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Effects of Gene and Cytoplasm Substitutions in Pearl Millet on Leaf Blight Epidemics and Infection by Pyricularia grisea. Jeffrey P. Wilson, Research plant pathologist, USDA-ARS Forage and Turf Research Unit, University of Georgia Coastal Plain Experiment Station, Tifton 31793; Wayne W. Hanna, Research geneticist, USDA-ARS Forage and Turf Research Unit, University of Georgia Coastal Plain Experiment Station, Tifton 31793. Phytopathology 82:839-842. Accepted for publication 6 April 1992. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1992. DOI: 10.1094/Phyto-82-839.

Derivatives of the pearl millet inbred Tift 23 with substitutions for various cytoplasms and alleles conferring morphologic or developmental traits were evaluated for differences in leaf blight epidemics in the field and their reactions to infection by Pyricularia grisea in the greenhouse. None of the experiments indicated an effect of the B, A1, or A4 cytoplasms; the tr allele for the trichomeless character; or the d2 allele for dwarf stature on leaf blight progress or on infection by P. grisea. An apparent increased susceptibility in the field was associated with the e1 allele for earliness. When disease progress curves were corrected for anthesis date, inbreds with the e1 allele were more resistant than inbreds without the allele. Disease ratings made early in the season in the 1991 field experiment did not correlate well with disease ratings made later in the season. Leaf blight increased on early cultivars after anthesis. Therefore, leaf blight in the field must be assessed at similar growth stages. When inoculated with P. grisea, seedlings of some inbreds with the e1 allele had smaller lesion dimensions than inbreds without the allele, and no lesions developed on Tift 23DA1E. Differences between reactions of the inbreds in the field and the greenhouse could be due in part to differences in susceptibility to other pathogens with an undetermined contribution to the leaf blight complex.

Additional keywords: alloplasmic, near-isogenic, Pennisetum glaucum, plant maturity.