Molecular Approach to the Role of ABA and GA3 in the Dormancy of Fagus sylvatica Seeds

Abstract

The dormancy of Fagus sylvatica seeds is eliminated by cold treatment at 4 degrees C over a period longer than 8 weeks. Application of GA(3) is able to substitute for the cold treatment, while the application of ABA reverses the effect of low temperature and GA(3) maintaining the seeds in the dormant state. In vitro translation of the mRNAs isolated from these seeds shows the presence of some polypeptides in dormant and in ABA-treated seeds, which tend to disappear during cold or GA(3) treatments. By differential screening of a cDNA library constructed from RNA of ABA-treated seeds, some positively ABA-induced clones have been isolated. A search of the sequence data bases showed that one of these clones is a Glycine Rich Protein (GRP) with a possible consensus sequence type RNA-binding protein. The role of this gene product, which seems to be up-regulated by ABA and repressed by GA(3), in the dormancy of beechnuts, is discussed.