Regulatory Divergence In Wound-Responsive Gene Expression In Domesticated And Wild Tomato

Abstract

BackgroundThe evolution of cis- and trans-regulatory components of transcription is central to how stress response and tolerance differ across species. However, it remains largely unknown how divergence in TF binding specificity and cis-regulatory sites contribute to the divergence of stress-responsive gene expression between wild and domesticated species.\n\nResultsUsing tomato as model, we analyzed the transcriptional profile of wound-responsive genes in wild Solanum pennellii and domesticated S. lycopersicum. We found that extensive expression divergence of wound-responsive genes is associated with speciation. To assess the degree of trans-regulatory divergence between these two species, 342 and 267 putative cis-regulatory elements (pCREs) in S. lycopersicum and S. pennellii, respectively, were identified that were predictive of wound-induced gene expression. We found that 35-66% of pCREs were conserved across species, suggesting that the remaining proportion (34-65%) of pCREs are species specific. This finding indicates a substantially higher degree of trans-regulatory divergence between these two plant species, which diverged [~]3-7 million years ago, compared to that observed in mouse and human, which diverged [~]100 million years ago. In addition, differences in pCRE sites were significantly associated with differences in wound-responsive gene expression between wild and domesticated tomato orthologs, suggesting the presence of substantial cis-regulatory divergence.\n\nConclusionsOur study provides new insights into the mechanistic basis of how the transcriptional response to wounding is regulated and, importantly, the contribution of cis- and trans-regulatory components to variation in wound-responsive gene expression during species domestication.