Fig. 2. Endogenous OMT activities and OMT mRNA levels distributed within maize control plants. Maize plants were sampled 7 wk after planting in the greenhouse. Lanes 1 through 8 represent leaf samples from the second youngest to the ninth youngest leaf; Lane 9, young internodes; Lane 10, extending internodes; Lane 11, leaf sheaths; Lane 12, sorghum stem. (A) OMT activity was measured on each maize plant part and the highest OMT activity (0.76 pkat/mg protein) was considered as 100%. (B) Relative OMT mRNA steady state levels were determined by RNA quantification of the northern blot data. (C) Northern blot analysis of the OMT steady state levels using the maize omt cDNA probe. The blot was also hybridized with the 28S rDNA probe to standardize RNA loading and transfer.