Introduction Tomato yellow leaf curl virus (TYLCV, Begomovirus coheni ), a whitefly-transmitted begomovirus, causes serious economic losses to tomato crops globally. Over the past three decades, several genetic sources of TYLCV resistance have been identified and incorporated into tomato breeding. Among these is a recessive source of resistance known as ty-5 . Methods In this study, we conducted a global transcriptome analysis to compare gene expression in a ty-5 near isogenic tomato line and its susceptible recurrent parent at various stages of TYLCV infection. Results We identified 1,394 differentially expressed genes, including numerous defense-related genes and genes involved in RNA-mediated DNA methylation. In addition, the expression of key regulatory genes such as protein kinases (PKs) and transcription factors (TFs) was also significantly altered. To explore the function of one upregulated TF encoding an APETALA2/Ethylene Responsive Factor (AP2/ERF), tomato plants overexpressing this gene were generated and demonstrated to confer resistance to TYLCV. Discussion These results lead us to hypothesize that ty-5 -mediated TYLCV resistance not only involves a pelota gene but is a product of two major pathways acting in concert: a typical host-disease resistance pathway and RNA-directed DNA methylation. Understanding the mechanism underlying ty-5 resistance will facilitate the development of tomato germplasm with more durable TYLCV resistance.
Padmanabhan et al. (Wed,) studied this question.