P-250 - m6A RNA methylation positively regulates the infection of tomato spotted wilt virus

Tomato spotted wilt virus (TSWV) is one of the most serious plant segmented negative-stranded RNA (NSR) viruses in the world, and posing a major threat to global food security. N6-methyladenosine (m⁶A) is an internal, reversible nucleotide modification that is an important regulatory mechanism in host-virus interaction. Here we show that the demethylase ALKBH9B negatively regulates the TSWV infection. The m⁶A abundance on the viral genome of TSWV-purified particles is identified by LC-MS/MS assays. Microscale thermophoresis (MST) assays show that TSWV-encoded N protein binds m⁶A-modified ssRNA significantly more than m⁶A-unmodified ssRNA. m⁶A of TSWV RNA is also controlled by host methyltransferases MTA and MTB, and overexpression of methyltransferases increases, while silencing methyltransferases, TSWV production. Moreover, we also investigated that the importance of diverse NSR viruses were mediated by host methyltransferases MTA, MTB, and the demethylase ALKBH9B, including Impatiens necrotic spot virus (INSV) and Tomato zonate spot virus (TZSV). Finally, we found that TSWV-encoded RNA-dependent RNA polymerase (RdRp) interacts with the host methyltransferase KAKKAI in vivo and in vitro, suggesting that RdRp recruits the host KAKKAI to increase the m⁶A abundance on the viral genome and positively regulate the virus infection in plants. Our findings suggest that NSR viruses may manipulate the host m⁶A modification complex to counteract the host antiviral defence.