Genetic Basis of Adaptation in Arabidopsis Thaliana: Local Adaptation at the Seed Dormancy QTL Dog1

Abstract

Local adaptation provides an opportunity to study the genetic basis of adaptation and investigate the allelic architecture of adaptive genes. We study DELAY OF GERMINATION 1 (DOG1), a gene controlling natural variation in seed dormancy in Arabidopsis thaliana and investigate evolution of dormancy in 41 populations distributed in four regions separated by natural barriers. Using The genetic basis of local adaptation is one of the fundamental questions in evolutionary biology. Local adaptation occurs if selection is strong enough relative to gene flow and favors different phenotypes in different populations (Kawecki and Ebert 2004).

Spatiotemporal Seed Development Analysis Provides Insight into Primary Dormancy Induction and Evolution of theLepidium DELAY OF GERMINATION1Genes

“…Interestingly, dormancy variation in Arabidopsis populations is associated with a series of functionally distinct alleles showing InDel variations in intron 1 that segregate at the AtDOG1 locus, which probably reflects local environmental adaptation (Kronholm et al, 2012). Although this does not generate any causal relationship, it demonstrates that for the interspecies comparison, a combination between exon sequence conservation (suggesting common function) and intron divergence (suggesting local environmental adaptation and/or speciation) is evident as well.…”

“…The phenomenon that the maternal environment during seed development and maturation determines the germination phenology of Arabidopsis and other species is well-established knowledge (Kugler, 1951;Gutterman, 1980Gutterman, /1981Munir et al, 2001). However, as a major advance, we now know from ecological work with Arabidopsis (Huang et al, 2010;Moyers and Kane, 2010;Chiang et al, 2011;Barua et al, 2012;Kronholm et al, 2012) that natural genetic variation at the DOG1 locus is a major determinant for the local adaptation to novel environments, and we also know that the maternal environment controls DOG1 gene expression during seed maturation. For example, low temperature during seed maturation causes increased DOG1 gene expression and deeper primary dormancy of mature seeds (Chiang et al, 2011;Kendall et al, 2011;Nakabayashi et al, 2012).…”

“…Several recent publications clearly demonstrate that in Arabidopsis, QTLs with large effects on fitness colocalize with QTLs for field germination timing and seed dormancy (Huang et al, 2010;Moyers and Kane, 2010;Chiang et al, 2011;Barua et al, 2012;Kronholm et al, 2012). Germination phenology is under intense, geographically variable, natural selection in Arabidopsis, since it is the major determinant of fitness during the earliest stages of colonization (Huang et al, 2010;Moyers and Kane, 2010;Chiang et al, 2011;Barua et al, 2012;Kronholm et al, 2012). It is also evident that QTLs including DOG1 determine the phenotypic plasticity of seed germination/dormancy responses already on the mother plant in interaction with environmental factors such as seed maturation photoperiod and temperature.…”

“…For seed dormancy, analysis of Arabidopsis natural genetic variation has led to the cloning of AtDOG1 as the first specific seed dormancy gene (Bentsink et al, 2006) and has been shown to be important for local adaptation to different environments (Huang et al, 2010;Chiang et al, 2011;Footitt et al, 2011;Kendall et al, 2011;Kronholm et al, 2012). Homologs of the AtDOG1 gene are also known for the Brassicaceae species B. rapa (BrDOG1) and Lepidium sativum (Lesa-DOG1; Graeber et al, 2010).…”

DELAY OF GERMINATION 1 mediates a conserved coat-dormancy mechanism for the temperature- and gibberellin-dependent control of seed germination

“…Ecophysiological work has shown that seed dormancy is a crucial fitness component with far-reaching consequences for the evolution of entire life histories (1)(2)(3). As an innate seed property, seed dormancy defines the environmental conditions in which a seed is able to germinate and ensures that the most vulnerable later phases of the plant life cycle occur during favorable seasonal and environmental conditions.…”