Tomato RAV Transcription Factor Is a Pivotal Modulator Involved in the AP2/EREBP-Mediated Defense Pathway    

Abstract

Ralstonia solanacearum is the causal agent of bacterial wilt (BW), one of the most important bacterial diseases worldwide. We used cDNA microarray to survey the gene expression profile in transgenic tomato (Solanum lycopersicum) overexpressing Arabidopsis (Arabidopsis thaliana) CBF1 (AtCBF1), which confers tolerance to BW. The disease-resistant phenotype is correlated with constitutive expression of the Related-to-ABI3/VP1 (RAV) transcription factor, ethylene-responsive factor (ERF) family genes, and several pathogenesis-related (PR) genes. Using a transient assay system, we show that tomato RAV2 (SlRAV2) can transactivate the reporter gene driven by the SlERF5 promoter. Virus-induced gene silencing of SlERF5 and SlRAV2 in AtCBF1 transgenic and BW-resistant cultivar Hawaii 7996 plants gave rise to plants with enhanced susceptibility to BW. Constitutive overexpression of SlRAV2 in transgenic tomato plants induced the expression of SlERF5 and PR5 genes and increased BW tolerance, while knockdown of expression of SlRAV2 inhibited SlERF5 and PR5 gene expression under pathogen infection and significantly decreased BW tolerance. In addition, transgenic tomato overexpressing SlERF5 also accumulated higher levels of PR5 transcripts and displayed better tolerance to pathogen than wild-type plants. From these results, we conclude that SlERFs may act as intermediate transcription factors between AtCBF1 and PR genes via SlRAV in tomato, which results in enhanced tolerance to BW.

Quantitative Peptidomics Study Reveals That a Wound-Induced Peptide from PR-1 Regulates Immune Signaling in Tomato

“…ERF5 was also demonstrated to positively regulate SA signaling and plant immunities against the bacterial pathogen Pst DC3000 and improve plant resistance to pathogens by activating several PR genes (Moffat et al, 2012;Son et al, 2012). In tomato, the overexpression of ERF5 was observed to induce PR genes and conferred tolerance to Ralstonia solanacearum (Li et al, 2011). This study suggested an alternative approach to enhance plant resistance through ERF5, which can be regulated by a low concentration of peptide without the use of transgenes.…”

Transcriptome-based discovery of AP2/ERF transcription factors related to temperature stress in tea plant (Camellia sinensis)

“…ERF subfamily TFs can bind to the GCC box (AGCCGCC) in the promoters of ethyleneinducible genes that encode pathogenesis-related proteins (Ohmetakagi and Shinshi 1995;Wan et al 2014;Deokar et al 2015). RAV subfamily TFs are involved in many physiological and developmental pathways (Woo et al 2010;Leivar and Quail 2011), and biotic and abiotic stresses (Sohn et al 2006;Li et al 2011). The AP2/ ERF TF-like protein At4g13040 (Soloist) in Arabidopsis positively regulates the accumulation of salicylic acid and the defense against bacterial pathogens (Giri et al 2014).…”

Low sodium chloride priming increases seedling vigor and stress tolerance to Ralstonia solanacearum in tomato

“…It has been reported that genes relative to both ethylene and salicylic acid defence signal transduction pathways were up-regulated in tomato plants infected by R. solanacearum (Milling et al 2011). In addition, transgenic tomatoes overexpressing ethylene-responsive transcription factor 5 gene (SlERF5) displayed better tolerance to bacterial wilt (Li et al 2011). Resistance to R. solanacearum in the tomato might be achieved, at least in part, by triggering the salicylic acid-defence-signalling pathway (Pan et al 2010).…”