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首页> 外文期刊>Frontiers in Plant Science >Factors contributing to deep supercooling capability and cold survival in dwarf bamboo ( Sasa senanensis) leaf blades
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Factors contributing to deep supercooling capability and cold survival in dwarf bamboo ( Sasa senanensis) leaf blades

机译:矮竹叶片深过冷能力和低温存活的影响因素

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摘要

Wintering Sasa senanensis , dwarf bamboo, is known to employ deep supercooling as the mechanism of cold hardiness in most of its tissues from leaves to rhizomes. The breakdown of supercooling in leaf blades has been shown to proceed in a random and scattered manner with a small piece of tissue surrounded by longitudinal and transverse veins serving as the unit of freezing. The unique cold hardiness mechanism of this plant was further characterized using current year leaf blades. Cold hardiness levels (LT_(20): the lethal temperature at which 20% of the leaf blades are injured) seasonally increased from August (?11°C) to December (?20°C). This coincided with the increases in supercooling capability of the leaf blades as expressed by the initiation temperature of low temperature exotherms (LTE) detected in differential thermal analyses (DTA). When leaf blades were stored at ?5°C for 1–14 days, there was no nucleation of the supercooled tissue units either in summer or winter. However, only summer leaf blades suffered significant injury after prolonged supercooling of the tissue units. This may be a novel type of low temperature-induced injury in supercooled state at subfreezing temperatures. When winter leaf blades were maintained at the threshold temperature (?20°C), a longer storage period (1–7 days) increased lethal freezing of the supercooled tissue units. Within a wintering shoot, the second or third leaf blade from the top was most cold hardy and leaf blades at lower positions tended to suffer more injury due to lethal freezing of the supercooled units. LTE were shifted to higher temperatures (2–5°C) after a lethal freeze-thaw cycle. The results demonstrate that the tissue unit compartmentalized with longitudinal and transverse veins serves as the unit of supercooling and temperature- and time-dependent freezing of the units is lethal both in laboratory freeze tests and in the field. To establish such supercooling in the unit, structural ice barriers such as development of sclerenchyma and biochemical mechanisms to increase the stability of supercooling are considered important. These mechanisms are discussed in regard to ecological and physiological significance in winter survival.
机译:矮小竹子Sasa senanensis越冬,其深层过冷是其从叶子到根茎的大多数组织耐寒性的机制。叶片中的过冷分解已显示出以随机和分散的方式进行,一小块组织被纵向和横向静脉包围,成为冷冻单位。使用当年的叶片进一步表征了该植物独特的抗寒性机制。从8月(?11°C)到12月(?20°C),耐寒性水平(LT_(20):20%的叶片受伤的致死温度)季节性增加。这与叶片的过冷能力的增加相吻合,如通过差热分析(​​DTA)中检测到的低温放热(LTE)的起始温度所表示的。当叶片在?5°C下保存1-14天时,在夏季或冬季,过冷的组织单位都没有成核。但是,只有长时间的组织单元过冷后,夏季刀片才会遭受重大伤害。这可能是在亚冰点温度下过冷状态下的新型低温诱导伤害。当冬季叶片保持在阈值温度(?20°C)时,更长的存储时间(1–7天)会增加过冷组织单位的致死性冷冻。在越冬芽中,从顶部开始的第二或第三片叶片耐寒性最强,而较低位置的叶片由于过冷装置的致死性冷冻而往往遭受更多伤害。致命的冻融循环后,LTE转移到更高的温度(2–5°C)。结果表明,用纵向和横向静脉分隔的组织单位是过冷的单位,并且随时间和温度而变的单位冻结在实验室冷冻测试和现场中都是致命的。为了在装置中建立这种过冷,人们认为重要的是结冰的结构性冰障,例如硬化层的形成以及增加过冷稳​​定性的生化机制。关于冬季生存中的生态和生理意义,讨论了这些机制。

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