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Updated: May 23, 2025
Genome-wide Analysis of Histone Modifications Distribution using the Chromatin Immunoprecipitation Sequencing Method in Magnaporthe oryzae
Published on: June 2, 2021
An unconventional effector MoRpa12 targeting host nuclei is essential for the development and pathogenicity of
Xiaoyan Cai1, Shengjie Zheng1, Xiuting Wang1
1Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, Hefei 230036, PR China; College of Plant Protection, Anhui Agricultural University, Hefei 230036, PR China.
Abstract:
RNA polymerase I (Pol I) is a multi-subunit protein complex associated with the transcription of most ribosomal RNA molecules in all eukaryotes. Rpa12 is a small subunit of the Pol I catalytic core and plays a critical role in RNA cleavage, transcription initiation and elongation during proliferation in yeast and mammals. However, the function of Rpa12 in phytopathogenic fungi has not yet been characterized. Here, we present the functional characterization of MoRpa12, a homologue of the yeast Rpa12, in Magnaporthe oryzae. MoRpa12 shows upregulation during the infection phase, and MoRpa12-GFP exhibits nuclear localization at different developmental stages of M. oryzae and translocates into the nuclei of plant cells after fungal penetration. The MoRpa12 mutants also exhibit significant defects on mitosis, autophagy, oxidative stress tolerance, cell wall integrity, septin ring assembly, lipid and glycogen metabolism, and pathogenicity. The four cysteine residues at the amino terminus of this protein are critical for the nuclear localization of MoRpa12, and their site-directed mutagenesis affects the localization, fungal invasion, and full virulence of M. oryzae. In conclusion, our findings indicate that MoRpa12 functions as an unconventional secreted effector targeting host nuclei and is essential for the fungal growth and plant infection of M. oryzae.
Insights
The study reveals MoRpa12, a RNA polymerase I subunit, is crucial for the growth and pathogenicity of the fungus Magnaporthe oryzae. It functions as a secreted effector, targeting host nuclei to facilitate infection.
Area of Science:
- Molecular Biology
- Mycology
- Plant Pathology
Background:
- RNA polymerase I (Pol I) transcribes ribosomal RNA in eukaryotes.
- Rpa12 is a vital subunit of Pol I, essential for transcription in yeast and mammals.
- The role of Rpa12 in phytopathogenic fungi remains uncharacterized.
Purpose of the Study:
- To functionally characterize MoRpa12, a homolog of yeast Rpa12, in the phytopathogenic fungus Magnaporthe oryzae.
- To investigate the role of MoRpa12 in fungal development, host interaction, and pathogenicity.
Main Methods:
- Gene expression analysis (RT-qPCR) to assess MoRpa12 upregulation during infection.
- Green fluorescent protein (GFP) tagging to track MoRpa12 localization in fungal and plant cells.
- Site-directed mutagenesis of cysteine residues to determine their role in MoRpa12 function.
- Phenotypic analysis of MoRpa12 mutants to evaluate defects in mitosis, autophagy, stress tolerance, metabolism, and pathogenicity.
Main Results:
- MoRpa12 expression is upregulated during M. oryzae infection.
- MoRpa12 localizes to the nucleus in M. oryzae and translocates into plant cell nuclei post-penetration.
- MoRpa12 mutants display severe defects in mitosis, autophagy, stress response, cell wall integrity, metabolism, and pathogenicity.
- Specific cysteine residues at the N-terminus are critical for MoRpa12 nuclear localization and virulence.
Conclusions:
- MoRpa12 is essential for M. oryzae growth, development, and pathogenicity.
- MoRpa12 acts as an unconventional secreted effector that targets host nuclei.
- MoRpa12 plays a multifaceted role beyond transcription, impacting various cellular processes and host-pathogen interactions.
