Abstract
Regulatory networks of salt stress and abscisic acid (ABA) responses have previously been analyzed in seed plants. Here, we report microarray expression profiles of 439 genes encoding transcription-associated proteins (TAPs) in response to salt stress and ABA in the salt-tolerant moss Physcomitrella patens. Fourteen and 56 TAP genes were differentially expressed within 60 min of NaCl and ABA treatment, respectively, indicating that these responses are regulated at the transcriptional level. Overlapping expression profiles, as well as the up-regulation of ABA biosynthesis genes, suggest that ABA mediates the salt stress responses in P. patens. Comparison to public gene expression data of Arabidopsis thaliana and phylogenetic analyses suggest that the role of DREB-like, Dof, and bHLH TAPs in salt stress responses have been conserved during embryophyte evolution, and that the function of ABI3-like, bZIP, HAP3, and CO-like TAPs in seed development and flowering emerged from pre-existing ABA and light signalling pathways.