Genome-wide identification, characterisation and expression profiles of calcium-dependent protein kinase genes in barley (Hordeum vulgareL.)

In plant cells, calcium-dependent protein kinases (CDPKs) are important sensors of Ca2+flux resulting from various environmental stresses like cold, drought or salt stress. Previous genome sequence analysis and comparative studies in Arabidopsis (Arabidopsis thalianaL.) and rice (Oryza sativaL.) defined a multi-gene family of CDPKs. Here, we identified and characterised the CDPK gene complement of the model plant, barley (Hordeum vulgareL.). Comparative analysis encompassed phylogeny reconstruction based on newly available barley genome sequence, as well as established model genomes (e.g. O. sativa, A. thaliana, Brachypodium distachyon). Functional gene copies possessed characteristic CDPK domain architecture, including a serine/threonine kinase domain and four regulatory EF-hand motifs. In silico verification was followed by measurements of transcript abundance via real-time polymerase chain reaction (PCR). The relative expression of CDPK genes was determined in the vegetative growth stage under intensifying drought stress conditions. The majority of barley CDPK genes showed distinct changes in patterns of expression during exposure to stress. Our study constitutes evidence for involvement of the barley CDPK gene complement in signal transduction pathways relating to adaptation to drought. Our bioinformatics and transcriptomic analyses will provide an important foundation for further functional dissection of the barley CDPK gene family.