Global analysis of non-animal peroxidases provides insights into the evolution of this gene family in the green lineage.

The non-animal peroxidases belong to a superfamily of oxidoreductases that reduce hydrogen peroxide and oxidize numerous substrates. Since their initial characterization in 1992, a number of studies have provided an understanding of the origin and evolution of this protein family. Here, we report a comprehensive evolutionary analysis of non-animal peroxidases using integrated in silico and biochemical approaches. Thanks to the availability of numerous genomic sequences from more than 2500 species belonging to 14 kingdoms together with expert and comprehensive annotation of peroxidase sequences that have been centralized in a dedicated database, we have been able to use phylogenetic reconstructions to increase our understanding of the evolutionary processes underlying the diversification of non-animal peroxidases. We analysed the distribution of all non-animal peroxidases in more than 200 eukaryotic organisms in silico. First, we show that the presence or absence of non-animal peroxidases correlates with the presence or absence of certain organelles or with specific biological processes. Examination of almost 2000 organisms determined that ascorbate peroxidases (APxs) and cytochrome c peroxidases (CcPs) are present in those containing chloroplasts and mitochondria, respectively. Plants, which contain both organelles, are an exception and contain only APxs without CcP. Class II peroxidases (CII Prxs) are only found in fungi with wood-decay and plant-degradation abilities. Class III peroxidases (CIII Prxs) are only found in streptophyte algae and land plants, and have been subjected to large family expansion. Biochemical activities of APx, CcP, and CIII Prx assessed using protein extracts from 30 different eukaryotic organisms support the distribution of the sequences resulting from our in silico analysis. The biochemical results confirmed both the presence and classification of the non-animal peroxidase encoding sequences.

Phenotypic Trait Variation as a Response to Altitude-Related Constraints in Arabidopsis Populations.

Natural variations help in identifying genetic mechanisms of morphologically and developmentally complex traits. Mountainous habitats provide an altitudinal gradient where one species encounters different abiotic conditions. We report the study of 341 individuals of Arabidopsis thaliana derived from 30 natural populations not belonging to the 1001 genomes, collected at increasing altitudes, between 200 and 1800 m in the Pyrenees. Class III peroxidases and ribosomal RNA sequences were used as markers to determine the putative genetic relationships among these populations along their altitudinal gradient. Using Bayesian-based statistics and phylogenetic analyses, these Pyrenean populations appear with significant divergence from the other regional accessions from 1001 genome (i.e., from north Spain or south France). Individuals of these populations exhibited varying phenotypic changes, when grown at sub-optimal temperature (22 vs. 15°C). These phenotypic variations under controlled conditions reflected intraspecific morphological variations. This study could bring new information regarding the west European population structure of A. thaliana and its phenotypic variations at different temperatures. The integrative analysis combining genetic, phenotypic variation and environmental datasets is used to analyze the acclimation of population in response to temperature changes. Regarding their geographical proximity and environmental diversity, these populations represent a tool of choice for studying plant response to temperature variation. HIGHLIGHTS: -Studying the natural diversity of A. thaliana in the Pyrenees mountains helps to understand European population structure and to evaluate the phenotypic trait variation in response to climate change.