Quantification of Colletotrichum fioriniae in Orchards and Deciduous Forests Indicates It Is Primarily a Leaf Endophyte

Abstract

Colletotrichum fioriniae of the C. acutatum species complex is an important hemi-biotrophic pathogen of vegetables and fruits in temperate regions world-wide. In apple, it is one of the primary species responsible for bitter rot disease. Understanding the disease cycle is complicated because many broadleaf plants can be hosts of C. fioriniae. By detecting and quantifying rain-splashed C. acutatum species complex conidia in over 500 samples from heavily bitter-rot-infected apple orchards and nearby forested woodlots over two summers we show that conidial quantities were higher in the woodlots than in the orchards. Testing of over 1,000 surface disinfected leaves of apple and 24 different forest plant species showed that overall C. fioriniae was an abundant leaf endophyte, with high variation in leaf colonization area. Endophytic isolates from leaves were pathogenic on apples, and multi-locus sequence analysis showed 100% identity between most isolates from leaves and diseased fruits. Apple leaves endophytically infected with C. fioriniae were present in a conventionally managed orchard and abundant in an untreated orchard. These lines of evidence, in the context of previously published research, lead us to hypothesize that the main ecological role of C. fioriniae is that of a leaf endophyte, which we present as a generalized C. fioriniae infection cycle that provides an updated framework for its integrated management in agricultural systems.

Fungi as potential factors limiting natural regeneration of pedunculate oak (Quercus robur) in mixed‐species forest stands in Poland

“…acutatum species complex (Damm et al, 2012), members of which are often implicated as the causative agents of plant diseases on a wide range of hosts worldwide (Baroncelli et al, 2017). Recently, Martin and Peter (2021) provided evidence that C . fioriniae is primarily a leaf endophyte on a wide range of broad‐leaved plants inhabiting temperate deciduous forests in the USA, and endophytic isolates from these leaves are pathogenic on apple leaf and fruit.…”

Characterization and Antagonistic Effect of Culturable Apple-Phyllosphere Endophytic Bacteria from the Cold Plateau in Yunnan, China

“…Thus far, studies have focused on exploring endophytic fungi and bacteria for biocontrol of the main apple pathogens. The potential resources of endophytic bacteria from apple trees have been reported from many countries, such as Canada, India, the United States, Lithuania, Japan, and China [13,[31][32][33][34][35]. Bacterial endophytes from domestic apples are common inhabitants of plant tissues, which play an important role in the regulation of plant growth and the prevention against pathogens [13].…”

Morphological and phylogenetic resolution ofConoideocrella luteorostrata(Hypocreales: Clavicipitaceae), a potential biocontrol fungus forFiorinia externain United States Christmas tree production areas

“…It is not subject to copyright under 17 USC The copyright holder for this preprint this version posted October 18, 2022. ; https://doi.org/10.1101/2022.10.18.512709 doi: bioRxiv preprint elongate hemlock scales and a rigorous phylogenetic analysis of multiple strains from across the survey area. We additionally examined the culturable mycobiome of fir needles to confirm whether C. luteorostrata is also a needle endophyte, since a previously proposed biocontrol agent for these insects (Marcelino et al, 2009), Colletotrichum fioriniae, is now known to be primarily a leaf endophyte (Martin & Peter, 2021). C. luteorostrata was not isolated from Fraser fir needles, even though it is readily culturable.…”

“…Fungal biocontrol agents are often highly host-specific, so they may have fewer non-target effects than chemical pesticides (McClure, 1977b). The fungus Colletotrichum fioriniae has been proposed as a biological control agent of EHS on eastern hemlock (Marcelino et al, 2009), but further research showed that it is primarily a leaf/stem endophyte (Martin & Peter, 2021). C. fioriniae also has been reported as a post-harvest pathogen of apples (Chechi et al, 2019), other fruits (Ling et al, 2021; Ivic et al, 2013), and native plants (Kasson et al, 2014), potentially limiting its potential as a biocontrol agent for EHS.…”