Cold-induced Changes in Gene Expression during Dormancy Breakage in Seeds of Douglas fir ( Pseudotsuga menziesii)

Abstract

The effects of cold, moist treatment (stratification) on dormancy break and associated changes in gene expression were determined for seeds of Douglas fir ( Pseudotsuga menziesii ). At a germination temperature of 20°C between 93–95% of the seed population failed to germinate after 42 days. A high percentage of germination (up to 73%) at 20°C only occurred if seeds were first pre-treated at 4°C. RNA was extracted from moist seeds maintained at either 4°C, 15°C or 20°C, and the RNA translated in vitro . The labelled translation products were analysed by two-dimensional gel electrophoresis followed by fluorography. In cold-treated seeds, transcripts encoding abundant translation products appeared after 7 days and reached a maximum level after 14 days. Although these translation products could also be observed on translation of RNA from seeds maintained at 15°C and 20°C (but not immediately following imbibition), the transcript levels in these seeds were increased substantially.