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

Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
Molecular Ecology (Impact Factor: 6.49). 08/2011; 20(16):3336-49. DOI: 10.1111/j.1365-294X.2011.05181.x
Source: PubMed


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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    • "Based on modeling work and empirical observations, we expect Ler and Col to both be capable of cycling through both winter-annual and summer-annual life cycles in central Europe (Wilczek et al., 2010; Burghardt et al., 2015; Springthorpe & Penfield, 2015). In addition, one of those models (Burghardt et al., 2015) and additional empirical work (Chiang et al., 2011) led to the expectation that the higher dormancy level conferred by the DOG1 allele from Cvi would result in delayed germination, and, depending on the degree of delay, a winter-or spring-annual life cycle. By contrast, we would expect the lower dormancy of the FLC allele from Cvi to result in even faster germination subsequent to dispersal. "
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    ABSTRACT: Germination timing influences plant fitness, and its sensitivity to temperature may cause it to change as climate shifts. These changes are likely to be complex because temperatures that occur during seed maturation and temperatures that occur post-dispersal interact to define germination timing. We used the model organism Arabidopsis thaliana to determine how flowering time (which defines seed-maturation temperature) and post-dispersal temperature influence germination and the expression of genetic variation for germination. Germination responses to temperature (germination envelopes) changed as seeds aged, or after-ripened, and these germination trajectories depended on seed-maturation temperature and genotype. Different combinations of genotype, seed-maturation temperature, and after-ripening produced similar germination envelopes. Likewise, different genotypes and seed-maturation temperatures combined to produce similar germination trajectories. Differences between genotypes were most likely to be observed at high and low germination temperatures. The germination behavior of some genotypes responds weakly to maternal temperature but others are highly plastic. We hypothesize that weak dormancy induction could synchronize germination of seeds dispersed at different times. By contrast, we hypothesize that strongly responsive genotypes may spread offspring germination over several possible germination windows. Considering germination responses to temperature is important for predicting phenology expression and evolution in future climates.
    New Phytologist 10/2015; DOI:10.1111/nph.13685 · 7.67 Impact Factor
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    • "Annona macroprophyllata is a species that grows in tropical deciduous forests in which the rainy and dry seasons are distinct; therefore, one adaptation for their survival is the timing of germination with the rainy season, which is possible with a dormancy period. Chiang et al. (2011) and Nakayabashi et al. (2012) noted that the degree of maturity of seeds can be induced by climatic factors, and in spontaneous conditions, plants must respond to changing conditions in time and space. If this is true, erratic germination and, consequently, the dormancy of A. macroprophyllata, constitutes a programmed strategy to adapt to small and large changes in the environment (a fact noted by Snyder, 2006; Donohue et al., 2010; Wang et al., 2012), allowing the survival of the species by controlling the propagation mechanisms in response to the close relationship that the species establish with the environment, using intricate ecological processes. "
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    ABSTRACT: Annona macroprophyllata (papausa or ilama) is an economically important species of fruit that is consumed in large quantities in Central America and is considered to have the finest flavour of all of the custard apples (Annonaceae). This species presents propagation problems including the six-month dormancy of the seeds, which has not been fully explained. Among the factors affecting the germination of Annona seeds are the position inside of the fruit and the presence of a micropylar woody plug. The present work addresses the importance of these factors in the germination and dormancy of this species, using a randomised design with seeds from 169 fruits of the white variety of Annona macroprophyllata. The fruits were divided into three sections (basal, middle, and apical) in which seeds were evaluated for nine months with the following parameters: the size and weight of the seeds and the viability and germination percentage considering the presence or absence of the micropylar plug. The results show no correlation between the breaking of dormancy and either the position of the seeds in the fruit or the micropylar plug, but they do establish the importance of the micropylar plug for germination. The breaking of dormancy requires storage for the length of the dry season in the tropical deciduous forest, the habitat of these plants.
    Botanical Sciences 09/2015; 93(3):509-515. DOI:10.17129/botsci.166 · 0.53 Impact Factor
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    • "Variation in DOG1 expression was found between Arabidopsis accessions. In southern accessions, which are more dormant, DOG1 is expressed earlier during seed maturation and achieves higher expression levels at the end of silique development than in northern accessions with lower dormancy levels (Chiang et al., 2011). In addition, a study with buried Arabidopsis seeds showed dynamic changes in dormancy levels which had a strong correlation with DOG1 expression levels (Footitt et al., 2011). "
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    ABSTRACT: Dormancy has evolved in plants to restrict germination to favourable growth seasons. Seeds from most crop plants have low dormancy levels due to selection for immediate germination during domestication. Seed dormancy is usually not completely lost and low levels are required to maintain sufficient seed quality. Brassica napus cultivars show low levels of primary seed dormancy. However, B. napus seeds are prone to the induction of secondary dormancy, which can lead to the occurrence of volunteers in the field in subsequent years after cultivation. The DELAY OF GERMINATION 1 (DOG1) gene has been identified as a major dormancy gene in the model plant Arabidopsis thaliana. DOG1 is a conserved gene and has been shown to be required for seed dormancy in various monocot and dicot plant species. We have identified three B. napus genes with high homology to AtDOG1, which we named BnaA.DOG1.a, BnaC.DOG1.a and BnaC.DOG1.b. The transcripts of these genes could only be detected in seeds and showed a similar expression pattern during seed maturation as AtDOG1. In addition, the BnaDOG1 genes showed enhanced transcript levels after the induction of secondary dormancy. These results suggest a role for DOG1 in the induction of secondary dormancy in B. napus.
    Seed Science Research 06/2015; 25(02):1-9. DOI:10.1017/S0960258514000427 · 1.70 Impact Factor
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