Environmental stressors, especially low temperature, are very common on the earth's dryland systems. Terrestrial cyanobacteria have evolved with cold adaptability in addition to extreme dryness and high irradiation resistance. The dryland soil surface‐dwelling species, Nostoc flagelliforme, serves as a potential model organism to gain insights into cyanobacterial cold adaptation. In this study, we performed transcriptomic analysis of N. flagelliforme samples in response to low temperature. The results revealed that the biological processes, such as terpenoid biosynthetic process, oxidoreductase activity, carbohydrate metabolism, biosynthesis of secondary metabolites, lipid and nitrogen metabolism, were significantly and dynamically changed during the cold stress. It was noteworthy that the transcription of the denitrification pathway for ammonia accumulation was enhanced, implying an importance for nitrogen utilization in stress resistance. In addition, characterization of a cold‐responsive hypothetical gene csrnf1 found that it could greatly improve the cold‐resistant performance of cells when it was heterologously expressed in transgenic Nostoc sp. PCC 7120. It was also found that csrnf1 transgenic strain exhibited resistance to nitrogen‐deficient environmental stress. Considering that dryland cyanobacteria have to cope with low temperature on infertile soils, this study would enrich our understanding on the importance of multifunction of the genes for environmental cold adaptation in drylands.

中文翻译：

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干旱地区的冷适应：冷胁迫的发菜鞭毛的转录组学见解和具有耐冷氮胁迫的假设基因的表征

环境压力源，尤其是低温，在地球上的旱地系统中非常常见。除了极度干燥和高抗辐射性外，陆生蓝细菌还具有冷适应性。旱地土壤表层种Nostoc flagelliforme是潜在的模式生物，可深入了解蓝细菌的冷适应能力。在这项研究中，我们进行了N的转录组分析。鞭毛样品响应低温。结果表明，在寒冷胁迫下，萜类生物合成过程，氧化还原酶活性，碳水化合物代谢，次生代谢产物的生物合成，脂质和氮代谢等生物学过程发生了显着动态变化。值得注意的是，反硝化途径的积累使氨的积累得以增强，这暗示着氮利用在抗逆性中的重要性。此外，对冷应答假设基因csrnf1的鉴定发现，当它在转基因Nostoc sp中异源表达时，它可以大大提高细胞的耐寒性能。PCC7120。还发现csrnf1转基因菌株表现出对缺氮环境胁迫的抗性。考虑到旱地蓝细菌必须应对不育土壤上的低温，这项研究将丰富我们对基因的多功能性对旱地环境冷适应的重要性的理解。