【作者】 窦伟；

【导师】 张华；

【作者基本信息】 合肥工业大学 ， 植物学， 2010， 硕士

【摘要】 硫化氢在动物体内作为一种具有生物活性的信号分子和氧化还原分子,业已被证明与气体信号物质NO和CO具有类似的生理功能。H2S在植物体中的生理功能以及相关信号机制的探究还刚刚起步,关于H2S是否能够作为一种信号调节物质,缓解植物体因盐胁迫和铝胁迫所引起的氧化损伤,目前尚未见文献报道。本文中以NaHS作为H2S供体,研究不同浓度的NaHS预处理小麦种子,探查其对盐胁迫和铝胁迫下的小麦种子萌发状况的影响,并对其可能的生理生化调节机制进行了初步的探讨和研究。盐(NaCl)胁迫严重抑制种子萌发,并且伴随着浓度的上升,胁迫作用逐步加重,严重影响小麦种子的胚根、胚芽的生长发育。通过实验研究发现,当NaCl浓度为0.16 mol/L时,小麦种子的发芽率约为对照组的一半,本文采用此浓度作为盐胁迫对小麦种子萌发的半抑制浓度。铝(Aluminum)离子在很低的浓度下,即对小麦种子的萌发产生明显的抑制效果,特别是对于胚根的生长的抑制效果尤其明显。伴随着Al3+浓度的上升,小麦种子的萌发率、根长和芽长逐渐降低,在Al3+浓度为30 mmol/L时,种子的萌发率相对于对照组降低50%,当Al3+大于30 mmol/L时,胚根的生长完全停止。以NaHS作为H2S供体研究发现,H2S供体NaHS能够显著缓解NaCl和AlCl3的胁迫作用,促进胁迫条件下小麦种子的萌发,并且具有一定的浓度依赖效应：在1.2 mmol/L的浓度下,NaHS缓解NaCl胁迫效果最为明显,其根长、芽长、发根数等都有很大提高,高于此浓度则显示出抑制作用；另一方面,浓度为0.6 mmol/L的NaHS缓解AlCl3胁迫的效果最为显著。NaHS的预处理可以显著提高小麦种子中淀粉酶和酯酶等水解酶的活性和还原糖的水平,促进胁迫条件下小麦种子中储藏物质的水解和动员。进一步研究H2S的抗氧化机理发现,H2S能诱导CAT、POD、APX和SOD等抗氧化酶活力的表达,抑制脂氧合酶(LOX)的活性,降低H2O2、O2-等活性氧(ROS)和膜质过氧化产物MDA的含量,从而缓解NaCl和AlCl3胁迫所诱导的氧化损伤。此外,H2S供体NaHS处理能够明显提高种子中内源H2S的水平。上述结果表明,H2S作为抗氧化信号分子介导了盐胁迫和铝胁迫下小麦种子萌发的内部机制。更多还原

【Abstract】 Hydrogen sulfide, as a signal and redox molecular with bioactivity, was proved to have the similar physiological function with nitric oxide and carbon monoxide in animals. It is just the beginning about the physical function and the related signal mechanism in plant. However, few studies have shown that H2S acts as a alleviant in plants under oxidative damage induced by salinity stress or aluminum stress. In this paper, we investigate that NaHS, as H2S donor, pretreated wheat seeds with different concentration affects seed germination and potential physiology and biochemistry mechanism under salinity stress or aluminum stress.Salnity (sadium chloride, NaCl) stress has badly inhibition on seed germination, radicle and coleoptile and becomes more seriously with the enhancement of concentration. We found that at the NaCl concentration of 0.16 mol/L germination percentage decreases about half of the control, which was regarded as semi-inhibitory concentration for subsequent experiments. Aluminum (Al) can significantly inhibit seed germination especially on radicle growth. With the enhancement of Al3+ concentration, germination percentage, length of radicle and coleoptile decreased gradually. At 30 mmol/L, germination percentage dropped by 50% compared with that of the control, when radicle growth nearly completely stopped.NaHS, H2S donor alleviated the inhibitory effect of NaCl and aluminum stress and promoted seed germination in a dose-dependent manner. The pretreatment with NaHS at 1.2 mmol/L could pronounced alleviate NaCl stress and increase the growth of radicle, coleptile and radicle numbers, when it was 0.6 mmol/L on aluminum stress. Besides, pretreated with NaHS could notably promote activities of hydrolase and content of reducing suger and amino acid. Further researches showed that H2S could induce the expression of antioxidase such as CAT, POD, APX and SOD, and sustain lower levels of LOX, ROS (H2O2, O2) and malondialdehyde which will result in oxidative stress. Furthermore, the pretreatment with NaHS, extraneous H2S donor enhanced levels of endogenous H2S. These data indicated that H2S was involved the mechanism of germination seeds as a anti-oxidant signal molecule under salinity stress and aluminum stress.更多还原