Stepwise signal transduction cascades under salt stress in leaves of wild barley (Hordeum spontaneum)

Abstract

The present study aims at the use of transcriptomic data of wild barley (Hordeum spontaneum) under salt stress in detecting regulated metabolites and crosstalking signal transduction pathways that help plants withstand harsh conditions. The studied pathways involved those emphasizing the roles of phytohormones auxin and abscisic acid (ABA) in conferring stress tolerance and adaptation. Of which, tryptophan-core pathways include metabolites that trigger auxin-responsive genes towards downstream signal transduction cascades and better plant growth. Analysis of ‘MAPK signalling’ pathway indicated active participation of several MAPK modules in receiving and delivering signals under salt stress towards appropriate downstream biological decisions. The results indicated that one enriched MEKK1 module, e.g. MEKK1-MKK2-MPK4/6, and two MKK3 modules, e.g. MEKK17/18-MKK3-MPK1/2/7/14 and ?-MKK3-MPK8, in this wild plant can effectively participate in salt stress adaptation and tolerance as well as homeostasis of reactive oxygen species (ROS). ABA seems to be a main player in the leaves of H. spontaneum in triggering signal transduction via MAPK modules. MKK7 was shown to be repressed under salt stress. This MAPK disturbs normal production, signalling and distribution of auxin, thus, enforces the plant to perform better under salt stress. In conclusion, the present study addresses signal transduction pathways that might justify the ability of this wild plant to tolerate salt stress.