Implications of the lack of desiccation tolerance in recalcitrant seeds.
Implications of the lack of desiccation tolerance in recalcitrant seeds.
复制标题
顽固种子缺乏干燥耐受性的含义。
DOI：
10.3389/fpls.2013.00478
复制
发表时间：
2013-11-22
影响因子：
5.6
通讯作者：
Pammenter NW
中科院分区：
文献类型：
--
作者：
Berjak P;Pammenter NW
一套相互作用的过程和机制，使耐受干燥和储存（保存）的正统种子在干燥状态。虽然这是优化条件下的长期选择，但干燥的正统种子不是不朽的，其寿命被描述为短，中和长。促进脱水耐受性的因素是代谢"关闭"和细胞内去分化。顽拗性种子缺乏这些机制，导致其脱水敏感性显着。因此，在高含水量下脱落的顽固种子只能在不允许脱水的条件下短期储存。这种水合储存的时间受到不需要外部水的发芽和种子相关真菌增殖的限制。超低温保存被认为是长期保存柑橘种子物种种质的唯一选择。这是不容易实现的，因为每一个必要的程序都会造成氧化损伤。完整的柠檬种子不能冷冻保存，通常的做法是使用切除的胚或胚轴作为外植体。脱水是暴露于低温之前的必要程序，但这与不受控制的活性氧生成和失效的抗氧化系统介导的代谢相关损伤有关。虽然可以通过最大化干燥速率（快速干燥）来减少这种情况发生的程度，但不能完全避免这种情况。冷冻保存前的外植体冷却和冷冻保存后的复温必须迅速，以避免冰结晶。干燥敏感性的后果进行了讨论，是在低温储存，特别是那些伴随着脱水和损害冰结晶后所涉及的问题。虽然干燥敏感性是种子顽固性的“事实”，但如上所述，解决涉及种质保存的困难是可能的。
A suite of interacting processes and mechanisms enables tolerance of desiccation and storage (conservation) of orthodox seeds in the dry state. While this is a long-term option under optimized conditions, dry orthodox seeds are not immortal, with life spans having been characterized as short, intermediate and long. Factors facilitating desiccation tolerance are metabolic “switch-off” and intracellular dedifferentiation. Recalcitrant seeds lack these mechanisms, contributing significantly to their desiccation sensitivity. Consequently, recalcitrant seeds, which are shed at high water contents, can be stored only in the short-term, under conditions not allowing dehydration. The periods of such hydrated storage are constrained by germination that occurs without the need for extraneous water, and the proliferation of seed-associated fungi. Cryopreservation is viewed as the only option for long-term conservation of the germplasm of recalcitrant-seeded species. This is not easily achieved, as each of the necessary procedures imposes oxidative damage. Intact recalcitrant seeds cannot be cryopreserved, the common practice being to use excised embryos or embryonic axes as explants. Dehydration is a necessary procedure prior to exposure to cryogenic temperatures, but this is associated with metabolism-linked injury mediated by uncontrolled reactive oxygen species generation and failing anti-oxidant systems. While the extent to which this occurs can be curtailed by maximizing drying rate (flash drying) it cannot be completely obviated. Explant cooling for, and rewarming after, cryostorage must necessarily be rapid, to avoid ice crystallization. The ramifications of desiccation sensitivity are discussed, as are problems involved in cryostorage, particularly those accompanying dehydration and damage consequent upon ice crystallization. While desiccation sensitivity is a “fact” of seed recalcitrance, resolutions of the difficulties involved germplasm conservation are possible as discussed.
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影响因子：
6.9
作者：
Delahaie J;Hundertmark M;Bove J;Leprince O;Rogniaux H;Buitink J
通讯作者：
Buitink J
影响因子：
2.1
作者：
Farrant, JM;Pammenter, NW;Walters, C
通讯作者：
Walters, C
影响因子：
4.2
作者：
Ellis, RH;Hong, TD
通讯作者：
Hong, TD
影响因子：
4.2
作者：
ELLIS, RH;ROBERTS, EH
通讯作者：
ROBERTS, EH
影响因子：
9.4
作者：
Daws, MI;Lydall, E;Pritchard, HW
通讯作者：
Pritchard, HW