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.
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ABSTRACT: Organisms develop through multiple life stages that differ in environmental tolerances. The seasonal timing, or phenology, of life-stage transitions determines the environmental conditions to which each life stage is exposed and the length of time required to complete a generation. Both environmental and genetic factors con-tribute to phenological variation, yet predicting their combined effect on life cycles across a geographic range remains a challenge. We linked submodels of the plasticity of individual life stages to create an in-tegrated model that predicts life-cycle phenology in complex envi-ronments. We parameterized the model for Arabidopsis thaliana and simulated life cycles in four locations. We compared multiple "ge-notypes" by varying two parameters associated with natural genetic variation in phenology: seed dormancy and floral repression. The model predicted variation in life cycles across locations that quali-tatively matches observed natural phenology. Seed dormancy had larger effects on life-cycle length than floral repression, and results suggest that a genetic cline in dormancy maintains a life-cycle length of 1 year across the geographic range of this species. By integrating across life stages, this approach demonstrates how genetic variation in one transition can influence subsequent transitions and the geo-graphic distribution of life cycles more generally. Plant life cycles are composed of multiple life stages (e.g., seed, vegetative, reproductive) that differ in environmental sensitivities and tolerances. In seasonal environments, the timing, or phenology, of life-stage transitions (e.g., germi-nation, flowering, seed dispersal) may have importantThe American Naturalist 02/2015; 93513(4). · 4.45 Impact Factor
- Seed Science Research 01/2014; · 1.85 Impact Factor
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ABSTRACT: * Environmental changes during seed production are important drivers of lot-to-lot variation in seed behaviour and enable wild species to time their life history with seasonal cues. Temperature during seed set is the dominant environmental signal determining the depth of primary dormancy, although the mechanisms though which temperature changes impart changes in dormancy state are still only partly understood. * We used molecular, genetic and biochemical techniques to examine the mechanism through which temperature variation affects Arabidopsis thaliana seed dormancy. * Here we show that, in Arabidopsis, low temperatures during seed maturation result in an increase in phenylpropanoid gene expression in seeds and that this correlates with higher concentrations of seed coat procyanidins. Lower maturation temperatures cause differences in coat permeability to tetrazolium, and mutants with increased seed coat permeability and/or low procyanidin concentrations are less able to enter strongly dormant states after exposure to low temperatures during seed maturation. * Our data show that maternal temperature signalling regulates seed coat properties, and this is an important pathway through which the environmental signals control primary dormancy depth.New Phytologist 11/2014; · 6.74 Impact Factor