27 research outputs found
Photobiont selectivity leads to ecological tolerance and evolutionary divergence in a polymorphic complex of lichenized fungi
Background and Aims The integrity and evolution of lichen symbioses depend on a fine-tuned combination of
algal and fungal genotypes. Geographically widespread species complexes of lichenized fungi can occur in habitats
with slightly varying ecological conditions, and it remains unclear howthis variation correlates with symbiont selectivity
patterns in lichens. In an attempt to address this question, .300 samples were taken of the globally distributed
and ecologically variable lichen-forming species complex Tephromela atra, together with closely allied species, in
order to study genetic diversity and the selectivity patterns of their photobionts.
\u2020 Methods Lichen thalli of T. atra and of closely related species T. grumosa, T. nashii and T. atrocaesia were
collected from six continents, across 24 countries and 62 localities representing a wide range of habitats. Analyses
of genetic diversity and phylogenetic relationships were carried out both for photobionts amplified directly from
the lichen thalli and from those isolated in axenic cultures. Morphological and anatomical traits were studied with
light and transmission electron microscopy in the isolated algal strains.
\u2020 Key Results Tephromela fungal species were found to associate with 12 lineages of Trebouxia. Five new clades
demonstrate the still-unrecognized genetic diversity of lichen algae. Culturable, undescribed lineageswere also characterized
by phenotypic traits. Strong selectivity of the mycobionts for the photobionts was observed in six monophyletic
Tephromela clades. Seven Trebouxia lineages were detected in the poorly resolved lineage T. atra sensu
lato, where co-occurrence of multiple photobiont lineages in single thalli was repeatedly observed.
\u2020Conclusions Lowselectivity apparently allows widespread lichen-forming fungi to establish successful symbioses
with locally adapted photobionts in a broader range of habitats. This flexibility might correlate with both lower phylogenetic
resolution and evolutionary divergence in species complexes of crustose lichen-forming fungi
Cadmium induced changes in subcellular glutathione contents within glandular trichomes of Cucurbita pepo L.
Morphological and quantitative data of plastids and mitochondria within drought-stressed spinach leaves
Morphological and phylogenetic study of algal partners associated with the lichen-forming fungus Tephromela atra from the Mediterranean region
Recent DNA sequence analyses have revealed the diversity of algal partners in lichen symbioses. Although morphologically similar, different genetic lineages of photobionts are detected in wide geographic ranges of the same lichen fungal species. We studied the photobiont of the genus Trebouxia, which are known as partners of diverse lichen-forming fungal species in the Mediterranean region. We studied the phylogeny of these algae with a multilocus dataset including three loci: ITS, rbcL, and actin type I gene. The two lineages found, informally
named Trebouxia sp. 1 and Trebouxia sp. 2, are related to
Trebouxia arboricola/decolorans. The cultivation under
axenic conditions succeeded only for one of them so far.
We used light microscopy, confocal laser scanning microscopy
and transmission electron microscopy for phenotypic
characterisation. The ultrastructural characters currently
used to describe species in the genus do not support the
segregation of Trebouxia sp.1 from Trebouxia arboricola.
The preferential presence in Mediterranean climates of
these strains suggests eco-physiological adaptation. Despite
their asexuality in long living lichen symbioses, coccoid algal lichen partners have apparently diversified genetically and physiologically
Organelle-specific localization of glutathione in plants grown under different light intensities and spectra
Plant ascorbate and glutathione metabolism counteracts oxidative stress mediated, for example, by excess light. In this review, we discuss the properties of immunocytochemistry and transmission electron microscopy, redox-sensitive dyes or probes and bright-field microscopy, confocal microscopy or fluorescence microscopy for the visualization and quantification of glutathione at the cellular or subcellular level in plants and the quantification of glutathione from isolated organelles. In previous studies, we showed that subcellular ascorbate and glutathione levels in Arabidopsis are affected by high light stress. The use of light-emitting diodes (LEDs) is gaining increasing importance in growing indoor crops and ornamental plants. A combination of different LED types allows custom-made combinations of wavelengths and prevents damage related to high photon flux rates. In this review we provide an overview on how different light spectra and light intensities affect glutathione metabolism at the cellular and subcellular levels in plants. Findings obtained in our most recent study demonstrate that both light intensity and spectrum significantly affected glutathione metabolism in wheat at the transcriptional level and caused genotype-specific reactions in the investigated Arabidopsis lines. © 2022, The Author(s)
Structural changes and physiological stress responses of spruce trees to SO2, O3 and elevated levels of CO2
Elevated thiol levels affect virus infection in Cucurbita pepo plants regenerated via somatic embryogenesis
Thiols are known to play crucial roles in plant defense responses, e.g. against pathogens. In the present study, the efficiency of these molecules was evaluated in regenerated
Cucurbita pepo
L. subsp.
pepo
var.
styriaca
Greb. plants in response to compatible
Zucchini yellow mosaic virus
infection. Thiol contents were modulated by applying the cysteine precursor L-2-oxothiazolidine-4-carboxylic acid (OTC) to callus cells. Cytological and biochemical methods were used for determination of glutathione within callus cells and leaves of plants regenerated via somatic embryogenesis. Reduced glutathione levels (GSH) significantly increased in callus cells one week after 1.0 mM OTC treatment by about 56% and resulted in enhanced GSH levels throughout the investigation period of 13 weeks. Three weeks after ZYMV infection untreated plants regenerated from callus culture exhibited stunted growth forms, yellowing, mosaic and blistering on the leaves whereas 68% of 1.0 mM OTC pretreated regenerated plants were characterized by a complete absence of symptoms. Treatment with OTC stimulated the synthesis, conversion and translocation of thiols during advanced ZYMV infection. Compared to untreated infected leaves, a graduate increase in cysteine (cys) and γ-glutamyl-cysteine (γ-glucys) contents was measured in 0.5 mM and 1.0 mM OTC treated older leaves, whereas total glutathione (tGSH) decreased significantly after infection. In OTC treated younger leaves cys and tGSH concentrations remained at control levels and were unaffected by ZYMV. In contrast, OTC treatment caused a dramatic induction of γ-glucys, up to 191% in younger infected leaves. The results show that altered levels of thiols by OTC were accompanied by enhanced tolerance against ZYMV, suppression of ZYMV induced symptoms as well as delayed symptom development