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低温光照是荒漠化地区蓝藻结皮经常面临的环境条件之一.报道了实验室条件下低温光照处理对蓝藻结皮形态、生理特性和超微结构的影响.本研究中,首先通过接种具鞘微鞘藻和爪哇伪枝藻形成人工蓝藻结皮,接着以人工蓝藻结皮为材料进行低温光照处理:28℃+60μE.(m2.s)-1(对照)、10℃+60μE.(m2.s)-1、2℃+60μE.(m2.s)-1和2℃+黑暗.在不同低温光照处理的第0、5和12 d分别测定蓝藻结皮光合活性(Fv/Fm)、叶绿素a、胞外多糖、伪枝藻素、类胡萝卜素和藻蓝蛋白的含量及藻蓝蛋白/叶绿素比值,同时采用扫描电镜观察低温光照处理下蓝藻结皮的微结构变化.此外,对结皮的表观形态特征如结皮颜色、厚度和干重等进行了测定.与对照结皮相比,低温光照下结皮的表观形态受到不利影响,所测定的结皮各项生理指标均呈现显著下降(P<0.05).在2℃+60μE.(m2.s)-1处理12 d时,结皮生物量、光合活性、胞外多糖含量、伪枝藻素含量、类胡萝卜素含量和藻蓝蛋白含量分别比同期对照结皮下降了61.48%、94.89%、66.37%、31.01%、59.38%和65.91%.电镜观察表明,低温光照导致蓝藻结皮的超微结构受到明显破坏,表现为结皮层出现大量蜂窝状空隙,藻丝体数量减少,呈网格状分布,对沙粒的束缚能力减弱等.研究表明低温光照对蓝藻结皮的形态和生理活性具有明显的抑制效应,而低温黑暗能较好地促进蓝藻结皮生理活性和结皮表观形态的恢复.本研究初步探索了蓝藻结皮对低温光照胁迫的耐受性,同时对于了解蓝藻结皮在野外极端环境条件下的生存状况具有一定的理论意义.
Low-temperature illumination is one of the environmental conditions often encountered in the cyanobacteria crusts in desertification areas.The effects of low-temperature photoperiod treatments on the morphology, physiological characteristics and ultrastructure of blue-green algae crusts were reported.In this study, The artificial algae crusts were formed by M. hyodysentris and P. pseudoacacia, then treated with artificial cyanobacterial crust at low temperature for 28 ℃ and 60μE. (M2.s) -1 (control), 10 ℃ and 60μE. (M2. s) -1,2 ℃ + 60μE. (m2.s) -1 and 2 ℃ + darkness.The photosynthetic activity (Fv / Fm), chlorophyll a, extracellular polysaccharides, pseudo-caryophyllan, carotenoid and phycocyanin and the ratio of phycocyanin / chlorophyll, and microscopic changes of the cyanobacteria crust under low temperature light were observed by scanning electron microscopy. The apparent morphological characteristics such as crust color, thickness and dry weight were measured.Compared with the control crust, the apparent morphology of the crust was adversely affected by low temperature light, and the physiological indexes of crusts were significantly different (P <0.05). Under the condition of 2 ℃ + 60μE. (M2.s) -1 for 12 d, the biomass of the crust, photosynthesis The contents of extracellular polysaccharides, extractive polysaccharides, pseudoalciccone, carotenoid and phycocyanin decreased by 61.48%, 94.89%, 66.37%, 31.01%, 59.38% and 65.91% The results showed that the ultrastructure of the cyanobacteria crust was damaged obviously by low temperature light, showing a large number of honeycomb voids in the cortex, reducing the number of the algal filaments, distributing in the form of a grid, reducing the binding capacity of the sand, etc. The research shows that the low temperature Light had a significant inhibitory effect on the morphology and physiological activity of Cyanobacteria crust, while low temperature darkness could promote the physiological activity of Cyanobacteria crusts and the recovery of the apparent morphology of the crusts.In this study, the effects of Cyanobacteria crusts on low temperature photoperiod Tolerance, and has certain theoretical significance for understanding the survival status of cyanobacteria crusts under the extreme environmental conditions in the wild.