Diversity and Cross-Infection Potential of Colletotrichum Causing Fruit Rots in Mixed-Fruit Orchards in Kentucky

• Published in: Plant disease Vol. 105; no. 4; p. 1115
• Main Authors: Eaton, Madison J, Edwards, Shanice, Inocencio, Harrison A, Machado, Franklin J, Nuckles, Etta M, Farman, Mark, Gauthier, Nicole A, Vaillancourt, Lisa J
• Format: Journal Article
• Language: English
• Published: United States 01-04-2021
• Subjects: Colletotrichum - genetics; Fruit; Kentucky; Phylogeny; Plant Diseases; Kentucky; genome; fungi; fruit; blueberry ripe rot; cross-infection; apple bitter rot; barcoding; fungal genomics; Colletotrichum; pathogen diversity; strawberry anthracnose
• ISSN: 0191-2917
• DOI: 10.1094/PDIS-06-20-1273-RE

Fungi in the genus
cause apple, blueberry, and strawberry fruit rots, which can result in significant losses. Accurate identification is important because species differ in aggressiveness, fungicide sensitivity, and other factors affecting management. Multiple
species can cause similar symptoms on the same host, and more than one fruit type can be infected by a single
species. Mixed-fruit orchards may facilitate cross-infection, with significant management implications.
isolates from small fruits in Kentucky orchards were characterized and compared with apple isolates via a combination of morphotyping, sequencing of voucher loci and whole genomes, and cross-inoculation assays. Seven morphotypes representing two species complexes (
and
) were identified. Morphotypes corresponded with phylogenetic species
,
,
, and
, identified by
or
barcodes. Phylogenetic trees built from nine single-gene sequences matched barcoding results with one exception, later determined to belong to an undescribed species. Comparison of single-gene trees with representative whole genome sequences revealed that
and
were the most informative for diagnosis of fruit rot species and individual morphotypes within the
or
complexes, respectively. All blueberry isolates belonged to
, and most strawberry isolates were
, with a few
and
also recovered. All three species cause fruit rot on apples in Kentucky. Cross-inoculation assays on detached apple, blueberry, and strawberry fruits showed that all species were pathogenic on all three hosts but with species-specific differences in aggressiveness.