United States Salinity Laboratory, Soil and Water Conservation Research Division, Agricultural Research Service, United States Department of Agriculture, Riverside, California 92502.
Plant Physiol. 1971 Mar;47(3):361-5. doi: 10.1104/pp.47.3.361.
A perfusion method is described whereby large discs of amphistomatous leaves are vacuum-perfused with water so that either successive fractions of perfusate may be analyzed for solutes or the infused water may be displaced and collected after equilibration with the leaf cells. With castor bean leaves, estimates of electrolyte concentration in cell wall water by the two methods were similar. Total electrolytes in leaf cell wall water of castor beans (Ricinus communis), sunflower (Helianthus annuus), and cabbage (Brassica oleracea capitata) from nonsaline cultures were about 2, 2, and 10 milliequivalents per liter, respectively, increasing to 4, 10, and 30 milliequivalents per liter under saline conditions. Electrolytes recovered in successive fractions were similar in composition, and continuous perfusion resulted in a steady release of solutes, the concentration in the perfusate varying inversely with the perfusion rate. Diffusional release of solutes from cells was less than expected at low perfusion rates, suggesting that solute reabsorption may increase as solute concentration in the perfusate increases with decreased perfusion rates. Perfusate concentration and composition were essentially unaffected by temperature (2 and 23 C) or by perfusing with 0.5 mm CaSO(4) rather than with water. Electrolytes in perfusates on an equivalent basis were Ca(2+), 30%; Mg(2+), 10%; and Na(+) + K(+), 60%, the proportions of sodium increasing from 10 to 50% in leaves (cabbage) that accumulated sodium under saline conditions. Salinity (added NaCl) of the root culture medium caused a 3- to 5-fold increase in total cell wall electrolyte concentration, but this amounted to an increase from less than 1 or a few per cent to no more than 7% (in cabbage) of the cell sap electrolyte concentrations. Solutes in the cell wall appear to be in dynamic equilibrium with intracellular solutes.
描述了一种灌注方法，通过该方法可以对具有两室气孔的叶片进行真空水灌注，以便对连续的灌注液级分进行分析以检测溶质，或者在与叶片细胞达到平衡后将灌注水置换和收集。对于蓖麻叶，两种方法估计的细胞壁水溶质浓度相似。非盐生培养的菜豆（Ricinus communis）、向日葵（Helianthus annuus）和结球甘蓝（Brassica oleracea capitata）叶片细胞壁水总电解质分别约为 2、2 和 10 毫当量/升，在盐生条件下分别增加到 4、10 和 30 毫当量/升。连续级分中回收的电解质组成相似，连续灌注导致溶质稳定释放，灌注率与灌注液浓度成反比。在低灌注率下，细胞中溶质的扩散释放低于预期，表明随着灌注液中溶质浓度的增加（由于灌注率降低），溶质可能会被重新吸收。在 2 和 23°C 的温度下，或用 0.5 mM CaSO4 而不是水进行灌注时，灌注液的浓度和组成基本不受影响。在等当量基础上，灌注液中的电解质为 Ca2+，30%；Mg2+，10%；和 Na++K+，60%，在盐生条件下积累钠的叶片（结球甘蓝）中，钠的比例从 10%增加到 50%。根培养液中的盐度（添加 NaCl）使总细胞壁电解质浓度增加 3-5 倍，但这相当于细胞溶质电解质浓度的增加不到 1%或几个百分点，不超过 7%（在结球甘蓝中）。细胞壁中的溶质似乎与细胞内溶质处于动态平衡中。
