REACTION OF TOBACCO AND RICE LEAF TISSUE INFILTRATED WITH BURKHOLDERIA-GLUMAE OR BURKHOLDERIA-GLADIOLI

Reaction of tobacco and rice leaf tissue infiltrated with either strai ns of Burkholderia glumae or B. gladioli was investigated. Visual alte ration areas of tobacco leaf at sites infiltrated with high concentrat ion (more than 10(7) cells/ml) of the bacteria mere categorized into t wo types, one causing necrosis with hypersensitive-like reaction (HLR) within 24 hr of infiltration, and the other developing only yellowish discoloration. Living bacterial cells and the toxoflavin were effecti ve for necrosis induction, whereas heat-killed cells, bacterial lipopo lysaccharide (LPS) and extracellular polysaccharide (EPS) were ineffec tive. In the case of B. glumae, necrosis occurred with toxoflavin prod ucing strains. No necrotic lesions developed with toxoflavin non-produ cing strains. Ail strains of B. gladioli induced necrosis with water s oaking lesions in tobacco leaf. Infiltration of toxoflavin producing s trains of B. glumae and B. gladioli to rice leaf caused necrosis or a chlorotic spot on the leaf. A toxoflavin dose of more than 100 mu g/ml induced necrosis, suggesting close relationship between virulence to rice and necrosis inductivity to an uncongenial plant such as tobacco. Thus, the principle which induces HLR can be regarded as an essential attribute for pathogenicity. In contrast to the reaction of rice leaf toward toxoflavin, necrosis in tobacco leaf could not simply be a rea ction to toxoflavin but rather to additional unknown factors.