Microarray analysis of the moss Physcomitrella patens reveals evolutionarily conserved transcriptional regulation of salt stress and abscisic acid signalling

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.

The Arabidopsis thaliana Med25 mediator subunit integrates environmental cues to control plant development

“…We further note that a moss cDNA that was annotated as encoding a DREB2A homolog is induced by dehydration (21). The AP2 domain transcription factors, to which DREB2A belongs, is a large protein family, and it is not easy to identify direct orthologs in mosses and angiosperms (22). Nevertheless, the fact that the moss DREB2A-related protein is induced by drought stress suggests that it could have a function analogous to that of Arabidopsis DREB2A.…”

“…It is further conceivable that both Med25 and DREB2A could function as downstream components in the ABA pathway. We note that ABI3, encoding a key mediator of the ABA response (23), is among the genes that are induced by dehydration in Physcomitrella (22).…”

Physcomitrella PpORS, Basal to Plant Type III Polyketide Synthases in Phylogenetic Trees, Is a Very Long Chain 2′-Oxoalkylresorcinol Synthase

“…The microarray experiments were done in biological triplicates. Data analysis with the Expressionist software (Genedata, Basel, Switzerland) was performed as described previously (25).…”

Abiotic stress-induced oscillations in steady-state transcript levels of Group 3LEAprotein genes in the moss,Physcomitrella patens

“…Physcomitrella patens has been shown to be highly tolerant of salt and osmotic stress, 7,11,12 and they can survive exposure to 1A and B) and Phypa_211998 ( Fig. 1C and D).…”

“…Keywords: abiotic stress, salt stress, osmotic stress, oscillations, gene expression data suggest, at least in the context of the moss, that dehydrationinduced temporal dynamics in steady-state transcript levels that is responsive to the severity of the stress may contribute to survival under periodic fluctuations of water availability and confer evolutionary advantages during colonization of land by plants. 10 In addition to its ability to survive moderate dehydration stress, P. patens has also been shown to be highly tolerant of salt and osmotic stress, 7,11,12 as P. patens can survive exposure to 350 mM NaCl and 500 mM sorbitol. 7 In this study, we aimed to address whether dosage-dependent oscillatory increases in steady-state transcript levels of stress-responsive genes are a more general phenomenon in moss, or whether it is restricted to dehydration stress.…”