A Coastal Cline in Sodium Accumulation in Arabidopsis thaliana Is Driven by Natural Variation of the Sodium Transporter AtHKT1;1

Abstract

The genetic model plant Arabidopsis thaliana, like many plant species, experiences a range of edaphic conditions across its natural habitat. Such heterogeneity may drive local adaptation, though the molecular genetic basis remains elusive. Here, we describe a study in which we used genome-wide association mapping, genetic complementation, and gene expression studies to identify cis-regulatory expression level polymorphisms at the AtHKT1;1 locus, encoding a known sodium (Na+) transporter, as being a major factor controlling natural variation in leaf Na+ accumulation capacity across the global A. thaliana population. A weak allele of AtHKT1;1 that drives elevated leaf Na+ in this population has been previously linked to elevated salinity tolerance. Inspection of the geographical distribution of this allele revealed its significant enrichment in populations associated with the coast and saline soils in Europe. The fixation of this weak AtHKT1;1 allele in these populations is genetic evidence supporting local adaptation to these potentially saline impacted environments.

Integration of Experiments across Diverse Environments Identifies the Genetic Determinants of Variation in Sorghum bicolor Seed Element Composition

“…Four seeds per replicate were weighed from each individual, and a minimum of two replicates from each line of the SAP 2008 and SAP 2013 panels were analyzed by ICP-MS. Each sample was digested with 2.5 mL of concentrated nitric acid at 95°C for 3 h. Elemental analysis was performed with ICP-MS for B, Na, Mg, Al, P, S, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, and Cd following established protocols (Baxter et al, 2010). A reference sample derived from a pool of sorghum seed samples was generated and run after every ninth sample to correct for ICP-MS run-to-run variation and within-run drift.…”

Sodium as nutrient and toxicant

“…More recently, screening of 12 A. thaliana accessions yielded two coastal populations with reduced AtHKT1 expression that apparently resulted in increased shoot Na + and, surprisingly, greater salt tolerance (Rus et al 2006). In a followup study (Baxter et al 2010), many more such salttolerant accessions displaying this "weak allele" at the AtHKT1;1 locus were discovered, often in populations growing in close proximity to coastal areas. Another recent survey, comparing four ecotypes of A. thaliana, indicated no inverse relationship between shoot Na + concentration and Na + tolerance (Jha et al 2010).…”

Genome-Wide Association Mapping of Fertility Reduction upon Heat Stress Reveals Developmental Stage-Specific QTLs in Arabidopsis thaliana

“…A collection consisting of 285 natural accessions of Arabidopsis thaliana (Supplemental Data Set 1) selected to capture most of the genetic variation present within the species (Platt et al, 2010) and genotyped with ;215k SNP markers (Affymetrix SNP-tilling array Atsnptile1; Atwell et al, 2010;Li et al, 2010) was obtained from the ABRC Stock Center (Baxter et al, 2010).…”