Tolerance to photoinhibition within lichen species is higher in melanised thalli

Mafole, T.C.; Solhaug, Knut Asbjørn; Minibayeva, Farida; Beckett, Richard P.

doi:10.32615/ps.2019.008

Cited by 16 publications

(18 citation statements)

References 32 publications

(37 reference statements)

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“…Earlier work (e.g. McEvoy et al 2007;Mafole et al 2019a) showed that photobionts in melanized lichens are more resistant to photoinhibition than those in pale ones, apparently due to fungal pigment synthesis. However, an inherent problem with these studies is that the melanized thalli were likely to have experienced stronger exposure to light than pale thalli.…”

Section: Discussionmentioning

confidence: 99%

“…2), consistent with the results of Mafole et al . (2019 a ). Protection was related to the absolute difference in reflectance between the pale and melanized thalli (compare Table 1 and Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The melanized thalli displayed a much smaller reduction of F v /F m (maximal efficiency of PSII photochemistry) than the material that had been in the more shaded sites, strongly suggesting that melanins are involved in photoprotection. Recently, Mafole et al (2019a) collected melanized and pale thalli from the same species only a few metres apart. Under laboratory conditions, melanized thalli were significantly less photoinhibited than pale thalli following a controlled exposure to high light.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Mafole et al . (2019 a ) collected melanized and pale thalli from the same species only a few metres apart. Under laboratory conditions, melanized thalli were significantly less photoinhibited than pale thalli following a controlled exposure to high light.…”

Section: Introductionmentioning

confidence: 99%

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Improved photoprotection in melanized lichens is a result of fungal solar radiation screening rather than photobiont acclimation

et al. 2019

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Some lichenized ascomycetes synthesize melanic pigments in their upper cortices when exposed to ultraviolet light and high solar radiation. Our previous work showed that melanized chloro- and cyanolichens from both high light and more shaded habitats were less photoinhibited than pale ones during controlled exposure to high light. However, protection from high light might not necessarily be the consequence of just sun-screening by melanins in upper cortices. An inherent problem with earlier experiments was that the photobionts of melanized thalli might have received more light than those beneath pale cortices. The photobionts may therefore have possessed other light-induced tolerance mechanisms that gave protection from photoinhibition. Here, we aimed to test directly the inherent tolerance of lichen photobionts to photoinhibition. The method involved removing the lower cortices and medullas of three lichen species, Cetraria islandica, Crocodia aurata and Lobaria pulmonaria, and exposing the photobionts to light from below. Results confirmed that most of the improvement in tolerance to photoinhibition in melanized lichens derives from fungal melanization in the upper cortex. However, in C. islandica, the most heavily melanized species, algae from melanized thalli possessed a significantly higher tolerance to photoinhibition than those from pale thalli, suggesting that photobionts can also adapt themselves to high light.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Improved photoprotection in melanized lichens is a result of fungal solar radiation screening rather than photobiont acclimation

et al. 2019

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“…Therefore, exposure to high or medium light levels of visible radiation for long periods in the dry state may result in accumulated severe damage (Gauslaa & Solhaug 1996; Gauslaa et al 2012; Mafole et al . 2019 b ).…”

Section: Avoidance By Light Screeningmentioning

confidence: 99%

Photoprotection in lichens: adaptations of photobionts to high light

et al. 2021

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Lichens often grow in microhabitats where they are exposed to severe abiotic stresses such as desiccation and temperature extremes. They are also often exposed to levels of light that are greater than lichen photobionts can use in carbon fixation. Unless regulated, excess energy absorbed by the photobionts can convert ground state oxygen to reactive oxygen species (ROS). These ROS can attack the photosynthetic apparatus, causing photoinhibition and photo-oxidative stress, reducing the ability of the photobionts to fix carbon. Here, we outline our current understanding of the effects of high light on lichens and the mechanisms they use to mitigate or tolerate this stress in hydrated and desiccated states. Tolerance to high light can be achieved first by lowering ROS formation, via synthesizing light screening pigments or by thermally dissipating the excess light energy absorbed; second, by scavenging ROS once formed; or third, by repairing ROS-induced damage. While the primary focus of this review is tolerance to high light in lichen photobionts, our knowledge is rather fragmentary, and therefore we also include recent findings in free-living relatives to stimulate new lines of research in the study of high light tolerance in lichens.

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UV‐B Resistance of Plants Grown in Natural Conditions

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Bilger

2020

Annual Plant Reviews Online

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Plants protect themselves against potentially harmful effects of solar ultraviolet‐B radiation by a variety of mechanisms conferring UV‐B resistance. The underlying resistance mechanisms of a plant can be acclimated corresponding to the prevailing UV‐B exposure in their habitat such that under natural conditions UV‐B damage does not seem to exist. UV‐B resistance is not only induced by UV‐B radiation but to a large extent also by other environmental factors. Here, we review current evidence on how abiotic variables, e.g. low temperature or water deficit, affect UV‐B resistance mechanisms. We are focusing on acclimation of UV‐B screening through the accumulation of UV absorbing compounds, which is well investigated, and on the removal of UV‐B‐induced DNA damage by repair. Although the latter is a resistance mechanism specifically directed to UV‐B‐induced damage, it is strongly underinvestigated. Interaction of UV‐B radiation and other environmental factors can occur at the level of signal transduction chains, most often leading to cross‐resistance. Additionally, the influence of environmental conditions on physiological reactions may lead either to cross‐resistance or cross‐sensitivity.

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Tolerance to photoinhibition within lichen species is higher in melanised thalli

Cited by 16 publications

References 32 publications

Improved photoprotection in melanized lichens is a result of fungal solar radiation screening rather than photobiont acclimation

Improved photoprotection in melanized lichens is a result of fungal solar radiation screening rather than photobiont acclimation

Photoprotection in lichens: adaptations of photobionts to high light

UV‐B Resistance of Plants Grown in Natural Conditions

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