Understanding environmental and physiological factors affecting the biology of Diaporthe ilicicola , the fungus causing latent fruit rot in winterberry

• Published in: Plant disease
• Main Authors: Emanuel, Isabel Brooke, Laird, Aleacia E, Peduto Hand, Francesca
• Format: Journal Article
• Language: English
• Published: United States 01.10.2023
• Subjects: disease development and spread; winterberry; Diaporthe ilicicola; environmental factors; Crop Type; fruit rot; Causal Agent; Epidemiology; Fungi; Ilex verticillata; Ornamentals; woody ornamentals; Subject Areas; phenolics
• ISSN: 0191-2917
• DOI: 10.1094/PDIS-11-22-2759-RE

Fruit rot in winterberry is associated with a complex of fungal pathogens. Among them, plays a unique role by infecting flowers at bloom, resulting in symptom development in mature fruit. This research aimed to identify at what stage of maturation fruit can develop disease symptoms, and correlate changes in fruit physiology (sugar and phenolic content) and the environment (temperature and light intensity) with disease incidence. Correlation data informed studies testing the ability of putative factors to alter growth of and select opportunistic fungi within the fruit rot complex: , , and . Results indicated that fruit do not develop symptoms until 81-108 days after inoculation. Temperature and fruit phenolic content were negatively correlated with disease incidence, while fruit sugar concentration and light intensity were positively correlated. assays revealed that sugar concentration had no effect on the growth of but increased light intensity increased hyphal growth and pycnidium formation. Additionally, phenolics extracted from fruit inhibited spore germination in , induced secondary conidiation in , and late season phenolic extracts increased hyphal melanization and pycnidial formation in . Finally, drops in field temperatures, when replicated , resulted in a decrease in hyphal growth and spore germination for all fungi. These results suggest that changes in Ilex fruit phenolics during maturation, and the increased exposure to light following defoliation, may play a role in symptom development by altering growth within the fruit.