Endo-1,4-beta-xylanase involved in the hydrolysis of xylan, a major structural heterogeneous polysaccharide found in plant biomass representing the second most abundant polysaccharide in the biosphere, after cellulose. Required for planr infection and the appearance of secondary lesions. Endohydrolysis of (1->4)-beta-D-xylosidic linkages in xylans. Significantly inhibited by the wheat xylanase inhibiting protein I (XIP-I) and the proteinaceous endoxylanase Triticum aestivum xylanase inhibitors I (TAXI-I), whereas no inhibition is detected with TAXI-II. Optimum pH is 4.5-5.0. Optimum temperature is between 38 and 42 degrees Celsius. Glycan degradation; xylan degradation. Shows constitutive expression during the early stage of tobacco leaves infection. Belongs to the glycosyl hydrolase 11 (cellulase G) family.