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Physiochemical mechanisms of cultivarietal differences in the heat tolerance in cucumber

黄瓜耐热性品种差异的理化机制

基本信息

批准号：
07456160
负责人：
TACHIBANA Shoji
金额：
$ 1.41万
依托单位：
MIE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

1.Mechanisms for heat tolerance increases of photosynthetic apparatus (PA) in leaves by environmental stress pretreatments to plants : Water stress and non-lethal high temperature pretreatments caused an increase in heat tolerance of PA as determined by photosynthetic activity and chlorophyll fluorescence of intact leaves before and after exposure to 45ﾟC for 20min. The effect of water stress seems to be mediated by ABA that was increased markedly by water stress, because ABA treatment to non-water-stressed leaves showed the similar effect. A main cause of the increaseed heat tolerance of PA by water stress pretreatment seems to lie on an increased heat stability of electron transport systems in thylakoid membranes, and that by non-lethal high temperature pretreatment on the decrease in fatty acid unsaturation of thylakoid membrane lipids. There were no distinct difference between cultivars in the heat tolerance of PA and the rate of its increase by environmental stress pretreatments.2 … More .Repair of heat injury in the greening of etiolated cucumber cotyledons : When etiolated cotyledons were exposed to various high temperatures for 30 min in the dark and then immediately illuminated at 28ﾟC for 12 hr, greening was more suppressed as the heat temperature was increased When the illumination was prolonged to 38 hr, they were able to green to almost the normal level unless the heat temperature did not exceed 46ﾟC.Cotyledons heat-stressed at 48ﾟC did not green even after 38hr. However, they greened to 80% of the control level when they were placed in the dark at 28ﾟC for 16 hr before illumination for 36 hr. These results suggest that heat injury of greening processes in etiolated cotyledons is repaired by certain mechanisms that are influenced by light and this system is a useful tool for a better understanding of the repair mechansims of heat injury in plants.3.Cultivar differences in heat tolerance ofcucumber roots : The degree of heat tolerance of various cultivars' roots as determined by ion leachage test as well as TTC reduction test did not coincide well with that as determined by regrowth test. High root-zone temperature was less inhibitory to growth but caused a greater inhibition to photosynthesis than high air temperature (both at 37ﾟC). A main cause of photosynthesis inhibition by high root-zone temperature was assumed to be a decrease in stomatal aperture and carboxylation as well ; the activity of photochemical reactions was normal. One of the most important factors responsible for growth inhibition by high root-zone temperatures was assumed to be a marked inhibithion of cytokinin biosynthesis in the roots. Less

1.环境胁迫预处理对植物叶片光合机构（PA）耐热性提高的影响机制：水分胁迫和非致死性高温预处理均可提高植物叶片的PA耐热性，通过测定45 C处理20min前后完整叶片的光合活性和叶绿素荧光测定。水分胁迫的影响可能是由ABA介导的，而ABA处理对非水分胁迫叶片的影响与ABA处理相似。水胁迫预处理提高PA耐热性的主要原因似乎在于提高了类囊体膜中电子传递系统的热稳定性，而非致死性高温预处理则降低了类囊体膜脂的脂肪酸不饱和。不同品种间PA的耐热性及环境胁迫预处理的增温速率无明显差异。2 .更多。黄化黄瓜子叶热损伤的修复：黄化子叶在黑暗中暴露于各种高温下30 min，然后立即在28ºC下照射12 h，随着加热温度的升高，黄化子叶的变绿受到更大的抑制。当照射时间延长到38小时时，除非加热温度不超过46ºC，否则黄化子叶的变绿基本能恢复到正常水平。在48oc温度下，子叶在38h后仍未变绿。然而，当他们被放置在28‰的黑暗中16小时，然后照明36小时时，他们的绿化率达到控制水平的80%。这些结果表明黄化子叶绿化过程的热损伤是通过一定的受光影响的机制修复的，该系统为更好地理解植物热损伤的修复机制提供了有益的工具。黄瓜根系耐热性的品种差异：离子淋滤试验和TTC还原试验测定的各品种根系耐热程度与再生试验测定的结果不太吻合。高根区温度对生长的抑制作用较小，但对光合作用的抑制作用大于高温（37℃）。认为高根区温度抑制光合作用的主要原因是气孔开度和羧化作用的减少；光化学反应活性正常。根区高温抑制生长的最重要因素之一被认为是根系细胞分裂素生物合成的显著抑制。少