DOG1 expression is predicted by the seed‐maturation environment and contributes to geographical variation in germination in Arabidopsis thaliana

Abstract

Seasonal germination timing of Arabidopsis thaliana strongly influences overall life history expression and is the target of intense natural selection. This seasonal germination timing depends strongly on the interaction between genetics and seasonal environments both before and after seed dispersal. DELAY OF GERMINATION 1 (DOG1) is the first gene that has been identified to be associated with natural variation in primary dormancy in A. thaliana. Here, we report interaccession variation in DOG1 expression and document that DOG1 expression is associated with seed-maturation temperature effects on germination; DOG1 expression increased when seeds were matured at low temperature, and this increased expression was associated with increased dormancy of those seeds. Variation in DOG1 expression suggests a geographical structure such that southern accessions, which are more dormant, tend to initiate DOG1 expression earlier during seed maturation and achieved higher expression levels at the end of silique development than did northern accessions. Although elimination of the synthesis of phytohormone abscisic acid (ABA) results in the elimination of maternal temperature effects on dormancy, DOG1 expression predicted dormancy better than expression of genes involved in ABA metabolism.

The Time Required for Dormancy Release in Arabidopsis Is Determined by DELAY OF GERMINATION1 Protein Levels in Freshly Harvested Seeds

“…An increase in seed dormancy levels by lower seed maturation temperatures could be important when Arabidopsis seeds mature in early spring or late autumn in temperate regions. Overall, our work confirms recent observations that DOG1 has an important role in the translation of seed maturation temperature to dormancy levels (Chiang et al, 2011;Footitt et al, 2011;Kendall et al, 2011). It will be of interest to find out whether DOG1 also plays a role in the influence on seed dormancy of other environmental conditions that occur during seed maturation, like light intensity, drought, daylength, and nitrate levels.…”

“…In addition, it was shown that differences in DOG1 expression between Arabidopsis accessions contribute to geographical variation in dormancy and germination (Chiang et al, 2011). We confirmed the observation of Bentsink et al (2006) that the strongly dormant NIL DOG1 genotype shows higher DOG1 transcript levels than the low dormant Ler accession ( Figure 2A).…”

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

“…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). Arabidopsis, therefore, is a very good model also for addressing intraspecific questions in ecological, evolutionary, and developmental biology.…”

“…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).…”