HYDROXAMIC ACID CONTENT IN UNDIFFERENTIATED AND DIFFERENTIATED TISSUES OF WHEAT

Hydroxamic acid content in wheat tissues was studied by HPLC. Undifferentiated tissues such as callus or meristem produce only the aglucones, 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA). DIMBOA beta-glucosidase activity was not detectable in these tissues. In seedlings, DIBOA-glucoside first appeared and then DIMBOA-glucoside. In seven-day-old seedlings a significant amount of aglucone was also detected, although the beta-glucosidase activity was inhibited by liquid nitrogen and methanol. The results suggest that hydroxamic acids are produced by undifferentiated tissues as aglucones; later glucosylation gives rise to the glucosides normally detected in differentiated shoots or roots.