Optimizing in-vitro production of Delaware-isolated Pythium zoospores

Pythium, which are fungus-like eukaryotic plant pathogens, are notorious for significant worldwide crop losses by causing damping off, seedling blights, root rots, foliar blights, or stalk rots across hundreds of plant species. Pythium propagates in various ecological niches by producing oospores, sporangia, and mycelial hyphae. However, infections on host tissue are primarily initiated by specialized, motile, asexual structures known as zoospores released from sporangia. Research focused on Pythium-plant interactions is advanced by understanding the biology of Pythium spp., particularly through observations of zoospore production and visualization of infection. While previous studies have successfully produced zoospores via in vitro methods, consistent and reproducible methods for specific species of pathogenic Pythium remain limited, particularly for species like Pythium graminicola, a prominent pathogen of corn in the Mid-Atlantic United States. By refining pre-existing techniques to improve zoospore yield, efficiency, and production reliability, a method optimized for in vitro zoospore production of P. graminicola was developed. A new strategy of chopped inoculum plugs was also tested, and increased surface area exposure was found to enhance zoospore release. Chopped inoculum plugs from 7-day-old cultures grown on lima bean agar media, soaked in deionized water, and incubated under constant light and temperature for 24 hours, produced the highest number of zoospores, with an average of 7.9 × 10^3 zoospores/mL for P. graminicola. This optimized method was later tested on P. dissotocum, P. inflatum, P. torulosum, and Globisporangium sylvaticum to induce zoospore production and examine the relationship between phylogenetic relatedness and method responsiveness. Two out of four species tested responded positively, with P. dissotocum producing the highest and P. torulosum comparable to P. graminicola, while G. sylvaticum and P. inflatum showed negligible to no zoospore production. This work builds on foundational methods, providing a reliable and reproducible approach for zoospore production to facilitate future research into Pythium biology, infection, diagnostics, and management within the framework of Mid-Atlantic corn.

Grantor dc:publisher

University of Delaware

Year dc:date.issued

2025

Author dc:creator

• Singh, Bali

• Pythium
• Zoospores
• Sporangia

Repository record dc:identifier.uri

https://udspace.udel.edu/handle/19716/36460

OAI identifier oai:identifier

oai:udspace.udel.edu:19716/36460