The histochemical location of arabinosidase and xylosidase in germinating wheat grains

α-L-Arabinofuranosidase (EC 3.2.1.55) and β-D-xylanopyranosidase (EC 3.2.1.37) activities were detected in the endosperms of germinated, dried and sanded wheat grains using the fluorescence of 4-methylumbelliferone released from appropriate synthetic substrates. The enzymes were not detected in ungerminated grains. Activities were first detected adjacent to the scutellum and advanced into the endosperm with increasing germination time, in some grains being slightly more advanced next to the aleurone layer. They were not detected in other tissues by this technique although analysis of extracts of the other tissues showed that they were present in greater amounts in the embryo and in the aleurone layer. The problems of interpretation caused by these findings are discussed.