ROS and Ca2+ interplay in inducing salt tolerance in rice

In the recent years, evidence has been reported of the interplay between Ca2+ and ROS in relaying both short- and long-distance signaling in plants. In this work we addressed the intriguing hypothesis of the presence of a central Ca2+-ROS hub responsible for the sorting of signals between the perception of the stimulus and the response in rice roots. Ca2+ signaling is known to be specific, showing different signatures in response to different stimuli, but the specificity of ROS signaling has not yet been demonstrated. In rice, we observed different salt-induced cytosolic ROS signatures in different genetic backgrounds (i.e., salt-tolerant and sensitive plants). We then wondered if Ca2+ dynamics too were different under the same treatment and if the two signaling pathways influenced each other. Using salt tolerant and sensitive rice plants, expressing Cameleon, we were able indeed to detect different Ca2+ dynamics triggered by salt stress in the two genetic backgrounds. Furthermore, we observed Ca2+ dynamics were influenced by ROS in the roots of the salt-sensitive rice variety, while this was not the case in salt-tolerant plants. Last but not least interesting result we obtained was that, through a ROS scavenger treatment, we were able to modulate the dynamics of Ca2+ in the sensitive variety, thus inducing a partial tolerance to stress.