Focal Accumulation of ROS Can Block <i>Pyricularia oryzae</i> Effector BAS4-Expression and Prevent Infection in Rice

• Main Authors: Yafei Chen, Sarmina Dangol, Juan Wang, Nam-Soo Jwa
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: International Journal of Molecular Sciences
• Subjects: rice; immunity; <i>Pyricularia oryzae</i> (syn. <i>Magnaporthe oryzae</i>); ROS; effector
• Online Access: https://www.mdpi.com/1422-0067/21/17/6196

The reactive oxygen species (ROS) burst is the most common plant immunity mechanism to prevent pathogen infection, although the exact role of ROS in plant immunity has not been fully elucidated. We investigated the expression and translocation of <i>Oryza sativa</i> respiratory burst oxidase homologue B (OsRBOHB) during compatible and incompatible interactions between rice epidermal cells and the pathogenic fungus <i>Pyricularia oryzae</i> (syn. <i>Magnaporthe oryzae</i>). We characterized the functional role of ROS focal accumulation around invading hyphae during <i>P. oryzae</i> infection process using the OsRBOHB inhibitor diphenyleneiodonium (DPI) and the actin filament polymerization inhibitor cytochalasin (Cyt) A. OsRBOHB was strongly induced during incompatible rice–<i>P. oryzae</i> interactions, and newly synthesized OsRBOHB was focally distributed at infection sites. High concentrations of ROS focally accumulated at the infection sites and suppressed effector biotrophy-associated secreted (BAS) proteins BAS4 expression and invasive hyphal growth. DPI and Cyt A abolished ROS focal accumulation and restored <i>P. oryzae</i> effector BAS4 expression. These results suggest that ROS focal accumulation is able to function as an effective immune mechanism that blocks some effectors including BAS4-expression during <i>P. oryzae</i> infection. Disruption of ROS focal accumulation around invading hyphae enables successful <i>P. oryzae</i> colonization of rice cells and disease development.