Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: June 17, 2000
Publication Date: N/A
Technical Abstract: Ineffective screening methods and low levels of disease resistance have hampered genetic analysis of maize resistance to maize chlorotic dwarf. This disease is caused by Maize chlorotic dwarf waikivirus, which is vectored by the leafhopper, Graminella nigrifrons. Germplasm identified as resistant using three screening methods (natural infection, 14-day old plants, and multiple inoculation of 3-4 day old seedlings) was re-evaluated with the highly effective multiple inoculation screening method. In this screen, inbreds Oh1VI, Mp705 and inbred lines derived from Compuesto Cuba 551 (CC551) and Dominican Republic (DR) were highly resistant. In contrast, T232, Oh1EP, Pa11 and CI121, which were resistant to MCDV in the natural infection and/or single inoculation screens, were susceptible in the multiple inoculation screen. Tests of F1 crosses (resistant inbred X susceptible inbred Va35) and subsequent F2 populations indicated the MCDV resistance was quantitative and AUDPC scores for the 1 crosses suggested the inheritance of resistance was polygenic. QTL analyses and ANOVA of 300 F2 progeny of Oh1VI x Va35 indicated two independent QTLs of equal strength located on chromosomes three and ten. Experiments to map loci controlling resistance in Mp705, CC551 and DR are still underway.