Genetic and physiological basis of adaptive salt tolerance divergence between coastal and inland Mimulus guttatus.
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.
Lowry
David B
DB
University Program in Genetics and Genomics, Box 3565 Duke University Medical Center, Durham, NC 27710, USA.|Department of Biology, Box 90338, Duke University, Durham NC 27708, USA.
Hall
Megan C
MC
Center for Genomics and Systems Biology, Department of Biology, 100 Washington Square East, New York University, New York, NY 10003, USA.
Salt
David E
DE
Horticultural and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907, USA.|Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907, USA.
Willis
John H
JH
University Program in Genetics and Genomics, Box 3565 Duke University Medical Center, Durham, NC 27710, USA.|Department of Biology, Box 90338, Duke University, Durham NC 27708, USA.
D002874:Chromosome Mapping; D008040:Genetic Linkage; D014644:Genetic Variation; D005838:Genotype; D007178:Inbreeding; D040582:Inheritance Patterns / Q000235:genetics; D032241:Mimulus / Q000235:genetics* / Q000502:physiology*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D040641:Quantitative Trait Loci / Q000235:genetics; D055049:Salt Tolerance / Q000235:genetics*; D012623:Seawater; D012639:Seeds / Q000254:growth & development; D012964:Sodium / Q000378:metabolism; D012987:Soil
D012987:Soil; D012964:Sodium