AP2/ERF Transcription Factors Involved in Response to Tomato Yellow Leaf Curly Virus in Tomato

Tomato yellow leaf curly virus (TYLCV), transmitted by the whitefly (Bemisia tabaci), causes leaf curling and yellowing, plant dwarfism, and growth inhibition in tomato (Solanum lycopersicum L.). The APETALA2 (AP2) and ethylene response factor (ERF) transcription factor (TF) family, the largest plant-specific TF family, was identified to function in plant development and pathogen defense. Our study aimed to analyze the mechanism underlying the function of S. lycopersicum ERF (SlERF) TFs in response to TYLCV infection and improve useful information to increase the resistance to TYLCV in tomato. A total of 22 tomato AP2/ERF TFs in response to TYLCV were identified according to transcriptome database. Five ERF-B3 TFs were identified in cultivars Hongbeibei (highly resistant), Zheza-301, Zhefen-702 (both resistant), Jinpeng-1, and Xianke-6 (both susceptible). Interaction network indicated that SlERF TFs could interact with mitogen-activated protein kinase (MAPK). Expression profiles of five ERF-B3 genes (Soly19, Soly36, Soly66, Soly67, and Soly106) were detected by quantitative real-time-polymerase chain reaction (qRT-PCR) after TYLCV infection in five tomato cultivars. Soly106 expression was upregulated in five tomato cultivars. The expressions of three genes (Soly19, Soly67, and Soly36) were upregulated in Zheza-301 and Zhefen-702. Soly66 and Soly36 expressions were downregulated in Hongbeibei and Xianke-6, respectively. Yeast one-hybrid showed that the GCC-box binding ability of ERF-B3 TFs differed in resistant and susceptible tomato cultivars. Expression profiles were related to the GCC-box binding ability of SlERF TFs in resistant and susceptible tomato cultivars. The defense mechanism underlying the tomato's response to TYLCV involved a complicated network, which provided important information for us in breeding and genetic analysis.