Regulation of glyoxysomal enzyme expression in maize zea mays cultivar indian chief
Tsaftaris, A.S.; Scandalios, J.G.
Differentiation 18(3): 133-140
The activity levels of 3 glyoxysomal enzymes (catalase, isocitric lyase and malate synthase) were measured in the scutellum following germination of the inbred lines W64A, R6-67 and A16. In W64A, as in most maize lines examined, germination was accompanied by a rapid and synchronous increase in the activities of all 3 enzymes and reached a peak at .apprx. day 4 and then declined. In R6-67, catalase activity continues to increase past day 4 and reaches its highest activity level on later days. In A16, catalase activity is very low due to the lack of expression of the Cat2 gene. Despite these significant differences in catalase expression, the levels of the other 2 glyoxysomal enzymes did not differ in these inbred lines. Artificial inhibition of catalase in W64A by exogenous application of 10-4 M aminotriazole did not inhibit germination nor did it alter the levels of the other 2 glyoxysomal enzymes. Similarly, application of 10-3 M itaconate to W64A seeds inhibited the appearance of isocitric lyase but did not inhibit germination or alter the levels of malate synthase or catalase. Comparative cell fractionation and immunological studies were conducted with W64A and A16 and their microbodies were observed under the EM. Cell fractionation studies were conducted with W64A seeds germinated in the presence of aminotriazole or itaconate. The expression of these 3 glyoxysomal enzymes is apparently not regulated coordinately in the maize scutellum.