Pepper gene encoding a basic class II chitinase is inducible by pathogen and ethephon

A chitinase cDNA clone (designated CAChi2) was isolated from the cDNA libra ry of pepper leaves infected with Xanthomonas campestris pv. vesicatoria. T he 1004-bp full-length CAChi2 cDNA encodes a basic chitinase with an N-term inal 24 amino acid signal peptide followed by a catalytic region. An analys is of its sequence indicates that CAChi2 is a class II chitinase, because i t does not have chitin-binding domain and C-terminal extension sequences. T he deduced amino acid sequence of CAChi2 has a high level of identity with class II chitinases from potato, tomato, tobacco and petunia. Southern anal ysis demonstrated that the CAChi2 chitinase is encoded by a single or two c opy genes in the pepper genome. Following X. campestris pv. vesicatoria or Phytophthora capsici infection, the CAChi2 chitinase mRNA was more highly e xpressed in the incompatible interaction, compared to expression in the com patible interaction. Treatment with ethylene-releasing ethephon resulted in a strong accumulation of the transcripts in the leaves. In contrast, DL-be ta-amino-n-butyric acid, salicylic acid and methyl jasmonate were not effec tive in inducing CAChi2 transcripts in pepper leaves. (C) 2000 Elsevier Sci ence Ireland Ltd. All rights reserved.