Oral: Pathogen Diversity
Illuminating the diversity of rust fungi infecting millets
J. DEMERS (1), L. Castlebury (1) (1) USDA-ARS, U.S.A.
Millets are a diverse assemblage of grains frequently grown in subsistence agriculture or as forage crops, and their popularity as nutritional alternative grains has recently increased. Millet pathogens are not well known, and modern collections of fungi associated with millets are lacking. Rust fungi are a significant group of pathogens that cause economically important diseases of three commonly grown millets: pearl millet (Pennisetum glaucum), foxtail millet (Setaria italica), and teff (Eragrostis tef), a millet becoming popular as a health food. 28S rDNA sequences were analyzed from over 40 herbarium specimens of rust fungi on millets, and related grasses, housed at the U.S. National Fungus Collections. Three taxa of rust fungi were observed on pearl millet, Puccinia substriata var. indica, P. substriata var. penicillariae, and P. cenchri, previously unreported on this host. The foxtail millet rust pathogen, Uromyces setariae-italicae, showed a high degree of intraspecific genetic diversity and was present on grasses in the Paniceae subtribes Cenchrinae and Melinidinae. The teff rust pathogen, previously known as U. eragrostidis, is actually distinct from U. eragrostidis and is identified as U. pedicellata. Knowledge of the diseases of millets is increasingly important as they become more widely grown as human food sources and pressure to increase yields in the presence of the pathogens intensifies.