Detection of pathogenesis-related proteins in cotton plants

Seeds of cotton (Gossypium hirsutum and Gossypium barbadense) were sown in pots and inoculated with or without vesicular-arbuscular mycorrhizal fungi (VAMP): Glomus mosseae, Glomus versiforme or Sclerocystis sinuosa and with or without Verticillium dahliae. The VAMF inoculation improved seedling growth, increased the yield of seed cotton and reduced the incidence and disease index of verticillium wilt. Some new soluble proteins were found in the roots and leaves of the cotton infected with the tested VAMF or V. dahliae. More than 10 types of new proteins were identified as pathogenesis-related proteins (PRs). One of the PRs exhibited chitinase activity. The contents of the PRs were enhanced following inoculation with the VAMP and V. dahliae. Tests in vitro showed that the PRs at certain concentrations were able to retard hyphal growth and kill conidia of V. dahliae. (C) 1995 Academic Press Limited