Photoprotection in lichens: adaptations of photobionts to high light

Beckett, Richard P.; Minibayeva, Farida; Solhaug, Knut Asbjørn; Roach, Thomas

doi:10.1017/s0024282920000535

Cited by 38 publications

(66 citation statements)

References 145 publications

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“…2012), since light in the dry state can be detrimental for poikilohydric organisms (as reviewed by Beckett et al . (2021)). The morphologically similar Pannariaceae species, Pectenia plumbea (Light.)…”

Section: Introductionmentioning

confidence: 99%

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The globally threatened epiphytic cyanolichenErioderma pedicellatumdepends on a rare combination of habitat factors

2022

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Lichen extinction occurs at rapid rates as a result of human activity, although species could potentially be rescued by conservation management based on ecophysiological knowledge. The boreal old forest cyanolichen Erioderma pedicellatum currently occurs in few sites worldwide. To protect it from extinction, it is essential to learn more about it. The last remaining good European site is a canyon with a waterfall, in a low-rainfall region of Norway. Here, a spatially restricted population of 1500–2000 thalli dominates the epiphytic vegetation of a small number of Picea abies canopies. We were able to document that 1) E. pedicellatum grew on thin branches with higher bark pH than is normal for P. abies in a canyon that provided an unusual combination of very high light, high air humidity, and cool temperatures in the growing season. However, the species did not inhabit the main waterfall spray zone. 2) Erioderma pedicellatum had a high light saturation point, high CO2 uptake at high light (≥ 600 μmol m−2 s−1) and cool temperatures (5–20 °C), and experienced strong suprasaturation depression of photosynthesis when fully hydrated. 3) It showed good tolerance of desiccation and high light; it was slightly more tolerant than the morphologically similar, but more common cyanolichen Pectenia plumbea. 4) The European population in its sunny habitat had higher water holding capacity than previously recorded in slightly shaded rainforest populations in Newfoundland, consistent with acclimation to compensate for high evaporative demands. Understanding the ecological niche and responses to critical environmental factors is essential for action plans to avoid extinction of E. pedicellatum. Methods used in this study could also be applicable for ecological understanding of other threatened lichen species.

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Section: Introductionmentioning

confidence: 99%

“…2012) and causes oxidative stress (Beckett et al . 2021). Thus, the interaction of high light and lasting desiccation can threaten various forest lichens.…”

Section: Introductionmentioning

confidence: 99%

The globally threatened epiphytic cyanolichenErioderma pedicellatumdepends on a rare combination of habitat factors

2022

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“…Many lichens possess a variety of tolerance mechanisms that enable them to grow in habitats where they are exposed to levels of light that are far greater than lichen photobionts can use in carbon fixation (Beckett et al 2021). However, some species grow in more shaded microhabitats.…”

Section: Introductionmentioning

confidence: 99%

“…Photobionts use several processes to regulate the efficiency with which light energy is used, collectively referred to as non-photochemical quenching (NPQ). Lichens possessing green (chlorophycean) photobionts have light harvesting complex (LHC) antenna proteins and, as a result, dissipate excess energy using strategies similar to those found in bryophytes and higher plants (Beckett et al 2021). In the enzyme-catalyzed xanthophyll cycle, the carotenoid violaxanthin is converted to zeaxanthin in a pH-regulated process that occurs during increases in light intensity.…”

Section: Introductionmentioning

confidence: 99%

Shade lichens are characterized by rapid relaxation of non-photochemical quenching on transition to darkness

2021

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Non-photochemical quenching (NPQ) plays an important role in protecting photosynthetic organisms from photoinhibition by dissipating excess light energy as heat. However, excess NPQ can greatly reduce the quantum yield of photosynthesis at lower light levels. Recently, there has been considerable interest in understanding how plants balance NPQ to ensure optimal productivity in environments in which light levels are rapidly changing. In the present study, chlorophyll fluorescence was used to study the induction and relaxation of non-photochemical quenching (NPQ) in the dark and the induction of photosynthesis in ten species of lichens, five sampled from exposed and five sampled from shaded habitats. Here we show that the main difference between sun and shade lichens is the rate at which NPQ relaxes in the dark, rather than the speed that photosynthesis starts upon illumination. During the first two minutes in the dark, NPQ values in the five sun species declined only by an average of 2%, while by contrast, in shade species the average decline was 40%. For lichens growing in microhabitats where light levels are rapidly changing, rapid relaxation of NPQ may enable their photobionts to use the available light most efficiently.

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“…Both the mycobiont and photobiont can defend against solar radiation damage by various mechanisms (Beckett et al 2021;Gasulla et al 2012;Kranner et al 2005;Nguyen et al 2013;Sadowsky and Ott 2016). Lack of water is a main limiting factor for lichen metabolism.…”

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Photoprotection and high-light acclimation in semi-arid grassland lichens – a cooperation between algal and fungal partners

Veres

Csintalan

Laufer³

et al. 2021

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In lichens, each symbiotic partner cooperates for the survival of the symbiotic association. The protection of the susceptible photosynthetic apparatus is essential for both participants. The mycobiont and photobiont contribute to the protection against the damaging effect of excess light by various mechanisms. The present study investigated the effect of seasonality and microhabitat exposure on photoprotection and photoacclimation in the photo- and the mycobiont of six lichen species with different thallus morphology in inland dune system in the Kiskunság region (Hungary) with shaded, more humid and exposed, drier dune sides. High-Performance Liquid Chromatography, spectrophotometry, chlorophyll a fluorescence kinetic technique were used, and micrometeorological data were collected. The four years data series revealed that the north-east-facing side was characterized by higher relative humidity and lower light intensities compared to the south-west-facing drier and more exposed sides. The south-west facing side was exposed to direct illumination 3–4 hours longer in winter and 1–2 hours shorter in summer than the north-east facing side of the dune, influencing the metabolism of sun and shade populations of various species. Because rapid desiccation caused short active periods of lichens during bright and drier seasons and on exposed microhabitats, the rapid, non-regulated non-photochemical quenching mechanisms in the photobiont had a significant role in protecting the photosynthetic system in the hydrated state. In dehydrated conditions, thalli were mainly defended by the solar screening metabolites produced by the mycobiont and curling during desiccation (also caused by the mycobiont). Furthermore, the efficacy of light use (higher chlorophyll and carotenoid concentration) increased because of short hydrated periods. Still, a lower level of received irradiation was appropriate for photosynthesis in dry seasons and on sun exposed habitats. In humid seasons and microhabitats, more extended active periods lead to increased photosynthesis and production of solar radiation protectant fungal metabolites, allowing a lower level of photoprotection in the form of regulated non-photochemical quenching by the photobiont. Interspecific differences were more pronounced than the intraspecific ones among seasons and microhabitat types.

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Photoprotection in lichens: adaptations of photobionts to high light

Cited by 38 publications

References 145 publications

The globally threatened epiphytic cyanolichenErioderma pedicellatumdepends on a rare combination of habitat factors

The globally threatened epiphytic cyanolichenErioderma pedicellatumdepends on a rare combination of habitat factors

Shade lichens are characterized by rapid relaxation of non-photochemical quenching on transition to darkness

Photoprotection and high-light acclimation in semi-arid grassland lichens – a cooperation between algal and fungal partners

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