Associate researcher/professor Academia Sinica Taipei, Taipei, Taiwan (Republic of China)
Body of Abstract: Salicylic acid (SA)-mediated immunity and RNA interference (RNAi) are crucial pathways involved in plant defense against viral infections. However, the connection between these two pathways remains poorly understood. Previous studies have identified A20/AN1 zinc-finger domain containing proteins, namely orchid Pha13 and Arabidopsis AtSAP5, as important players in antiviral immunity by regulating the expression of SA-responsive genes, including the master regulator gene NPR1 and the marker gene PR1. In this study, we investigated the role of another orchid homolog gene, Pha21, in conferring antiviral immunity. Our findings demonstrate that Pha21 is involved in the expression of the orchid homologs of NPR1 and PR1, and its expression is induced early by SA treatment. Furthermore, we discovered that Pha21 plays a significant role in initiating the RNAi pathway in Phalaenopsis orchids. Importantly, our results indicate that Pha21 acts as an SA-induced enhancer of RNAi, suggesting that A20/AN1 proteins may serve as a link between SA-mediated immunity and the RNAi pathway in SA-induced antiviral defense. This study provides insights into the interplay between SA-mediated immunity and RNAi, uncovering a potential mechanism involving A20/AN1 proteins, and contributes to our understanding of plant immune responses against viral infections.