Desiccation-tolerant (DT) plant germplasm (i.e. seeds, pollen and spores) survive drying to low moisture contents, when cytoplasm solidifies, forming a glass, and chemical reactions are slowed. DT germplasm may survive for long periods in this state, though inter-specific and intra-specific variation occurs and is not currently explained. Such variability has consequences for agriculture, forestry and biodiversity conservation. Longevity was previously considered in the context of morphological features, cellular constituents or habitat characteristics. We suggest, however, that a biophysical perspective, which considers the molecular organization – or structure – within dried cytoplasm, can provide a more integrated understanding of the fundamental mechanisms that control ageing rates, hence the variation of longevity among species and cell types. Based on biochemical composition and physical–chemical properties of dried materials, we explore three types of the interplay between structural conformations of dried cytoplasm and ageing: (1) cells that lack chlorophyll and contain few storage lipids may exhibit long shelf life, with ageing probably occurring through slow autoxidative processes within the glassy matrix as it relaxes; (2) cells with active chlorophyll may die quickly, possibly because they are prone to oxidative stress promoted by the photosynthetic pigments in the absence of metabolic water and (3) cells that lack chloroplasts but contain high storage lipids may die quickly during storage at −20°C, possibly because lipids crystallize and destabilize the glassy matrix. Understanding the complex variation in structural conformation in space and time may help to design strategies that increase longevity in germplasm with generally poor shelf life.

中文翻译：

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干结构：对耐干燥种质寿命变化的理解

耐干燥 (DT) 植物种质（即种子、花粉和孢子）在干燥至低水分含量时仍能存活，此时细胞质凝固形成玻璃，化学反应减慢。DT 种质可以在这种状态下长期存活，尽管会发生种间和种内变异，目前尚未解释。这种可变性会对农业、林业和生物多样性保护产生影响。长寿以前是在形态特征、细胞成分或栖息地特征的背景下考虑的。然而，我们建议，考虑干燥细胞质内的分子组织或结构的生物物理学观点可以更全面地理解控制衰老速率的基本机制，从而控制物种和细胞类型之间的寿命差异。基于干物质的生化成分和理化性质，我们探讨了干细胞质结构构象与老化之间的三种相互作用：（1）缺乏叶绿素和含有少量储存脂质的细胞可能具有较长的保质期，可能会老化玻璃质基质松弛时通过缓慢的自氧化过程发生；(2) 具有活性叶绿素的细胞可能会很快死亡，这可能是因为它们在没有代谢水的情况下容易受到光合色素促进的氧化应激；(3) 缺乏叶绿体但含有高储存脂质的细胞可能会在储存期间迅速死亡 - 20°C，可能是因为脂质结晶并使玻璃状基质不稳定。