Effect of Whole Plant and Local Heating on the ABA Content in Cucumber Seedling Leaves and Roots and on Their Heat Tolerance

Abstract

The effects of heating at 38°C of whole cucumber (Cucumis sativus L.) seedlings or local heating of their shoots and roots on ABA content and heat tolerance of leaves and roots were investigated. During the initial period of the high-temperature treatment of whole seedlings, the ABA concentration in leaves and roots increased considerably. Local heating of the shoot or root resulted in an increase in the ABA concentration not only in the heated organ, but also in unheated seedling parts. A high-temperature treatment of the whole seedlings and the local treatment of shoots or roots caused an increase in the heat tolerance of leaf cells. The heat tolerance of root cells virtually did not change after heating of the whole seedlings or shoots, but decreased after heating of roots. The possible role of ABA in changing the heat tolerance of leaf and root cells by local heating of the seedling is discussed.