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Genetics

Genetics of Resistance of Two Dent Corn Inbreds to Maize Dwarf Mosaic Virus and Transfer of Resistance into Sweet Corn. M. A. Mikel, Former graduate student, Department of Plant Pathology, University of Illinois, Urbana 61801; Cleora J. D' Arcy(2), A. M. Rhodes(3), and R. E. Ford(4). (2)(4)Assistant professor, and professor and head, respectively, Department of Plant Pathology, University of Illinois, Urbana 61801; (3)Professor emeritus, Department of Horticulture, University of Illinois, Urbana 61801. Phytopathology 74:467-473. Accepted for publication 16 November 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-467.

Based on inoculation tests, dent corn inbreds Pa405, B68, Oh1EP, and Ga209 are good sources of resistance to maize dwarf mosaic virus (MDMV). When the other inbreds were crossed to Pa405, little or no segregation for resistance to MDMV was observed in the F₁ or F₂ progeny. In crosses to sweet corn susceptible to MDMV, resistance to MDMV in the F₁ hybrids of sweet corn × Pa405, × B68, × Oh1EP, and × Ga209 was 97, 61, 69, and 0%, respectively, of the plants tested. Based on three years' data from F₂ [(sweet corn × Pa405)F₂] and testcross [sweet corn × (sweet corn × Pa405)F₁] progeny, we estimated that three genes controlled resistance to MDMV. For effective resistance, one gene must be present with either of the other two. For F₂ and testcross progeny of (sweet corn × B68) F₂ and sweet corn × (sweet corn × B68)F₁, respectively, three genes were required for MDMV resistance. With selfing and selection of resistant plants from two-way (sweet corn × Pa405), three-way [sweet corn × (sweet corn × Pa405)F₁], and delayed three-way [sweet corn × (sweet corn × Pa405)F_x] crosses we have obtained homozygously resistant sweet corn lines.