The Defense Response of Honeyberry to Root Rot Pathogens: Evidence Based on Pathogen Identification and Host Mechanism.

Honeyberry plants (Lonicera caerulea L., family Caprifoliaceae), which produce small, highly nutritious berries, have recently been subject to an outbreak of root rot, resulting in a drastic decrease in fruit yield. In this study, we isolated the fungal community from the roots of diseased plants and analyzed the mechanisms of interaction between key fungi and honeyberry plants. Nine fungal morphotypes were identified via observation of cultures and internal transcribed spacer gene sequence analysis. Pathogenicity assays showed that infection with isolates from the genus Fusarium reproduced the typical root rot symptoms, and Fusarium foetens caused the most severe inhibition of root growth. Transcriptomic analysis of infected plants and Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that the biosynthesis of secondary metabolites was enriched in roots of honeyberry plants infected with F. foetens. This study elucidates that when honeyberry is affected by root rot disease, it produces secondary metabolites to defend against pathogenic invasion, providing a theoretical basis and molecular targets for the green management of this disease.