Seed structural and physiological properties, together with environmental conditions, control dormancy. Cold stratification is known to alleviate seed physiological dormancy promoting seed germination. The present research aimed to investigate changes in the proteome during seed cold stratification and germination of silver fir (Abies alba Mill.), a conifer gymnosperm tree native to the mountains of Europe. Analysis of the identified proteins’ functions and associated metabolic pathways would enhance the knowledge of these processes. The proteomes were analysed separately for embryo and megagametophyte using 2D electrophoresis. Forty-nine proteins displaying significant differential abundance during seed dormancy breaking and germiantion were characterised using mass spectrometry. Thirty four proteins were characteristic of the embryo germination and 41 of the megagametophyte. Twenty-six proteins differed between embryos and megagametophytes. Thirteen spots were identified as vicilin-like storage proteins, which were generally abundant in the megagametophyte, slowed down accumulation during cold stratification, and reached minimal abundance during germination. Vicilin-like proteins are the main storage reserves of most angiosperms and gymnosperms. Biological process analysis showed that proteins of both seed tissues were generally associated with protein folding, defence response and seed maturation. Molecular function analysis suggested an involvment of the identified proteins in ATP binding, nutrient reservoir activity and metal ion binding. Proteins were generally predicted to localise in the nucleus, cytosol and plastids. Dormancy breaking and germination of silver fir seed required proteins involved in diverse processes: facilitating plasmodesmata aperture (Gnk2-homologous domain-containing protein), nitrogen remobilisation from protein degradation (glutamine synthetase), abscisic acid signalling (cytochrome P450 protein CYP720PB12 ), transcription (R2R3-Myb14 transcription factor, HDAC) and protein modification (PNGase A).
Pawłowski et al. (Tue,) studied this question.