荒漠齿肋赤藓(Syntrichia caninervis)非结构性碳水化合物含量对植株脱水的响应

苔藓结皮作为生物土壤结皮演替的最高阶段和生物量的最主要贡献者,具有很强的环境适应性,对维持荒漠地表稳定和改善微环境具有重要作用。非结构性碳水化合物是植物重要的组成部分,能够抵御环境胁迫对植物造成的损伤。目前,荒漠藓类植物非结构碳水化合物对干旱的响应机制尚不清楚。选取古尔班通古特沙漠南缘和腹地苔藓结皮中优势藓类植物齿肋赤藓(Syntrichia caninervis)为研究对象,对其在复水后脱水过程中非结构性碳水化合物含量变化特征进行了分析。结果表明:植株含水量在脱水24 h内下降趋势显著,此后趋于稳定。可溶性总糖、蔗糖、果糖、淀粉含量在脱水1h内显著下降。可溶性总糖、蔗糖、果糖、淀粉含量在脱水2—16 h没有显著的变化。但16—24 h可溶性总糖、蔗糖、果糖、淀粉含量出现显著增加,脱水24—48 h,腹地齿肋赤藓可溶性总糖、蔗糖、果糖、淀粉含量缓慢下降到复水前水平,而南缘可溶性总糖、蔗糖、果糖含量低于复水前水平。复水前不同地区齿肋赤藓非结构性碳水化合物含量存在显著性差异,脱水结束后两个地区齿肋赤藓非结构碳水化合物含量无显著差异。结果说明齿肋赤藓在不同地区其非结构性碳水化合物含量不同,在同一脱复水过程中不同地区齿肋赤藓非结构性碳水化合物含量表现出不同的变化趋势,主要原因是可溶性糖含量对脱水过程中水分胁迫的响应不同。齿肋赤藓脱水过程中非结构性碳水化合物的研究,有助于抗旱非维管植物在干旱环境中从降雨湿润进入干旱过程的适应策略研究。

Response of non-structural carbohydrate content of Syntrichia caninervis to dehydration process

As the highest stage in the development of biological soil crusts and the most important contributor of biomass to biological soil crusts, moss crust plays an important role in stabilizing the desert surface and improving the moisture and nutrient conditions of the micro-environment. Mosses are poikilohydric and are sensitive to pulsed precipitation and drought. Non-structural carbohydrates (NSC) are the important part of plants and can withstand the damage caused by environmental stress to plants. However, the response mechanism of non-structural carbohydrate to drought is not clear. In the present study, we chose Syntrichia caninervis, the dominant species of moss crusts in the Gurbantunggut desert, as the target species and examined the change in NSC content during the period of dehydration. The results showed that the water content decreased with the duration of dehydration, declining rapidly during 1-24 h, and then declining slowly. The change in NSC content is complicated. Soluble total sugar content (TSC), fructose content (FC), sucrose content (SUC), and starch content (STC) decreased rapidly in the first hour. The NSC, TSC, FC, SUC, and STC did not change significantly in the stem and leaves of plants during the second hour to sixteenth hour. The NSC, TSC, FC, SUC, and STC increased significantly during the sixteenth hour to twenty-fourth hour. From twenty-fourth hour to forty-eighth hour, the NSC, TSC, FC, SUC, and STC of moss in the central region of the desert decreased slowly and reached the level of incipient dehydration, and the TSC, FC, and SUC of the moss in the southern region of the desert significantly decreased. However, the NSC of moss present in the central region of the desert was not significantly different. This result indicated that the plant water content and NSC of moss from different regions show different changes in the process of rehydration and dehydration. The NSC of S. caninervis was differed significantly among regions. This study contributes to the understanding of the process by which non-vascular plants respond to pulsed precipitation and drought stress in desert.