Secondary dormancy inBrassica napusis correlated with enhancedBnaDOG1transcript levels

Abstract

AbstractDormancy 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 napuscultivars show low levels of primary seed dormancy. However,B. napusseeds are prone to the induction of secondary dormancy, which can lead to the occurrence of volunteers in the field in subsequent years after cultivation. TheDELAY OF GERMINATION 1(DOG1) gene has been identified as a major dormancy gene in the model plantArabidopsis thaliana.DOG1is a conserved gene and has been shown to be required for seed dormancy in various monocot and dicot plant species. We have identified threeB. napusgenes with high homology toAtDOG1, which we namedBnaA.DOG1.a,BnaC.DOG1.aandBnaC.DOG1.b. The transcripts of these genes could only be detected in seeds and showed a similar expression pattern during seed maturation asAtDOG1. In addition, theBnaDOG1genes showed enhanced transcript levels after the induction of secondary dormancy. These results suggest a role forDOG1in the induction of secondary dormancy inB. napus.