulated organic substances, but in a different way. Indeed, L. pruinosum accumulated sucrose, fructose, and citrate, while L. tunetanum accumulated sucrose, xylitol, citrate, and malate, indicating a major role of these osmolytes in the stress tolerance mechanisms. In both species, the results also showed that all traits were highly correlated with the edaphic variables (i.e., pH, EC, Na , K , Ca , and Mg concentrations) and with temperature as the climatic variable.
为了应对非生物胁迫，盐生植物利用了各种耐受机制，但有些盐生植物的耐受机制尚不完全清楚。本研究旨在建立模型，以研究一年中突尼斯盐沼生境下两种盐生植物（Limonium pruinosum 和 Limonium tunetanum）对环境条件变化的响应。我们的研究结果表明，该模型能够很好地描述该地区一年内所有研究特征的季节性变化（R > 0.80）。土壤的 pH 值、电导率（EC）和矿物组成（即钠[Na ]、钾[K ]、钙[Ca ]和镁[Mg ]浓度）在一年内有显著变化（P < 0.01）。土壤中 Na 浓度在旱季（6-8 月）最高，与地上部分 Na 含量高相对应（即 8 月时 L. pruinosum 和 L. tunetanum 的 Na 含量分别为 2455.1 和 3366.0 μmol g SDM）。这种积累伴随着营养物质的缺乏，特别是 K 和 Mg，以及 Ca 的缺乏程度较小。在这些干扰之后，两种植物的光合作用活性、水势以及相对含水量都有所下降，尤其是在 8 月。为了对抗这些有害影响，这些植物积累了有机物质，但方式不同。事实上，L. pruinosum 积累了蔗糖、果糖和柠檬酸，而 L. tunetanum 积累了蔗糖、木糖醇、柠檬酸和苹果酸，表明这些渗透物在应激耐受机制中起着重要作用。在这两个物种中，结果还表明，所有特征都与土壤变量（即 pH 值、EC 值、Na 、K 、Ca 和 Mg 浓度）和温度（作为气候变量）高度相关。
