A small secreted protein, RsMf8HN, in Rhizoctonia solani triggers plant immune response, which interacts with rice OsHIPP28

Microbiol Res. 2023 Jan;266:127219. doi: 10.1016/j.micres.2022.127219. Epub 2022 Oct 11.


The necrotrophic phytopathogen Rhizoctonia solani (R. solani) causes disease in many plant species. This fungal genome encodes abundant small cysteine-rich (SCR)-secreted proteins in R. solani that may induce pathogenesis. To test their molecular functions, we introduced 10 SCR-secreted protein genes from R. solani into tobacco leaves via agroinfiltration. Consequently, we identified RsMf8HN, a novel SCR protein that triggers cell death and an oxidative burst in tobacco. RsMf8HN comprises 182 amino acids (aa), including a signal peptide (SP) of 17aa, and the protein has unique features: it is orthologous to an allergen protein Mal f 8 occurring in Malassezia species, and possesses a high glycine and serine content. RsMf8HN is coded in a genomic location along with its paralogues and a few other effector candidates. The elicitation of plant immunity by RsMf8HN was dependent on HSP90 and SGT1. RsMf8HN was translocated to multiple locations within the host cells: i.e., nuclei, chloroplasts, and plasma membranes. We confirmed the occurrence of in vivo cross-interactions of RsMf8HN with a rice molecule, the heavy metal-associated isoprenylated plant protein OsHIPP28, which is a protein related to the disease susceptibility factor Pi21. In summary, our results suggest that RsMf8HN is a potential effector that enables necrotrophic phytopathogens to interfere with host plant immunity.

Keywords: Cell death; Immune response; Nicotiana benthamiana (N. benthamiana); Protein interaction; R. solani AG1IA; SCR secreted protein.

MeSH terms

  • Oryza* / microbiology
  • Plant Diseases / microbiology
  • Plant Immunity / genetics
  • Plants
  • Rhizoctonia / genetics

Supplementary concepts

  • Rhizoctonia solani