P-112 - Bacterial virulence effectors play a crucial role in regulating the stability of NLR transcripts during Pseudomonas infection

Nonsense-mediated mRNA decay (NMD) is a conserved mRNA surveillance mechanism that mitigates gene expression errors by degrading aberrant mRNA transcripts in eukaryotic cells. Recent studies highlight the importance of NMD in plant immunity. In Arabidopsis thaliana, the stability of NLR transcripts carrying NMD-sensitive features increased after pathogen infection, while a key NMD component, UPF3, underwent robust degradation upon infection with Pseudomonas syringae pv. tomato DC3000 (PstDC3000) compared to PstDC3000 ΔAvrPto ΔAvrPtoB. Total RNAomes analyses revealed the changes of transcripts’ stability in PstDC3000- and PstDC3000 ΔAvrPto ΔAvrPtoB- infected wild-type plants and upf3-1 upf1-5 double mutants. These findings suggest that Pseudomonas infection modulates transcript stability in Arabidopsis. However, whether PstDC3000 affects NMD activity in crop plants remains unknown. Micro-Tom (Solanum lycopersicum cv. Micro-Tom) do not express SlPto, which is targeted by AvrPto and AvrPtoB. After infection of PstDC3000 and PstDC3000 ΔAvrPto ΔAvrPtoB, distinct disease resistance responses were observed. Micro-Tom infected with PstDC3000 ΔAvrPto ΔAvrPtoB was more susceptible than those infected with wild-type PstDC3000. Transcriptome analyses further revealed differences among treatments. Together, these results suggest that AvrPto and AvrPtoB influence NMD, regulating NLR transcript stability and immune responses by modulating mRNA stabilities during Pseudomonas infection.