摘要
利用玻璃微电极技术测定了扬稻6号(籼稻)幼苗根尖细胞在吸收不同NO3-浓度(0.01、0.02、0.1、0.2、0.5、1.0和2.0 mmol/L)过程中膜电位的变化。结果表明,1)水稻根系吸收NO3-引起膜的去极化,去极化到一定程度后出现复极化;有小部分水稻根表现为超极化。在0.011~.0 mmol/L范围内,去极化大小随外界NO3-浓度的增加而增加,且差异显著(P<0.05)。0.01 mmol/L NO3-产生较小的去极化,平均为3.8 mV;0.5 mmol/L NO3-产生了最大去极化,平均为40.2 mV;当外界NO3-浓度大于1.0 mmol/L时膜电位去极化大小呈下降趋势。根系吸收不同浓度的NO3-而使膜电位去极化的进程符合Michaelis-Menten动力学。2)复极化有部分复极化和完全复极化两种。超极化也有两种:一种是膜电位先超极化,后缓慢复极化;另一种是先出现一个小的去极化,然后是较大幅度的超极化。3)运输蛋白抑制剂PGO抑制了根系吸收NO3-而产生的膜电位的响应。4)对于经CaSO4溶液预培养的水稻来说,Ca2+主要引起膜电位超极化。
Changes of plasma membrane potential in young root tip cells of rice （ Oryza Sativa L）, Yang dao 6 （Indica） were monitored using glass microelectrodes during the uptake of different concentrations of NO3^- （0.01,0.02, 0.1, 0.2, 0.5, 1.0 and 2.0 mmol/L, respectively）. The results were as follows： 1） The absorption of NO3^- by the roots made membrane potential depolarized and then repolarized. Furthermore, hyperpolarization was found in some root cells. Within concentration of 0.01-1 mmol/L NO3^- , the magnitude of depolarization increased with the increasing of NO3^- concentrations and there existed a significant difference in the size of depolarization between treatments （ P 〈 0.05）. The average depolarization, for example, was only 3.8 mV under the concentrations of 0.01 mmol/L NO3^- but it reached the largest size, i.e., 40.2mV in 0.5 mmol/L NO3^- . The magnitude of depolariztion declined with the further increasing of NO3^- from 1-2 mmol/L. The course of NO3^- uptake by rice roots reflected by the response of depolarization of plasma membrane potential to external NO3^- concentrations exhibited Michaelis-Menten kinetics. 2） Partial and complete repolarizations after depolariztion were found during the uptake of NO3^-. Hyperpolarization also displayed two modes： one was the hyperpolarization followed by a slow repolarization and the other was a big hyperpolarization after a small depolarization. 3） The response of the membrane potential to NO3^- in rice roots was inhibited by PGO, an inhibitor of NO3^- transporter, showing that the transport through plasma membrane was completely finished by the NO3^- transporters in rice roots. 4） Ca^2＋ mainly caused hyperpolarization in rice roots that precultured in CaSO4 solution.
出处
《植物营养与肥料学报》
CAS
CSCD
北大核心
2006年第4期500-505,共6页
Journal of Plant Nutrition and Fertilizers
基金
国家自然科学基金项目(40471074
30390082)资助
关键词
水稻根
NO3^-
浓度
膜电位
rice root
NO3^- concentration
plasma membrane potential
