Deciphering the adjustment between environment and life history in annuals: lessons from a geographically-explicit approach in Arabidopsis thaliana

The role that different life-history traits may have in the process of adaptation caused by divergent selection can be assessed by using extensive collections of geographically-explicit populations. This is because adaptive phenotypic variation shifts gradually across space as a result of the geographic patterns of variation in environmental selective pressures. Hence, large-scale experiments are needed to identify relevant adaptive life-history traits as well as their relationships with putative selective agents. We conducted a field experiment with 279 geo-referenced accessions of the annual plant Arabidopsis thaliana collected across a native region of its distribution range, the Iberian Peninsula. We quantified variation in life-history traits throughout the entire life cycle. We built a geographic information system to generate an environmental data set encompassing climate, vegetation and soil data. We analysed the spatial autocorrelation patterns of environmental variables and life-history traits, as well as the relationship between environmental and phenotypic data. Almost all environmental variables were significantly spatially autocorrelated. By contrast, only two life-history traits, seed weight and flowering time, exhibited significant spatial autocorrelation. Flowering time, and to a lower extent seed weight, were the life-history traits with the highest significant correlation coefficients with environmental factors, in particular with annual mean temperature. In general, individual fitness was higher for accessions with more vigorous seed germination, higher recruitment and later flowering times. Variation in flowering time mediated by temperature appears to be the main life-history trait by which A. thaliana adjusts its life history to the varying Iberian environmental conditions. The use of extensive geographically-explicit data sets obtained from field experiments represents a powerful approach to unravel adaptive patterns of variation. In a context of current global warming, geographically-explicit approaches, evaluating the match between organisms and the environments where they live, may contribute to better assess and predict the consequences of global warming

The role of the transient atropisomerism and chirality of flurbiprofen unveiled by laser‐ablation rotational spectroscopy

Producción CientíficaThe combination of atropisomerism and chirality in flurbiprofen is shown to be relevant concerning its pharmacological activity. The two most stable conformers of a total of eight theoretically predicted for each R- or S- flurbiprofen enantiomers have been isolated in the cooling conditions of a supersonic jet and structurally characterized by laser ablation Fourier transform microwave spectroscopy. The detected conformers, whose structure is mainly defined by three dihedral angles, only differ in the sign of the phenyl torsion angle giving rise to Sa and Ra atropisomers. A comparison with the structures available for the R- and S- enantiomers complexed to COX isoforms reveals that the enzymes select only the Saatropisomers, resulting in a diastereoisomer-specific recognition. The most stable gas phase conformer is exclusively selected when using the S- enantiomer while the second is recognized only for the R- enantiomer. These experimental results highlight the importance of atropisomerism in drug design.Junta de Castilla y León (Grant INFRARED-FEDER IR2020-1-UVa02)Ministerio de Economía y Competitividad (Grant CTQ2016-75253-P)Ministerio de Ciencia e Innovación (Grant PID2021-125207NB-C33

PII: S1360-1385(99)01510-1

T he wild crucifer Arabidopsis thaliana has become an important model system because it allows genetics to combine with molecular biology (i.e. it has a short generation time, a small genome and is easily transformed) Genetic variation is required for the functional analysis of the Arabidopsis genome Laboratory-induced mutants Currently, the functional analysis of Arabidopsis genes and the dissection of complex traits are based largely on the phenotypic characterization of mutants selected by forward and reverse genetics in a few laboratory 'wild-type' genotypes. The inbred strains generally used are Landsberg erecta (Ler), Columbia (Col) and Wassilewskija (Ws), originally collected from the wild by the pioneers of Arabidopsis research, Friedrich Laibach and colleagues 3 . These forward and reverse genetic approaches using classical (physical or chemical) and insertional (biological) mutagens have proven their usefulness 1 . The possibility of identifying genotypes with an insertion in a gene of known nucleotide sequence, independently of the presence of a phenotype, has led to large-scale projects for disrupting most of the Arabidopsis genes Naturally occurring variants: new times for an old resource As an alternative to generating laboratory-induced mutants, another source of genetic variation can be found among and within naturally occurring populations of Arabidopsis Exploitation of the genetic variation among accessions has been limited because of its mostly quantitative (continuous) nature, in contrast with the commonly studied mutants, which provide qualitative (discrete) variation. This dichotomy is defined basically by the number of loci and the environmental effect underlying the variation under study, which determine the tools used for its analysis. Only in the past decade, with the advent of efficient molecular marker technologies and specific statistical methods, has the map position and the effects of quantitative trait loci (QTL) been establishe

Hydrogen-Bond Cooperativity in Formamide2–Water: A Model for Water-Mediated Interactions

Producción CientíficaThe rotational spectrum of formamide2-H2O formed in a supersonic jet has been characterized by Fourier transform microwave spectroscopy. This adduct provides a simple model of water mediated interaction involving the amide linkages, as occur in protein folding or amide association processes, showing the interplay between self-association and solvation. Mono-substituted 13C, 15N, 18O and 2H isotopologues have been observed to investigate the structure. The adduct forms an almost planar three body sequential cycle. The two formamide molecules link on one side through an N-H···O hydrogen bond and on the other side through a water-mediated interaction with the formation of C=O···H-O and O···H-N hydrogen bonds. The analysis of the quadrupole coupling effects due to the presence of two 14N-nuclei reveal the subtle inductive forces associated to cooperative hydrogen bonding. These forces are involved in the changes detected in the C=O and C-N bond distances with respect to bare formamide.2018-03-03Ministerio de Economía, Industria y Competitividad (CTQ2013-40717-P)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA334U14

Tackling intraspecific genetic structure in distribution models better reflects species geographical range

Genetic diversity provides insight into heterogeneous demographic and adaptive history across organisms' distribution ranges. For this reason, decomposing single species into genetic units may represent a powerful tool to better understand biogeographical patterns as well as improve predictions of the effects of GCC (global climate change) on biodiversity loss. Using 279 georeferenced Iberian accessions, we used classes of three intraspecific genetic units of the annual plant Arabidopsis thaliana obtained from the genetic analyses of nuclear SNPs (single nucleotide polymorphisms), chloroplast SNPs, and the vernalization requirement for flowering. We used SDM (species distribution models), including climate, vegetation, and soil data, at the whole-species and genetic-unit levels. We compared model outputs for present environmental conditions and with a particularly severe GCC scenario. SDM accuracy was high for genetic units with smaller distribution ranges. Kernel density plots identified the environmental variables underpinning potential distribution ranges of genetic units. Combinations of environmental variables accounted for potential distribution ranges of genetic units, which shrank dramatically with GCC at almost all levels. Only two genetic clusters increased their potential distribution ranges with GCC. The application of SDM to intraspecific genetic units provides a detailed picture on the biogeographical patterns of distinct genetic groups based on different genetic criteria. Our approach also allowed us to pinpoint the genetic changes, in terms of genetic background and physiological requirements for flowering, that Iberian A. thaliana may experience with a GCC scenario applying SDM to intraspecific genetic units

A high-density collection of EMS-induced mutations for TILLING in Landsberg erecta genetic background of Arabidopsis

<p>Abstract</p> <p>Background</p> <p><it>Arabidopsis thaliana </it>is the main model species for plant molecular genetics studies and world-wide efforts are devoted to identify the function of all its genes. To this end, reverse genetics by TILLING (Targeting Induced Local Lesions IN Genomes) in a permanent collection of chemically induced mutants is providing a unique resource in Columbia genetic background. In this work, we aim to extend TILLING resources available in <it>A. thaliana </it>by developing a new population of ethyl methanesulphonate (EMS) induced mutants in the second commonest reference strain. In addition, we pursue to saturate the number of EMS induced mutations that can be tolerated by viable and fertile plants.</p> <p>Results</p> <p>By mutagenizing with different EMS concentrations we have developed a permanent collection of 3712 M₂/M₃independent mutant lines in the reference strain Landsberg <it>erecta </it>(L<it>er</it>) of <it>A. thaliana</it>. This population has been named as the Arabidopsis TILL<it>er </it>collection. The frequency of mutations per line was maximized by using M₁plants with low but sufficient seed fertility. Application of TILLING to search for mutants in 14 genes identified 21 to 46 mutations per gene, which correspond to a total of 450 mutations. Missense mutations were found for all genes while truncations were selected for all except one. We estimated that, on average, these lines carry one mutation every 89 kb, L<it>er </it>population providing a total of more than five million induced mutations. It is estimated that TILL<it>er </it>collection shows a two to three fold higher EMS mutation density per individual than previously reported <it>A. thaliana </it>population.</p> <p>Conclusions</p> <p>Analysis of TILL<it>er </it>collection demonstrates its usefulness for large scale TILLING reverse genetics in another reference genetic background of <it>A. thaliana</it>. Comparisons with TILLING populations in other organisms indicate that this new <it>A. thaliana </it>collection carries the highest chemically induced mutation density per individual known in diploid species.</p

Water-Induced Structural Changes in Crown Ethers from Broadband Rotational Spectroscopy

Producción CientíficaThe complexes of 12-crown-4 ether (12C4) with water, generated in a supersonic jet, have been studied using broadband Fourier transform microwave spectroscopy. Three 1:1 and one 1:2 clusters have been observed and their structures unambiguously identified through the observation of isotopologue spectra. The structures of the clusters are based on networks of O-H···O and C-H···O hydrogen bonds. The most abundant 1:1 cluster is formed from the most stable S4 symmetry conformer of 12C4, even though it is not the energetically favored water complex. Interestingly, the structures of the most stable water cluster and the other remaining observed 1:1 and 1:2 complexes are formed from the third or the fifth most abundant conformers of 12C4. This shows the existence of a mechanism that changes the configuration of 12C4 so that the host-guest interactions can be maximized, even for a “soft” ligand like water.2018-03-03Ministerio de Economía, Industria y Competitividad (CTQ2013-40717-P)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA334U14)Deutsche Forschungsgemeinschaft SPP1807(SCHN1280/4-1

Genetic basis of adaptation in Arabidopsis thaliana: Local adaptation at the seed dormancy QTL DOG1

Local adaptation provides an opportunity to study the genetic basis of adaptation and investigate the allelic architecture of adaptive genes. We study DELAY OF GERMINATION 1 (DOG1), a gene controlling natural variation in seed dormancy in Arabidopsis thaliana and investigate evolution of dormancy in 41 populations distributed in four regions separated by natural barriers. Using F ST and Q ST comparisons, we compare variation at DOG1 with neutral markers and quantitative variation in seed dormancy. Patterns of genetic differentiation among populations suggest that the gene DOG1 contributes to local adaptation. Although Q ST for seed dormancy is not different from F ST for neutral markers, a correlation with variation in summer precipitation supports that seed dormancy is adaptive. We characterize dormancy variation in several F 2-populations and show that a series of functionally distinct alleles segregate at the DOG1 locus. Theoretical models have shown that the number and effect of alleles segregatin at quantitative trait loci (QTL) have important consequences for adaptation. Our results provide support to models postulating a large number of alleles at quantitative trait loci involved in adaptation. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.Peer Reviewe

Quantifying temporal change in plant population attributes : insights from a resurrection approach

Rapid evolution in annual plants can be quantified by comparing phenotypic and genetic changes between past and contemporary individuals from the same populations over several generations. Such knowledge will help understand the response of plants to rapid environmental shifts, such as the ones imposed by global climate change. To that end, we undertook a resurrection approach in Spanish populations of the annual plant Arabidopsis thaliana that were sampled twice over a decade. Annual weather records were compared to their historical records to extract patterns of climatic shifts over time. We evaluated the differences between samplings in flowering time, a key life-history trait with adaptive significance, with a field experiment. We also estimated genetic diversity and differentiation based on neutral nuclear markers and nucleotide diversity in candidate flowering time (FRI and FLC) and seed dormancy (DOG1) genes. The role of genetic drift was estimated by computing effective population sizes with the temporal method. Overall, two climatic scenarios were detected: intense warming with increased precipitation and moderate warming with decreased precipitation. The average flowering time varied little between samplings. Instead, within-population variation in flowering time exhibited a decreasing trend over time. Substantial temporal changes in genetic diversity and differentiation were observed with both nuclear microsatellites and candidate genes in all populations, which were interpreted as the result of natural demographic fluctuations. We conclude that drought stress caused by moderate warming with decreased precipitation may have the potential to reduce within-population variation in key life-cycle traits, perhaps as a result of stabilizing selection on them, and to constrain the genetic differentiation over time. Besides, the demographic behaviour of populations probably accounts for the substantial temporal patterns of genetic variation, while keeping rather constant those of phenotypic variation