Isolation of a gibberellin-producing fungus (Penicillium sp. MH7) and growth promotion of crown daisy (Chrysanthemum coronarium)

Plant growth promoting fungi (PGPF) are well known for the production of useful secondary metabolites. However, limited information is available on the gibberellin (GA) production capacity of PGPF of endophytic origin. In the current study, 15 fungal endophytes were isolated from the roots of Crown daisy, and then screened on Waito-c rice, in order to identify plant growth promoting fungi. The fungal isolate MH7 significantly increased the shoot length (12.1 cm) of Waito-c in comparison with control treatment (7.9 cm). In a separate experiment, the culture filtrate (CF) of MH7 significantly promoted the growth attributes of Crown daisy. The MH7 CF was analyzed for gibberellins and it contained all physiologically active gibberellins (GA₁, 1.37 ng/ml; GA₃, 5.88 ng/ml; GA₄, 8.62 ng/ml; and GA₇, 2.05 ng/ml) in conjunction with physiologically inactive GA₉(0.83 ng/ml), GA₁₂(0.44 ng/ml), GA₁₅(0.74 ng/ml), GA₁₉(1.16 ng/ml), and GA₂₀(0.98 ng/ml). The CF of MH7 produced higher amounts of GA₃, GA₄, GA₇, GA₉, and GA ₁₂ than wild-type Fusarium fujikuroi, which was used as a control for GA production. The fungal isolate MH7 was later identified as a new strain of Penicillium on the basis of its morphological characteristics and phylogenetic analysis of the 18S rDNA sequence.