Departamento de Mejora Vegetal, Estación Experimental La Mayora, Consejo Superior de Investigaciones Cientí ficas, 29750 Algarrobo-Costa, Málaga, Spain.
Physiol Plant. 2009 Sep;137(1):36-43. doi: 10.1111/j.1399-3054.2009.01259.x. Epub 2009 Jun 9.
The tos1 (tomato osmotically sensitive) mutant, isolated from an in vitro screen of root growth during osmotic stress, was less sensitive to exogenous ABA, but accumulated more ABA under osmotic stress than WT plants. We assessed growth and water relations characteristics of hydroponically grown tos1 seedlings (in the absence of osmotic stress) at low and high evaporative demands. Growth of tos1 was severely inhibited at both high and low evaporative demands. Twenty DAS, WT and tos1 genotypes had a similar leaf water and turgor potential, but mature tos1 plants (45 day old) showed a significant diurnal loss of leaf turgor, with recovery overnight. Increased evaporative demand increased turgor loss of tos1 plants. High evaporative demand at the beginning of the day decreased stomatal conductance of tos1, without diurnal recovery, thus whole plant transpiration was decreased. De-topped tos1 seedlings showed decreased root hydraulic conductance and had a 1.4-fold increase in root ABA concentration. Impaired root function of tos1 plants failed to meet transpirational water demand and resulted in shoot turgor loss, stomatal closure and growth inhibition.
tos1（番茄渗透敏感）突变体是从渗透胁迫下的根生长体外筛选中分离出来的，与 WT 植物相比，它对外源 ABA 的敏感性较低，但在渗透胁迫下积累的 ABA 更多。我们评估了在低和高蒸发需求下水培生长的 tos1 幼苗（在没有渗透胁迫的情况下）的生长和水分关系特性。tos1 的生长在高和低蒸发需求下都受到严重抑制。20 DAS 时，WT 和 tos1 基因型具有相似的叶片水势和膨压势，但成熟的 tos1 植株（45 天大）表现出明显的叶片膨压昼夜损失，夜间恢复。增加蒸发需求会增加 tos1 植株的膨压损失。一天开始时高蒸发需求降低了 tos1 的气孔导度，没有昼夜恢复，因此整个植物的蒸腾作用降低。去顶 tos1 幼苗表现出根水力传导率降低，根 ABA 浓度增加了 1.4 倍。tos1 植物的根系功能受损，无法满足蒸腾需水，导致叶片膨压损失、气孔关闭和生长抑制。
