Antagonistic yeasts competes for iron with winter wheat stem base pathogens

Aureobasidium pullulans and Sporobolomyces roseus are a saprotrophic yeasts fungi commonly found on the leaves of winter wheat and on wheat kernels. The objective of this study was to compare the inhibitory effects of two species of yeasts fungi, Aureobasidium pullulans var. pullulans (de Bary) G. Arnaud and Sporobolomyces roseus Kluyver & van Niel, on the causal agents of stem base diseases, Rhizoctonia cerealis v. d. Hoeven, Gaeumannomyces graminis (Sacc.) Arx & D. Olivier, Helgardia herpotrichoides (Fron) Crous & W. Gams, Fusarium oxysporum (Schlecht) Snyd. et Hans.) and Fusarium culmorum (W. G. Smith). A. pullulans showed stronger inhibitory activity than S. roseus. Among the 70 A. pullulans isolates tested in the study, 25 were capable of suppressing the colony growth of R. cerealis under in vitro conditions. This is the first study to show that A. pullulans competes for iron with stem base pathogens, in particular with fast-growing R. cerealis and F. culmorum. Under greenhouse conditions, A. pullulans protected winter wheat seedlings against infection caused by F. culmorum, from two to four times compared with the control, and its protective effect was determined by the infection susceptibility of wheat cultivars and the time interval between the application of A. pullulans and inoculation with F. culmorum.