Anti-Oomycete Effect and Mechanism of Salicylic Acid on Phytophthora infestans

Pathogenic oomycetes infect a wide variety of organisms,
including
plants, animals, and humans, and cause massive economic losses in
global agriculture, aquaculture, and human health. Salicylic acid
(SA), an endogenous phytohormone, is regarded as an inducer of plant
immunity. Here, the potato late blight pathogen Phytophthora
infestans was used as a model system to uncover the
inhibitory mechanisms of SA on pathogenic oomycetes. In this research,
SA significantly inhibited the mycelial growth, sporulation, sporangium
germination, and virulence of P. infestans. Inhibition was closely related to enhanced autophagy, suppression
of translation initiation, and ribosomal biogenesis in P. infestans, as shown by multiomics analysis (transcriptomics,
proteomics, and phosphorylated proteomics). Monodansylcadaverine (MDC)
staining and Western blotting analysis showed that SA promoted autophagy
in P. infestans by probably targeting
the TOR signaling pathway. These observations suggest that SA has
the potential to control late blight caused by P. infestans.