Effect of mutations affecting the Xyn11A xylan-hydrolysis active site on its necrotizing and H
-inducing activities on tomato (cv. Moneymaker) leaves. Development of necrotic lesions (A) and production of H2O2 (B) in the leaves by infiltration with wild-type and site-directed mutant Xyn11A. X: infiltration with wild-type xylanase (wt) or the indicated non-xylan-hydrolyzing mutant proteins. W: Control infiltration with water.