P-331 - RNA exchange between plants and fungal pathogens initiates at the leaf surface during the epiphytic phase of infection

Monday, July 14, 2025

13:30 - 15:15

Location: Confex Hall 3

RNA on the move: Advances in Cross-Species communiation &Translational Research

Presenting Author(s)

MS

Meenu Singla-Rastogi, PhD (she/her/hers)

Postdoctoral Research Associate
Indiana University
Bloomington, Indiana, United States

Author(s)

LB

Lucia Borniego

Postdoctoral Research Associate
Indiana University
Bloomington, Indiana, United States
JD

Jean-Felix Dallery

Group Leader
Universite Paris-Saclay, INRAE, UR BIOGER
Palaiseau
HZ

Hana Zand Karimi

Indiana University Bloomington
Bloomington, Indiana, United States
PB

Patricia Baldrich

Director of Strategic Initiatives and Research Funding
University of California - Davis
Davis, California, United States
BM

Blake Meyers

Distinguished Professor
University of California - Davis
Davis, California, United States
RO

Richard J. O'Connell

Scientific Advisor of IMAFUN
Université Paris-Saclay, INRAE, UR BIOGER
Palaiseau, Ile-de-France, France
RI

Roger W. Innes, PhD (he/him/his)

Distinguished Professor
Indiana University Bloomington
Bloomington, Indiana, United States

We have recently shown that plants secrete diverse RNA species onto leaf surfaces, a crucial interface for the initial interactions between plants and microbes. These extracellular RNAs (exRNAs) differ from cellular RNAs and exRNAs found inside leaves in composition and size. Interestingly, leaf surface RNAs are neither protected by extracellular vesicles nor RNA-binding proteins. Moreover, the amount of leaf surface RNA increases rapidly following the perception of pathogen-derived molecules, such as flg22 from bacterial flagellin or chitin from fungal cell walls. To assess whether leaf surface RNAs are enriched in silencing RNAs, we transiently expressed an artificial hairpin RNA in Nicotiana benthamiana targeting the SGE1/Gti1 transcript, which encodes a key transcription factor in the phytopathogenic fungus Colletotrichum higginsianum. Two days post-infiltration, plants showed an accumulation of long double-stranded RNA derived from the artificial hairpin on leaf surfaces. To test the efficiency of these leaf surface RNAs in inducing silencing in C. higginsianum during the epiphytic phase of infection, we applied these RNAs on Arabidopsis cotyledons followed by infection with C. higginsianum. Exogenous application of this RNA to the surface of Arabidopsis cotyledons blocked infection before penetration of host cell walls, indicating that C. higginsianum is taking up RNA from leaf surfaces via a novel mechanism of RNA transfer during plant-pathogen interaction.