【作者】 王颖；

【导师】 杨光伟；

【作者基本信息】 西南农业大学 ， 生物化学与分子生物学， 2005， 硕士

【摘要】 印楝(Azadirachta indica A. Juss)是目前公认的高效植物性杀虫剂,同时具有广谱、低毒、易降解、无残留等特点,由于巨大的商业价值而倍受世界各国政府与科学家的关注。但由于其原产热带、亚热带地区,形成了喜温而不耐寒冻的生态特性,越冬期间的低温是影响我国印楝生产的主要农业气象灾害。 为解决这一问题我们对其进行冷驯化,因为植物的低温抗性是适应性的一种,也是生物特有的。低温蛋白在植物的低温抗性形成中起作用。当外界冷压力刚刚触及植物时,植物细胞膜最先感应到冷刺激信号,细胞合成膜关联耐冻性多肽蛋白质改变膜脂组成成分,对低温形成初期抗性和适应性。随着低温逆境程度的加剧,植物启动合成低温防护蛋白。当低温逆境进一步加深,即将引起植物细胞结冰时,植物合成抗冻蛋白(antifreeze proteins, AFP)。利用抗冻蛋白的热滞效应、冰晶形态效应和重结晶抑制效应等特有功能阻止细胞结冰。但当植物处在零下几十度的低温时,引起细胞内外不同程度的颗粒结冰,致使细胞脱水,此时植物合成的植物脱水素(dehydrin)保护蛋白质不变性,可以形成植物的最后一道防线而去努力维持生命。 抗冻蛋白的发现可追溯至20世纪60年代。人们从极区鱼的血清中发现了这种奇妙的物质,它能阻止体液内冰核的形成与生长,维持体液的非冰冻状态。这一发现引起了许多实验室的研究兴趣,研究对象从极区鱼扩展到昆虫,最后又扩展到植物,甚至微生物。科学家发现,原来AFPs在生物界广泛存在,是生物适应低温、抵御冻害的一种机制。虽然植物的低温诱导表达基因众多,能表达产生许多不同的蛋白,但但已研究过的植物材料绝大多数为草本植物,而且目前真正被分离和纯化出来的低温诱导蛋白并不多,并且它们在细胞中的定位、结构、功能、作用方式及基因表达调控机理仍不清楚。 本研究主要采用木本植物材料——印楝,通过组织培养建立快繁体系,然后对其进行冷驯化处理,分析检测印楝植物体内抗冻蛋白,主要结果如下:更多还原

【Abstract】 Neem(Azadirachta indica A.Juss) is the highly effective vegetative pesticide at present, at the same time it is broad-spectrum , lowly poisonous, easy to degrade, no residual and so on . As a result of it’s huge commercial value which has aroused up the government and scientist’s attentions all over the world, and it has formed the ecology characteristic of being thermophilic but non- resisting frozen, just because it originally produces in the tropics or subtropics areas, the low temperature in winter is the main agricultural meteorology disaster of affecting the neem’s production in our countries.In order to solve this problem we carried on cold acclimation to it, because plant’s low temperature resistance was not only one of the adaptabilities but also the unique biological characteristic. The low temperature protein could take effect on the plant’s low temperature resistance. That is to say, When the outside cold pressure just touched the plant, the plant cell membrane first felt the cold stimulation signals, Cell synthesis membrane which connected frost-resisting multi-peptides protein changed membrane fat component, and the plant forms the initial period resistance and the adaptabilities to the low temperature. Along with the intensifying of low temperature and adverse circumstance degree, Plant started to synthesize low temperature protection proteins. Antifreeze proteins synthesized when the low temperature or adverse circumstance further deepened and would cause the vegetable cell to ice up. It is used antifreeze proteins’ special functions including thormal hysteresis, ice crystal forming, recrystalization inhibition and so on to prevent cells icing up. When the plants were placed in several decades below zero, to some extend, it would cause cells to ice up inside and out side. Further more , it would cause cells to dehudrate, when dehydrin which was used of protecting proteins not denaturalization was synthesized and maintained lives in plants.The discovery of antifreeze proteins (antifreeze proteins, AFP) may trace to 1960s, When更多还原