Lehrstuhl Botanik I, Universität Würzburg, Mittlerer Dallenbergweg 64, 8700 Würzburg, Federal Republic of Germany.
Plant Physiol. 1991 Nov;97(3):990-7. doi: 10.1104/pp.97.3.990.
Salt tolerant spinach (Spinacia oleracea) and salt sensitive pea (Pisum sativum) plants were exposed to mild salinity under identical growth conditions. In order to compare the ability of the two species for extra- and intracellular solute compartmentation in leaves, various solutes were determined in intercellular washing fluids and in aqueously isolated intact chloroplasts. In pea plants exposed to 100 millimolar NaCl for 14 days, apoplastic salt concentrations in leaflets increased continuously with time up to 204 (Cl(-)) and 87 millimolar (Na(+)), whereas the two ions reached a steady concentration of only 13 and 7 millimolar, respectively, in spinach leaves. In isolated intact chloroplasts from both species, sodium concentrations were not much different, but chloride concentrations were significantly higher in pea than in spinach. Together with data from whole leaf extracts, these measurements permitted an estimation of apoplastic, cytoplasmic, and vacuolar solute concentrations. Sodium and chloride concentration gradients across the tonoplast were rather similar in both species, but spinach was able to maintain much steeper sodium gradients across the plasmamembrane compared with peas. Between day 12 and day 17, concentrations of other inorganic ions in the pea leaf apoplast increased abruptly, indicating the onset of cell disintegration. It is concluded that the differential salt sensitivity of pea and spinach cannot be traced back to a single plant performance. Major differences appear to be the inability of pea to control salt accumulation in the shoot, to maintain steep ion gradients across the leaf cell plasmalemma, and to synthesize compatible solutes. Perhaps less important is a lower selectivity of pea for K(+)/Na(+) and NO(3) (-)/Cl(-) uptake by roots.
在相同的生长条件下，将耐盐菠菜（Spinacia oleracea）和盐敏感豌豆（Pisum sativum）暴露于轻度盐胁迫下。为了比较这两个物种在叶片中外源和细胞内溶质区室化的能力，在细胞间洗涤液和水分离的完整叶绿体中测定了各种溶质。在暴露于 100 毫摩尔 NaCl 14 天的豌豆植物中，叶小片中的质外体盐浓度随时间持续增加，分别达到 204（Cl(-))和 87 毫摩尔（Na(+))，而这两种离子在菠菜叶片中仅达到 13 和 7 毫摩尔的稳定浓度。在来自两个物种的分离完整叶绿体中，钠离子浓度没有太大差异，但氯离子浓度在豌豆中明显高于菠菜。结合来自整片叶提取物的数据，这些测量值允许估计质外体、细胞质和液泡溶质浓度。两种物种质膜中的钠和氯离子浓度梯度相当相似，但与豌豆相比，菠菜能够维持穿过质膜的更高的钠浓度梯度。在第 12 天到第 17 天之间，豌豆叶片质外体中其他无机离子的浓度突然增加，表明细胞开始解体。研究得出结论，豌豆和菠菜的差异盐敏感性不能归因于单一的植物表现。主要差异似乎是豌豆无法控制地上部分的盐积累，无法维持叶片细胞质膜中的陡峭离子梯度，也无法合成相容的溶质。或许不太重要的是豌豆对 K(+)/Na(+)和 NO(3) (-)/Cl(-)吸收的选择性较低。
