Isolation and characterization of pectin inducible cDNA clones from the phytopathogenic fungus Fusarium moniliforme

Abstract

Growth of many fungal pathogens in a culture medium containing pectin is known to promote induced synthesis of pectic enzymes and other proteins. A cDNA library was constructed in λgt10 using poly(A)-containing RNA isolated from Fusarium moniliforme that had been grown in Czapek-Dox broth containing 1% pectin as the carbon source. The library was screened by differential hybridization using radioactive cDNAs prepared from poly(A)-containing RNA isolated from the pectin-induced and non-induced fungus. Fourteen clones hybridized only with pectin-induced cDNA and did not hybridize at all with the non-induced cDNA. On the basis of cross hybridization characteristics, the fourteen clones were classified into six homology groups each of which did not hybridize to the others. Northern analysis of poly(A)-containing RNA isolated from the pectin-induced fungus was performed using a single clone, harbouring the largest insert, from each of the six homology groups. All clones hybridized to mRNAs induced by pectin. The isolation of pectin-induced cDNA clones provides a tool to study gene expression in the phytopathogenic fungus, F. moniliforme , during the early stages of interaction with a potential host plant.