Reduced within-population quantitative genetic variation is associated with climate harshness in maritime pine.

How evolutionary forces interact to maintain genetic variation within populations has been a matter of extensive theoretical debates. While mutation and exogenous gene flow increase genetic variation, stabilizing selection and genetic drift are expected to deplete it. To date, levels of genetic variation observed in natural populations are hard to predict without accounting for other processes, such as balancing selection in heterogeneous environments.

Gene expression and genetic divergence in oak species highlight adaptive genes to soil water constraints.

Drought and waterlogging impede tree growth and may even lead to tree death. Oaks, an emblematic group of tree species, have evolved a range of adaptations to cope with these constraints. The two most widely distributed European species, pedunculate (PO; Quercus robur L.

Plant genetic effects on microbial hubs impact host fitness in repeated field trials.

Although complex interactions between hosts and microbial associates are increasingly well documented, we still know little about how and why hosts shape microbial communities in nature. In addition, host genetic effects on microbial communities vary widely depending on the environment, obscuring conclusions about which microbes are impacted and which plant functions are important. We characterized the leaf microbiota of 200 genotypes in eight field experiments and detected consistent host effects on specific, broadly distributed microbial species (operational taxonomic unit [OTUs]).

Assessing the potential to harness the microbiome through plant genetics.

Microbial communities are influenced by a complex system of host effects, including traits involved in physical barriers, immunity, hormones, metabolisms and nutrient homeostasis. Variation of host control within species is governed by many genes of small effect and is sensitive to biotic and abiotic environments. On the flip side, these host impacts seem targeted on particular microbial species, with that impact percolating through the microbial community.

The genetics of exapted resistance to two exotic pathogens in pedunculate oak.

Exotic pathogens cause severe damage in natural populations in the absence of coevolutionary dynamics with their hosts. However, some resistance to such pathogens may occur in naive populations. The objective of this study was to investigate the genetics of this so-called 'exapted' resistance to two pathogens of Asian origin (Erysiphe alphitoides and Phytophthora cinnamomi) in European oak.

Oak genotype and phenolic compounds differently affect the performance of two insect herbivores with contrasting diet breadth.

Research on plant-herbivore interactions has long recognized that plant genetic variation plays a central role in driving insect abundance and herbivory, as well as in determining plant defense. However, how plant genes influence herbivore feeding performances, and which plant defensive traits mediate these effects, remain poorly understood. Here we investigated the feeding performances of two insect leaf chewers with contrasting diet breadth (the generalist Lymantria dispar L.

Genome-wide association studies on the phyllosphere microbiome: Embracing complexity in host-microbe interactions.

Environmental sequencing shows that plants harbor complex communities of microbes that vary across environments. However, many approaches for mapping plant genetic variation to microbe-related traits were developed in the relatively simple context of binary host-microbe interactions under controlled conditions. Recent advances in sequencing and statistics make genome-wide association studies (GWAS) an increasingly promising approach for identifying the plant genetic variation associated with microbes in a community context.

The rate and potential relevance of new mutations in a colonizing plant lineage.

By following the evolution of populations that are initially genetically homogeneous, much can be learned about core biological principles. For example, it allows for detailed studies of the rate of emergence of de novo mutations and their change in frequency due to drift and selection. Unfortunately, in multicellular organisms with generation times of months or years, it is difficult to set up and carry out such experiments over many generations.

Coselected genes determine adaptive variation in herbivore resistance throughout the native range of Arabidopsis thaliana.

The "mustard oil bomb" is a major defense mechanism in the Brassicaceae, which includes crops such as canola and the model plant Arabidopsis thaliana. These plants produce and store blends of amino acid-derived secondary metabolites called glucosinolates. Upon tissue rupture by natural enemies, the myrosinase enzyme hydrolyses glucosinolates, releasing defense molecules.

Genome-wide association mapping of flowering time in in nature: genetics for underlying components and reaction norms across two successive years.

Often used as a proxy for the transition to reproduction, flowering time (FT) is an integrative trait of two successive biological processes, bolting time (BT) and the interval between bolting and flowering time (INT). In this study, we aimed to identify candidate genes associated with these composite traits in using a field experiment. Genome-wide association (GWA) mapping was performed on BT, INT and FT based on a sample of 179 worldwide natural accessions genotyped for 216,509 SNPs.

Investigation of the geographical scale of adaptive phenological variation and its underlying genetics in Arabidopsis thaliana.

Despite the increasing number of genomic tools, identifying the genetics underlying adaptive complex traits remains challenging in the model species Arabidopsis thaliana. This is due, at least in part, to the lack of data on the geographical scale of adaptive phenotypic variation. The aims of this study were (i) to tease apart the historical roles of adaptive and nonselective processes in shaping phenological variation in A.

Adaptive value of phenological traits in stressful environments: predictions based on seed production and laboratory natural selection.

Phenological traits often show variation within and among natural populations of annual plants. Nevertheless, the adaptive value of post-anthesis traits is seldom tested. In this study, we estimated the adaptive values of pre- and post-anthesis traits in two stressful environments (water stress and interspecific competition), using the selfing annual species Arabidopsis thaliana.

Genome-wide association studies in plants: the missing heritability is in the field.

Genome-wide association studies (GWAS) have been even more successful in plants than in humans. Mapping approaches can be extended to dissect adaptive genetic variation from structured background variation in an ecological context.

Adaptation to climate across the Arabidopsis thaliana genome.

Understanding the genetic bases and modes of adaptation to current climatic conditions is essential to accurately predict responses to future environmental change. We conducted a genome-wide scan to identify climate-adaptive genetic loci and pathways in the plant Arabidopsis thaliana. Amino acid-changing variants were significantly enriched among the loci strongly correlated with climate, suggesting that our scan effectively detects adaptive alleles.

Genetic determination of male sterility in gynodioecious Silene nutans.

Gynodioecy, the coexistence of female and hermaphrodite plants within a species, is often under nuclear-cytoplasmic sex determination, involving cytoplasmic male sterility (CMS) genes and nuclear restorers. A good knowledge of CMS and restorer polymorphism is essential for understanding the evolution and maintenance of gynodioecy, but reciprocal crossing studies remain scarce. Although mitochondrial diversity has been studied in a few gynodioecious species, the relationship between mitotype diversity and CMS status is poorly known.

Linkage and association mapping of Arabidopsis thaliana flowering time in nature.

Flowering time is a key life-history trait in the plant life cycle. Most studies to unravel the genetics of flowering time in Arabidopsis thaliana have been performed under greenhouse conditions. Here, we describe a study about the genetics of flowering time that differs from previous studies in two important ways: first, we measure flowering time in a more complex and ecologically realistic environment; and, second, we combine the advantages of genome-wide association (GWA) and traditional linkage (QTL) mapping.

Genome-wide association study of 107 phenotypes in Arabidopsis thaliana inbred lines.

Although pioneered by human geneticists as a potential solution to the challenging problem of finding the genetic basis of common human diseases, genome-wide association (GWA) studies have, owing to advances in genotyping and sequencing technology, become an obvious general approach for studying the genetics of natural variation and traits of agricultural importance. They are particularly useful when inbred lines are available, because once these lines have been genotyped they can be phenotyped multiple times, making it possible (as well as extremely cost effective) to study many different traits in many different environments, while replicating the phenotypic measurements to reduce environmental noise. Here we demonstrate the power of this approach by carrying out a GWA study of 107 phenotypes in Arabidopsis thaliana, a widely distributed, predominantly self-fertilizing model plant known to harbour considerable genetic variation for many adaptively important traits.