Low synthesis of secondary compounds in the lichen <i>Lobaria pulmonaria</i> infected by the lichenicolous fungus <i>Plectocarpon lichenum</i>

Asplund, Johan; Gauslaa, Yngvar; Merinero, Sonia

doi:10.1111/nph.14978

Cited by 10 publications

(5 citation statements)

References 23 publications

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“…Since the fungus could spread more easily on thalli with lowered levels of usnic acid in the cortex and fumarprotocetraric acid in the medulla due to acetone treatment, the antifungal role of usnic acid and fumarprotocetraric acid can be hypothesised. It corresponds well with former results on influencing lichen fitness by lichenicolous fungi via reducing their growth rates (Asplund et al 2018 , Lawrey 1993 , Merinero and Gauslaa 2018 ). Lawrey et al ( 1994 ) and Lawrey ( 2000 ) explain easier colonisation on the lichen thallus by enzymatic degradation of lichen secondary metabolites from the lichenicolous fungi.…”

Section: Discussionsupporting

confidence: 92%

The long-term effect of removing the UV-protectant usnic acid from the thalli of the lichen Cladonia foliacea

et al. 2022

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Terricolous lichens are abundant in semi-arid areas, where they are exposed to high irradiation. Photoprotection is essential for the algae as the photobiont provides the primer carbon source for both symbionts. The UV-protectant lichen metabolites and different quenching procedures of the alga ensure adequate photoprotection. Since the long-term effect of diminishing UV-protectant lichen metabolites is unknown, a major part of lichen secondary metabolites was removed from Cladonia foliacea thalli by acetone rinsing, and the lichens were then maintained under field conditions to investigate the effect on both symbionts for 3 years. Our aim was to determine if the decreased level of UV-protectant metabolites caused an elevated photoprotection in the algae and to reveal the dynamics of production of the metabolites. Photosynthetic activity and light protection were checked by chlorophyll a fluorescence kinetics measurements every 6 months. The concentrations of fumarprotocetraric and usnic acids were monitored by chromatographic methods. Our results proved that seasonality had a more pronounced effect than that of acetone treatment on the function of lichens over a long-term scale. Even after 3 years, the acetone-treated thalli contained half as much usnic acid as the control thalli, and the level of photoprotection remained unchanged in the algae. However, the amount of available humidity was a more critical limiting environmental factor than the amount of incoming irradiation affecting usnic acid production. The lichenicolous fungus Didymocyrtis cladoniicola became relatively more abundant in the acetone-treated samples than in the control samples, indicating a slight change caused by the treatment.

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Section: Discussionsupporting

confidence: 92%

The long-term effect of removing the UV-protectant usnic acid from the thalli of the lichen Cladonia foliacea

et al. 2022

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“…Given that earlier studies indicated that the concentration of lichen secondary metabolites was reduced in Lobaria pulmonaria thalli parasitized by P. lichenum (Asplund et al 2016, 2018), we hypothesized that the presence of the lichenicolous fungus P. lichenum would have an effect on the expression of polyketide synthase genes, leading to their down-regulation (biotic component of gene expression variation). However, since polyketide production may increase due to environmental stress, we expected higher gene expression in polyketide synthases under thermal stress conditions.…”

Section: Introductionmentioning

confidence: 99%

Stressed out: the effects of heat stress and parasitism on gene expression of the lichen-forming fungus Lobaria pulmonaria

2022

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Gene expression variation can be partitioned into different components (regulatory, genetic and acclimatory effects) but for lichen-forming fungi, the relative importance of each of these effects is unclear. Here, we studied gene expression in the lichen-forming fungus Lobaria pulmonaria in response to thermal stress and parasitism by the lichenicolous fungus Plectocarpon lichenum. Our experimental procedure was to acclimate lichen thalli to 4 °C over three weeks and then expose them to 15 °C and 25 °C for 2 hours each, sampling infected and visually asymptomatic thalli at each temperature. Quantitative Real-Time PCR was utilized to quantify gene expression of six candidate genes, normalizing expression values with two reference genes. We found that two genes encoding heat shock proteins (hsp88 and hsp98), two polyketide synthase genes (rPKS1, nrPKS3) and elongation factor 1-1-α (efa) were upregulated at higher temperatures. Moreover, we observed higher expression of hsp98 at 25 °C in samples infected by P. lichenum than in uninfected samples. Finally, in partial redundancy analyses, most of the explained variation in gene expression was related to temperature treatment; genetic variation and long-term acclimatization to sites contributed far less. Hence, regulatory effects (i.e. direct adjustments of gene expression in response to the temperature change) dominated over genetic and acclimatory effects in the gene expression variability of L. pulmonaria. This study suggests that L. pulmonaria could become a valuable lichen model for studying heat shock protein responses in vivo.

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“…Plants have evolved diverse strategies such as the production of metabolites to protect against various environmental stresses (Yang et al, 2018;Ashraf et al, 2018). In the whole course of plant life, metabolites play a variety of vital roles in acting as the defender against predators and pathogens (Asplund et al, 2018), as the protector against ultraviolet radiation (Solhaug and Gauslaa, 2012), as the deterrenter to inhibit foraging, ovipositing, growing and propagating of insects (Wink, 2018), as allelopathic agents to attract pollinators and resist the invasion of weeds and viruses (Li et al, 2014), as antioxidant agents and even as signal molecules of nodulation in legume-Rhizobium symbiosis (Stambulska and Bayliak, 2019). It has been identified that secondary metabolites were mainly produced by the shikimic, malonic, mevalonic and MEP pathways (Prinsloo and Nogemane, 2018).…”

Section: Introductionmentioning

confidence: 99%

Seasonal Variation of Biosynthetic Path Selectivity of Flavonoids, and Content and Antioxidant Activity of Metabolites in Tetrastigma Hemsleyanum Diels Et Gilg

Shi¹,

Li²,

et al. 2021

Preprint

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This work investigated the seasonal variations in biosynthetic path selectivity of nine individual flavonoids, and content and antioxidant activity of three major metabolites in Tetrastigma hemsleyanum. The results revealed that under conditions of precipitation (2.0~6.6 mm), temperature (17.5~24.1°C), humidity (67.3~80.2%) and sunshine duration (3.4~5.8 h) in April and May, the total content of flavonoids reached higher levels between 282 and 394.5 μg/g; in the second half of April with the highest accumulation of flavonoids, the production selectivity (PS) of isoorientin, orientin, rutin, isoquercitin, kaempferol-3-0-rutinoside, astragalin, quercetin, apigenin and kaempferol were 0.30, 0.06, 0.07, 0.07, 0.00, 0.04, 0.38, 0.05 and 0.03, respectively; also according to the reaction network consisting of three main pathways for flavonoids syntheses in T. hemsleyanum, the selectivity of reaction Path II to synthesize quercetin, isoquercitin and rutin in April, May and June fluctuated between 0.52 and 0.66, much higher than that of reaction Path I or Path III.

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Low synthesis of secondary compounds in the lichen Lobaria pulmonaria infected by the lichenicolous fungus Plectocarpon lichenum

Cited by 10 publications

References 23 publications

The long-term effect of removing the UV-protectant usnic acid from the thalli of the lichen Cladonia foliacea

The long-term effect of removing the UV-protectant usnic acid from the thalli of the lichen Cladonia foliacea

Stressed out: the effects of heat stress and parasitism on gene expression of the lichen-forming fungus Lobaria pulmonaria

Seasonal Variation of Biosynthetic Path Selectivity of Flavonoids, and Content and Antioxidant Activity of Metabolites in Tetrastigma Hemsleyanum Diels Et Gilg

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