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Plants are daily challenged by multiple abiotic and biotic stresses. A major biotic constraint corresponds to competition with other plant species. Although plants simultaneously interact with multiple neighboring species throughout their life cycle, there is still very limited information about the genetics of the competitive response in the context of plurispecific interactions. Using a local mapping population of Arabidopsis thaliana , we set up a genome wide association study (GWAS) to estimate the extent of genetic variation of competitive response in 12 plant species assemblages, based on three competitor species ( Poa annua , Stellaria media , and Veronica arvensis ). Based on five phenotypic traits, we detected strong crossing reaction norms not only between the three bispecific neighborhoods but also among the plurispecific neighborhoods. The genetic architecture of competitive response was highly dependent on the identity and the relative abundance of the neighboring species. In addition, most of the enriched biological processes underlying competitive responses largely differ among neighborhoods. While the RNA related processes might confer a broad range response toolkit for multiple traits in diverse neighborhoods, some processes, such as signaling and transport, might play a specific role in particular assemblages. Altogether, our results suggest that plants can integrate and respond to different species assemblages depending on the identity and number of each neighboring species, through a large range of candidate genes associated with diverse and unexpected processes leading to developmental and stress responses., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Libourel, Baron, Lenglet, Amsellem, Roby and Roux.)

In the version of this Article previously published, there was a typographical error ('4' instead of '2') in the equations relating F ST and effective population size (N e ) in the Methods section 'Genome-wide scan for selection based on temporal differentiation'. The correct equations are given below.[Formula: see text] [Formula: see text].

Rapid phenotypic evolution of quantitative traits can occur within years, but its underlying genetic architecture remains uncharacterized. Here we test the theoretical prediction that genes with intermediate pleiotropy drive adaptive evolution in nature. Through a resurrection experiment, we grew Arabidopsis thaliana accessions collected across an 8-year period in six micro-habitats representative of that local population. We then used genome-wide association mapping to identify the single-nucleotide polymorphisms (SNPs) associated with evolved and unevolved traits in each micro-habitat. Finally, we performed a selection scan by testing for temporal differentiation in these SNPs. Phenotypic evolution was consistent across micro-habitats, but its associated genetic bases were largely distinct. Adaptive evolutionary change was most strongly driven by a small number of quantitative trait loci (QTLs) with intermediate degrees of pleiotropy; this pleiotropy was synergistic with the per-trait effect size of the SNPs, increasing with the degree of pleiotropy. In addition, weak selection was detected for frequent micro-habitat-specific QTLs that shape single traits. In this population, A. thaliana probably responded to local warming and increased competition, in part mediated by central regulators of flowering time. This genetic architecture, which includes both synergistic pleiotropic QTLs and distinct QTLs within particular micro-habitats, enables rapid phenotypic evolution while still maintaining genetic variation in wild populations.

We compared the reproductive system of Rubus alceifolius in its native range in Southeast Asia, in Madagascar, where the plant was introduced apparently some centuries ago, and in La Réunion, an Indian Ocean island onto which R. alceifolius was introduced (from Madagascan source populations) around 1850. While tetraploidy makes it impossible to analyze variation in R. alceifolius using classical methods of population genetics, both the patterns of genetic diversity (as revealed by AFLP [amplified fragment length polymorphism] markers) and differences between half-sib progeny and their maternal parents (revealed by microsatellite markers) show that in the plant's native range in southeast Asia, seeds are produced sexually. In contrast, in Madagascar sexual reproduction cannot alone account for the genetic patterns observed with microsatellite markers. Over 85% of the half-sib progeny resulting from open pollination gave multilocus genotypes identical to those of their respective maternal parents, despite the fact that the latter had alleles that were rare in the population. The other progeny differed in having an allele with one motif more or less than that of the maternal parent. Seeds thus appear to be produced mostly or exclusively by apomixis in Madagascar. We present findings suggesting that Madagascan populations result from hybridization of introduced R. alceifolius and native populations of R. roridus, a closely related species of Rubus subgenus Malachobatus, and suggest that apomixis was a consequence of this hybridization. In Reunionese populations of R. alceifolius (derived from Madagascan populations), seeds obtained in controlled pollination experiments were all genetically identical to maternal parents. While genetic variation (microsatellite markers) in Reunionese populations was low, it was sufficient to allow us to demonstrate that seeds could not have resulted from fertilization by the pollen donors chosen for controlled pollinations, or from autogamy, and were produced exclusively by apomixis.

Theory predicts that colonization of new areas will be associated with population bottlenecks that reduce within-population genetic diversity and increase genetic differentiation among populations. This should be especially true for weedy plant species, which are often characterized by self-compatible breeding systems and vegetative propagation. To test this prediction, and to evaluate alternative scenarios for the history of introduction, the genetic diversity of Rubus alceifolius was studied with amplified fragment length polymorphism (AFLP) markers in its native range in southeast Asia and in several areas where this plant has been introduced and is now a serious weed (Indian Ocean islands, Australia). In its native range, R. alceifolius showed great genetic variability within populations and among geographically close populations (populations sampled ranging from northern Vietnam to Java). In Madagascar, genetic variability was somewhat lower than in its native range, but still considerable. Each population sampled in the other Indian Ocean islands (Mayotte, La Réunion, Mauritius) was characterized by a single different genotype of R. alceifolius for the markers studied, and closely related to individuals from Madagascar. Queensland populations also included only a single genotype, identical to that found in Mauritius. These results suggest that R. alceifolius was first introduced into Madagascar, perhaps on multiple occasions, and that Madagascan individuals were the immediate source of plants that colonized other areas of introduction. Successive nested founder events appear to have resulted in cumulative reduction in genetic diversity. Possible explanations for the monoclonality of R. alceifolius in many areas of introduction are discussed.

We investigated factors influencing alkaline phosphatase activity in the course of developing criteria for the establishment of a standardized method for its determination in human serum at 30 degrees C. The effects of pH, phosphorylatable acceptor (2-amino-2-methyl-1-propanol and diethanolamine), 4-nitrophenyl phosphate, magnesium ion, zinc ion, temperature, volume fraction of specimen, and details of initiation of the reaction have been studied, with use of partly purified enzymes from bone, intestine, liver, and placenta, and sera from patients with a predominant characterized isoenzyme. The purity of the diethanolamine was examined and contaminant monoethanolamine was characterized as a competitive inhibitor. Two sets of recommended conditions are: 2-amino-2-methyl-1-propanol, 0.9 mol/liter; 4-nitrophenyl phosphate, 16 mmol/liter; magnesium ion, 1 mmol/liter; volume fraction of specimen 1/30, and pH30 degrees C 10.5; diethanolamine, 1.8 mol/liter; 4-nitrophenyl phosphate, 18 mmol/liter; magnesium ion, 1 mmol/liter; volume fraction of specimen 1/60, and pH30 degrees C 10.1. Serum is preincubated with all reagents but 4-nitrophenyl phosphate, which is used as the reaction-initiating substrate.