Substantial reprogramming of the Eutrema salsugineum (Thellungiella salsuginea) transcriptome in response to UV and silver nitrate challenge

Abstract

BackgroundCruciferous plants synthesize a large variety of tryptophan-derived phytoalexins in response to pathogen infection, UV irradiation, or high dosages of heavy metals. The major phytoalexins of Eutrema salsugineum (Thellungiella salsuginea), which has recently been established as an extremophile model plant, are probably derivatives of indole glucosinolates, in contrast to Arabidopsis, which synthesizes characteristic camalexin from the glucosinolate precursor indole-3-acetaldoxime.ResultsThe transcriptional response of E. salsugineum to UV irradiation and AgNO3 was monitored by RNAseq and microarray analysis. Most transcripts (respectively 70% and 78%) were significantly differentially regulated and a large overlap between the two treatments was observed (54% of total). While core genes of the biosynthesis of aliphatic glucosinolates were repressed, tryptophan and indole glucosinolate biosynthetic genes, as well as defence-related WRKY transcription factors, were consistently upregulated. The putative Eutrema WRKY33 ortholog was functionally tested and shown to complement camalexin deficiency in Atwrky33 mutant.ConclusionsIn E. salsugineum, UV irradiation or heavy metal application resulted in substantial transcriptional reprogramming. Consistently induced genes of indole glucosinolate biosynthesis and modification will serve as candidate genes for the biosynthesis of Eutrema-specific phytoalexins.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0506-5) contains supplementary material, which is available to authorized users.

Dark period transcriptomic and metabolic profiling of two diverseEutrema salsugineumaccessions

“…However, knock-out of either PMSR2 (Bechtold et al, 2004) or PMSR4 (Romero et al, 2004) results in decreased oxidative stress tolerance and overexpression of either gene increases stress tolerance in A. thaliana . Expression of PMSR4 (but not PMSR1 , PMSR2 , or PMSR3 ) was induced in response to UV and AgNO 3 in E. salsuginea SH (Mucha et al, 2015). It is plausible that the overexpression of PMSR3 by YK could provide greater oxidative stress tolerance in this accession.…”

Lipid remodelling: Unravelling the response to cold stress in Arabidopsis and its extremophile relative Eutrema salsugineum

“…In fact, only the UBIQUITIN-DEPENDENT PROTEIN MODIFICATION gene family was shown to have a statistically significant increase in gene copy number in Eutrema. This evidence suggests that a highly stress-specific translational and transcriptional reprogramming occurs in Eutrema under abiotic stresses, which ultimately leads to metabolic and signalling changes [50] . According to Taji et al [51] , only six Eutrema genes were salt stress-inducible whose log 2 ratios of salt vs. control were ≥1.5, whereas the same experiment in Arabidopsis showed 40 such salt stress-inducible genes.…”

Dark period transcriptomic and metabolic profiling of two diverse Eutrema salsugineum accessions

“…However, knockout of either PMSR2 (Bechtold, Murphy, & Mullineaux, ) or PMSR4 (Romero, Berlett, Jensen, Pell, & Tien, ) results in decreased oxidative stress tolerance and overexpression of either gene increases stress tolerance in A. thaliana . Expression of PMSR4 (but not PMSR1 , PMSR2 , or PMSR3 ) was induced in response to UV and AgNO 3 in E. salsuginea SH (Mucha, Walther, Muller, Hincha, & Glaswischnig, ). It is plausible that the overexpression of PMSR3 by YK could provide greater oxidative stress tolerance in this accession.…”