Abstract
To characterize and dissect genetic variation for salinity tolerance, we assessed variation in salinity tolerance during germination and seedling growth for a worldwide sample of Arabidopsis thaliana accessions. By combining QTL mapping, association mapping and expression data, we identified genomic regions involved in salinity response. Among the worldwide sample, we found germination ability within a moderately saline environment (150 mM NaCl) varied considerable, from >90% among the most tolerant lines to complete inability to germinate among the most susceptible. Our results also demonstrated wide variation in salinity tolerance within A. thaliana RIL populations and identified multiple genomic regions that contribute to this variation. These regions contain known candidate genes, but at least four of the regions contain loci not yet associated with salinity tolerance response phenotypes. Our observations suggest A. thaliana natural variation may be an underutilized resource for investigating salinity stress response.
Highlights
Abiotic factors like temperature, drought and salinity are often temporally and spatially heterogeneous
The plant response to osmotic stress is physiologically similar to the response to drought stress; both responses lead to the accumulation of osmolytes and other compounds [17,18,19,20,6,8], often via regulation by abscisic acid (ABA) signaling [21,22]
We show that A. thaliana has wide variation in phenotypes relating to salt tolerance, that this variation has a geographic component, and that the genetic architecture underlying phenotypic variation consists of several major QTL and manifold genes of smaller effect
Summary
Drought and salinity are often temporally and spatially heterogeneous. Plants have evolved complex physiological mechanisms to respond to abiotic stresses [1,2,3], many of which are shared among different stress factors [4,5,6,7,8]. Soil salinity is a pernicious abiotic stress, both because it is an agricultural problem (.20% of arable land worldwide is currently affected by irrigation-induced salinification; [13,14]), and because it fundamentally disrupts plant physiology [15]. If the initial response to either ionic or osmotic stress is insufficient, plants have several mechanisms to limit salt damage, including developmental modifications and the production of hormones and anti-oxidative enzymes [23,24,25,26,15]
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