【作者】 马晓娣；

【导师】 王丽；

【作者基本信息】 中国农业大学 ， 植物学， 2004， 硕士

【摘要】 本实验选用耐热性不同的小麦品种幼苗为材料，在热锻炼(34℃)和热胁迫(49℃)条件下，测定了叶片的相对电导率，并观察了叶肉细胞超微结构的变化；在热击状态(38℃)下，应用cDNA扩增片段长度多态性(cDNA-AFLP)技术，对耐热与不耐热品种叶片基因表达差异进行了分析；从生理学、细胞学及分子生物学角度初步探讨了不同小麦品种耐热性差别的原因，取得的主要结果如下： 1．热锻炼可降低叶片的相对电导率，延缓热胁迫对叶肉细胞超微结构的破坏，延缓程度耐热品种比不耐热品种更为明显。 2．叶肉细胞中液泡膜对高温最敏感，其次为线粒体和叶绿体。线粒体的嵴和内膜比外膜对高温更敏感；叶绿体的类囊体膜在热胁迫下较早出现排列紊乱，但解体时间却比叶绿体被膜晚。 耐热品种核膜的热稳定性最高，不耐热品种核膜的热稳定性可通过热锻炼明显提高，即细胞核(尤其核膜)的热稳定性直接影响细胞结构的稳定性，而且与品种的耐热性明显相关。 3．在热击60min时，耐热品种热击表达基因与热击沉默基因数值相差较大。热击60min后，不耐热品种热击表达基因数量迅速减少。热击后60min左右是研究基因表达差异的关键时期。 与不耐热品种相比，热击条件下耐热品种持续表达的热击基因相对数量较多，热击基因持续表达的时间较长。 在热锻炼和热胁迫过程中叶片相对电导率、叶肉细胞超微结构的变化，以及热击条件下叶片基因表达差异，可分别作为耐热性评价的生理学、细胞学和分子生物学指标。更多还原

【Abstract】 In the experiment, wheat seedlings with different heat tolerance were used as experiment materials. Under heat acclimation(34℃) and heat stress(49℃) , the relative conductivities of leaves were measured, the ultrastructural changes of mesophyllous cells were observed. Under heat shock(38℃), the differences in gene expression of leaves between thermotolerant and thermosusceptible varieties were analyzed by using cDNA amplified fragment length polymorphism(cDNA-AFLP). The causes that resulted in different heat tolerance between wheat varieties were discussed from several aspects of physiology, cytology and molecular biology. The results were as follows:1. Heat acclimation reduced relative conductivity of leaves, delayed the ultrastructural destruction of mesophyllous cells induced by heat stress, and the degree of delay was higher in thermotolerant varieties than that in thermosusceptible ones.2. In mesophyllous cell, vacuolar membrane was the most susceptible one to high temperature, and mitochondrion was more susceptible than chloroplast. In mitochondria, mitochondrial crista and inner membrane was more susceptible than outer membrane. In chloroplasts, though the arrangement of thylakoid membrane appeared disturbance priorly, the disintegration of thylakoid membrane was later than chloroplast envelope.The nuclear membrane of thermotolerant varieties was the most stable one to high temperature, and the thermal stability of nuclear membrane of thermosusceptible varieties was improved by heat acclimation. Thus, the thermal stability of cell nucleus(especially nuclear membrane) played an important role in maintaining the thermal stability of cell architecture, and was associated closely with heat tolerance of varieties.3. Under 60min’ heat shock, the difference in quantity between heat shock gene expression and gene silencing of thermotolerant variety was more obvious than that of thermosusceptible variety. After 60min’ heat shock, the quantity of heat shock gene expression of thermosusceptible variety was decreased rapidly. The important period of investigating the difference in gene expression was round about 60min’ heat shock.Under heat shock, the comparative quantity of heat shock gene that expressed continuously of thermotolerant variety was larger and the continuous time of heat shock gene expression was longer than that of thermosusceptible variety.The relative conductivity of leaves, ultrastructural changes of mesophyllous cells under heat acclimation and heat stress, the differences in gene expression of leaves under hest shock can be used as physiologic, cytologic and molecular biologic indexes respectively for evaluating heat tolerance.更多还原