【作者】 赵普庆；

【导师】 汪俏梅；

【作者基本信息】 浙江大学 ， 蔬菜学， 2005， 硕士

【摘要】 本实验以新泰密刺黄瓜为实验材料,研究了生理活性最强的一种油菜素甾醇类（BRs）——油菜素内酯（BL）低温处理对次适温下黄瓜种子萌发的影响,并对其萌发过程中的生理生化变化进行了研究,结果表明: 1) BL在10^-9-10^-7M浓度范围内可以促进种子在次适温下的萌发,其中以10^-8M BL低温5℃处理三天效果最明显,能显著提高黄瓜种子在15℃下的萌发率、活力指数和根长。 2) BL处理能够减少黄瓜种子萌发过程中渗出液的相对电导率和256nm紫外吸收值。对其低温处理后渗出液中的Ca²⁺、Na⁺、Mg²⁺、K⁺四种离子的分析表明,BL处理可以减少低温处理过程中这四种离子的外渗,其中以Ca²⁺的减少最明显。在萌发过程中四种离子的外渗有类似的规律,但BL处理使萌发高峰期的K⁺/Na⁺和Mg²⁺/Ca²⁺的比值高于对照,表明K⁺/Na⁺和Mg²⁺/Ca²⁺可能更精确地反映种子活力的真实水平。 3) BL处理使黄瓜种子在萌发过程中碳水化合物含量均高于对照,以蔗糖的增加最为明显,表明黄瓜在次适温逆境下萌发过程中糖分的积累主要是以蔗糖为主。对黄瓜种子萌发过程中与蔗糖代谢相关的酶的活性分析表明,BL处理后可降低与蔗糖分解相关的蔗糖合成酶的活性;增强与蔗糖合成相关的蔗糖磷酸合成酶的活性,从而使蔗糖的含量增加。在整个萌发过程中,BL处理使淀粉酶的活力高于对照,从而使其淀粉含量低于对照。此外,BL处理使萌发过程中幼苗的蛋白质、游离氨基酸和脯氨酸的含量也较对照有所提高。 4) BL处理能提高萌发过程中幼苗的超氧化物歧化酶（SOD）,过氧化氢酶（CAT）的活性,可明显减缓酯酶活性下降趋势,从而使酯酶活性保持在一个较高的水平,并降低膜脂过氧化产物丙二醛（MDA）的含量。BL处理还能抑制H⁺-ATPase酶活性,特别是液泡中H⁺-ATPase的活性。Ca²⁺-ATPase活性在黄瓜萌发过程中有明显的变化,很可能参与了黄瓜逆境萌发过程的信号转导途径调节,这也为今后的信号转导研究提供了新的思路。更多还原

【Abstract】 The effect of Brassinolide (BL), the most active Brasinosteroids (BRs) treatments at low temperature on seed germination under suboptimal temperature and the physiological and biochemical changes during germination were analyzed in our study using cucumber (Cucumis sativus) variety "Xin tai mi ci" as the material. The main results are as follows:1) BL treatments at the concentration range of 10-9 to 10-7M can promote seed germination under suboptimal temperature, among which 10-8 M BL in a dark incubator at 5℃ for 3 days is most effective in improvement of germination rate, vigor index and root length during seed germination.2) BL treatment reduced relative electrical conductivity and 256nm UV absorbance of electrolyte during seed germination. The K+, Ca2+,Na+ and Mg2+ leakage in Ieachates were also reduced after 3 day BL treatment at 5℃, with the reduction of Ca2+ being the most significant. The K+、 Ca2+、 Na+ and Mg2+ leakage in leachates during germination changed similarly, but the ratios of K+/Na+ and Mg2+/Ca2+ by BL treatment were significantly higher than control at the peak of germination, which indicates that the ratios of K+/Na+ Mg2+/Ca2+might reflect the true level of seed vigor.3) The levels of different carbohydrates were higher in cucumber seedlings treated with BL than in control during germination, with sucrose being the most significant one, which indicated that the accumulate of carbohydrate was mainly in the form of sucrose during germination under suboptimal temperature stress. Analysis of activity of enzymes related to the metabolism of sucrose showed that BL treatment reduced the activity of sucrose synthase which contributes to the catabolism of sucrose, and increased the activity of sucrose-6-phosphate which contributes to the synthesis of sucrose. Therefore, the content of sucrose is increased by BL treatment. BL treatment increased the activity of amylase, which led to the lower level of starch in cucumber seedlings treated with BL than in control. In addition, BL treatment also increased the content of protein、 free amino acid and proline in cucumber seedlings during germination.4) BL treatment increased the activity of SOD and CAT, inhibited the decrease of the activity of botanical esterase, and therefore decreased the content of MDA in cucumber seedling during germination. BL treatment also inhibited the activity of H+-ATPase, especially the one in the vacuole. The significant change of Ca2+-ATPase activity during germination suggested the possible involvement of Ca2+-ATPase in the signaling pathway regulation of germination under stress, which might provide new insight into the signal tranducation study in the future.更多还原