RT Journal Article
SR Electronic
T1 Guanosine-specific single-stranded ribonuclease effectors of a phytopathogenic fungus potentiate host immune responses
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.10.13.464185
DO 10.1101/2021.10.13.464185
A1 Naoyoshi Kumakura
A1 Suthitar Singkaravanit-Ogawa
A1 Pamela Gan
A1 Ayako Tsushima
A1 Nobuaki Ishihama
A1 Shunsuke Watanabe
A1 Mitsunori Seo
A1 Shintaro Iwasaki
A1 Mari Narusaka
A1 Yoshihiro Narusaka
A1 Yoshitaka Takano
A1 Ken Shirasu
YR 2021
UL http://biorxiv.org/content/early/2021/10/13/2021.10.13.464185.abstract
AB Plants activate immunity upon recognition of pathogen-associated molecular patterns. Although phytopathogens have evolved a set of effector proteins to counteract plant immunity, some effectors are perceived by hosts and induce immune responses. Here, we show that two secreted ribonuclease effectors, SRN1 and SRN2, encoded in a phytopathogenic fungus, Colletotrichum orbiculare, induce cell death in a signal peptide- and catalytic residue-dependent manner, when transiently expressed in Nicotiana benthamiana. The pervasive presence of SRN genes across Colletotrichum species suggested the conserved roles. Using a transient gene expression system in cucumber (Cucumis sativus), an original host of C. orbiculare, we show that SRN1 and SRN2 potentiate host pattern-triggered immunity. Consistent with this, C. orbiculare SRN1 and SRN2 deletion mutants exhibited increased virulence on the host. In vitro analysis revealed that SRN1 specifically cleaves single-stranded RNAs at guanosine, leaving a 3′-end phosphate. This activity has not been reported in plants. Importantly, the potentiation of C. sativus responses by SRN1 and SRN2 depends on the signal peptide and ribonuclease catalytic residues, suggesting that secreted SRNs cleave RNAs in apoplast and are detected by the host. We propose that the pathogen-derived apoplastic guanosine-specific single-stranded endoribonucleases lead to immunity potentiation in plants.Competing Interest StatementThe authors have declared no competing interest.