Unravelling the ageing mechanims of dry seeds: molecular mobility within biological glasses.

Faster-than-expected ageing is observed in some seeds (e.g. orchids, coffee, citrus, willows) stored dry at -20°C, the standard temperatures of seed banks. This ageing has been related to two issues: unstable amorphous solids that retain high molecular mobility, and crystallization/melting events occurring in the seed storage lipids that are entrapped in the solid cytoplasm. However, the molecular mechanisms underlying seed ageing are not well explored due to the difficulty of measuring solid life at freezing temperatures. Biophysical tools are efficient to study these events and provide clues to improve current seed banking options. We plan to use neutron scattering techniques, a novel and innovative way to explore the ageing mechanisms of seeds, to research the crystallization and molecular mobility that could be leading to the fast ageing observed in seeds stored in seed banks.在-20℃（种子库的标准储存温度）下干燥储存的部分种子（如兰科植物、咖啡、柑橘、柳树）中，观测到了快于预期的老化现象。此类老化现象与两类问题相关：一是保留高分子迁移率（molecular mobility）的不稳定非晶态固体（amorphous solids），二是包裹于固态细胞质中的种子储存脂质所发生的结晶/熔融事件。然而，由于在冷冻温度下测量固态寿命存在技术难点，种子老化背后的分子机制尚未得到充分探究。生物物理工具可高效研究此类过程，为优化现有种子库储存方案提供关键线索。本研究拟采用中子散射技术（neutron scattering techniques）——一种探索种子老化机制的新颖创新方法——来研究可能导致种子库储存种子快速老化的结晶过程与分子迁移率。