Evolution of Salt Tolerance in Arabidopsis Thaliana on Siliceous Soils Does Not Convey Tolerance to Saline Calcareous Soils

Abstract

Purpose Alkaline salinity constrains crop yield. Previously, we found local adaptation of Arabidopsis thaliana demes to saline-siliceous soils (pH≤7) and to non-saline carbonate soils. However, any natural population of A. thaliana was localized on saline-alkaline soils. This suggests that salinity tolerance evolved on saline-siliceous soils may not confer tolerance to alkaline salinity. This hypothesis was explored by addressing physiological and molecular responses to saline-alkaline conditions of A. thaliana demes differing in salinity and carbonate tolerance.Methods A. thaliana native to saline-siliceous soils (G3), to non-saline carbonate soils (G1), or to soils with intermediate levels of these factors (G2) were cultivated in common gardens on saline-siliceous or saline-calcareous substrate. Hydroponics and irrigation experiments confirmed the phenotypes. Growth, mineral concentrations, genome differences, and expression of candidate genes were assessed in the different groups.Results G3 performed best on saline-siliceous soil and in hydroponics with salinity (pH 5.9). However, G3 was more sensitive to saline-alkaline conditions than G1 and G2. Fitness under saline-alkaline conditions was G2 > G1>G3 and G2 best maintained ion homeostasis under alkaline salinity. Whole genome scan did not differentiate among the groups, while distinctive patterns for FRO2, NINJA, and CCB4 were found and confirmed by qPCR.Conclusion In A. thaliana, salinity tolerance evolved on saline-siliceous soils does not provide tolerance to alkaline salinity. Plants from soils with intermediate conditions (G2) have more plasticity to adapt to alkaline salinity than those locally adapted to these individual stress factors. Higher expression of NINJA and CCB4 may contribute to this better adaptation.

A genome‐wide association study identifies novel players in Na and Fe homeostasis in Arabidopsis thaliana under alkaline‐salinity stress

“…The SCS used for treatment was a mix of soil originating from a parcel of natural saline‐carbonated soil in L'Escala, NE Catalunya, Spain (42°13′03″N 3°11′30″E) and perlite (3:1). The SCS had previously been characterized as suitable for saline‐carbonate stress analysis (Table S1) (Pérez‐Martín, 2020 ). Aratrays were placed in a growth chamber with 150 μmol m −2 sec −1 of PAR, 10 h light/14 h dark photoperiod, and 25°C/20°C day/night temperature.…”

“…The diversity of stress responses present within one species can be harnessed by screening natural diversity panels and performing subsequent Genome‐Wide Association Studies (GWAS) to identify genetic components of various stress responses, as has been done in the past for e.g., salinity (Baxter et al., 2010 ; Katori et al., 2010 ; Rus et al., 2006 ), carbonates (Pérez‐Martín, 2020 ; Terés, 2017 ) or combinations of stress factors (Davila Olivas et al., 2017 ; Kawa et al., 2016 ). GWA studies enumerate underlying SNPs (single nucleotide polymorphisms) responsible for certain phenotypic traits by exploiting the natural variation in a population or collection of populations of the studied species (Ogura & Busch, 2015 ; Weigel, 2012 ).…”