Induction of new chitinase isoforms in tomato roots during interactions with Glomus mosseae and/or Phytophthora nicotianae var parasitica

Abstract

Chitinase activities were investigated by native and denaturing SDS-PAGE in tomato roots during symbiosis with the arbuscular mycorrhizal (AM) fungus Glomus mosseae, in a pathogenic interaction with Phytophthora nicotianae var parasitica and in pathogen-infected roots pre-inoculated with G mosseae for 2 weeks. Several native acidic chitinase isoforms were found in control roots. One additional isoform was detected in G mosseae-colonized roots, while a different one was found in pathogen-infected roots, as well as stronger expression of constitutive isoforms. All the chitinase isoforms were found in tomato roots pre-inoculated with G mosseae and post-infected with the pathogen. Four basic isoforms were present in all extracts, but they only showed enhanced activities in pathogen-infected roots. Chitinases from AM roots renatured more quickly and easily than those from non-mycorrhizal roots, after denaturing under non-reducing conditions, even when mycorrhizal plants were post-infected with the pathogen.