【作者】 单树花；

【导师】 宋克敏；

【作者基本信息】 华中农业大学 ， 植物学， 2005， 硕士

【摘要】 本文以“世纪星”番茄为材料,研究了磷饥饿下番茄幼苗的生长状况、体内磷含量的变化及其根部液泡膜H~+-ATPase活性的适应性变化。研究获得的主要结果如下: 1 磷饥饿下番茄幼苗的平均高度均低于供磷充足的对照苗的平均高度,而平均主根长度在整个胁迫期间里均显著长于对照。另外,磷饥饿初期对番茄幼苗鲜重累积影响不大,但随着饥饿的继续,受胁迫的番茄幼苗的鲜重累积与对照间的差异逐渐加大并且明显低于对照。磷饥饿还降低了番茄幼苗的干重累积,但不是很明显。 2 磷饥饿下番茄幼苗根部及地上部Pi含量随饥饿时间的延长不断下降且均低于对照,对照苗Pi含量则比较稳定。 3 磷饥饿时,番茄幼苗的Pi吸收速率大大增加且明显高于对照,且当胁迫7d时达到Pi吸收的高峰。 4 磷饥饿提高了番茄幼苗根部液泡膜H~+-ATPase的水解活性。随着磷胁迫时间的延长,液泡膜H~+-ATPase水解活性增大,在磷饥饿第七天时达到最大,后又稍有所降低。而对照的番茄幼苗根部液泡膜H~+-ATPase的水解活性基本保持不变。动力学分析表明:磷饥饿使番茄幼苗根部液泡膜H~+-ATPase酶的Km值明显降低,但对该酶的Vmax影响不大。这说明磷饥饿提高了该酶对其底物的亲和力。此外,磷饥饿并不改变H~+-ATPase酶的最适pH值(最适pH值7.5)。 5 用连续监测吖啶橙的荧光猝灭法测定了番茄幼苗根系液泡膜H~+-ATPase的质子转运活性。结果表明:磷饥饿提高了番茄幼苗根系液泡膜H~+-ATPase质子转运活性。这说明,磷饥饿能刺激番茄幼苗根系液泡膜H~+-ATPase的质子转运活性。 综合以上结果,推测液泡对胞质Pi稳态的调节作用可能与V型H~+-ATPase活性变化有关。更多还原

【Abstract】 The paper has studied the effects of phosphate starvation on growth state and the change of Pi contents from tomato seedlings and the adaptive changes of H⁺-ATPase activity in tonoplast vesicles under phosphate starvation by different days （5d, 7d, 9d, 11d, 13d） sampling from the roots of tomato seedlings. The results are as follows:1. The average height of the seedlings decreased to a certain degree under phosphate starvation, while the main roots of the seedlings were obviously longer than those of the controls. In addition, the early days of phosphate starvation had no obvious effect on the fresh weight （FW） accumulation of the seedlings gradually became markedly less than the control. Phosphate starvation also decreased the dry weight （DW） accumulation of the seedlings.2. Under Pi-Starved conditions, the Pi contents of main root and overground seedlings decreased continually while the late days of phosphate starvation and were obviously less than the control.3. Tomato seedlings distinctly increased their Pi uptake rates that were much higher than the controls after 7d of Phosphate starvation.4. The hydrolytic activity of H⁺-ATPase in tonoplast vesicles from the roots of tomato seedlings was increased under phosphate starvation. The hydrolytic activity was highest to phosphate starvation for 7 days. Therefore the hydrolytic activity that of the controls was unchanged. Kinetic analysis of the tonoplast H⁺-ATPase from the roots of tomato seedlings showed that phosphate starvation obviously lowered the Km value, which indicated that phosphate starvation increased the affinity of the enzyme to its substrate, but had no significant effect on the V_max value of the enzyme. In addition, phosphate starvation did not alter the optimum pH of the ATPase. The optimal pH for H⁺-ATPase activity was 7.5.5. The properties of proton pumping activity of H⁺-ATPase in tonoplast vesicleswere studied by acridine orange fluorescent quenching measured at 22°C. the proton pumping activity of H+-ATPase was increased under phosphate starvation. The results in the study showed that salinity stimulated the increase of the pump efficiency of the V-H+-ATPase from roots.To a certain degree, these results suggest that the V-ATPase was involved in the induction of high-affinity phosphate transport systems by phosphate starvation.更多还原