Biology subjects

Bog, M.

Publications and source records attributed to Bog, M..

8 recordsLinked to original sources

bioRxiv2026

Less is more? Faster growth is associated with lower ectomycorrhizal diversity in mature Picea glauca at the Alaskan treelines

Root-associated fungal (RAF) communities can influence tree nutrition and performance, yet their environmental drivers and relationship with tree growth remain poorly understood, particularly near treelines. We characterized RAF communities, with a focus on ectomycorrhizal (ECM) fungi, associated with fine roots of white spruce (Picea glauca [Moench] Voss) across paired forest and treeline plots representing two elevational and one drought-limited treeline ecotones in Alaska. Using ITS2 DNA metabarcoding, we assessed fungal community composition and alpha diversity and related these metrics to basal area increment (BAI) over 5-30 years for individual trees. Sampling site was the strongest predictor of RAF community composition, explaining 19.6% of variation, followed by soil pH (11.7%), whereas habitat explained only 2.1%. Treeline effects were context-dependent: RAF composition differed between forest and treeline only in the Alaska Range, alpha diversity was lower at the treeline in Interior Alaska, and ECM relative abundance was higher at the Brooks Range treeline. In contrast, RAF community composition did not differ between fast- and slow-growing trees within sites. Interestingly, alpha diversity indices were significantly associated with BAI over the previous 5, 10 and 15 years, with lower diversity associated with faster tree growth. These relationships weakened with increasing BAI averaging period. Our results indicate that, in mature P. glauca, tree growth is associated with lower RAF and ECM diversity but not with distinct fungal community composition, suggesting that growth may be linked to greater dominance by a subset of fungal partners rather than higher fungal diversity.

ecology↗

bioRxiv2026

Population genomics reveals divergent lineages in the European peatland plant Drosera rotundifolia

Genomic variation within populations reflects both past and contemporary evolutionary processes. The genetic structure of the European peatland plant species is shaped by complex postglacial recolonization and recent habitat loss. Here, we investigate population genomic patterns in the vulnerable mire plant, round-leaved sundew (Drosera rotundifolia L.). Using ddRAD sequencing of 311 individuals from 38 populations across Europe, we detected significant genetic differentiation (Fst = 0.02-0.44, p < 0.05) and a consistent deficit of heterozygosity (Fis = 0.248) across populations. In contrast, sequencing of 10,449 bp of chloroplast DNA revealed extremely low variation, with only one SNP detected. Clustering analyses (Admixture and DAPC) both identified pronounced genetic structure comprising three major clusters (Western, Northern, and Eastern) that broadly correspond to European biogeographic regions. Genetic differentiation was partially explained by geographic distance (3.3%; p = 0.0001; Mantel test), while climatic variables, particularly temperature and precipitation, accounted for 2.9% of genomic variation (p < 0.0001; redundancy analysis). The observed pattern is consistent with polygenic responses to climatic gradients and is supported by 1,022 SNPs, distributed across 632 loci, that were significantly associated with environmental variables. Demographic reconstruction revealed distinct evolutionary trajectories among clusters, with the Western cluster showing a more recent expansion. Together, our results suggest that the genetic structure of D. rotundifolia is a result of postglacial recolonization, geographic isolation, and climate influence. We highlight the importance of conserving genetic diversity of D. rotundifolia across all three clusters and accounting for potential local adaptation and population vulnerability in future conservation strategies.

evolutionary biology↗

bioRxiv2025

How drought and ploidy level shape gene expression and DNA methylation in Phragmites australis

Drought stress significantly affects plant physiology and growth, yet the molecular mechanisms underlying drought responses remain poorly understood. In this study, we investigate how tetraploid and octoploid Phragmites australis (common reed), a key species in wetland ecosystems and paludiculture, respond to drought at the transcriptional and epigenetic levels. Using RNA-seq, we identify changes in gene expression after 20 and 30 days of drought and assess methylation-sensitive amplification polymorphism (MSAP) over 50 days of drought. Transcriptomic analysis reveals that key drought-response genes are shared between ploidy levels, including those involved in the saccharopine pathway, water deprivation response, cell wall remodelling, and the mevalonate pathway. Drought supresses photosynthesis, with a pronounced down-regulation of the photosynthetic gene PsbP. Ploidy level influences gene expression under both drought and non-stress conditions, highlighting distinct adaptive strategies. In control samples, gene expression differed between ploidy levels, with octoploids up-regulating genes related to translation and metabolism, while tetraploids activate genes involved in cell wall modification and transmembrane transport. Prolonged drought increases DNA methylation variability, though no significant correlation is found between methylation levels and drought duration. Methylation differences are more pronounced between ploidy levels, with octoploids exhibiting lower overall methylation. These findings highlight the complex interactions between gene expression, epigenetic modifications, and polyploidy in drought response and provide a theoretical framework for future selection, hybridization, and conservation initiatives. Main ConclusionKey drought-response genes regulate saccharopine and mevalonate pathways, and cell wall remodelling. Ploidy level influences gene expression under drought and non-stress conditions. Octoploids overall exhibit lower methylation than tetraploids.

ecology↗

bioRxiv2025

Higher ploidy coincides with inferior performance and no difference in stress tolerance in reed

(1) Climate change leads to more extreme weather events. Therefore, a high stress tolerance is becoming more critical for plants, with higher ploidy being reported to lead to higher stress tolerance. Phragmites australis (P. australis) is a target species for paludiculture, i.e. the wet use of peatlands, and well known for its many ploidy levels. (2) We expected octoploid genotypes of P. australis to outperform tetraploid ones in a 15-month mesocosm experiment including a gradient of 0 to 100 days of drought. We used pairs of genotypes differing in ploidy from three different geographic regions. (3) Increasing drought length led to a decrease in growth, biomass, morphological and ecophysiological traits in both ploidy levels, but 4x outperformed 8x in almost all traits under constant water supply (e.g., 2.5-fold more biomass production) and up to moderate drought (about 50 days). Under severe and prolonged drought, both ploidy levels performed equally poorly. (4) Our study suggests that higher ploidy levels do not necessarily outperform lower ploidy levels of P. australis under stressful conditions. In this species, ploidy alone may not explain performance, but the genotype can be as or more important than ploidy.

ecology↗

bioRxiv2025

Triploidy is prominent in the duckweed Lemna minor complex

Duckweeds (Lemnaceae Martinov) are aquatic monocotyledonous flowering plants comprising five genera and 35 recognized species, known for being the smallest and fastest-growing flowering plants on Earth. Many species are morphologically indistinguishable due to their highly reduced structures, yet molecular evidence suggests that visually similar clones may represent distinct species or hybrids. For example, clonal accessions of the globally distributed Lemna minor in the Landolt Duckweed Collection exhibit genome size variations of several hundred megabases (Mb), raising questions about their taxonomic classification and evolutionary origins. We analyzed 58 presumed L. minor clones to resolve these relationships using a comprehensive suite of methods, including whole-genome sequencing (WGS), flow-cytometric genome size measurements, molecular markers, chromosome counting, and genomic in situ hybridization (GISH). Our findings reveal extensive genome plasticity within the "Lemna minor complex," identifying diploid and triploid L. minor clones, as well as di-haploid and triploid interspecific hybrids called L. x japonica (L. minor x L. turionifera), L. x mediterranea (L. minor x L. gibba), and a novel African-clade distinct from known L. minor lineages. Triploidy was prevalent, occurring in 29% of the clones, and was associated with enhanced growth under optimal conditions but reduced performance under high light and temperature. These findings highlight the widespread role of triploidy, cryptic species, and hybridization in the L. minor complex, emphasizing the importance of multiple approaches for accurately classifying duckweed species and understanding their evolutionary trajectories.

plant biology↗

bioRxiv2025

Phylogenetically distant but cohabiting: Fungal communities of fine roots in Diphasiastrum complanatum, Pinus sylvestris, and Vaccinium myrtillus in a Lithuanian pine forest

Throughout evolution, distinct plant lineages independently established mutualistic relationships with various fungal taxa. However, the extent to which these relationships are conserved across different plant and fungal lineages remains unclear. In this study, we compared fungal communities associated with the fine roots of three phylogenetically distant yet cohabiting plant species: Diphasiastrum complanatum, a member of lycophytes, the most basal extant vascular plant lineages; Pinus sylvestris, a gymnosperm; and Vaccinium myrtillus, an angiosperm, an evolutionary relatively young lineage. To minimize environmental variability, fine roots of three species were collected from each of 19 five-square-meter plots within a Scots pine forest in Lithuania. Using metabarcoding and microscopic techniques, we observed significant differences in the fungal community composition and diversity among the three plant species. We detected no signs of arbuscular mycorrhiza in any species. Samples of D. complanatum showed significantly higher taxonomical diversity, while P. sylvestris showed lowest diversity, with ectomycorrhizal fungi being most abundant. Samples of V. myrtillus had a prevalence of putative ericoid mycorrhiza taxa, classes Sebacinales and Trechisporales, likely forming hyphal coils detected through microscopy. In contrast, no mycorrhiza was detected in D. complanatum sporophytes. This, along with the presence of well-developed root hairs and similarity to the fungal community inhabiting soil suggests a low dependency on mycorrhizal associations and a more opportunistic fungi-plant relationship. This is the first study of fungi associated with the sporophytes of D. complanatum. Our findings provide valuable insights into the complex interactions between fungi and plants from diverse phylogenetic lineages in natural environments.

ecology↗

bioRxiv2024

The microbiome of the lichen Lobaria pulmonaria varies according to climate in Europe

The Lobaria pulmonaria holobiont comprises algal, fungal, cyanobacterial, and bacterial components. We investigated L. pulmonarias bacterial microbiome in the adaptation of this ecologically sensitive lichen species to diverse climatic conditions. Our central hypothesis posited that microbiome composition and functionality aligns with continental-scale climatic parameters related to temperature and precipitation. We also tested the impact of short-term weather dynamics, sampling season, and algal/fungal genotypes on microbiome variation. Metaproteomics provided insights into compositional and functional changes within the microbiome. Climatic variables explained 41.64% of microbiome variation, surpassing the combined influence of local weather and sampling season at 31.63%. Notably, annual mean temperature and temperature seasonality emerged as significant climatic drivers. Microbiome composition correlated with algal, not fungal genotype, suggesting similar environmental recruitment for the algal partner and microbiome. Differential abundance analyses revealed distinct protein compositions in sub-atlantic lowland and alpine regions, indicating differential microbiome responses to contrasting environmental/climatic conditions. Proteins involved in oxidative and cellular stress were notably different. Our findings highlight microbiome plasticity in adapting to stable climates, with limited responsiveness to short-term fluctuations, offering new insights into climate adaptation in lichen symbiosis.

microbiology↗

bioRxiv2023

Characterization of the cryptic interspecific hybrid Lemna x mediterranea by an integrated approach provides new insights into duckweed diversity

Lemnaceae taxonomy is challenged by the particular morphology of these tiny free-floating angiosperms, reduced to a single leaf-like structure called frond, without or with one to few roots. Although molecular taxonomy has helped clarify the phylogenetic history of this family, inconsistency between morphological data and nuclear and plastid markers still poses challenging questions in some cases, leading to frequent misclassifications in the genus Lemna. Recently, the finding that Lemna japonica is an interspecific hybrid between Lemna minor and Lemna turionifera, provided a clear explanation to one of such taxonomic questions. Here we demonstrated that L. minor is also capable to hybridize with Lemna gibba, generating a cryptic, previously unrecognized, but widespread taxon in the Mediterranean area. The nothotaxon Lemna x mediterranea is described through the detailed investigation of seven hybrid clones from a living germplasm collection and compared with clones of the putative parental species L. minor and L. gibba. Genetic analysis revealed that two different cytotypes, diploid and triploid, originated by at least two independent hybridization events. Despite high overall similarity, morphometrical, physiological and biochemical analyses showed an intermediate position of L. x mediterranea between its parental species in most qualitative and quantitative characters, and also separation of the two hybrid cytotypes by some criteria. These data provide evidence that hybridization and polyploidization, driving forces of terrestrial plant evolution, contribute to the duckweed genetic diversity and may have also shaped the phylogenetic history of these mainly asexual, aquatic plants. Further elucidation of hybridization mechanisms and flowering regulation will provide perspectives for future breeding strategies.

plant biology↗