Location: Plant Germplasm Preservation ResearchTitle: The kinetics of aging in dry-stored seeds: a comparison of viability loss and RNA degradation in unique ‘legacy’ seed collections Author
Submitted to: Annals Of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2018
Publication Date: 12/19/2018
Citation: Fleming, M.B., Hill, L.M., Walters, C.T. 2018. The kinetics of aging in dry-stored seeds: a comparison of viability loss and RNA degradation in unique ‘legacy’ seed collections. Annals Of Botany. https://doi.org/10.1093/aob/mcy217.
DOI: https://doi.org/10.1093/aob/mcy217 Interpretive Summary: We are looking for a rapid, reliable test to measure the progress of seed aging without having to actually germinate lots of seeds. Previously, we found that we could correlate RNA integrity of soybean with loss of seed viability during aging and that measuring RNA integrity was simple and robust. In this paper, we expanded the study to 10 additional species. The experiments are particularly interesting because they used "legacy" experiments that had been placed in storage by a past generation of scientists. Moreover, many of the seeds were still viable! We learned that changes in RNA integrity could be detected even though changes in seed viability weren't yet detectable, indicating that this new assay is also quite sensitive.
Technical Abstract: • Background and Aims. Seed longevity, or the storage period during which seeds remain germinable, is an important but difficult trait to assess. The standard assessment, germination proportion, reveals seed longevity by showing that germination proportion declines, but cannot be used to predict when germination will be significantly compromised. An assessment of molecular integrity, such as RNA integrity, may be more informative about changes in seed health that precede viability loss, and has been shown to be useful in soybean. • Methods. We used a collection of seeds stored at 5 °C and 35-50% relative humidity for 1-30 years to test how germination proportion and RNA integrity are affected by storage time. We also used a collection of seeds stored at temperatures from +32 to -12 °C for 59 years to manipulate aging rate. RNA integrity was calculated using total RNA extracted from one to five seeds per sample, and analyzed on an Agilent Bioanalyzer. • Results.Decreased RIN was usually observed before viability loss. Correlation of RNA integrity and storage time or storage temperature was negative and significant for most species tested. Exceptions were watermelon, for which germination proportion and storage time were poorly correlated, and tomato, which showed anomalous electropherograms that affected RIN calculation. Temperature dependencies of aging reactions were not significantly different across species or mode of detection. The overall correlation between germination proportion and RNA integrity, across all experiments, was positive and significant.