Department of Life Sciences, University of Siena, Siena, Italy.
CeSMA, University of Napoli, Naples, Italy.
Environ Sci Pollut Res Int. 2018 Mar;25(9):8104-8112. doi: 10.1007/s11356-017-9545-9. Epub 2017 Jul 12.
The physiological and ultrastructural effects induced by acute exposure to ozone (O) were investigated in the lichen Xanthoria parietina. Our working hypothesis was that parietin content and hydration of the thalli may play a role in the modulation of the effects of O exposure. Four batches of X. parietina samples, dry and wet, with (P+) and without (P-) parietin, were fumigated for 1 h with 3 ppm O. The effects of O were assessed immediately after the fumigation and after one week of recovery under controlled conditions. O fumigation caused physiological and ultrastructural impairment both to the photobiont and the mycobiont, irrespective if samples were fumigated wet or dry, and P+ or P-. However, one week after fumigation, a recovery was observed in P+ samples for the photobiont and in dry samples for the mycobiont. We suggest that the hydration state may play a major role in determining the severity of the damage, while the presence of parietin may promote the recovery. Our results provide physiological and ultrastructural basis to explain the ecological insensitivity of lichens to high environmental levels of ozone occurring during dry Mediterranean summers.
本研究旨在探讨急性臭氧（O）暴露对地衣 Xanthoria parietina 的生理和超微结构的影响。我们的工作假设是，石耳素含量和藻菌共生体的水合作用可能在调节臭氧暴露的影响中发挥作用。将四批地衣 X. parietina 样本（干样和湿样）分为有（P+）和无（P-）石耳素两组，分别用 3ppm 的 O 进行 1 小时的熏气处理。在熏气后立即以及在控制条件下恢复一周后，评估 O 的影响。无论样本是熏气前湿样还是干样，有石耳素还是无石耳素，臭氧熏气都会导致光和生物和菌物共生体的生理和超微结构损伤。然而，熏气一周后，有石耳素的样本中光和生物恢复，而干样中菌物共生体恢复。我们认为水合状态可能在决定损伤严重程度方面起着主要作用，而石耳素的存在可能促进了恢复。我们的结果为解释地衣在干燥的地中海夏季高环境水平臭氧下的生态不敏感性提供了生理和超微结构基础。
