Lemon zinc finger protein ClSUP induces the accumulation of reactive oxygen species and inhibits citrus yellow vein-clearing virus infection via interactions with ClDOF3.4.

Abstract

Citrus yellow vein-clearing virus (CYVCV) is an increasing threat to citrus cultivation. Notably, the role of zinc finger proteins (ZFPs) in mediating viral resistance in citrus plants is unclear. In this study, we demonstrate that ZFPs ClSUP and ClDOF3.4 enhance citrus defense responses against CYVCV in Eureka lemon. ClSUP interacted with the coat protein (CP) of CYVCV to reduce CP accumulation and inhibit its silencing suppressor function. Overexpression of CISUP triggered reactive oxygen species (ROS) and salicylic acid (SA) pathways, and enhanced resistance to CYVCV infection. In contrast, ClSUP-silencing resulted in increased CP accumulation and down-regulated ROS and SA-related genes. ClDOF3.4 interacts with ClSUP to facilitate its interactions with CP. Furthermore, ClDOF3.4 synergistically regulated the accumulation of ROS and SA with ClSUP and accelerated the down-regulation of CP accumulation. Transgenic plants co-expressing ClSUP and ClDOF3.4 remarkedly decrease the CYVCV. These findings provide a new reference for understanding the interaction mechanism between the host and CYVCV.