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

Abstract

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.

An Integrative Study Showing the Adaptation to Sub-Optimal Growth Conditions of Natural Populations of Arabidopsis thaliana: A Focus on Cell Wall Changes

“…We have selected four A. thaliana populations (Roch, Grip, Hern and Hosp) among the 30 new populations collected in the Pyrenees Mountains recently characterized [ 38 ]. They constitute four independent homogeneous populations originating from various altitudes ( Table 1 ) and they do not belong to the genetic cluster of Col (named III) which was taken as a reference ecotype.…”

“…The annual plant A. thaliana was studied: the Columbia ecotype (Col) originating from Poland where it was originally collecting at 200 m in altitude, as a reference; and four Pyrenean populations named after their geographical origin Roch (Chapelle Saint Roch), Grip (Grip), Hern (Herran) and Hosp (L’Hospitalet-près-l’Andorre), which are living between 700 and 1400 m in altitude in the Pyrenees Mountain [ 38 ]. We have used one genotype per homogeneous population, and 20 plants of this genotype for each of the three biological replicate for all the analyses.…”

“… 1 MASL: Meters Above Sea Level. 2 The genetics clusters refer to the previous characterization of the Pyrenean populations [ 38 ]. 3 Climate PC1 (index that describes and explains the climate gradients).…”

“…A. thaliana natural diversity is a major resource to study local adaptation to major temperature variation. In order to evaluate the genetic background contribution to CW plasticity at sub-optimal temperature growth conditions, the well-described Col ecotype of A. thaliana as well as four newly-described populations originated from contrasted natural environments in the French Pyrenees Mountains [ 38 ] were studied. Two vegetative organs were analyzed, the rosette and the floral stem.…”

“…Two different growth temperatures (22 and 15 °C) were used in laboratory conditions to simulate the temperature effect. The 22 °C temperature has been chosen as the optimal growth temperature for the Col ecotype, whereas the 15 °C temperature was used to simulate the higher altitude temperature conditions [ 38 ]. To tackle the complex mechanisms of adaptation to sub-optimal temperatures, a systems biology approach combining climate parameters, phenomics, metabolomics, proteomics and transcriptomics has been developed.…”