S02 - Session P6 - Comparative lipid thermal fingerprinting of long-term stored oily Brassicaceae crop wild relative species seeds

Authors: Jayanthi Nadarajan *, Sara Mira, Udayangani Liu, Elena González-Benito, Hugh Pritchard

We hypothesize that seeds tolerate long-term cold, dry storage best when the seed lipids have thermal stability, i.e. when the lipids are at low risk of phase change. Thermal fingerprints for seeds of 20 wild-relative species of Brassicaceae stored for 8 to 44 years at the Plant Germplasm BankmUniversidad Politecnica de Madrid and the Royal Botanic Gardens, Kew's Millennium Seed Bankmwere generated using differential scanning calorimetry (DSC) and analyzed in relation to storage stability. Oily seeds that stored relatively poorly at -20 ░C tended to have lipids with crystallization and melting transitions spread over a wide temperature range (c. 40 ░C) that spanned the storage temperature, plus a melting end temperature of around 15 ░C. We postulated that in dry storage, the variable longevity in Brassicaceae seeds could be associated with the presence of a metastable lipid phase at the temperature at which they are being stored. Consistent with that, when highly viable seed samples of various species were assessed after banking at -5 to -10 ░C for c. 40 years, melting end temperatures were observed to be much lower (c. 0 to -30 ░C) and multiple lipid phases did not occur at the storage temperature. We conclude that multiple features of the seed lipid thermal fingerprint could be used as biophysical markers to predict potential poor performance of oily seeds during long-term, decadal storage.