Onele Alfred O, Swid Moatasem A, Leksin Ilya Y, Rakhmatullina Daniya F, Galeeva Ekaterina I, Beckett Richard P, Minibayeva Farida V, Valitova Julia N
Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center, P.O. Box 261, 420111 Kazan, Russia.
Institute of Fundamental Medicine and Biology, Kazan Federal University, Kremlyovskaya 18, 420008 Kazan, Russia.
J Fungi (Basel). 2024 Oct 9;10(10):705. doi: 10.3390/jof10100705.
Currently, due to the increasing impact of anthropogenic factors and changes in solar activity, the temperature on Earth is rising, posing a threat to biodiversity. Lichens are among the most sensitive organisms to climate change. Elevated ambient temperatures can have a significant impact on lichens, resulting in more frequent and intense drying events that can impede metabolic activity. It has been suggested that the possession of a diverse sterol composition may contribute to the tolerance of lichens to adverse temperatures and other biotic and abiotic stresses. The major sterol found in lichens is ergosterol (ERG); however, the regulation of the ERG biosynthetic pathway, specifically the step of epoxidation of squalene to 2,3-oxidosqualene catalyzed by squalene epoxidase during stress, has not been extensively studied. In this study, we used lichen as a model species that is well known to be sensitive to air pollution and habitat loss. Using in silico analysis, we identified cDNAs encoding squalene epoxidase from , designating them as for the mycobiont and for the photobiont . Our results showed that compared with a control kept at room temperature (+20 °C), mild temperatures (+4 °C and +30 °C) did not affect the physiology of , assessed by changes in membrane integrity, respiration rates, and PSII activity. An extreme negative temperature (-20 °C) noticeably inhibited respiration but did not affect membrane stability. In contrast, treating lichen with a high positive temperature (+40 °C) significantly reduced all physiological parameters. Quantitative PCR analysis revealed that exposing thalli to -20 °C, +4 °C, +30 °C, and +40 °C stimulated the expression levels of and and led to a significant upregulation of . These data provide new information regarding the roles of sterols and Hsps in the response of lichens to climate change.
目前，由于人为因素影响的增加以及太阳活动的变化，地球温度正在上升，这对生物多样性构成了威胁。地衣是对气候变化最敏感的生物之一。环境温度升高会对地衣产生重大影响，导致更频繁、更强烈的干燥事件，从而阻碍新陈代谢活动。有人提出，拥有多样的甾醇成分可能有助于地衣耐受不利温度以及其他生物和非生物胁迫。地衣中发现的主要甾醇是麦角甾醇（ERG）；然而，在胁迫期间，麦角甾醇生物合成途径的调节，特别是由角鲨烯环氧酶催化的角鲨烯环氧化为2,3-氧化角鲨烯的步骤，尚未得到广泛研究。在本研究中，我们使用对地衣空气污染和栖息地丧失敏感的地衣作为模式物种。通过计算机分析，我们从地衣中鉴定出编码角鲨烯环氧酶的cDNA，将它们分别命名为地衣共生菌的 和地衣共生藻的 。我们的结果表明，与保持在室温（+20°C）的对照相比，温和温度（+4°C和+30°C）不会影响地衣的生理状况，这通过膜完整性、呼吸速率和PSII活性的变化来评估。极端低温（-20°C）显著抑制呼吸，但不影响膜稳定性。相比之下，用地衣高温（+40°C）处理会显著降低所有生理参数。定量PCR分析表明，将地衣体暴露于-20°C、+4°C、+30°C和+40°C会刺激 和 的表达水平，并导致 的显著上调。这些数据提供了关于甾醇和热休克蛋白在地衣对气候变化响应中作用的新信息。
