Low Temperature-Induced Changes of Abscisic Acid Contents in Barley and Cucumber Leaves in Relation to their Water Status

Abstract

Levels of abscisic acid (ABA) and its trans-isomer (t-ABA) were examined in comparison to changes in water status and development of injuries in primary leaves of barley (Hordeum vulgare) and in cotyledons of cucumber (Cucumis sativus) exposed to low temperature. In the chilling-tolerant barley no changes in water status and ABA content were observed during the low temperature treatment which lasted 96 h. In the cotyledons of the chilling-sensitive cucumber, however, 7–10 fold increases in ABA and t-ABA occurred which were related to temperature as well as to degree of humidity. The increase in ABA was preceded by low temperature-induced water stress. It is concluded that low temperature stress induces a rise in ABA through development of water stress. The possible protective function of the rise in ABA is discussed.