Fungal melanins as a sun screen for symbiotic green algae in the lichen Lobaria pulmonaria
Fungal melanins as a sun screen for symbiotic green algae in the lichen Lobaria pulmonaria
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DOI：
10.1007/s004420000541
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发表时间：
2001-02-01
期刊：
影响因子：
2.7
通讯作者：
Solhaug, KA
中科院分区：
文献类型：
--
作者：
Gauslaa, Y;Solhaug, KA
高光敏感的森林地衣Lobaria pulmonaria的真菌被证明在上部皮质的外层沉积棕色，黑色化合物，这取决于其自然栖息地的长期太阳辐射水平。此外，从阴暗的栖息地移植到阳光充足的栖息地后，苍白的菌体产生了黑素化合物。大脑皮层的褐变似乎是一个生理上活跃的过程，只发生在频繁补水的时期。黑色素分泌缓慢。后移植。适应遮荫的菌体需要1年以上的时间才能将皮质透过率（230-1000 nm）降低到与自然暴露在阳光下的标本相似的水平。黑素化合物起到了遮阳的作用，特别是在光生物水平上减少了中波紫外线和长波紫外线的波长，但也减少了可见光的波长。在近红外范围内，适应遮荫和阳光的皮质在透射率上只有很小的差异。自然光照水平与700 nm以下波长的皮质透射率呈负相关。然而，先前的研究表明，即使是黑色肺乳杆菌的光生成物也相对容易受到强光照射。由于黑色素也增加了整个菌体对太阳能的吸收，因此，对于这种高度热敏感的地衣来说，在紫外线和光线保护方面获得的好处可能会被暴露在过高温度下的增加所抵消。
The mycobiont of the high-light-susceptible forest lichen Lobaria pulmonaria was shown to deposit brown, melanic compounds in the outer layer of the upper cortex, depending on the long-term level of solar radiation in its natural habitat. Furthermore, pale thalli from a shady habitat produced melanic compounds after transplantation to a sunny habitat. This browning of the cortex appeared to be a physiologically active process, taking place only during periods with frequent hydration. Melanin production was slow. After transplantation. more than 1 year was needed for a shade-adapted thallus to reduce the cortical transmittance (230-1000 nm) to a similar level to that of naturally sun-exposed specimens. Melanic compounds acted as a sun screen, especially reducing UVB and UVA wavelengths, but also visible wavelengths, at the photobiont Level. In the near infrared range, there was only a small difference in transmittance between shade- and sun-adapted cortices. A negative correlation was found between the natural light level and the cortical transmittance of wavelengths below 700 nm. However, previous studies have shown that even photobionts of melanic L. pulmonaria thalli are relatively susceptible to high-light exposure. Since melanins also increase the absorbance of solar energy for the whole thallus, it appears that what is gained in terms of UV- and light protection in melanic L. pulmonaria specimens may be offset by increased exposure to excess temperatures for this highly heat-susceptible lichen.