Maize inbred lines, derived from both Australian and exotic sources, and used in a breeding programme at Kairi, Qld, were screened for resistance to a Johnson grass strain of sugarcane mosaic virus (SCMV-Jg). There was a good correlation between ratings made following manual inoculation in a glasshouse and those following exposure to natural field infection. Seven lines were highly resistant in both glasshouse and field ratings. A further nine lines showed an intermediate level of resistance following manual inoculation and developed from 0 to 7 % infection under field conditions when a susceptible line developed 99 % infection. Data obtained following the manual inoculation of plants in segregating generations of crosses between resistant KL 57 and susceptible KL 9 were consistent with resistance being controlled by a single dominant gene. Six lines (Pa 405, CI 44, Tx 601, Oh 07, Oh 7B, 38-11) that were used as sources of resistance to maize dwarf mosaic virus, strain A (MDMV-A) in the U.S.A. developed natural infection levels of less than 15% with SCMV-Jg. Only Pa 405 was highly resistant to manual inoculation. Four of 11 SCMV-Jg resistant lines were also highly resistant to manual inoculations with the sugarcane, Sabi grass and Queensland blue couch grass strains.
Peroxidase Activity in Maize Inbred Lines Resistant or Susceptible to Maize Dwarf Mosaic Virus
