Citrus transcription factor CsERF098 cooperates with CsWRKY70 to participate in response of fruit to green mold

As plant-specific transcription factors (TFs), AP2/ERF can participate in regulating disease resistance in plants. Currently, researches on regulation of disease resistance of AP2/ERF TFs were mainly focused on model plants, and the regulatory mechanisms in non-model plants such as citrus fruit, an important economical fruit which is seriously infected by Penicillium digitatum, are still unclear. In this study, transcriptional activator CsERF098 overexpression enhanced the resistance of citrus fruit against green mold. Transcriptome sequencing revealed that CsERF098 was involved in four disease resistance pathways, including salicylic acid (SA) signaling pathway, lignin and waxy biosynthesis pathway, chitinase and jasmonic acid signaling pathway. CsERF098 could bind to promoter of SA pathway CsSAMT and CsSABP2, activate the transcriptional activities of CsSAMT, CsSABP2, CsTLP1b and CsTLP. Furthermore, the interaction of CsERF098 and CsWRKY70 was confirmed, which enhanced the trans-activation of CsERF098 on CsSAMT and CsSABP2. These results indicated that CsERF098 could mediate salicylic acid signaling pathway and enhance the synergistic regulation of CsSAMT and CsSABP2 through interaction with CsWRKY70, thereby in controlling the resistance of citrus fruit to Penicillium digitatum. The present study provides new thoughts on the role and mechanism of AP2/ERF transcription factor involved in regulating citrus disease resistance.