use of aba treatment for the activation of drought protective mechanisms in barley under non-stress conditions

The present study evaluated the sensitivity of three different barley genotypes to stress simulated by the application of exogenous abscisic acid (20 µmol.l−1) at the early stage of the plant development. We used RIA method, instantaneous water use efficiency (WUE), the discrimination of 13C (Δ13C) and the expression levels of Dhn4 gene. The increase of ABA concentration in leaves after exogenous ABA application was detected in all tested genotypes; however, the lowest amount was found in the most tolerant genotype. Increased level of the instantaneous WUE after ABA treatment was found in all genotypes. The Δ13C in ABA treated plants decreased, however, relatively drought-tolerant genotype Tadmor showed lower discrimination even in control variant. The genotype-dependent differences were observed in the expression levels of Dhn4 gene in the leaves. High expression level of this gene was observed in Tadmor. Based on the exogenous ABA level, it was possible to distinguish two types of response of plants to exogenous ABA. Tadmor represented one of them as manifesting high sensitivity to exogenous ABA, leading to fast induction of Dhn4 gene relative expression. Conversely, spring genotypes of Jersey and Malz manifested slower response to exogenous ABA as well as lower WUE values and relative expression of Dhn4. The results supported the idea that ABA application may activate similar stress reactions in plants as drought conditions and additionally the intensity of this reaction is genotype dependent.