biological control of gray mold on apple by combining of some yeast and bacillus subtilis isolates and induction of defense responses

the biocontrol agents candida  membranifuciens (isolates a4 and a5), pichia  guilliermondi (a6) and bacillus subtilis (b2 and b6) were tested both individually and in combination for biological control of the grey mold in fruit apple caused by botrytis cinerea pers.:fr. regarding the compatibility of the biocontrol agents, it showed that antagonists were compatible with each other according to in vitro antibiosis and cell-free metabolite by applying  cellophane test. the interaction of the antagonists in liquid media showed that  the growth of yeast isolates was not affected by the presence of b. subtilis isolates, and then the yeast population increased until the end of the experiment. results of storage experiments of yeast, bacteria and their mixture indicated that the lesion diameters caused by the biocontrol agents combinations of b2+a5 and b6+a6 treated fruit were 5.23 and7.43mm, respectively, at 20 c° and 3.48 and 3.87 mm for 4 oc respectively, that provided better control than the antagonist alone. the combination of b2+a5 caused an increase in peroxidase activity and  phenolic accumulation showing a maximum level 2 day after pathogen inoculation. this combination decreased catalase activities 4 day after pathogen inoculation. these results indicated that by using antagonist mixtures, it is possible to further of induction of resistance in apple fruits and improving biological control.