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Poster

Session: Session 2 Presenting Authors at Posters (Odds)

P-125 - Elucidating the role of a ribonuclease-like effector secreted by the fungal pea powdery mildew pathogen Erysiphe pisi

Wednesday, July 16, 2025
13:30 - 15:15  
Location: Confex Hall 3
Effector Interference Mechanisms

    Presenting Author(s)

  • DS

    Debashish Sahu

    PhD student
    Regional Centre for Biotechnology, Faridabad, India
    Faridabad, Haryana, India

    • Author(s)

  • PG

    Puja Ghosh

    PhD student
    Regional Centre for Biotechnology, Faridabad, India
    Faridabad, Haryana, India

  • VK

    Vineet Kumar

    Researcher
    University of Texas at Austin
    Austin, Texas, United States

  • SM

    Smritilekha Mukherjee

    PhD student
    Regional Centre for Biotechnology, Faridabad, India
    Faridabad, Haryana, India

  • DJ

    Deepti Jain

    Associate Professor
    Regional Centre for Biotechnology, Faridabad, India
    Faridabad, Haryana, India

  • DC

    Divya Chandran

    Associate Professor
    Regional Centre for Biotechnology, Faridabad, India
    Faridabad, Haryana, India

Powdery mildew (PM) fungi are obligate biotrophic pathogens that secrete a plethora of effectors whose primary role is to promote successful colonization of living host plants. Among these, ribonuclease-like proteins associated with haustoria or ‘RALPH’ effectors that show structural similarity to fungal T1/F1 RNases are significantly expanded in the PMs that infect cereal crops; however, they are deficient in the enzymatic activities of these classical RNases. We previously showed that the pea PM Erysiphe pisi (Ep) contains RALPHs with conserved catalytic residues; however, a comprehensive analysis was lacking. Comparative genomics analysis revealed that RALPHs are undergoing expansion in certain dicot-infecting PMs, including Ep. EpRALPHs are expressed preferentially in fungal haustoria and at early time points during the infection process, implying a crucial role in pathogen establishment. Structural analysis revealed that all EpRALPHs possess an F1 RNase-like scaffold with low sequence conservation, but differ from the F1/T1 RNases in their surface charge distribution, indicating a conserved structural fold with functional divergence. Remarkably, only two EpRALPHs have retained the catalytic residues responsible for RNA hydrolysis, and in vitro studies demonstrate that one of these effectors may have retained the T1/F1 RNase activity. We are currently investigating the in planta localization and host targets of this EpRALPH to elucidate its role in pea-PM interactions.