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。
译 名：
Effects of nitrate uptake on the changes of plasma membrane potential of rice roots
作 者：
YIN Xiao-ming,FAN Xiao-rong,JIA Li-jun,CAO yun,SHEN Qi-rong~*(College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China)
关键词：
rice root;NO~-_3concentration;plasma membrane potential
摘 要：
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 NO~-_3(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 NO~-_3 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) NO~-_3,the magnitude of depolarization increased with the increasing of NO~-_3 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) NO~-_3 but it reached the largest size,i.e.,40.2mV in 0.5(mmol/L) NO~-_3.The magnitude of depolariztion declined with the further increasing of NO~-_3 from 1—2(mmol/L). The course of NO~-_3 uptake by rice roots reflected by the response of depolarization of plasma membrane potential to external NO~-_3 concentrations exhibited Michaelis-Menten kinetics.2) Partial and complete repolarizations after depolariztion were found during the uptake of NO~-_3.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 NO~-_3 in rice roots was inhibited by PGO,an inhibitor of NO~-_3 transporter,showing that the transport through plasma membrane was completely finished by the NO~-_3 transporters in rice roots.4) Ca~(2+) mainly caused hyperpolarization in rice roots that precultured in CaSO_4 solution.
