Bernstein N., Lauchli A., Silk W. K.
Department of Land, Air and Water Resources, University of California, Davis, California 95616.
Plant Physiol. 1993 Dec;103(4):1107-1114. doi: 10.1104/pp.103.4.1107.
In many salt-sensitive species, elevated concentrations of Ca in the root growth media ameliorate part of the shoot growth reduction caused by NaCl stress. The physiological mechanisms by which Ca exerts protective effects on leaf growth are still not understood. Understanding growth inhibition caused by a stress necessitates locating the leaf expansion region and quantifying the profile of the growth reduction. This will enable comparisons and correlations with spatial gradients of probable physiologically inhibiting factors. In this work we applied the methods of growth kinematics to analyze the effects of elevated Ca concentrations on the spatial and temporal distributions of growth within the intercalary expanding region of salinized sorghum (Sorghum bicolor [L.] Moench, cv NK 265) leaves. NaCl (100 mM) caused a decrease in leaf elongation rate by shortening the leaf growing zone by 20%, as well as reducing the peak value of the longitudinal relative elemental growth rate (REG rate). Increasing the Ca concentrations from 1 to 10 mM restored the length of the growing zone of both emerged and unemerged salinized leaves and increased the peak value of the REG rate. The beneficial effects of supplemental Ca were, however, more pronounced in leaves after their appearance above the whorl of encircling older leaf sheaths. Elevated Ca then resulted in a peak value of REG rate higher than in the salinized leaves. The peak value of unemerged leaves was not increased, although it was maintained over a longer distance. The duration of elongation growth associated with a cell during its displacement from the leaf base was longer in salinized than control leaves, despite the fact that the elongation zone was shorter in salinity. Although partially restoring the length of the elongation region, supplemental Ca had no effect on the age of cessation of growth. Elongation of a tissue element, therefore, ceased when a cellular element reached a certain age and not a specific distance from the leaf base.
在许多盐敏感物种中，根部生长培养基中钙浓度的升高可缓解因氯化钠胁迫导致的部分地上部生长抑制。钙对叶片生长产生保护作用的生理机制仍不清楚。要了解由胁迫引起的生长抑制，就需要确定叶片扩展区域并量化生长减少的情况。这将有助于与可能的生理抑制因子的空间梯度进行比较和关联。在这项研究中，我们应用生长运动学方法来分析钙浓度升高对盐渍化高粱（高粱[L.] Moench，品种NK 265）叶片居间扩展区域内生长的空间和时间分布的影响。100 mM的氯化钠通过使叶片生长区缩短20%，导致叶片伸长率降低，同时也降低了纵向相对元素生长速率（REG速率）的峰值。将钙浓度从1 mM提高到10 mM可恢复已出现和未出现的盐渍化叶片生长区的长度，并提高REG速率的峰值。然而，补充钙的有益效果在叶片从包围的老叶鞘轮生体上方出现后更为明显。钙浓度升高后，REG速率的峰值高于盐渍化叶片。未出现叶片的峰值没有增加，尽管其在更长的距离上保持。尽管盐渍化叶片的伸长区较短，但与细胞从叶基部位移相关的伸长生长持续时间在盐渍化叶片中比对照叶片更长。尽管补充钙部分恢复了伸长区域的长度，但对生长停止的年龄没有影响。因此，当细胞成分达到一定年龄而不是距叶基部的特定距离时，组织成分的伸长就会停止。
