Lynch J, Cramer G R, Läuchli A
Department of Land, Air, and Water Resources, University of California, Davis, California 95616.
Plant Physiol. 1987 Feb;83(2):390-4. doi: 10.1104/pp.83.2.390.
Calcium is an important factor in the ability of plants to resist salt stress, possibly because of its role in maintaining membrane integrity. We studied the effects of NaCl stress on membrane-associated Ca in corn root protoplasts (Zea mays L. cv Pioneer 3377) using the fluorescent Ca probe chlorotetracycline (CTC). Protoplasts were isolated from the cortex of primary roots of corn seedlings (Gronwald and Leonard, Plant Physiol 1982 70: 1391-1395). After a 30 minute incubation in 50 micromolar CTC, the protoplasts were exposed to isosmotic treatment solutions containing various concentrations of NaCl just before fluorimetric analysis. Increasing NaCl concentrations caused a progressive reduction in net CTC fluorescence, to 50% of control values at 150 mm NaCl. NaCl did not displace CTC from the cells, nor did it directly interfere with Ca-CTC binding. Tests with CsCl, RbCl, KCl, LiCl, Na(2)SO(4), NaNO(3), and NaBr indicated that the reduction in CTC fluorescence was not specific to either Na or Cl, but may have been due to increased ionic strength of the treatment solutions. Like CTC fluorescence, root growth of intact corn seedlings was not specifically sensitive to Na, but was inhibited by several monovalent cations in the order Li > Cs >> Rb > Na > K. CTC fluorescence at 100 mm NaCl was restored to unstressed levels by increasing Ca concentrations. Since our salt treatments were isosmotic, we conclude that the ionic component of salt stress displaces Ca from membranes of corn root cells.
钙是植物抵抗盐胁迫能力的一个重要因素，这可能是因为它在维持膜完整性方面发挥作用。我们使用荧光钙探针氯四环素（CTC）研究了NaCl胁迫对玉米根原生质体（玉米品种先锋3377）中与膜相关的钙的影响。原生质体从玉米幼苗初生根的皮层中分离出来（Gronwald和Leonard，《植物生理学》1982年，70：1391 - 1395）。在50微摩尔的CTC中孵育30分钟后，就在荧光分析之前，将原生质体暴露于含有不同浓度NaCl的等渗处理溶液中。NaCl浓度的增加导致净CTC荧光逐渐降低，在150毫米NaCl时降至对照值的50%。NaCl既没有将CTC从细胞中置换出来，也没有直接干扰Ca - CTC结合。用CsCl、RbCl、KCl、LiCl、Na₂SO₄、NaNO₃和NaBr进行的测试表明，CTC荧光的降低并非特定于Na或Cl，而可能是由于处理溶液离子强度的增加。与CTC荧光一样，完整玉米幼苗的根生长并非对Na特别敏感，而是被几种单价阳离子按Li > Cs >> Rb > Na > K的顺序抑制。通过增加钙浓度，100毫米NaCl时的CTC荧光恢复到未受胁迫的水平。由于我们的盐处理是等渗的，我们得出结论，盐胁迫的离子成分将钙从玉米根细胞膜中置换出来。
