The resistance of maize inbred lines to sugarcane mosaic virus in Australia

Abstract

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.