Chitinolytic activities of Eucalyptus pilularis and Pinus sylvestris root systems challenged with mycorrhizal and pathogenic fungi

SUMMARY The chitinolytic activities of Pinus sylvestris L. and Eucalyptus pilularis Sm. roots were measured after an exposure for 24 h to either ectomycorrhizal ( Pisolithus tinctorius (Pers.) Coker and Couch) or root‐infecting pathogenic fungi ( Heterobasidion annosum (Fr.) Karst. and Phytophthora cinnamomi Rands.). P. sylvestris roots not exposed to fungal hyphae had low levels of β‐ N ‐acetylglucosaminidase. This activity greatly increased after exposure to H. annosum but not P. cinnamomi or P. tinctorius. β‐ N ‐Acetylglucosaminidase activity in E. pilularis roots was unchanged after exposure to P. cinnamomi or P. tinctorius. Exo‐ and endochitinase activity increased after P. sylvestris roots were challenged with H. annosum , but not by the other fungi. These results suggest that β‐ N ‐acetylglucosaminidase might be an important early response to chitinous pathogens.