THE ASSOCIATION OF PEROXIDASE-ACTIVITY AND RESISTANCE OF MAIZE TO EXSEROHILUM-TURCICUM

Peroxidase activity in leaves of maize (Zea mays L.) differing in susceptibility to Exserobilum turcicum has been investigated in relation to their resistance to Northern Leaf Blight (NLB) caused by the fungal pathogen E. turcicum. In non-inoculated plants, high peroxidase activity was detected in leaves of the resistant isolines B37HtN and B73HtN as compared with the susceptible isolines B37 and B73 and the sweet corn variety Jubilee. After inoculation with E. turcicum, peroxidase activity increased in both susceptible and resistant isolines B73 and B73HtN. However, marked enhancement of peroxidase activity was detected 6 days after inoculation and became remarkable in isoline B73HtN, although symptoms started to show up in both susceptible and resistant plants only 10 days after inoculation. Using polyacrylamide gel electrophoresis separations, different banding pattern of isoperoxidases was found in the susceptible plants as compared with the resistant ones. In non-inoculated plants, three differential bands which appeared in the resistant isoline B37HtN, were absent in the susceptible Jubilee plants, and were as traces in the isoline B37. These bands first appeared in Jubilee and as clear bands in B37, only after inoculation with E. turcicum. The association of these isoperoxidases and resistance of maize to E. turcicum is discussed.