The CaAP2/ERF064 Regulates Dual Functions in Pepper: Plant Cell Death and Resistance to Phytophthora capsici

Abstract

<i>Phytophthora</i> blight is one of the most destructive diseases of pepper (<i>Capsicum annuum</i> L.) globally. The APETALA2/Ethylene Responsive Factors (<i>AP2/ERF</i>) genes play a crucial role in plant response to biotic stresses but, to date, have not been studied in the context of <i>Phytophthora</i> resistance in pepper. Here, we documented potential roles for the pepper <i>CaAP2/ERF064</i> gene in inducing cell death and conferring resistance to <i>Phytophthora capsici</i> (<i>P. capsici</i>) infection. Results revealed that the N-terminal, AP2 domain, and C-terminal of CaAP2/ERF064 protein is responsible for triggering cell death in <i>Nicotiana benthamiana (N. benthamiana)</i>. Moreover, the transcription of <i>CaAP2/ERF064</i> in plant is synergistically regulated by the Methyl-Jasmonate (MeJA) and ethephon (ET) signaling pathway. <i>CaAP2/ERF064</i> was found to regulate the expression of <i>CaBPR1</i>, which is a pathogenesis-related (<i>PR</i>) gene of pepper. Furthermore, the silencing of <i>CaAP2/ERF064</i> compromised the pepper plant resistance to <i>P.</i><i>capsici</i> by reducing the transcript level of defense-related genes <i>CaBPR1</i>, <i>CaPO2</i>, and <i>CaSAR82</i>, while the ectopic expression of <i>CaAP2/ERF064</i> in <i>N. benthamiana</i> plant elevated the expression level of <i>NbPR1b</i> and enhanced resistance to <i>P.</i><i>capsici</i>. These results suggest that <i>CaAP2/ERF064</i> could positively regulate the defense response against <i>P. capsici</i> by modulating the transcription of <i>PR</i> genes in the plant.