Seminars

Seed dormancy is an important adaptive trait that is a primary component of different life history strategies (winter and spring habits) of annual plants. Dormancy can be considered as a mechanism where growth and development is arrested, despite favourable environmental conditions. Specific environmental and developmental triggers can overcome this arrest.

Surprisingly, very little is known about the mechanism of this important process, except that the major role of the plant hormones ABA and GA is well established as is the role of the testa. To investigate the genetic regulation of this process we exploited the large differences in dormancy among natural variants of Arabidopsis by performing genetic (QTL = Quantitative Trait Loci) analysis in mapping populations derived from 7 accessions differing in dormancy. For a major QTL called DOG1, located on chromosome 5 the corresponding gene was isolated using this approach in combination with mutant analysis. Using common garden experiments it was found that germination in natural conditions is controlled by similar genes as dormancy assayed in laboratory experiments. The analysis of seed dormancy in a large population identified that variation for seed dormancy correlates with summer precipitation and that the DOG1 gene has undergone selection for local adaptation. By combining mutant, genomic QTL approaches the pathways controlling seed dormancy are elucidated, whereas the combination with evolutionary ecology allows the better understanding of the variation for seed dormancy in nature including knowledge about the genes underlying adaptation.