模拟降雨对齿肋赤藓(Syntrichia caninervis)生理特性的影响

新疆古尔班通古特沙漠地表具有发育完好的生物土壤结皮,本文以参与组成生物土壤结皮的优势藓类———齿肋赤藓(Syntrichia caninervis)为研究对象,在实验室内对其进行模拟降雨处理,降雨量分别为0mm(对照)、2mm、6mm、10mm和15mm,研究模拟降雨影响下齿肋赤藓植株含水量、光合色素含量及可溶性糖、游离脯氨酸、可溶性蛋白、抗氧化酶(SOD、CAT和POD)、丙二醛含量的变化,以探讨其对降雨的生理生化响应。结果表明:随降雨量的增加,齿肋赤藓植株含水量显著增加;随齿肋赤藓植株含水量的增加,其光合色素含量和可溶性蛋白含量显著增加;随降雨量增加,抗氧化酶(SOD、CAT和POD)活性和可溶性糖含量呈大致递减的趋势,游离脯氨酸和丙二醛含量呈先下降后上升的变化趋势。在干燥状态下齿肋赤藓通过提高体内保护酶(SOD、CAT和POD)活性,增加可溶性糖和游离脯氨酸含量来抵御外界干旱胁迫的环境;而降雨能够增加齿肋赤藓植株含水量,激活其光合生理活性,显著提高光合色素含量,但是降雨量过大又将加剧齿肋赤藓膜脂过氧化的程度。

Influence of Simulated Rainfall on the Physiological Characteristics of Syntrichia caninervis

Biological soil crusts developed well in the Gurbantunggut Desert, Xinjiang. Syntrichia caninervis Mitt., the dominant species of moss crusts, was studied in this paper. The experiments described here were conducted in laboratory to investigate the influence of simulated rainfall on the physiological characteristics of S. caninervis. The amounts of simulated rainfall were set as 0 mm (control), 2 mm, 6 mm, 10 mm and 15 mm. A series of important physiological index were measured, including water content of plant tissue, pigment content, soluble sugar, free proline, soluble protein, antioxidant enzymes (SOD, CAT, POD) and malondialdehyde (MDA). The results showed that along with an increase in simulated rainfall amounts the water content of plant tissue increased significantly. In other words, along with an increase in the water content of plant tissue, pigment content and soluble protein increased; activities of antioxidant enzymes (SOD, CAT, POD) and soluble sugar content exhibited a general decrease; free proline and MDA decreased firstly and then increased. Under dehydrated conditions, S. caninervis was able to acclimate to the external drought stress by adjusting the activities of antioxidant enzymes (SOD, CAT, POD), as well as the content of soluble sugar and free proline; while S. caninervis was prompt in its response to rainfall in different aspects, the water content of plant tissue and pigment content increased significantly, photosynthetic physiological activities were activated immediately after simulated rainfall, whereas, membrane lipid peroxidation of S. caninervis may be aggravated by excessive rainfall.