Pectic polysaccharides elicit chitinase accumulation in tobacco

Upon infection of leaves of tobacco ( Nicotiana tabacum L. ev. Havana) with Erwinia carotovora (Jones) Holl, strain 3912, a phytopathogenic bacterium that secretes pectinolytic enzymes, chitinase (EC 3.2.1.14) levels increased 12‐fold within 48 h. Heat‐killed E. carotovara cells did not induce this response. In young excised tobacco plants supplied with pectic polysaccharides, chitinase activity increased to about the same level as in leaves infected with E. carotovora . The amount of pectic polysaccharides required for half‐maximal induction was about 160 μg (g fresh weight) −1 . Using in vivo labeling of plants with [ 35 S]‐cysteine, it could be demonstrated that elicitormediated chitinase induction is due to enhanced de novo synthesis of the enzyme.