Volatile signature indicates viability of dormant orthodox seeds

Abstract

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 (À196 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.

Choosing the Right Path for the Successful Storage of Seeds

“…Finally, it is crucial to ensure proper storage conditions that do not exert any deleterious impacts on seedling development. Therefore, in addition to the assessment of germination, other seed and seedling properties should also be more commonly tested such as morphological properties [ 188 ], proteome and metabolome status [ 98 ], and genetic and epigenetic stability [ 96 , 120 , 145 , 189 , 190 ]. Consequently, there is a huge need for new biochemical or molecular markers of seed viability that improve the process of monitoring plant material during storage in gene banks and to help with the understanding of the concomitant aging process occurring in seeds.…”

“…Consequently, there is a huge need for new biochemical or molecular markers of seed viability that improve the process of monitoring plant material during storage in gene banks and to help with the understanding of the concomitant aging process occurring in seeds. These studies have developed rapidly over the last decade and substantiate the importance of volatile organic compounds [ 94 , 95 , 98 ], proteomic studies [ 191 ], RNA integrity [ 192 , 193 , 194 , 195 , 196 ] and DNA damage markers or epigenetic marks [ 96 , 97 , 99 , 190 , 197 , 198 , 199 , 200 ] that are highly promising and should be more widely explored.…”

“…Importantly, a meta-analysis of germination data indicated that predicted germinability was often higher than actual values that were experimentally obtained [ 87 ]. Therefore, further research which focuses on obtaining more accurate predictions of orthodox seed longevity based upon the testing of new markers of seed viability and quality in real-time appear warranted and necessary [ 91 , 94 , 95 , 96 , 97 , 98 , 99 ].…”

Seed Longevity—The Evolution of Knowledge and a Conceptual Framework

“…Volatile molecules accumulate throughout storage and are detectable prior to the onset of viability loss [ 170 ]. Several volatile compounds have been reported to correlate with seed viability across different species and under a range of storage conditions [ 29 , 31 , 186 , 187 , 188 ]; this has raised the possibility of using volatile analysis for non-invasive monitoring of seed viability.…”

“…This understanding led to research in developing biochemical markers that could robustly predict viability loss, which can augment traditional germination tests. For small seed lots, non-destructive methods, such as seed volatile quantification and seed thermal fingerprinting, have been proposed for seed viability prediction [ 28 , 29 , 30 , 31 ].…”