Submitted to: Seed Science Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2006
Publication Date: 8/1/2006
Citation: Walters, C., A.A. Reilley, P.A. Reeves, J. Baszczak, and C.M. Richards. 2006. The utility of aged seeds in DNA banks. Seed Science Research 16:169-178. Interpretive Summary: Seeds stored at ambient conditions typically survive for less than 10 years. However, genetic information can be retrieved from thousand year old seeds found in archeological sites. The reported utility of DNA from ancient seeds prompted us to analyze yield and quality of DNA extracted from seeds ranging in age from 1 (fresh) to ~135 years old (seeds found in an attic in Georgia, USA wrapped in newspaper dating to the Civil War Era). Even though DNA from the ~135 year old seed was of poor quality, we obtained relatively high molecular weight amplification products using standard extraction and polymerase chain reactions (PCR) protocols. DNA appears to be far more stable in seeds compared to leaf tissues, which points to the potential of using seeds as source material for DNA banks.
Technical Abstract: The long-term utility of DNA banks is predicated on the stability of DNA structure during storage. The quality and yield of DNA extracted from seeds from four garden species that varied in age from 1 to about 135 years old (seeds found in an attic in Georgia, USA wrapped in newspaper dating to the Civil War Era) was used to examine the early stages of DNA degradation. Seeds that were 70 years old provided high molecular weight template for amplification of DNA coding for a 650 bp segment of the internal transcribed spacer (ITS region) of the nuclear ribosomal RNA gene family and for a 487 bp segment of the plastid-encoded large subunit of rubisco (rbcL). DNA extracted from seeds estimated to be about 135 years old was degraded, but still provided amplification products when routine extraction procedures were used. The sequences for the amplified rbcL segments obtained from ~135 year old cucurbit seeds were consistent with species identifications based on morphological features; however the sequences for the amplified ITS region were homologous to Aspergillus. Our results on the age of seeds and the size of fragments of genomic DNA or amplified products is consistent with reports using seeds stored at herbaria or found at archeological sites, and suggests that DNA within seeds degrades more slowly than DNA within leaf specimens.