INHERITANCE OF RESISTANCE TO MAIZE-DWARF MOSAIC-VIRUS AND SUGARCANE MOSAIC-VIRUS IN MAIZE

Eleven maize inbred lines and their hybrids were mechanically inoculated with maize dwarf mosaic Potyvirus A strain (MDMV-A) and sugarcane mosaic Potyvirus strains (SCMV-MB and SCMV-A). Inbreds GK210 and GK211 were moderately and highly susceptible to all the three virus strains. Inbred GK202 became infected in 73% of the inoculated plants by SCMV-MB and 34% by SCMV-A, but the symptoms appeared 5-8 days later than in GK210 and GK211. In the case of other inbred lines the rate of diseased plants was lower than 10%. In the F1 crosses of susceptible line (GK211) x resistant lines (GK201-GK209) the disease incidence ranged from 0 to 88%. If we take into consideration only the maximum disease incidence estimated 20 days after inoculation, the inheritance of virus resistance changed from the complete dominance of resistance to the complete dominance of susceptibility. In hybrids, which became infected at a higher level, the symptoms appeared 5-8 days later than in the case of their susceptible parental line GK211. Because as susceptible as inbred GK211. The use of Kuhn and Smith's (1977) evaluating resistance. The index considered both the number of diseased plants and the rate of symptom development. Based on these index values the inheritance of virus resistance was largely or partially dominant in the majority of inbred lines and only in a few cases was intermediate.