Identification and partial characterization of beta-1,3-glucanase from virus-infected cucumber cotyledons.

One of the five "pathogenesis-related" (PR) proteins known to accumulate in Cucumis sativus L. cv. Laura and to react hypersensitively to tobacco necrosis virus (TNV) was shown to to have beta-1,3-glucanase activity. The TNV-induced acidic beta-1,3-glucanase activity increased 6-fold after infection and had extracellular localization and estimated M(r) of 25,700. The beta-1,3-glucanase activity was investigated with a new method of activity staining using a conjugated substrate in overlay gels. By using the antiserum against tobacco beta-1,3-glucanase purified to homogeneity, a close serological relationship was demonstrated between cucumber and tobacco beta-1,3-glucanases on immunoblots.