The jasmonic acid-signalling and abscisic acid-signalling pathways cross talk during one, but not repeated,...

Experiencing diverse and recurring biotic and abiotic stresses throughout life, plants have evolved mechanisms to respond, survive and, eventually, adapt to changing habitats. The initial response to drought involves a large number of genes that are involved also in response to other stresses. According to current models, this initial response is non-specific, becoming stress-specific only at later time points. The question, then, is whether non-specific activation of various stress-signalling systems leading to the expression of numerous stress-regulated genes is a false-alarm (panicky) response or whether it has biologically relevant consequences for the plant. Here, it is argued that the initial activation of genes associated other stresses reflects an important event during which stress-specific mechanisms are generated to prevent subsequent activation of non-drought signalling pathways. How plants discriminate between a first and a repeated dehydration stress and how repression of non-drought specific genes is achieved will be discussed on the example of jasmonic acid-associated Arabidopsis genes activated by a first, but not subsequent, dehydration stresses. Revealing how expression of various biotic/abiotic stress responding genes is prevented under recurring drought spells may be critical for our understanding of how plants respond to dynamically changing environments.