Abstract
BackgroundTo combat infection to biotic stress plants elicit the biosynthesis of numerous natural products, many of which are valuable pharmaceutical compounds. Jasmonate is a central regulator of defense response to pathogens and accumulation of specialized metabolites. Catharanthus roseus produces a large number of terpenoid indole alkaloids (TIAs) and is an excellent model for understanding the regulation of this class of valuable compounds. Recent work illustrates a possible role for the Catharanthus WRKY transcription factors (TFs) in regulating TIA biosynthesis. In Arabidopsis and other plants, the WRKY TF family is also shown to play important role in controlling tolerance to biotic and abiotic stresses, as well as secondary metabolism.ResultsHere, we describe the WRKY TF families in response to jasmonate in Arabidopsis and Catharanthus. Publically available Arabidopsis microarrays revealed at least 30% (22 of 72) of WRKY TFs respond to jasmonate treatments. Microarray analysis identified at least six jasmonate responsive Arabidopsis WRKY genes (AtWRKY7, AtWRKY20, AtWRKY26, AtWRKY45, AtWRKY48, and AtWRKY72) that have not been previously reported. The Catharanthus WRKY TF family is comprised of at least 48 members. Phylogenetic clustering reveals 11 group I, 32 group II, and 5 group III WRKY TFs. Furthermore, we found that at least 25% (12 of 48) were jasmonate responsive, and 75% (9 of 12) of the jasmonate responsive CrWRKYs are orthologs of AtWRKYs known to be regulated by jasmonate.ConclusionOverall, the CrWRKY family, ascertained from transcriptome sequences, contains approximately 75% of the number of WRKYs found in other sequenced asterid species (pepper, tomato, potato, and bladderwort). Microarray and transcriptomic data indicate that expression of WRKY TFs in Arabidopsis and Catharanthus are under tight spatio-temporal and developmental control, and potentially have a significant role in jasmonate signaling. Profiling of CrWRKY expression in response to jasmonate treatment revealed potential associations with secondary metabolism. This study provides a foundation for further characterization of WRKY TFs in jasmonate responses and regulation of natural product biosynthesis.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-502) contains supplementary material, which is available to authorized users.
Highlights
To combat infection to biotic stress plants elicit the biosynthesis of numerous natural products, many of which are valuable pharmaceutical compounds
WRKY Transcription factor (TF) are involved in Jasmonate signaling The role of WRKY TF family in salicylic acid (SA) signaling and plant defense is well established and has been systematically analyzed in Arabidopsis, but remains less clear for jasmonate signaling
We wanted to elucidate jasmonate responsive AtWRKYs to aid the identification of CrWRKY orthologs with potentially conserved regulatory functions
Summary
To combat infection to biotic stress plants elicit the biosynthesis of numerous natural products, many of which are valuable pharmaceutical compounds. Vinblastine and vincristine provide antineoplastic compounds effective in the treatment of several types of cancer [4] The biosynthesis of these compounds, along with other TIAs, is regulated by UV light [5,6], fungal elicitors [7], wounding [8,9], drought [10], cold [11,12] and salt stress [12]. A principal elicitor of TIA production in Catharanthus, as well as natural products in many other medicinal species, is the phytohormone jasmonate which functions in plant defense signaling to protect the plant from biotic stresses [3,13]
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