The effect of abscisic acid on chlorophyll fluorescence in lichens under extreme water regimes

Dietz, S. M.; Hartung, Wolfram

doi:10.1046/j.1469-8137.1999.00473.x

Cited by 14 publications

(7 citation statements)

References 16 publications

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“…Because hyphal branching is not stimulated with these substances alone, but when unicellular algae grow in proximity (81), further metabolites seem to be involved in the signalling of lichenization. Such molecules probably include phytohormones abscisic acid and ethylene, as well as others (82,83,84).…”

Section: The Upcoming Genomics Perspective For Understanding Lichen Smentioning

confidence: 99%

Lichenized Fungi and the Evolution of Symbiotic Organization

Grube

Wedin

2016

Microbiol Spectr

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Lichen symbioses comprise a fascinating relationship between algae and fungi. The lichen symbiotic lifestyle evolved early in the evolution of ascomycetes and is also known from a few basidiomycetes. The ascomycete lineages have diversified in the lichenized stage to give rise to a tremendous variety of morphologies. Their thalli are often internally complex and stratified for optimized integration of algal and fungal metabolisms. Thalli are frequently colonized by specific nonlichenized fungi and occasionally also by other lichens. Microscopy has revealed various ways these fungi interact with their hosts. Besides the morphologically recognizable diversity of the lichen mycobionts and lichenicolous (lichen-inhabiting) fungi, many other microorganisms including other fungi and bacterial communities are now detected in lichens by culture-dependent and culture-independent approaches. The application of multi-omics approaches, refined microscopic techniques, and physiological studies has added to our knowledge of lichens, not only about the taxa involved in the lichen interactions, but also about their functions.

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Section: The Upcoming Genomics Perspective For Understanding Lichen Smentioning

confidence: 99%

Lichenized Fungi and the Evolution of Symbiotic Organization

Grube

Wedin

2016

Microbiol Spectr

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“…Xanthoria parietina and Peltigera praetextata suffer less from excess of water when pre-treated with ABA or sprayed with ABA solutions (Dietz and Hartung 1999).…”

Section: Aba In Lichensmentioning

confidence: 99%

The evolution of abscisic acid (ABA) and ABA function in lower plants, fungi and lichen

Hartung¹

2010

Functional Plant Biol.

127

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Abstract. Abscisic acid (ABA) -the universal stress hormone of cormophytes -was detected in very low concentrations in almost all organisms tested from a range of cyanobacteria, algae, bryophytes, fungi and lichens and higher plants (Fig. 1). There are a few reports only on stress-induced ABA biosynthesis in cyanobacteria and algae. This extra ABA is released to the external medium. Application of external ABA has been shown to produce weak and contradicting effects on development and metabolism of algae. In most studies, extremely high concentrations of external ABA have been applied, those being far beyond any physiological concentration range. It is, therefore, extremely difficult to discuss those data satisfactorily. When organisms start to colonise terrestrial habitats (e.g. aquatic liverworts, mosses), endogenous ABA is increased even under mild drought stress, then desiccation protecting mechanisms are stimulated and the formation of terrestrial organs is induced. The same can be observed in water ferns (Marsilea) and in a range of heterophyllous angiosperms. Sporophytes of hornwort and mosses that bear true stomata, have particularly high ABA levels and their stomata respond to ABA as is the case in cormophytes, although a significant regulatory function of these stomata does not exist. Fungi produce large amounts of ABA that are released into the external medium and do not seem to have a function for the fungus. Fungal ABA, however, may be significant in associations of fungi with cyanophytes and algae (lichens), in mycorrhizal associations and in the rhizosphere of higher plants.

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“…We suggest that this potentially limited microbial activity in peat under lichen mats is due to the abiotic factors described above, and that these factors may be important feedback mechanisms for regulating decomposition processes in peatland areas with different vegetation cover. For areas dominated by lichen, these feedbacks may prevent rapid decomposition of peat under slow‐growing lichen mats that would be at greater risk of decay closer to the water‐table and in a continuously wet substrate (Dietz & Hartung, ).…”

Section: Discussionmentioning

confidence: 99%

Lichens: A limit to peat growth?

et al. 2018

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1. The fruticose lichens Cladina stellaris and Cladina rangiferina, form thick mats that can cover large areas of northern peatlands (above c. 50° latitude), including the extensive peatlands of the Hudson Bay Lowland (HBL) in Canada, where lichens may cover up to 50% of the landscape. Despite the abundance of lichens in northern peatlands, our understanding of their role within peatland ecosystems, and peat accumulation in particular, is limited.2. We investigate the potential effect of these mat-forming lichens on peat production and decomposition processes, using field data from an ombrogenous bog in the HBL and laboratory analyses. We hypothesize that (a) production in lichenshrub hummocks is less than in Sphagnum-shrub hummocks; (b) the decay of lichen litter is faster than that of Sphagnum moss, so the mass litter input to the peat profile is reduced; and (c) faster decomposition of the underlying peat is stimulated by lichen leachates, resulting in greater mass loss.3. We found that thick lichen mats alter vegetation composition in peatlands, reducing Sphagnum cover and inhibiting the growth of small shrubs. Coupled with low lichen productivity that is constrained by moisture conditions, production for lichen-shrub hummocks is significantly smaller than for Sphagnum-shrub hummocks, confirming hypothesis (a). Our data also support hypothesis (b), with chemical analyses of lichen mats and leachates from lichen mats indicating faster decay of lichens compared to Sphagnum moss, and therefore reduced mass litter input to the peat profile in lichen-dominated hummocks. Although we found no evidence to suggest leachates from lichens enhance decomposition processes in peatlands (hypothesis c), larger dry bulk densities for peat under lichen mats indicate a loss of structural integrity and potential collapse of the peat column. Synthesis.As production of new material added to the peat column is less in lichen-dominated hummocks, local peat accumulation slows or ceases, representing a potential temporary limit to peat growth. Our results highlight the importance of lichens as a vegetation feedback in peatland development, with thick mats probably constraining or reducing hummock height relative to adjacent, lichenfree hollows.

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The effect of abscisic acid on chlorophyll fluorescence in lichens under extreme water regimes

Cited by 14 publications

References 16 publications

Lichenized Fungi and the Evolution of Symbiotic Organization

Lichenized Fungi and the Evolution of Symbiotic Organization

The evolution of abscisic acid (ABA) and ABA function in lower plants, fungi and lichen

Lichens: A limit to peat growth?

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