共生与非共生爪哇伪枝藻对高温胁迫的响应

研究以自由生长的爪哇伪枝藻(Free-living S. javanicum, fs)和分离自地衣的爪哇伪枝藻(Symbiotic S. javanicum, ss)为研究对象, 探究了不同生长状态爪哇伪枝藻对高温(45℃)胁迫的响应。结果发现在高温胁迫下, 爪哇伪枝藻光合活性、叶绿素a及类胡萝卜素含量下降; 丙二醛(MDA)、胞外多糖及可溶性蛋白含量上升。在高温处理下, 与fs相比, ss光合活性下降较慢, 且高温处理后ss的叶绿素a及类胡萝卜素含量也明显高于fs。高温处理下, 与fs相比, ss的MDA含量和增长速度均较低; 并且在面临高温胁迫时, ss能够更快的分泌胞外多糖和可溶性蛋白质, 从而在一定程度上达到自我保护的目的。研究结果表明, 在暴露于高温胁迫时, 相较于自由生长状态, 来自地衣的爪哇伪枝藻具有更高的自我保护效率。

RESPONSE TO HIGH TEMPERATURE STRESS IN SYMBIOTIC AND FREE-LIVINGSCYTONEMA JAVANICUM

Biological soil crusts (BSCs) are widely distributed in global arid and semi-arid environment, where high temperature stress is one of the critical environmental factors to control the survival of algae. As a common species in BSCs,Scytonema javanicum appears in alga crust stage as free-living form and in lichen crust as symbiotic form to regu-late the formation and development of BSCs. This study explored the effect of high temperature stress (45℃) on symbio-tic (ss) and free-living S. javanicum (fs). The results showed that high temperature stress declined the photosynthetic activity more dramatically in ss compared with in fs, and high temperature stress induced a higher biomass in ss com-pared with in fs. Compared with fs, ss had lower growth rate and MDA content, and faster extropolysaccharides-re-leased and soluble protein- to protect from damages. The results showed that, compared with free-living form, the S. javanicum from lichens had higher self-protection efficiency when exposed to high temperature.