脱水胁迫对连翘和冬青卫矛叶片细胞质外体和微环境的影响

用压力室、电导法和原子吸收分光光度分析法综合分析测定了连翘[Forsythiasuspensa (Thunb.) Vahl]和冬青卫矛(Euonymus japonicus Thunb.)在不同程度脱水胁迫时细胞外部微环境的变化.结果表明:(1)在脱水胁迫条件下,叶片细胞随着脱水胁迫强度的加大,细胞内离子外渗的累计量不断加大,但细胞内离子外渗的速度在不同的区间内并无明显的改变,即细胞膜的透性在所测范围内没有明显变化.(2)脱水胁迫同时造成了叶片质外体和共质体溶液中钠、钾离子浓度的增加,但质外体比共质体溶液中钠、钾离子浓度的增加幅度更高,导致细胞内、外离子浓度梯度的改变和离子平衡膜电位的改变,这些改变有可能引起细胞的次生生理变化,并有可能与植物的伤害反应和抗性有关.

Impact of Dehydration Stress on the Apoplasts and the Micro-environment of Cells in the Leaves of Forsythia suspensa and Euonymus japonicus

The impact of dehydration stress on the apoplasts and the microenvironment of cells in leaves in Forsythia suspensa(Thunb.) Vahl and Euonymus japonicus Thunb.were analysed by means of the pressure probe,electrolyte conductivity,and atomic absorption spectroscopy.The results showed that the leakage of electrolytes from cells to apoplastic spaces increased with the increase of the intensity of dehydration stress.However,in contrast to the conventional view that dehydration stress would result in enhanced permeability of plasma membrane,our result showed that the rate of electrolyte leakage did not show significant change in the dehydration process,although the amount of sodium and potassium did increase with elevated dehydration levels.The stepwise analysis showed that the increase in apoplastic ions was due to the accumulation of ions in the efflux following the dehydration process rather than the enhanced permeability of plasma membrane.Although dehydration stress resulted in the increases in sodium and potassium concentrations both in the symplasts and apoplasts of both plants,the increases in the apoplasts were much faster,leading to the alteration of the ion gradient as well as the shift of membrane potential across the cell membrane.These changes may bring secondary physiological changes to plants under dehydration stress.