【作者】 白团辉；

【导师】 马锋旺；

【作者基本信息】 西北农林科技大学 ， 园艺植物种质资源学， 2008， 硕士

【摘要】 氧是线粒体电子传递链的末端受体,也是一些酶所必需的,是高等植物正常生理代谢和生长发育必不可少的条件。但土壤雨涝积水、灌溉不均和土壤质地紧实等均会造成土壤通气受阻,导致植物根际缺氧。苹果是重要的果树树种之一,会因季节性降雨不均、水肥管理不当而遭受根际低氧胁迫。本文以我国12种苹果砧木为试材,采用营养液水培低氧和淹水处理相结合的方法,研究了不同苹果根际低氧耐性的强弱,并从中选择差异较大的两中砧木,低氧耐性较强的砧木为平邑甜茶(Malus hupehensis Rehd.)和低氧敏感型砧木为变叶海棠(M. toringoides Hughes.)为试材,研究了不同耐性苹果砧木对低氧胁迫响应的差异机理。同时以耐性中等的八棱海棠(M. robusta Rehd.)为试材,研究了水杨酸(Salicylic acid,SA)对其耐低氧性的诱导作用,探讨了低氧胁迫及耐性诱导措施对苹果砧木生理机制的影响,旨在为苹果栽培与土壤管理提供指导和理论依据。主要结果如下:1.根际低氧胁迫下,所有供试苹果砧木植株的生长都受到了不同程度的抑制。低氧处理15 d后,苹果砧木幼苗新叶数、根长、株高、生物量较对照明显降低,各种类整株鲜重减少9%～41%,干重减少14%～40%。不同苹果砧木对低氧胁迫响应的敏感性明显不同。在低氧胁迫下,12种苹果砧木根系中可溶性蛋白质含量都降低,脯氨酸(Pro)大量积累,但不同苹果砧木降低或升高幅度有显著差异。2.用隶属函数、湿害指数及抗逆系数对12种苹果砧木根际低氧耐性进行综合评价,以9个根系生理指标和6个生长指标对不同砧木进行聚类。分析认为平邑甜茶、平顶海棠和卢氏红果为耐低氧砧木,新疆野苹果和变叶海棠为低氧敏感型砧木。3.低氧胁迫下,苹果砧木根系活性氧(ROS)积累,其超氧阴离子(O2 )产生速率和过氧化氢(H2O2)含量增加,细胞膜脂质过氧化加重,丙二醛(MDA)含量上升,从而使细胞膜受到伤害,耐性较弱的变叶海棠根系细胞膜受到的氧化伤害大于低氧耐性较强的平邑甜茶。4.苹果砧木根系的抗氧化防御系统能一定程度上减轻低氧胁迫所造成的膜伤害,其根系中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)酶活性增加,抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性前期有所提高而后期降低并低于对照,但平邑甜茶的抗氧化酶活性显著高于变叶海棠。抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量及抗坏血酸/脱氢抗坏血酸(AsA/DHA)和还原性谷胱甘肽/氧化性谷胱甘肽(GSH/GSSG)比值在胁迫早期增加而后逐渐减少,中期后期低于同期对照。表明低氧胁迫对植株的影响存在基因型差异,低氧耐性较弱的变叶海棠受到的伤害较重,平邑甜茶可通过提高抗氧化酶活性来增强其耐低氧能力,抵御低氧胁迫所造成的伤害。5.低氧胁迫显著抑制了八棱海棠幼苗生长,外源0.5 mmol?L-1SA可以改善低氧胁迫下八棱海棠幼苗植株的生长情况,显著地提高低氧胁迫下八棱海棠幼苗的鲜重和干重。表明外施0.5 mmol?L-1SA处理缓解了低氧胁迫对八棱海棠幼苗生长的抑制,对低氧胁迫下八棱海棠幼苗的伤害有显著的缓解效应。6.低氧胁迫下八棱海棠叶片MDA、O2、H2O2、GSH含量和抗氧化酶活性均高于对照,而AsA含量低于对照;外源SA明显抑制MDA和O2的积累,显著增强SOD、POD、APX和GR的活性。说明SA作为化学诱抗剂,可抑制低氧胁迫下苹果幼苗体内活ROS的产生,提高抗氧化酶的活性,降低膜脂过氧化水平,从而减轻低氧胁迫对植株的伤害。更多还原

【Abstract】 Molecular oxygen is the terminal electron acceptor in the mitochondrial electron transport chain and is required by several enzymes, higher plants need oxygen for growth and metabolism. But frequently they experience oxygen deficiency in the root-zone mainly due to soil waterlogging、soil compaction and submergence. Apple is one of the most important fruit crops in the world; hypoxia stress in the root-zone is thought to be one of those important factors which restrict the development of apple. 12 apple rootstocks were treated with hydroponics hypoxia and waterlogging to study their root-zone hypoxia tolerance, hypoxia-tolerance apple rootstock Malus hupehensis Rehd and hypoxia-sensitive apple rootstock M.toringoides Hughes were selected as experimental materials to study physiological responses difference, and M.robusta Rehd was used to induce hypoxia-tolerance under hypoxia stress. The physiology and biochemical mechanism of hypoxia stress on apple rootstocks and salicylic acid (SA) was also discussed under hypoxia stress, all above provided the theoretic base and technical guideline for apple tree cultivation and soil management. The results as follows:1. Growth of all apple rootstocks was inhibited to various degrees under root-zone hypoxia stress. After 15 days hypoxia treatment,the number of new leaves, root length, plant height, plant biomass and content of soluble protein in roots under root-zone hypoxia stress obviously declined comparing with control, fresh weight decreased 9%～41% and dry weight decreased 14%～40%. The sensitivities of 12 apple rootstocks to hypoxia stress were obviously different,The content of soluble protein in roots under root-zone hypoxia stress obviously declined comparing with control, while proline(Pro) increased and variation percentage of the was significantly different.2. Based on subordinate function, adversity resistance coefficient, waterlogging index and cluster analysis of 9 physiological and 6 growing indexes, the hypoxia-tolerance of 12 apple rootstocks were comprehensively evaluated and revealed M.hupehensis Rehd, M. robusta Rehd and M. sieboldii Rehd held higher tolerance to root-zone hypoxia stress, while M. sieverii Roem and M.toringoides Hughes were sensitive to root-zone hypoxia stress.3. The reactive oxygen species (ROS) in roots of apple rootstock under hypoxia stress accumulated, the generation rate of superoxide radical (O2 ) and the content of hydrogen peroxide (H2O2) increased, the membrane lipid peroxidation was more serious, which leaded to more content of malonaldehyde (MDA), so the membrane was damaged. The oxidative damages to membrane in roots of M. toringoides Rehd were more serious than M. hupenensis Rehd.4. The anti-oxidative system could reduce the damages to membrane in roots of apple rootstock under hypoxia stress at some extent. The activities of peroxidse (POD), superoxide dismutase (SOD), catalase (CAT) increased during the stress; the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) increased in early period of stress, but decreased in later period until less than control, while the anti-oxidative enzyme activities of M. hupehensis Rehd increased rapidly. The contents of antioxidants such as ascorbic acid (AsA) and glutathione (GSH), the ratio of AsA and oxidative ascorbic acid (AsA/DHA), the ratio of GSH and oxidative glutathione (GSH/GSSG) also increased in early period, but gradually decreased later and were less than control in media and latter period of stress. The results suggested the effects of hypoxia stress on the plant were different from genotype; the damages to M.toringoides Hughes were more serious than M.hupehensis Rehd.and M. hupehensis Rehd could enhance their tolerant ability through increasing the activities of anti-oxidation enzymes.5. Exogenous 0.5 mmol?L-1 SA application could relieve the harm caused by hypoxia stress and result in improved growth of M. robusta Rehd, increased fresh and dry weight of M. robusta Rehd The results suggested treatment with 0.5 mmol?L-1SA mitigated the growth inhibitions in M. robusta Rehd.under root-zone hypoxia stress.6. Under root-zone hypoxia stress, the contents of MDA, O2 , H2O2 and GSH, and activities of antioxidant enzymes were higher than the control, however, the level of AsA were decreased. Exogenous SA significantly decreased the content of O2 , MDA and GSH, increased the activities of SOD, POD, APX and GR under hypoxia stress. It was proposed that exogenous SA as a chemical activator could induce resistance, reduce production of reactive oxygen species, raise the activities of anti-oxidative enzymes, and decrease the membrane lipid peroxidation; therefore it alleviated the damage degree of hypoxia stress of M. robusta Rehd.更多还原