【作者】 武杭菊；

【导师】 胡景江；

【作者基本信息】 西北农林科技大学 ， 植物学， 2007， 硕士

【摘要】 干旱和低温作为两种最常见的逆境,严重地影响着植物的正常生长发育以及生理代谢。本文选用对干旱、低温抗性不同的长武134、晋麦47号和郑引1号3个小麦品种为试验材料,在人工控制条件下,通过PEG处理模拟干旱胁迫和人工气候箱程序降温模拟低温胁迫,研究小麦幼苗对干旱、低温逆境交叉适应的生理生化基础和可能机理。同时,用外施ABA作为一种预处理条件,探讨ABA在交叉适应中的调节作用。主要研究结果如下:(1)经单一干旱、低温逆境处理后,3个小麦品种的叶水势都显著下降,降幅在1.01~1.26Mpa之间,其中抗旱性弱的郑引1号下降的幅度最大。单一干旱、低温逆境处理后恢复正常条件,生长恢复正常后两种逆境进行交叉处理,结果表明“干旱+低温”和“低温+干旱”处理后3种小麦的叶水势下降幅度在0.39~0.77Mpa之间,均比单一低温或干旱逆境下水势下降幅度明显减小。在“ABA+干旱”和“ABA+低温”的交叉组合处理中,叶水势的下降幅度也明显小于单一干旱和低温逆境处理。这表明ABA在一定程度上可代替干旱、低温预处理的效果在交叉适应中起作用。(2)单一干旱或低温胁迫时,与正常生长的幼苗相比,3个品种小麦幼苗的细胞膜相对透性都明显增大,丙二醛含量增多,其中细胞膜相对透性增加幅度在54.48%～68.63%,丙二醛含量增加在40.88%～64.29%,说明细胞膜严重受损,膜脂质过氧化程度加深。而经干旱、低温和外施ABA预处理的小麦幼苗,与单一干旱或低温胁迫相比,质膜相对透性明显降低,降幅在25.45%～38.96%,丙二醛含量也显著降低,降幅在9.52%～23.21%,明显地抑制了膜脂过氧化作用,表明交叉处理的小麦幼苗比单一进行胁迫的小麦幼苗确实具有较强的抗性,交叉适应性可避免或减轻膜受损的程度,提高抗逆性,且外施ABA处理具有同交叉适应性相同的处理效果。(3)经单一干旱、低温逆境处理后,与正常生长的幼苗相比,3个小麦品种的SOD、CAT活性及GSH含量均明显下降,降幅分别在25.08%～39.65%、7.71%～9.78%和9.60%～25.97%,POD活性及AsA含量虽有上升,但上升幅度很小且郑引1号表现为下降,总体表现为活性氧清除能力下降;而经干旱、低温和外施ABA预处理的小麦幼苗,与单一干旱或低温胁迫相比,SOD、CAT、POD活性分别上升在25.37%～42.68%、10.77%～19.57%和2.23%～31.14%,GSH及AsA含量上升在0.59%～41.87%,表明交叉处理的小麦幼苗保护酶活性及内源抗氧化剂含量均明显增高,说明活性氧清除能力增强,且抗性强的品种表现出更强的活性氧清除能力。(4)单一干旱或低温胁迫时,由于活性氧对蛋白质等生物大分子伤害极其严重,而引起了可溶性蛋白质含量的下降。与正常生长的幼苗相比,3个品种小麦幼苗的可溶性蛋白质含量的降幅在2.47%～12.18%。而经干旱、低温、外施ABA预处理后经历干旱或低温逆境,与单一干旱或低温胁迫相比,可溶性蛋白质含量也有明显增多,增幅在14.33%～53.89%。表明交叉适应明显提高植株的抗逆性,其生理基础与ABA的作用机制密切相关。更多还原

【Abstract】 As two most commonly seen stresses , drought and chilling affected the growth and metabolism of plant seriously . In this thesis, three different resistance to drought and chilling of wheat seedlings ( Changwu 134 , Jinmai No.47 and Zhengyin No.1 ) were used for experimental material . At the artificial controlled condition , the mechanism of drought and chilling injury and cross-adaptation was induced by drought and chilling in wheat seedlings were studied , by PEG was used to simulated drought stress and procedural lower temperature was used to simulated chilling stress in this experimentation ; meanwhile , as another pretreated method , exogenous abscisic acid ( ABA ) was used to discuss the adjustment function of ABA in cross-adaptation .The main result are as follows:1. After the injury of drought or chilling , the leaf water potential of three wheat seedlings decreased observably, the degressive range at 1.01~1.26Mpa, and the infirm resistance to drought of Zhengyin No.1 decreased mostly in the three breeds. When the wheat seedlings renewed up to snuff, drought and chilling injury were used to cross- disposal in wheat seedlings, the result was shown that the degressive range of the leaf water potential at 0.39~0.77Mpa, which decreased visibly compared with the injury of drought or chilling, after the wheat seedlings were treated by“drought + chilling”and“chilling + drought”. At the cross- disposal of“ABA + drought”and“ABA + chilling”, the leaf water potential of three wheat seedlings have same change. The change was shown that ABA can replace the pretreated seedlings of drought and chilling at a certain extent and react on the cross-adaptation.2. When the wheat seedlings were treated by the injury of drought or chilling, compared with natural seedlings, membrane leakage rate and the content of MDA , a product of membrane lipid peroxidation of three wheat seedlings increased markedly. The increased range of the membrane leakage rate at 54.48%～68.63%, and the content of MDA increased at 40.88%～64.29%, the result was shown that the membrane system damnified badly, which growed on the extent of membrane lipid peroxidation. Compared with the injury of drought or chilling, the membrane leakage rate of wheat seedlings which pretreated by the drought or chilling or ABA decreased observably, the degressive range at 25.45%～38.96%, the content of MDA decreased too, and the degressive range at 9.52%～23.21%, which restrained membrane lipid peroxidation clearly, and shown that the seedlings of cross- disposal have doughty resistance in troth. Cross-adaptation can avoid or mitigate the mangled of membrane system , which could improved the resistance of plant, and ABA pretreated have similar impact.3. After the injury of drought or chilling , compared with natural seedlings, the SOD、CAT activity and GSH content of three wheat seedlings decreased observably, the degressive range at 25.08%～39.65%、7.71%～9.78% and 9.60%～25.97% respectively. POD activity and AsA content have little rise and Zhengyin No.1 decreased, but the ability of activated oxygen scavenging system decreased in the mass; Compared with the injury of drought or chilling, the SOD、CAT、POD activity and GSH、AsA content of wheat seedlings which pretreated by the drought or chilling or ABA increased observably, the degressive range at 25.37%～42.68%、10.77%～19.57%、2.23%～31.14% and 0.59%～41.87% respectively. The result was shown that the activity of protected enzyme and the content of endogenesis antioxidant all heightened visibly, the ability of activated oxygen scavenging system enhanced, and the strong resistance of breed puttde up stronger than others.4. When the wheat seedlings were treated by the injury of drought or chilling, the content of soluble protein decreased because of the activated oxygen injured badly to great biology numerator as protein. Compared with natural seedlings, the content of soluble protein of three wheat seedlings decreased range at 2.47%～12.18%. Compared with the injury of drought or chilling, the content of soluble protein of wheat seedlings which pretreated by the drought or chilling or ABA also increased observably, the increased range at 14.33%～53.89%. The result was shown that cross-adaptation enhanced resistance of plant obviously , the physiological elements have nearly relation to functionary mechanism of ABA.更多还原