Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2000
Publication Date: August 1, 2000
Citation: Dugan, F.M., Lupien, S.L. 2000. Fungi quiescent in field and storage samples of grass seeds. Phytopathology. 90:S20. Interpretive Summary: Aside from clavicipitaceoius endophytes and mycorrhizal fungi, there is little information on fungi endophytic and/or quiescent in vegetative and/or reproductive tissues of grasses. This work represents initiation of baseline floristic data for fungi quiescent in seeds of various grass species taken from field and storage samples. The study provides for grass seeds information analogous to that long existing for cereal grains. Extensive information is available relative to colonization of cereal grains by fungi in the field and in storage, and the implications of the type and degree of colonization are well documented. Such data is pertinent to seed ecology and pathology. With regard to conditions of seed storage at WRPIS, data affirm that classical storage fungi have not replaced field fungi in stored seed lots; the data therefore represent an indirect affirmation of high quality seed storage in this distribution- oriented seed collection.
Technical Abstract: Seeds from 12 grass species were recovered from germplasm storage (4C, 30- 35 percent RH), and from field samples in the Palouse region of WA and ID, stripped of paleas and lemmas, and examined at 10-50X. Asymptomatic seeds were selected, disinfested by immersion in 70 percent ethanol for 30 seconds, 5 minutes in 0.525 percent NaOC1, then plated to malt extract agar (with and without antibiotics or rose bengal) for recovery of fungi. Fungi most commonly recovered included Alternaria spp., Cladosporium spp., Aureobasidium spp. and other dematiaceous hyphomycetes; Phoma spp. and other coelomycetes. Selenophoma spp., agents of halo spot, were isolated from field samples on multiple occasions. Total infection for most samples ranged from 0-45 percent, with field samples generally yielding fungi at higher rates than storage samples; species with large seeds tended to high infection rates. Classical storage fungi such as Aspergillus and Penicillium were rare or absent in both field and storage samples. Continued dominance by field fungi and exclusion of storage fungi reflects appropriate conditions for germplasm storage.