ATP-dependent binding cassette transporter ClABCI6 promotes the expression of citrus yellow vein clearing virus via inhibiting salicylic acid pathway.

Abstract

ATP-dependent binding cassette (ABC) transporters constitute a class of proteins that utilize ATP hydrolysis to actively transport diverse substrates across cellular membranes and play crucial roles in various physiological processes in plants. However, the specific function of ABC transporters in plant antiviral defense remains poorly characterized. In this study, the homologous ABCI6 proteins originating from Citrus L. spp. showed high evolutionary conservation (higher than 75.82%). The expression of ClABCI6, the ABCI6 homologous gene in Eureka lemon (Citrus limon (L.) Osbeck), was significantly upregulated following infection with citrus yellow vein clearing virus (CYVCV). Further study showed that ClABCI6 localized specifically to the chloroplast and physically interacted with the RNA-dependent RNA polymerase domain (He-RdRp) of CYVCV using yeasts two-hybrid assays. In addition, ClABCI6 promoted the expression of He-RdRp and CYVCV, while concurrently suppressing the expression of salicylic acid (SA) pathway genes in lemon, thus facilitating viral proliferation. This study provides novel insights into the evolution and molecular function of ClABCI6, and reveals its response patterns to CYVCV-infection.