P-422 - New answers to old problems: Genomic insights into pathogenicity of invasive Discula destructiva, the dogwood anthracnose pathogen

Tuesday, August 5, 2025

10:15 AM - 11:00 AM HST

Location: Exhibit Hall 3

Presenting Author(s)

MN

Marcin Nowicki, PhD

University of Tennessee, Entomology and Plant Pathology Department
Knoxville, Tennessee, United States

Author(s)

SB

Sarah L. Boggess, MS

Lab Manager and Sr. Research Associate
University of Tennessee - Knoxville, TN
Knoxville, Tennessee, United States
RT

Robert Trigiano

University of Tennessee, Entomology and Plant Pathology Department
Knoxville, Tennessee, United States
WK

William Klingeman

University of Tennessee
Knoxville, Tennessee, United States
DH

Denita Hadziabdic, PhD

Associate Professor
University of Tennessee, Entomology and Plant Pathology Department
Knoxville, Tennessee, United States
KR

Kayleigh Redington

University of Tennessee
Knoxville, Tennessee, United States
PB

Patrick Barry

University of Tennessee
Knoxville, Tennessee, United States
SN

Shade Niece

University of Tennessee
Knoxville, Tennessee, United States
AP

Alina Pokhrel

UNIVERSITY OF TENNESSEE AT KNOXVILLE
KNOXVILLE, Tennessee, United States
MS

Margaret Staton

University of Tennessee
Knoxville, Tennessee, United States

Abstract Text: Dogwood anthracnose fungus Discula destructiva Redlin has devastated native and cultivated flowering dogwood and threatens Pacific dogwood trees. We aimed to leverage new genome resources to better understand the roles of pathogenicity genes and host responses. A hybrid assembly approach yielded a gapless, chromosome-scale reference genome of D. destructiva, which has 8 chromosomes spanning 46.6 Mb and 10,373 annotated genes. RNAseq data showed 162 upregulated and 78 downregulated genes that highlight key metabolic pathways involved in pathogenesis, including plant cell wall degradation and iron binding activity in sporulating cultures. The D. destructiva mtDNA SNP vs. nuclear data confirmed the absence of recombination signatures, as postulated by classical mycelial mating assays. Sterile-culture enzyme assays revealed that D. destructiva is rich in polyphenol oxidases that are essential for pathogen establishment and survival. Analyses of culture growth dynamics suggested novel opportunities for managing D. destructiva, like adjusted pH in fungicide formulations. To quickly track resistance genes in plants, we identified Arabidopsis ecotypes of variable responses to both, D. destructiva 4HBA toxin and mycelial cultures. To translate the findings into the host plant, we performed plate assays with fungal toxin 4HBA on dogwood leaves from susceptible × resistant F2 hybrids. Challenged leaves were phenotyped and cross-studied via whole-genome sequencing. Our integrated study provides crucial information for the continued protection of dogwoods, an important ornamental crop.