Department of Botany, Duke University, Durham, North Carolina 27706.
Plant Physiol. 1975 Feb;55(2):317-21. doi: 10.1104/pp.55.2.317.
The effects of low and high relative humidity and of polyethylene glycol-induced root water stress on chlorophyll accumulation, on formation of the lamellar chlorophyll-protein complexes, and on the development of photosynthetic activity during chloroplast differentiation were examined. Low relative humidity or polyethylene glycol-induced root water stress (stress conditions) resulted in a 3 to 4 hour lag in chlorophyll accumulation, retarded the rate of chlorophyll b accumulation, and reduced the rate of formation of the light-harvesting chlorophyll a/b protein. All of these effects could be overcome by high relative humidity (nonstress) conditions. Concomitant measurement of leaf water potential showed that under stress conditions greening leaves were subjected to initial water deficits of -8 bars which decreased to -5 bars after 3 to 4 hours of illumination corresponding to the end of the lag phase. Leaves greening under nonstress conditions did not experience leaf water deficits greater than about -5 bars. It seems that the attainment of a minimum leaf water potential of -5 bars may be critical in the control of early chloroplast development. These results demonstrate that the lag phase is not indicative of a programmed event in chloroplast development, but rather is attributable to environmental conditions prevailing during leaf development and greening.
研究了低相对湿度和高相对湿度以及聚乙二醇诱导的根系水分胁迫对叶绿素积累、类囊体叶绿素蛋白复合物形成以及叶绿体分化过程中光合活性发展的影响。低相对湿度或聚乙二醇诱导的根系水分胁迫（胁迫条件）导致叶绿素积累滞后 3 至 4 小时，延缓了叶绿素 b 积累的速度，并降低了光收集叶绿素 a/b 蛋白的形成速度。所有这些影响都可以通过高相对湿度（非胁迫）条件来克服。同时测量叶片水势表明，在胁迫条件下，正在变绿的叶片最初受到 -8 巴的水分亏缺，在 3 至 4 小时的光照后，水分亏缺减少到 -5 巴，相当于滞后阶段的结束。在非胁迫条件下变绿的叶片没有经历超过约 -5 巴的叶片水分亏缺。似乎达到 -5 巴的最小叶片水势可能是控制早期叶绿体发育的关键。这些结果表明，滞后阶段不是叶绿体发育中程序性事件的指标，而是归因于叶片发育和变绿过程中存在的环境条件。
