THE EXPRESSION OF DEHYDRIN PROTEINS IN DESICCATION-SENSITIVE (RECALCITRANT) SEEDS OF TEMPERATE TREES

Proteins that have homology with dehydrins have been identified immuno logically in the desiccation-sensitive (recalcitrant) seeds of English oak (Quercus robur L.), European chestnut (Castanea sativa L.), horse chestnut (Aesculus hippocastanum L.), sycamore (Acer psuedoplatanus L .) and silver maple (Acer saccharinum L.), and in the desiccation-tole rant seeds of Norway maple (Acer platanoides L.). The mRNA for a late embryogenesis abundant (LEA) protein (dehydrin) was also detected by N orthern blotting, using a cDNA clone (D 11) from cotton embryos, in th e recalcitrant and orthodox seeds. Medium-stringency washing was requi red to detect this hybridization. In Q. robur the amount of dehydrin p rotein increased during seed development, and LEA mRNA was induced by limited desiccation and by abscisic acid. Confirmation of the presence of dehydrin mRNA in mature Q. robur and C. sativa seeds was obtained by in-vitro translation of the extracted polyadenylated RNA followed b y analysis of the immunoprecipitation products. Thus the presence of d ehydrin proteins is not sufficient to confer desiccation tolerance on truly recalcitrant seeds, nor can their presence or absence be used as clear criteria for identification of recalcitrant seeds.