Establishment of an infection system for gentian (

Gentians (Gentiana spp.) as floriculture crops are constantly exposed to several fungal and viral pathogens in the field. Among the fungal diseases afflicting gentian production, gentian sclerotial flower blight caused by Ciborinia gentianae incurs economic losses as it affects both flowers pre- and post-harvest. Currently, preventive measures for this disease are limited, and no resistant cultivar has been reported. This is partly because of the lack of a reliable infection system that could promote research on this plant-fungus interaction. In this study, Gentiana plant tissue culture material was inoculated with C. gentianiae culture filtrate. We successfully demonstrated non-ascospore mediated infection of C. gentianae. Inoculation of individual hyphal structures present in the culture filtrate suggested that sclerotial primordia are the main agents of this infection. Interestingly, we observe that primary infection of C. gentianae in petals but not leaves potentiates systemic infection resembling the fungus' infection strategy in the field. Moreover, we show that, 1) non-ascospore hyphal structures can also cause disease in flowers grown in the field and, 2) ascosporic infection can also be observed using the in vitro system, opening possibilities for both practical and basic researches aimed to combat gentian sclerotial flower blight disease.