VARIATION IN METABOLITE PRODUCTION BY SEPTORIA-NODORUM ISOLATES ADAPTED TO WHEAT OR TO BARLEY

The production of secondary metabolites by S. nodorum strains was exam ined in relation to their adaptation to wheat or to barley. Eleven str ains of each type previously characterized were tested for the product ion in culture of (-)-(3R)-mellein (ochracin), (3R)-O-methylmellein; ( -)-(3R, 4R)-4-hydroxymellein, ( -)-(3R, 4S)-4-hydroxymellein, mycophe nolic acid, septorine, N-methoxyseptorine, N-methoxyseptorinol, and a new compound (= UN). Mellein was produced by every strain. Both 4-hydr oxymellein isomers were yielded by all wheat-adapted strains and six b arley-adapted strains. Most of the strains produced mycophenolic acid. On the other hand the pigmentation of culture filtrates of wheat-adap ted strains was pale-yellow whereas the pigmentation of barley-adapted strains was grey-blue. The productions of O-methylmellein, septorine, N-methoxyseptorine and N-methoxyseptorinol were typical for wheat-ada pted strains. The detection of UN was restricted to the filtrates of b arley-adapted strains. If the pigmentation of filtrates and the produc tion of septorines, UN and O-methylmellein are considered the strains fell into two groups. This classification is related to the host adapt ation except for one barley-adapted strain that showed characteristics of wheat-adapted strains and one wheat-adapted strain which did not p roduce septorines.