Genetic and physiological basis of adaptive salt tolerance divergence between coastal and inland Mimulus guttatus
Article first published online: 22 JUN 2009
© The Authors (2009). Journal compilation © New Phytologist (2009)
Special Issue: Plant adaptation - following in Darwin's footsteps
Volume 183, Issue 3, pages 776–788, August 2009
How to Cite
Lowry, D. B., Hall, M. C., Salt, D. E. and Willis, J. H. (2009), Genetic and physiological basis of adaptive salt tolerance divergence between coastal and inland Mimulus guttatus. New Phytologist, 183: 776–788. doi: 10.1111/j.1469-8137.2009.02901.x
- Issue published online: 17 JUL 2009
- Article first published online: 22 JUN 2009
- Received: 18 January 2009Accepted: 24 April 2009
- local adaptation;
- osmotic stress;
- quantitative trait loci (QTLs);
- reciprocal transplant;
- transmission ratio distortion
- • Local adaptation is a well-established phenomenon whereby habitat-mediated natural selection drives the differentiation of populations. However, little is known about how specific traits and loci combine to cause local adaptation.
- • Here, we conducted a set of experiments to determine which physiological mechanisms contribute to locally adaptive divergence in salt tolerance between coastal perennial and inland annual ecotypes of Mimulus guttatus. Quantitative trait locus (QTL) mapping was used to discover loci involved in salt spray tolerance and leaf sodium (Na+) concentration. To determine whether these QTLs confer fitness in the field, we examined their effects in reciprocal transplant experiments using recombinant inbred lines (RILs).
- • Coastal plants had constitutively higher leaf Na+ concentrations and greater levels of tissue tolerance, but no difference in osmotic stress tolerance. Three QTLs contributed to salt spray tolerance and two QTLs to leaf Na+ concentration. All three salt-spray tolerance QTLs had a significant fitness effects at the coastal field site but no effects inland. Leaf Na+ QTLs had no detectable fitness effects in the field.
- • Physiological results are consistent with adaptation of coastal populations to salt spray and soil salinity. Field results suggest that there may not be trade-offs across habitats for alleles involved in local salt spray adaptations.