Tanino K, Weiser C J, Fuchigami L H, Chen T H
Department of Horticulture, Oregon State University, Corvallis, Oregon 97331-2911.
Plant Physiol. 1990 Jun;93(2):460-4. doi: 10.1104/pp.93.2.460.
Changes in water content and dry weight were determined in control cells and those induced to cold harden in response to abscisic acid (ABA) treatment (7.5 x 10(-5) molar). Bromegrass (Bromus inermis Leyss cv Manchar) cells grown in suspension culture at room temperature (23 degrees C) for 7 days acclimated to -28 degrees C (LT(50)) when treated with ABA, or to -5 degrees C when untreated. ABA significantly reduced cell growth rates at 5 and 7 days after treatment. Growth reduction was due to a decrease in cell number rather than cell size. When the cell water content was expressed as percent water (percent H(2)O) or as grams water per gram dry weight (gram H(2)O/gram dry weight [g DW]), the water content of hardy, ABA-treated cells decreased from 85% to 77% or from 6.4 to 3.3 g H(2)O/g DW in 7 days. Control cell water content remained static at approximately 87% and 7.5 g H(2)O/g DW. However, cell water content, expressed as milligrams water per million cells (milligram H(2)O/10(6) cells), did not differ in ABA-treated or control cells. The dry matter content of ABA-treated cells, expressed as milligram DW/10(6) cells increased to 3.3 milligram/10(6) cells in 7 days, whereas the dry weight of the control cells remained between 1.4 to 2.1 milligrams/10(6) cells. The osmotic potential of ABA-treated cells decreased by the fifth day while that of control cells increased significantly and then decreased by day 7. Elevated osmotic potentials were not associated with increased ion uptake. In contrast to much published literature, these results suggest that cell water content does not decrease in ABA-treated cells during the induction of freezing tolerance, rather the dry matter mass per cell increased. Cell water content may be more accurately expressed as a function of cell number when accompanying changes to dry cell matter occur.
测定了对照细胞以及经脱落酸（ABA）处理（7.5×10⁻⁵摩尔）诱导进行抗寒锻炼的细胞的含水量和干重变化。在室温（23℃）下悬浮培养7天的无芒雀麦（Bromus inermis Leyss cv Manchar）细胞，经ABA处理后可适应-28℃（LT₅₀），未处理则只能适应-5℃。ABA在处理后第5天和第7天显著降低了细胞生长速率。生长速率降低是由于细胞数量减少而非细胞大小减小。当细胞含水量以水的百分比（H₂O百分比）或每克干重的水克数（克H₂O/克干重[g DW]）表示时，经ABA处理的耐寒细胞的含水量在7天内从85%降至77%，或从6.4降至3.3克H₂O/克DW。对照细胞的含水量保持在约87%和7.5克H₂O/克DW不变。然而，以每百万细胞的水毫克数（毫克H₂O/10⁶细胞）表示时，经ABA处理的细胞和对照细胞的含水量并无差异。经ABA处理的细胞的干物质含量，以毫克DW/10⁶细胞表示，在7天内增加到3.3毫克/10⁶细胞，而对照细胞的干重保持在1.4至2.1毫克/10⁶细胞之间。经ABA处理的细胞的渗透势在第5天下降，而对照细胞的渗透势在第7天显著升高后又下降。渗透势升高与离子吸收增加无关。与许多已发表的文献不同，这些结果表明，在诱导抗冻性过程中，经ABA处理的细胞含水量并未降低，而是每个细胞的干物质质量增加。当伴随干细胞物质发生变化时，细胞含水量可能更准确地表示为细胞数量的函数。
