Neumann P M, Van Volkenburgh E, Cleland R E
Department of Botany, University of Washington, Seattle 98195, USA.
Plant Physiol. 1988;88(1):233-7. doi: 10.1104/pp.88.1.233.
Treatment of bean (Phaseolus vulgaris L.) seedlings with low levels of salinity (50 or 100 millimolar NaCl) decreased the rate of light-induced leaf cell expansion in the primary leaves over a 3 day period. This decrease could be due to a reduction in one or both of the primary cellular growth parameters: wall extensibility and cell turgor. Wall extensibility was assessed by the Instron technique. Salinity did not decrease extensibility and caused small increases relative to the controls after 72 hours. On the other hand, 50 millimolar NaCl caused a significant reduction in leaf bulk turgor at 24 hours; adaptive decreases in leaf osmotic potential (osmotic adjustment) were more than compensated by parallel decreases in xylem tension potential and the leaf apoplastic solute potential, resulting in a decreased leaf water potential. It is concluded that in bean seedlings, mild salinity initially affects leaf growth rate by a decrease in turgor rather than by a reduction in wall extensibility. Moreover, long-term salinization (10 days) resulted in an apparent mechanical adjustment, i.e. an increase in wall extensibility, which may help counteract reductions in turgor and maintain leaf growth rates.
用低水平盐度（50或100毫摩尔氯化钠）处理菜豆（菜豆属普通菜豆）幼苗，在3天时间内降低了初生叶中光诱导的叶细胞扩展速率。这种降低可能是由于一个或两个主要细胞生长参数的降低：细胞壁伸展性和细胞膨压。通过英斯特朗技术评估细胞壁伸展性。盐度并未降低伸展性，且在72小时后相对于对照有小幅增加。另一方面，50毫摩尔氯化钠在24小时时导致叶片整体膨压显著降低；叶片渗透势（渗透调节）的适应性降低被木质部张力势和叶片质外体溶质势的平行降低所抵消，导致叶片水势降低。得出的结论是，在菜豆幼苗中，轻度盐度最初通过降低膨压而非通过降低细胞壁伸展性来影响叶片生长速率。此外，长期盐化（10天）导致明显的机械调节，即细胞壁伸展性增加，这可能有助于抵消膨压的降低并维持叶片生长速率。
