Chemistry and Biology Research Institute, Agriculture Canada, Ottawa K1A 0C6 Canada.
Plant Physiol. 1979 Jul;64(1):120-5. doi: 10.1104/pp.64.1.120.
Ice encasement damages cold-hardened winter wheat without major disruption of cellular organelles. CO(2) accumulates during total ice encasement to higher levels in Kharkov than in less hardy Fredrick wheat. Partial ice encasement and exposure to a nitrogen atmosphere at -1 C allows greater CO(2) accumulation but neither treatment is as damaging as total ice encasement. Lactic acid accumulates to low levels only during the 1st day of encasement and thereafter remains constant. Exposure of plants to a combination of 50% CO(2) and 5% ethanol reduces survival, with a cultivar difference similar to that found in ice-encased plants. Plants in CO(2) and ethanol show a proliferation of membranes and nuclear condensation similar to that in cells of ice-encased plants. Permeability increases markedly in the presence of CO(2) and ethanol, to levels similar to or greater than those of iced plants. Ethanol alone does not increase permeability but in combination with CO(2) raises permeability of the less hardy Fredrick, although not of Kharkov, but reduces survival of both cultivars. A comparison of the endogenous levels of ethanol, CO(2), and lactic acid at the 50% kill point of plants due to ice encasement or due to externally supplied metabolite indicates that only CO(2) accumulates to independently toxic levels. Permeability and ultrastructural evidence suggest that CO(2) and ethanol in combination are the agents reducing plant viability during ice encasement.
冰包裹会损坏经过耐寒处理的冬小麦，而不会对细胞器官造成重大破坏。在完全被冰包裹的情况下，Kharkov 小麦体内的 CO2 积累到比不太耐寒的 Fredrick 小麦更高的水平。部分冰包裹并在-1°C 的氮气环境下暴露会允许更多的 CO2 积累，但这两种处理都不如完全冰包裹那样具有破坏性。只有在包裹的第一天，乳酸才会积累到低水平，此后保持不变。将植物暴露于 50%CO2 和 5%乙醇的组合中会降低存活率，与在冰包裹植物中发现的差异相似。在 CO2 和乙醇中暴露的植物表现出类似于冰包裹植物细胞中的膜和核浓缩的增殖。在 CO2 和乙醇存在的情况下，通透性显著增加，达到与冰包裹植物相似或更高的水平。单独的乙醇不会增加通透性，但与 CO2 结合会增加不太耐寒的 Fredrick 的通透性，尽管对 Kharkov 小麦没有影响，但会降低两种品种的存活率。将由于冰包裹或外部供应代谢物而导致植物 50%致死的内源性乙醇、CO2 和乳酸水平进行比较表明，只有 CO2 积累到独立的毒性水平。通透性和超微结构证据表明，CO2 和乙醇的组合是在冰包裹过程中降低植物活力的因素。
