Physiological responses of soil crust‐forming cyanobacteria to diurnal temperature variation
Physiological responses of soil crust‐forming cyanobacteria to diurnal temperature variation
复制标题
DOI：
10.1002/jobm.201100510
复制
发表时间：
2013-01
影响因子：
3.1
通讯作者：
Weibo Wang;Yingcai Wang;Xiao Shu;Quanfa Zhang
中科院分区：
文献类型：
--
作者：
Weibo Wang;Yingcai Wang;Xiao Shu;Quanfa Zhang
土壤结皮形成蓝藻物种的最佳生长发生在21至30 °C之间。当温度降至-5 °C以下时，蓝藻细胞中的液态水可能会冻结。在自然环境中，温度从秋季到冬季逐渐下降，日温差波动很大。据推测，蓝藻细胞的生理变化在晚秋，以适应即将到来的冻结温度的细胞。在本研究中，在生长箱中的培养实验设计，以刺激蓝藻细胞的反应，在深秋冻结前的昼夜温度变化。结果表明，“浅色”的蓝藻结皮比“深色”的蓝藻结皮更能耐受昼夜温度波动。在第一个昼夜温度循环（24--4 °C）后，丙二醛（MDA）含量增加，光合活性下降。超氧化物歧化酶活性增加，胞外多糖（EPS）分泌增加，捕光色素和遮光色素的比例下降。随着温度日变化次数的增加，丙二醛含量和光合活性逐渐恢复到初始水平。我们的研究结果表明，至少有三种途径，结皮蓝藻适应秋末的昼夜温度周期在霍布茨沙漠，西北中国。这三种途径包括增加EPS的分泌，调节捕光和遮光色素的比例，以及激活抗氧化系统。研究结果还表明，深秋是库布齐沙漠蓝藻结皮保护与恢复的关键时期。
The optimum growth of soil crust‐forming cyanobacterial species occurs between 21 and 30 °C. When the temperature decreases below −5 °C, the liquid water in the cyanobacterial cells may freeze. In the natural environment, the temperature gradually decreases from autumn to winter, and the diurnal temperatures fluctuate enormously. It was hypothesized that the physiology of cyanobacterial cells changes in later autumn to acclimatize the cells to the upcoming freezing temperatures. In the present study, an incubation experiment in growth chambers was designed to stimulate the responses of cyanobacterial cells to diurnal temperature variations before freezing in late autumn. The results showed that “light” cyanobacterial soil crusts are more tolerant to diurnal temperature fluctuations than “dark” cyanobacterial soil crusts. After the first diurnal temperature cycle between 24 and −4 °C, the malondialdehyde (MDA) contents increased and the photosynthetic activity decreased. The superoxide dismutase activity increased, more extracellular polysaccharides (EPS) were secreted and the ratios of the light‐harvesting and light‐screening pigments decreased. With increasing numbers of diurnal temperature cycles, the MDA contents and photosynthetic activity gradually returned to their initial levels. Our results suggest that there are at least three pathways by which crust‐forming cyanobacteria acclimate to the diurnal temperature cycles in the late autumn in the Hopq Desert, Northwest China. These three pathways include increased secretion of EPS, regulation of the ratios of light‐harvesting and light‐screening pigments, and activation of the antioxidant system. The results also indicate that late autumn is a critical period for the protection and restoration of the cyanobacterial soil crusts in the Hopq Desert.