Volatile signature indicates viability of dormant orthodox seeds

All seeds eventually die even under optimal storage conditions. The moment of viability loss is difficult to predict and detect. In order to differentiate between dead and viable dormant orthodox seeds, GC-MS analysis was used to non-invasively evaluate the volatile signature of seeds of Pyrus communis L. and Sorbus aucuparia L. Dormant seeds are capable of extended metabolic depression. However, their low metabolic rate remains largely unquantified, and there are no measurements of metabolites, i.e. volatile organic compounds (VOC) for physiologically dormant seeds during storage. Therefore, to address this issue, seeds were stored at a broad range of moisture content (MC) ranging from 2 to 30% under cryogenic (-196°C), cool (5°C) and elevated (40°C) temperatures. Volatile emission was highly dependent on seed MC and storage temperature and was higher under conditions associated with seed viability loss. However, changes in the emission of volatiles entrapped in seeds and released during 24 h after storage were detected for all conditions, providing insight into the processes occurring in dry dormant seeds. Among the 36 volatiles identified, three (acetaldehyde, ethanol, ethyl acetate) were highly correlated with seed germinability and show potential for the non-invasive screening of viability. Significantly, all three VOC are derived mostly from glycolysis and peroxidation and were detected even under very low moisture and temperature storage conditions. This is the first study to report on VOC accumulation and emission from physiologically dormant seeds and provide a broader view into their viability.