The effect of gums induced by Fusarium oxysporum f. sp. tulipae in tulip bulbs on in vitro growth of the pathogen and its production of gum degrading enzymes.

摘要

A study was conducted to investigate the effect of tulip gums on the in vitro growth and development of F. oxysporum f.sp. tulipae and on the secretion of some enzymes to the culture medium. Addition of tulip gums to solid Czapek-Dox-Agar (CzDA) medium greatly stimulated mycelium growth and sporulation of F. oxysporum f.sp. tulipae. For measurements of enzyme production, F. oxysporum f.sp. tulipae was grown on liquid Czapek-Dox-Broth (CzDB) medium containing 3% sucrose and on mineral CzDB without sucrose, and supplemented with tulip gums at 0.1 and 0.5%. F. oxysporum f.sp. tulipae grown on CzDB containing sucrose did not secrete enzymes. However, on the CzDB medium supplemented with tulip gums, the pathogen secreted beta -1,4-glucosidase, alpha -1,4-galactosidase, beta -xylosidase and polygalacturonase. Incubation of the pathogen on mineral liquid CzDB medium caused secretion of beta -1,4-glucosidase, alpha -1,4-galactosidase and polygalacturonase to the medium, and supplementation of the medium with tulip gums greatly increased secretion of those enzymes and caused secretion of beta -xylosidase. At 24, 48, 96, 144 and 192 h after F. oxysporum f.sp. tulipae incubation, there were not detected activity of beta -1,4-galactosidase, beta -1,4-glucuronidase, alpha -1,4-xylosidase, alpha -1,4-arabinosidase, alpha -1,4-L-arabinosidase, beta -L-arabinosidase, alpha -1,4-mannosidase, alpha -1,4-rhamnosidase and beta -1,4-galacturonidase. Tulip gums added to the CzDB medium containing sucrose or only mineral compounds substantially stimulated sporulation of the pathogen.