Genetic and morphological differentiation in Populus nigra L.:isolation by colonization or isolation by adaptation?

Identifying processes underlying the genetic and morphological differences among populations is a central question of evolutionary biology. Forest trees typically contain high levels of neutral genetic variation, and genetic differences are often correlated with geographic distance between populations [isolation by distance (IBD)] or are due to historic vicariance events [isolation by colonization (IBC)]. In contrast, morphological differences are largely due to local adaptation. Here, we examined genetic (microsatellite) and morphological (from a common garden experiment) variation in Populus nigra L., European black poplar, collected from 13 sites across western Europe and grown in a common garden in Belgium. Significant genetic differentiation was observed, with populations from France displaying greater admixture than the distinct Spanish and central European gene pools, consistent with previously described glacial refugia (IBC). Many quantitative traits displayed a bimodal distribution, approximately corresponding to small-leaf and large-leaf ecotypes. Examination of nine climatic variables revealed the sampling locations to have diverse climates, and although the correlation between morphological and climatic differences was significant, the pattern was not consistent with strict local adaptation. Partial Mantel tests based on multivariate summary statistics identified significant residual correlation in comparisons of small-leaf to large-leaf ecotypes, and within the small-leaf samples, but not within large-leaf ecotypes, indicating that variation within the small-leaf morphotype in particular may be adaptive. Some small-leaf populations experience climates very similar to those in large-leaf sites. We conclude that adaptive differentiation and persistent IBC acted in combination to produce the genetic and morphological patterns observed in P. nigra

Sesquiterpenoids lactones: benefits to plants and people

Sesquiterpenoids, and specifically sesquiterpene lactones from Asteraceae, may play a highly significant role in human health, both as part of a balanced diet and as pharmaceutical agents, due to their potential for the treatment of cardiovascular disease and cancer. This review highlights the role of sesquiterpene lactones endogenously in the plants that produce them, and explores mechanisms by which they interact in animal and human consumers of these plants. Several mechanisms are proposed for the reduction of inflammation and tumorigenesis at potentially achievable levels in humans. Plants can be classified by their specific array of produced sesquiterpene lactones, showing high levels of translational control. Studies of folk medicines implicate sesquiterpene lactones as the active ingredient in many treatments for other ailments such as diarrhea, burns, influenza, and neurodegradation. In addition to the anti-inflammatory response, sesquiterpene lactones have been found to sensitize tumor cells to conventional drug treatments. This review explores the varied ecological roles of sesquiterpenes in the plant producer, depending upon the plant and the compound. These include allelopathy with other plants, insects, and microbes, thereby causing behavioural or developmental modification to these secondary organisms to the benefit of the sesquiterpenoid producer. Some sesquiterpenoid lactones are antimicrobial, disrupting the cell wall of fungi and invasive bacteria, whereas others protect the plant from environmental stresses that would otherwise cause oxidative damage. Many of the compounds are effective due to their bitter flavor, which has obvious implications for human consumers. The implications of sesquiterpenoid lactone qualitiesfor future crop production are discussed

Linking transcript, QTL and association mapping to understand the genetic control of leaf size and shape in Populus

Leaf size in Populus is an adaptive trait and early indicator of biomass yield. In order to investigate the genetic variance contributing to this variation in leaf size a collection of Populus nigra L. were made from across Europe and were planted at a single site in Belgium, in a fully randomized and replicated trial, with leaf traits measured in three consecutive years and biomass estimated at one point in time. Results indicate that leaf traits vary with latitude of sample origin, with significant differences observed in leaf area, epidermal cell number and biomass, but not in leaf shape (leaf ratio), epidermal cell area, stomatal density and stomatal index. Overall a significant positive relationship between latitude of origin and leaf traits was observed with small-leaved genotypes containing fewer epidermal cells observed in the south west (Spain), and large-leaved genotypes occurring in the north and east (the Netherlands, Germany and Italy). A sequence-based genetic study was conducted to identify Single Nucleotide Polymorphisms (SNPs) associated with leaf phenotype. Given that linkage disequilibrium (LD), decays rapidly (r2 = 0.09) in P.nigra, a candidate gene approach for association is valid. Candidate genes were selected from Quantitative Trait Loci (QTL), from a microarray experiment and from bioinformatics and literature searches, identifying sixty robust genes. From this list eight candidate genes were selected for further analysis; ASYMMETRIC LEAVES 1 (AS1), ASYMMETRIC LEAVES 2 (AS2), ACC OXIDASE ( ACO), ERECTA (ER), PHABULOSA (PHAB), ANGUSTOFOLIA (AN), E2Fc and LEAFY. Genetic association was conducted using a General Linear Model (GLM) both with and without population structure. The strongest genetic association was found in AS1, a gene involved in leaf initiation that acts by repressing KNOX genes to increase cell differentiation. Gene expression of the eight candidate genes were examined across extreme leaf genotypes using real time qPCR (RT-qPCR), at three growth stages. Extreme leaf genotypes consisted of five „small? and five „big? leaf genotypes selected from the association population. Significant differences in gene expression was seen between „small? and „big? genotypes in AN, AS2 and AS1. These results suggest that AS1 is a strong candidate gene for leaf size

Data from: Genetic and morphological differentiation in Populus nigra L.: isolation by colonization or isolation by adaptation?

Identifying processes underlying the genetic and morphological differences among populations is a central question of evolutionary biology. Forest trees typically contain high levels of neutral genetic variation, and genetic differences are often correlated with geographic distance between populations [isolation by distance (IBD)] or are due to historic vicariance events [isolation by colonization (IBC)]. In contrast, morphological differences are largely due to local adaptation. Here, we examined genetic (microsatellite) and morphological (from a common garden experiment) variation in Populus nigra L., European black poplar, collected from 13 sites across western Europe and grown in a common garden in Belgium. Significant genetic differentiation was observed, with populations from France displaying greater admixture than the distinct Spanish and central European gene pools, consistent with previously described glacial refugia (IBC). Many quantitative traits displayed a bimodal distribution, approximately corresponding to small-leaf and large-leaf ecotypes. Examination of nine climatic variables revealed the sampling locations to have diverse climates, and although the correlation between morphological and climatic differences was significant, the pattern was not consistent with strict local adaptation. Partial Mantel tests based on multivariate summary statistics identified significant residual correlation in comparisons of small-leaf to large-leaf ecotypes, and within the small-leaf samples, but not within large-leaf ecotypes, indicating that variation within the small-leaf morphotype in particular may be adaptive. Some small-leaf populations experience climates very similar to those in large-leaf sites. We conclude that adaptive differentiation and persistent IBC acted in combination to produce the genetic and morphological patterns observed in P. nigra

DeWoody et al Pnigra morphological data Dryad

Morphological data from common garden experiment used in DeWoody, Trewin & Taylor, Genetic and morphological differentiation in Populus nigra L.: Isolation by colonization or isolation by adaptation

Genetic and morphological differentiation in Populus nigra L.: isolation by colonization or isolation by adaptation?

Identifying processes underlying the genetic and morphological differences among populations is a central question of evolutionary biology. Forest trees typically contain high levels of neutral genetic variation, and genetic differences are often correlated with geographic distance between populations [isolation by distance (IBD)] or are due to historic vicariance events [isolation by colonization (IBC)]. In contrast, morphological differences are largely due to local adaptation. Here, we examined genetic (microsatellite) and morphological (from a common garden experiment) variation in Populus nigra L., European black poplar, collected from 13 sites across western Europe and grown in a common garden in Belgium. Significant genetic differentiation was observed, with populations from France displaying greater admixture than the distinct Spanish and central European gene pools, consistent with previously described glacial refugia (IBC). Many quantitative traits displayed a bimodal distribution, approximately corresponding to small-leaf and large-leaf ecotypes. Examination of nine climatic variables revealed the sampling locations to have diverse climates, and although the correlation between morphological and climatic differences was significant, the pattern was not consistent with strict local adaptation. Partial Mantel tests based on multivariate summary statistics identified significant residual correlation in comparisons of small-leaf to large-leaf ecotypes, and within the small-leaf samples, but not within large-leaf ecotypes, indicating that variation within the small-leaf morphotype in particular may be adaptive. Some small-leaf populations experience climates very similar to those in large-leaf sites. We conclude that adaptive differentiation and persistent IBC acted in combination to produce the genetic and morphological patterns observed in P. nigra

Data from: Genetic and morphological differentiation in Populus nigra L.: isolation by colonization or isolation by adaptation?

Identifying processes underlying the genetic and morphological differences among populations is a central question of evolutionary biology. Forest trees typically contain high levels of neutral genetic variation, and genetic differences are often correlated with geographic distance between populations [isolation by distance (IBD)] or are due to historic vicariance events [isolation by colonization (IBC)]. In contrast, morphological differences are largely due to local adaptation. Here, we examined genetic (microsatellite) and morphological (from a common garden experiment) variation in Populus nigra L., European black poplar, collected from 13 sites across western Europe and grown in a common garden in Belgium. Significant genetic differentiation was observed, with populations from France displaying greater admixture than the distinct Spanish and central European gene pools, consistent with previously described glacial refugia (IBC). Many quantitative traits displayed a bimodal distribution, approximately corresponding to small-leaf and large-leaf ecotypes. Examination of nine climatic variables revealed the sampling locations to have diverse climates, and although the correlation between morphological and climatic differences was significant, the pattern was not consistent with strict local adaptation. Partial Mantel tests based on multivariate summary statistics identified significant residual correlation in comparisons of small-leaf to large-leaf ecotypes, and within the small-leaf samples, but not within large-leaf ecotypes, indicating that variation within the small-leaf morphotype in particular may be adaptive. Some small-leaf populations experience climates very similar to those in large-leaf sites. We conclude that adaptive differentiation and persistent IBC acted in combination to produce the genetic and morphological patterns observed in P. nigra.,DeWoody P. nigra metadataMicrosatellite data associated with DeWoody, Trewin &amp;amp; Taylor, Genetic and morphological differentiation in Populus nigra L.: Isolation by colonization or isolation by adaptation?DeWoody et al Pnigra microsatellite data Dryad.csvDeWoody et al Pnigra morphological data DryadMorphological data from common garden experiment used in DeWoody, Trewin &amp;amp; Taylor, Genetic and morphological differentiation in Populus nigra L.: Isolation by colonization or isolation by adaptation?DeWoody et al Pnigra climate data DryadWorldClim climate data for Populus nigra sampling sites, plus the first three factors resulting from the multivariate analysis of such.,</span

DeWoody et al Pnigra climate data Dryad

WorldClim climate data for Populus nigra sampling sites, plus the first three factors resulting from the multivariate analysis of such

DeWoody P. nigra metadata

Microsatellite data associated with DeWoody, Trewin & Taylor, Genetic and morphological differentiation in Populus nigra L.: Isolation by colonization or isolation by adaptation