Enhancing citrus resistance against Huanglongbing (HLB) through foliar application of MAMPs

Monday, August 4, 2025

10:15 AM - 10:30 AM HST

Location: Room 313 A

Presenting Author(s)

JL

Jinyun Li, PhD

Biological Scientist, SR.
University of Florida
Lake Alfred, Florida, United States

Author(s)

ZP

Zhiqian Pang

University of Florida Citrus Research and Education Center
Lake Alfred, Florida, United States
GC

Gitta Coaker, PhD (she/her/hers)

Professor
UC Davis
Davis, CA, USA
NW

Nian Wang

Professor
University of Florida
Lake Alfred, FL, USA

Abstract Text: Citrus Huanglongbing (HLB) caused by Candidatus Liberibacter asiaticus (CLas) is currently the most devastating citrus disease worldwide. Enhancing host resistance is of vital importance for disease management in crop production. Here we explored using microbe-associated molecular patterns (MAMPs) to boost disease resistance in new plantings against HLB under greenhouse and field conditions. Foliar spray of lipopolysaccharide (LPS), harpin, and chitin activated pathogen-associated molecular patterns (PAMPs) triggered immunity (PTI) in sweet orange plants in a dosage-dependent manner. Peak levels of expression of citrus PTI-related genes including FRK1, MKK4, PAL1, WRKY22, and WRKY29 were recorded at 12 to72 hours post treatment. Moreover, applications of LPS, harpin, and chitin at an optimized concentration weekly reduced CLas population growth in HLB-infected sweet orange plants in greenhouse assays. In a 2-year test under natural conditions, foliar spray of harpin and chitin monthly delayed population establishment of CLas vectored by psyllids and decreased CLas growth after infection in sweet orange and mandarin plants. This study demonstrates that MAMPs can enhance citrus resistance against CLas, with implications in HLB disease management. The long-term implications of plant defense inducers will be discussed.