Plant growth promoting rhizobacteria (PGPR) are potential natural alternatives to chemical fungicides in greenhouse production via inducing plant immune system against biotic stresses. In this research, 126
Streptomyces
isolates were recovered from rhizosphere soils of 13 different commercial vegetable greenhouses in Iran.
Streptomyces
isolates were screened for
in vitro
Plant growth promoting (PGP) traits and ability to antagonize
Fusarium oxysporum
f. sp.
lycopersici
race 3 (
FOL
), the causal agent of Fusarium wilt of tomato (FWT). Six isolates with the highest antagonistic activity and at least three PGP traits were selected and compared with chemical fungicide Carbendazim
®
in a greenhouse experiment. All bacterial treatments mitigated FWT disease symptoms like chlorosis, stunting and wilting at the same level or better than Carbendazim
®
. Strains IC10 and Y28 increased shoot length and shoot fresh and dry weight compared to not inoculated control plants. Phenotypic characterization and 16S rRNA gene sequencing showed, strains IC10 and Y28 were closely related to
S. enissocaesilis
and
S. rochei
, respectively. The ability of the superior biocontrol strains to induce antioxidant enzymes activity and systemic resistance (ISR) was investigated. Increased activity of catalase (CAT) in plant treated with both strains as well as an increase in peroxidase (POX) activity in plants treated with Y28 pointed to a strain specific-induced systemic resistance (ss-ISR) in tomato against
FOL
. The differential induced expression of
WRKY70
and
ERF1
(two transcription factors involved in plant defense) and
LOX
and
TPX
by the analyzed
Streptomyces
strains, especially after inoculation with
FOL
, suggests that ss-ISR is triggered at the molecular level.