褪黑素缓解番茄低温与水分胁迫机理研究

发布时间：2019-01-18 14:43

【摘要】：低温和干旱是常见的环境胁迫因子,影响自然界中植物的分布、生长发育以及全球农业生产并威胁食品安全。番茄(Solanum lycopersicum)是一种重要的园艺作物,世界范围内番茄(果实)需求量大,但番茄的生长和发育极易受低温和干旱影响,造成产量降低和品质下降。因此,研究提高番茄的抗寒性和抗旱性对于保障番茄的可持续生产具有重要意义。研究证明,褪黑素在植物中具有重要的作用,参与调控生长、发育以及胁迫响应等过程的调控。目前,褪黑素调控番茄抗寒性和抗旱性机理研究尚不多见。本研究以番茄为试验材料,通过测定低温和水分胁迫下番茄叶片的光合能力、非光化学猝灭水平、抗氧化系统、冷响应基因表达、渗透调节物质积累、表皮蜡质积累以及叶片渗透势等,研究褪黑素对番茄低温胁迫和水分胁迫的缓解作用,并探讨了其机理。主要研究结果如下:1.褪黑素缓解低温对番茄植株的伤害。褪黑素预处理可以显著提高低温胁迫下番茄植株的光合能力,缓解由低温引起的氧化胁迫,表现在褪黑素处理可以降低丙二醛含量和电解质渗透率;提高低温胁迫下番茄抗氧化酶活性和非酶抗氧化物质的含量,增强了番茄的抗氧化能力;褪黑素促进番茄景天庚酮糖二磷酸酶基因的表达并维持低温胁迫下景天庚酮糖二磷酸酶的活性,有助于改善低温胁迫下番茄叶片的光合能力;褪黑素显著诱导了低温胁迫下番茄冷响应基因的表达,可溶性糖和脯氨酸的积累,对于提高番茄的抗寒性起着重要的作用。2.褪黑素缓解低温胁迫下番茄的光抑制。褪黑素处理促进低温胁迫下番茄叶片叶黄素循环中紫黄质脱环氧化酶基因的表达和紫黄质脱环氧化酶辅助因子抗坏血酸的含量,以此提高紫黄质脱环氧化酶的活性。紫黄质脱环氧化酶活性的提高引起叶黄素脱环氧化水平增加,由此提高了非光化学猝灭水平,缓解番茄低温胁迫引起的光抑制。3.褪黑素缓解番茄水分胁迫。褪黑素显著提高了干旱条件下番茄的光合能力和降低了干旱诱导的氧化伤害;提高了番茄的抗氧化能力;褪黑素促进了番茄叶片表皮蜡质合成基因的表达,增加了叶片表皮蜡质的含量,减少了叶片非气孔水分散失;褪黑素明显的改变了水分胁迫下番茄老叶和幼叶之间的渗透势梯度。这些结果说明,褪黑素处理有助于缓解番茄的水分胁迫。4.褪黑素可能依赖ABA调控水分胁迫下番茄的抗氧化能力。褪黑素显著降低了干旱诱导的氧化伤害,明显的提高了番茄叶片的抗氧化能力,而用ABA生物合成抑制剂氟啶酮处理番茄后,褪黑素对番茄的影响减小。氟啶酮处理后,褪黑素对水分胁迫下番茄叶片中丙二醛的含量、电解质渗透率以及抗氧化酶的影响明显减小,说明褪黑素可能依赖于ABA来提高番茄的抗氧化能力。
[Abstract]:Low temperature and drought are common environmental stress factors, which affect the distribution, growth and development of plants in nature, as well as global agricultural production and threaten food safety. Tomato (Solanum lycopersicum) is an important horticultural crop. Tomato (fruit) is in great demand all over the world. However, the growth and development of tomato are easily affected by low temperature and drought, resulting in lower yield and lower quality. Therefore, it is of great significance to improve the cold resistance and drought resistance of tomato to ensure the sustainable production of tomato. Melatonin plays an important role in plant growth, development and stress response. At present, the mechanism of melatonin regulating cold resistance and drought resistance of tomato is rare. In this study, tomato was used as experimental material. The photosynthetic ability, non-photochemical quenching level, antioxidant system, cold response gene expression and osmotic regulatory substance accumulation in tomato leaves were measured under low temperature and water stress. The effects of melatonin on tomato low temperature stress and water stress were studied and its mechanism was discussed. The main results are as follows: 1. Melatonin alleviates the injury of tomato plants caused by low temperature. The pretreatment of melatonin could significantly improve the photosynthetic ability of tomato plants under low temperature stress and alleviate the oxidative stress caused by low temperature, which showed that melatonin treatment could reduce the content of malondialdehyde and electrolyte permeability. The activities of antioxidant enzymes and the contents of non-enzymatic antioxidants in tomato under low temperature stress were increased, and the antioxidant capacity of tomato was enhanced. Melatonin promoted the expression of Jingtian heptanone glycosyldiphosphatase gene and maintained the activity of Jingtian heptanone glycosyldiphosphatase under low temperature stress, which was helpful to improve the photosynthetic ability of tomato leaves under low temperature stress. Melatonin significantly induced the expression of cold response genes and the accumulation of soluble sugar and proline in tomato under low temperature stress, which played an important role in improving the cold resistance of tomato. 2. Melatonin alleviated the photoinhibition of tomato under low temperature stress. Melatonin treatment promoted the expression of Purple lutein Decyclooxygenase gene and the content of ascorbic acid in lutein cycle of tomato leaves under low temperature stress, so as to improve the activity of purple lutein de-cyclooxygenase. The increase of the activity of violaxanthin deepoxylase caused the increase of lutein deepoxidation level, which increased the non-photochemical quenching level and alleviated the photoinhibition induced by low temperature stress of tomato. 3. Melatonin alleviated tomato water stress. Melatonin significantly increased the photosynthetic capacity of tomato under drought conditions and decreased the oxidative injury induced by drought, and increased the antioxidant capacity of tomato. Melatonin promoted the expression of epidermal wax synthesis gene, increased the content of epidermal wax, and reduced the loss of non-stomatal moisture in tomato leaves. Melatonin significantly changed the osmotic potential gradient between old and young leaves of tomato under water stress. These results suggest that melatonin treatment can alleviate water stress in tomato. 4. 4. Melatonin may depend on ABA to regulate the antioxidant capacity of tomato under water stress. Melatonin significantly reduced the oxidative damage induced by drought and significantly increased the antioxidant ability of tomato leaves. However, the effect of melatonin on tomato was decreased after treated with ABA biosynthesis inhibitor flurazone. The effects of melatonin on malondialdehyde (MDA) content, electrolyte permeability and antioxidant enzymes in tomato leaves were significantly decreased after treatment with flurazone, suggesting that melatonin may depend on ABA to improve the antioxidant capacity of tomato.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S641.2

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