| 1. |
- Alatalo, J. M., et al.
(författare)
-
Responses of lichen communities to 18 years of natural and experimental warming
- 2017
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 120:1, s. 159-170
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Climate change is expected to have major impacts on high alpine and arctic ecosystems in the future, but empirical data on the impact of long-term warming on lichen diversity and richness are sparse. This study report the effects of 18 years of ambient and experimental warming on lichens and vascular plant cover in two alpine plant communities, a dry heath with sparse canopy cover (54 %) and a mesic meadow with a more developed (67 %) canopy cover, in sub-arctic Sweden. Methods The effects of long-term passive experimental warming using open top chambers (OTCs) on lichens and total vascular plant cover, and the impact of plant cover on lichen community parameters, were analysed. Key Results Between 1993 and 2013, mean annual temperature increased about 2 degrees C. Both site and experimental warming had a significant effect on cover, species richness, effective number of species evenness of lichens, and total plant canopy cover. Lichen cover increased in the heath under ambient conditions, and remained more stable under experimental warming. The negative effect on species richness and effective number of species was driven by a decrease in lichens under experimental warming in the meadow. Lichen cover, species richness, effective number of species evenness were negatively correlated with plant canopy cover. There was a significant negative impact on one species and a non-significant tendency of lower abundance of the most common species in response to experimental warming. Conclusions The results from the long-term warming study imply that arctic and high alpine lichen communities are likely to be negatively affected by climate change and an increase in plant canopy cover. Both biotic and abiotic factors are thus important for future impacts of climate change on lichens.
|
|
| 2. |
- Andersson, Stefan, et al.
(författare)
-
Effects of mating system on adaptive potential for leaf morphology in Crepis tectorum (Asteraceae).
- 2013
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 112:5, s. 947-955
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Aims A shift from outcrossing to selfing is thought to reduce the long-term survival of populations by decreasing the genetic variation necessary for adaptation to novel ecological conditions. However, theory also predicts an increase in adaptive potential as more of the existing variation becomes expressed as homozygous genotypes. So far, relatively few studies have examined how a transition to selfing simultaneously affects means, variances and covariances for characters that might be under stabilizing selection for a spatially varying optimum, e.g. characters describing leaf morphology. Methods Experimental crosses within an initially self-sterile population of Crepis tectorum were performed to produce an outbred and inbred progeny population to assess how a shift to selfing affects the adaptive potential for measures of leaf morphology, with special emphasis on the degree of leaf dissection, a major target of diversifying selection within the study species. Key Results Three consecutive generations of selfing had a minor impact on survival, the total number of heads produced and the mean leaf phenotype, but caused a proportional increase in the genetic (co)variance matrix for foliar characters. For the degree of leaf dissection, the lowest 50th percentile of the inbred progeny population showed a disproportionate increase in the genetic variance, consistent with the recessive nature of the weakly lobed phenotype observed in interpopulation crosses. Comparison of inbreeding response with large-scale patterns of variation indicates a potential for selection in a (recently) inbred population to drive a large evolutionary reduction in degree of leaf dissection by increasing the frequency of particular sibling lines. Conclusions The results point to a positive role for inbreeding in phenotypic evolution, at least during or immediately after a rapid shift in mating system.
|
|
| 3. |
- Appelhans, M. S., et al.
(författare)
-
Phylogeny, evolutionary trends and classification of the Spathelia-Ptaeroxylon clade : morphological and molecular insights
- 2011
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 107:8, s. 1259-1277
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Aims The Spathelia-Ptaeroxylon clade is a group of morphologically diverse plants that have been classified together as a result of molecular phylogenetic studies. The clade is currently included in Rutaceae and recognized at a subfamilial level (Spathelioideae) despite the fact that most of its genera have traditionally been associated with other families and that there are no obvious morphological synapomorphies for the clade. The aim of the present study is to construct phylogenetic trees for the Spathelia-Ptaeroxylon clade and to investigate anatomical characters in order to decide whether it should be kept in Rutaceae or recognized at the familial level. Anatomical characters were plotted on a cladogram to help explain character evolution within the group. Moreover, phylogenetic relationships and generic limits within the clade are also addressed. Methods A species-level phylogenetic analysis of the Spathelia-Ptaeroxylon clade based on five plastid DNA regions (rbcL, atpB, trnL-trnF, rps16 and psbA-trnH) was conducted using Bayesian, maximum parsimony and maximum likelihood methods. Leaf and seed anatomical characters of all genera were (re) investigated by light and scanning electron microscopy. Key Results With the exception of Spathelia, all genera of the Spathelila-Ptaeroxylon clade are monophyletic. The typical leaf and seed anatomical characters of Rutaceae were found. Further, the presence of oil cells in the leaves provides a possible synapomorphy for the clade. Conclusions The Spathelia-Ptaeroxylon clade is well placed in Rutaceae and it is reasonable to unite the genera into one subfamily (Spathelioideae). We propose a new tribal classification of Spathelioideae. A narrow circumscription of Spathelia is established to make the genus monophyletic, and Sohnreyia is resurrected to accommodate the South American species of Spathelia. The most recent common ancestor of Spathelioideae probably had leaves with secretory cavities and oil cells, haplostemonous flowers with appendaged staminal filaments, and a tracheidal tegmen.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Asari, Shashidar, et al.
(författare)
-
Insights into the molecular basis of biocontrol of Brassica pathogens by Bacillus amyloliquefaciens UCMB5113 lipopeptides
- 2017
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 120, s. 551-562
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Certain micro-organisms can improve plant protection against pathogens. The protective effect may be direct, e.g. due to antibiotic compounds, or indirect, by priming of plant defence as induced systemic resistance (ISR). The plant growth-promoting rhizobacterium Bacillus amyloliquefaciens UCMB5113 shows potential for disease management of oilseed rape. To investigate the mode of action of this protection, especially in relation to jasmonic acid-dependent ISR, Bacillus UCMB5113 was tested with Arabidopsis thaliana mutants and several important fungal pathogens of Brassica species.Methods Secreted lipopeptide fractions from Bacillus UCMB5113, together with synthetic peptide mimics, were evaluated for their effects on fungal phytopathogens and A. thaliana. The structures of secreted lipopeptides were analysed using mass spectrometry. Plant mutants and reporter lines were used to identify signalling steps involved in disease suppression by lipopeptides.Key Results In plate tests Bacillus UCMB5113 and lipopeptide extracts suppressed growth of several fungal pathogens infecting Brassica plants. Separation of secreted lipopeptides using reversed-phase high-performance liquid chromatography revealed several fractions that inhibited fungal growth. Analysis by mass spectrometry identified the most potent compounds as novel linear forms of antifungal fengycins, with synthetic peptide mimics confirming the biological activity. Application of the lipopeptide extracts on Arabidopsis roots provided systemic protection against Alternaria brassicicola on leaves. Arabidopsis signalling mutants and PDF1.2 and VSP2 promoter-driven GUS lines indicated that the lipopeptide fraction involved jasmonic-acid-dependent host responses for suppression of fungal growth indicative of ISR.Conclusions The ability of Bacillus UCMB5113 to counteract pathogens using both antagonistic lipopeptides and through ISR provides a promising tool for sustainable crop production.
|
|
| 7. |
- Bacon, Christine D., et al.
(författare)
-
Soil fertility and flood regime are correlated with phylogenetic structure of Amazonian palm communities
- 2019
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 123:4, s. 641-655
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Identifying the processes that generate and maintain biodiversity requires understanding of how evolutionary processes interact with abiotic conditions to structure communities. Edaphic gradients are strongly associated with floristic patterns but, compared with climatic gradients, have received relatively little attention. We asked (1) How does the phylogenetic composition of palm communities vary along edaphic gradients within major habitat types? and (2) To what extent are phylogenetic patterns determined by (a) habitat specialists, (b) small versus large palms, and (c) hyperdiverse genera? Methods We paired data on palm community composition from 501 transects of 0.25 ha located in two main habitat types (non-inundated uplands and seasonally inundated floodplains) in western Amazonian rain forests with information on soil chemistry, climate, phylogeny and metrics of plant size. We focused on exchangeable base concentration (cmol(+) kg(-1)) as a metric of soil fertility and a floristic index of inundation intensity. We used a null model approach to quantify the standard effect size of mean phylogenetic distance for each transect (a metric of phylogenetic community composition) and related this value to edaphic variables using generalized linear mixed models, including a term for spatial autocorrelation. Key Results Overall, we recorded 112 008 individuals belonging to 110 species. Palm communities in non-inundated upland transects (but not floodplain transects) were more phylogenetically clustered in areas of low soil fertility, measured as exchangeable base concentration. In contrast, floodplain transects with more severe flood regimes (as inferred from floristic structure) tended to be phylogenetically clustered. Nearly half of the species recorded (44 %) were upland specialists while 18 % were floodplain specialists. In both habitat types, phylogenetic clustering was largely due to the co-occurrence of small-sized habitat specialists belonging to two hyperdiverse genera (Bactris and Geonoma). Conclusions Edaphic conditions are associated with the phylogenetic community structure of palms across western Amazonia, and different factors (specifically, soil fertility and inundation intensity) appear to underlie diversity patterns in non-inundated upland versus floodplain habitats. By linking edaphic gradients with palm community phylogenetic structure, our study reinforces the need to integrate edaphic conditions in eco-evolutionary studies in order to better understand the processes that generate and maintain tropical forest diversity. Our results suggest a role for edaphic niche conservatism in the evolution and distribution of Amazonian palms, a finding with potential relevance for other clades.
|
|
| 8. |
- Barros, Jaime, et al.
(författare)
-
The cell biology of lignification in higher plants
- 2015
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 115:7, s. 1053-1074
-
Forskningsöversikt (refereegranskat)abstract
- Background Lignin is a polyphenolic polymer that strengthens and waterproofs the cell wall of specialized plant cell types. Lignification is part of the normal differentiation programme and functioning of specific cell types, but can also be triggered as a response to various biotic and abiotic stresses in cells that would not otherwise be lignifying.Scope Cell wall lignification exhibits specific characteristics depending on the cell type being considered. These characteristics include the timing of lignification during cell differentiation, the palette of associated enzymes and substrates, the sub-cellular deposition sites, the monomeric composition and the cellular autonomy for lignin monomer production. This review provides an overview of the current understanding of lignin biosynthesis and polymerization at the cell biology level.Conclusions The lignification process ranges from full autonomy to complete co-operation depending on the cell type. The different roles of lignin for the function of each specific plant cell type are clearly illustrated by the multiple phenotypic defects exhibited by knock-out mutants in lignin synthesis, which may explain why no general mechanism for lignification has yet been defined. The range of phenotypic effects observed include altered xylem sap transport, loss of mechanical support, reduced seed protection and dispersion, and/or increased pest and disease susceptibility.
|
|
| 9. |
- Bengtsson, Fia, et al.
(författare)
-
Mechanisms behind species-specific water economy responses to water level drawdown in peat mosses
- 2020
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 126:2, s. 219-230
-
Tidskriftsartikel (refereegranskat)abstract
- Background and AimsThe ecosystem engineers Sphagnum (peat mosses) are responsible for sequestering a large proportion of carbon in northern peatlands. Species may respond differently to hydrological changes, and water level changes may lead to vegetation shifts in peatlands, causing them to revert from sinks to sources of carbon. We aimed to compare species-specific responses to water level drawdown within Sphagnum, and investigate which traits affect water economy in this genus.MethodsIn a mesocosm experiment, we investigated how water level drawdown affected water content (WC) in the photosynthetically active apex of the moss and maximum quantum yield of photosystem II (i.e. Fv/Fm) of 13 Sphagnum species. Structural traits were measured, and eight anatomical traits were quantified from scanning electron microscopy micrographs.Key ResultsMixed-effects models indicated that at high water level, large leaves were the most influential predictor of high WC, and at low water level WC was higher in species growing drier in the field, with larger hyaline cell pore sizes and total pore areas associated with higher WC. Higher stem and peat bulk density increased WC, while capitulum mass per area and numerical shoot density did not. We observed a clear positive relationship between Fv/Fm and WC in wet-growing species.ConclusionsWhile we found that most hummock species had a relatively high water loss resistance, we propose that some species are able to maintain a high WC at drawdown by storing large amounts of water at a high water level. Our result showing that leaf traits are important warrants further research using advanced morphometric methods. As climate change may lead to more frequent droughts and thereby water level drawdowns in peatlands, a mechanistic understanding of species-specific traits and responses is crucial for predicting future changes in these systems.
|
|
| 10. |
- Berlin Kolm, Sofia, et al.
(författare)
-
Genetics of phenotypic plasticity and biomass traits in hybrid willows across contrasting environments and years
- 2017
-
Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 120, s. 87-100
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Phenotypic plasticity can affect the geographical distribution of taxa and greatly impact the productivity of crops across contrasting and variable environments. The main objectives of this study were to identify genotype-phenotype associations in key biomass and phenology traits and the strength of phenotypic plasticity of these traits in a short-rotation coppice willow population across multiple years and contrasting environments to facilitate marker-assisted selection for these traits.Methods A hybrid Salix viminalis x (S. viminalis x Salix schwerinii) population with 463 individuals was clonally propagated and planted in three common garden experiments comprising one climatic contrast between Sweden and Italy and one water availability contrast in Italy. Several key phenotypic traits were measured and phenotypic plasticity was estimated as the trait value difference between experiments. Quantitative trait locus (QTL) mapping analyses were conducted using a dense linkage map and phenotypic effects of S. schwerinii haplotypes derived from detected QTL were assessed.Key Results Across the climatic contrast, clone predictor correlations for biomass traits were low and few common biomass QTL were detected. This indicates that the genetic regulation of biomass traits was sensitive to environmental variation. Biomass QTL were, however, frequently shared across years and across the water availability contrast. Phenology QTL were generally shared between all experiments. Substantial phenotypic plasticity was found among the hybrid offspring, that to a large extent had a genetic origin. Individuals carrying influential S. schwerinii haplotypes generally performed well in Sweden but less well in Italy in terms of biomass production.Conclusions The results indicate that specific genetic elements of S. schwerinii are more suited to Swedish conditions than to those of Italy. Therefore, selection should preferably be conducted separately for such environments in order to maximize biomass production in admixed S. viminalis x S. schwerinii populations.
|
|
