Interactions between abscisic acid and cytokinins during water stress and subsequent rehydration

Abstract

With the aim to contribute to elucidation of the role of phytohormones in plant responses to stresses the endogenous contents of abscisic acid (ABA) and cytokinins (CK) were followed in French bean, maize, sugar beet, and tobacco during water stress and subsequent rehydration. The effects of pre-treatments with exogenous ABA or benzyladenine (BA) before imposition of water stress were also evaluated. The content of ABA increased by water stress, and with the exception of bean plants increased content of ABA remained also after rehydration. In all plant species the ABA content was further increased by ABA pre-treatment, but in bean and maize it decreased by BA pre-treatment. The highest total content of CK was observed in bean and the lowest in maize during water stress. In their spectrum, the storage CK were dominant in bean, and inactive CK in tobacco while in sugar beet and maize all groups were present in comparable amounts. In all plant species, the contents of CK increased during water stress and with exception of bean they decreased back after rehydration. ABA pre-treatment further increased contents of CK in water-stressed bean and tobacco. BA pretreatment increased contents of CK in sugar beet and tobacco after rehydration.Additional key words: benzyladenine, isopentenyladenine, Phaseolus vulgaris, relative water content, zeatin, zeatin riboside.

Analysis of Cytokinin Mutants and Regulation of Cytokinin Metabolic Genes Reveals Important Regulatory Roles of Cytokinins in Drought, Salt and Abscisic Acid Responses, and Abscisic Acid Biosynthesis

“…Generally, stresses, such as drought, decrease the production and transport of CKs from roots. Additionally, application of exogenous CKs can increase stomatal apertures and transpiration of many plants (Davies and Zhang, 1991;Pospisilova and Batkova, 2004;Pospisilova et al, 2005). In plants such as Arabidopsis thaliana, the key enzymes involved in CK metabolism are adenosine phosphate-isopentenyltransferases (IPTs) and CK oxidases/dehydrogenases (CKXs) (Hirose et al, 2008;Werner and Schmü lling, 2009).…”

“…Specifically, the accumulation of ABA promotes stomatal closure to minimize water loss, accelerates leaf senescence, downregulates plant growth, and induces the biosynthesis of protective substances (e.g., late embryogenesisabundant proteins). On the other hand, CKs trigger responses to delay both stomatal closure and leaf senescence (Finkelstein et al, 2002;Hansen and Dö rffling, 2003;Pospisilova, 2003;Chow and McCourt, 2004;Pospisilova and Batkova, 2004;Pospisilova et al, 2005). Many studies have focused on the molecular functions of ABA in relation to abiotic stress and vice versa and the influence of environmental stresses on ABA metabolism (Bartels and Sunkar, 2005;Hirayama and Shinozaki, 2010).…”

Role of abscisic acid and drought stress on the activities of antioxidant enzymes in wheat

“…It is reported to gradually degrade upon removal of stress (Zhang et al 2006). Pospíšilová et al (2005) reported that ABA pre treatment further increased the endogenous ABA level in maize seedling. Pre-soaking seed treatment with ABA was reported to significantly enhance the antioxidant enzymes activity in maize seedlings subjected to water stress (Jiang and Zhang 2002).…”

Effect of hydrogen cyanamide on the endogenous hormonal content of pea seedlings (Pisum sativum L.)

“…This increase in CK levels could be the consequence of this increased metabolic activity of stressed plants. Pospíšilová et al (2005) found a strong increase in endogenous levels of CKs in French bean and tobacco plants treated with 100 µM ABA and afterwards exposed to severe water stress.…”