A mitochondrial RNA processing protein mediates plant immunity to a broad spectrum of pathogens by modulating the mitochondrial oxidative burst

Abstract

Mitochondrial function depends on the RNA processing of mitochondrial gene transcripts by nucleus-encoded proteins. This post-transcriptional processing involves the large group of nuclear-encoded pentatricopeptide repeat (PPR) proteins. Mitochondrial processes represent a crucial part in animal immunity, but whether mitochondria play similar roles in plants remains unclear. Here, we report the identification of RESISTANCE TO PHYTOPHTHORA PARASITICA 7 (AtRTP7), a P-type PPR protein, in Arabidopsis thaliana and its conserved function in immunity to diverse pathogens across distantly related plant species. RTP7 affects the levels of mitochondrial reactive oxygen species (mROS) by participating in RNA splicing of nad7, which encodes a critical subunit of the mitochondrial respiratory chain Complex I, the largest of the four major components of the mitochondrial oxidative phosphorylation system. The enhanced resistance of rtp7 plants to Phytophthora parasitica is dependent on an elevated mROS burst, but might be independent from the ROS burst associated with plasma membrane-localized NADPH oxidases. Our study reveals the immune function of RTP7 and the defective processing of Complex I subunits in rtp7 plants resulted in enhanced resistance to both biotrophic and necrotrophic pathogens without affecting overall plant development.

A P‐type pentatricopeptide repeat protein ZmRF5 promotes 5′ region partial cleavages of atp6c transcripts to restore the fertility of CMS‐C maize by recruiting a splicing factor

“…P‐type PPR proteins are often involved in RNA splicing of mitochondrial group II introns, 5′ end processing, and translation (Manavski et al ., 2012 ; Wang et al ., 2021 ; Yang et al ., 2022c ; Zhang et al ., 2017 ). The restorer gene ZmRf5 identified in this study encodes a canonical P‐type PPR protein without direct contacting with atp6c (Figure S3 ).…”

Phytophthora infestans RXLR effector Pi23014 targets host RNA‐binding protein NbRBP3a to suppress plant immunity

“…After the control GFP was removed, the remaining proteins were the candidate target proteins. For CM-H2DCFDA staining assay, TRV-GFP and TRV-NbRBP3 silenced plants treated with 10 μM flg22 for 0.5 h were stained with 10 μM CM-H 2 DCFDA for 0.5-1 h to detect ROS, then washed twice before imaging (Yang et al, 2022). CM-H 2 DCFDA was excited at 488 nm with emission collected at 500-540 nm.…”

Suppression of ZEAXANTHIN EPOXIDASE 1 restricts stripe rust growth in wheat

“…Yr36 encodes an unusual fusion protein called wheat kinase START 1 (WKS1) with an N-terminal protein kinase domain and a C-terminal START domain; it governs wheat Pst resistance by regulating accumulation of reactive oxygen species (ROS) ( Fu et al., 2009 ; Gou et al., 2015 ). Arabidopsis RESISTANCE TO PHYTOPHTHORA PARASITICA 7 (AtRTP7) participates in RNA splicing of a critical subunit of the mitochondrial respiratory chain, affects levels of mitochondrial ROS, and increases susceptibility to both biotrophic and necrotrophic pathogens ( Yang et al., 2022 ). Genes related to changes in metabolites such as ROS can accelerate cell death and participate in non-specific plant defenses ( Prasad et al., 2022 ).…”