Mycorrhizal symbiosis is one of the oldest types of symbiosis known between fungi and a wide variety of plants. Mycorrhizae benefit more than 80% of the plants on the earth. It improves regulation of water absorption, increases absorption of immobile mineral elements from the soil and conferring resistance to stress with activation of plant defense system. Recently, arbuscular mycorrhizal fungi have been considered as bio-fertilizers to increase productivity and reduce the use of chemical fertilizers. Endophytic fungi are an important and novel resource of naturally bioactive compounds having potential applications in environmental interactions. Previous studies showed that endophytes have the capability to produce physiologically active gibberellins. The symbiosis of gibberellins producing endophytic fungi with crops can be a promising strategy to overcome the adverse effects of abiotic stresses. The association of such endophytes has not only increased plant biomass but also ameliorated plant-growth during extreme environmental conditions. GAs were initially isolated from the pathogenic fungus (Fusarium fujikuroi: a teleomorph of Gibberella fujikuroi)). Another strain of the fungus, Phaeosphaeria sp. L487 produces GA1, GA4 and GA9. Other fungal species such as Aspergillus niger, Neurospora crassa, Sporisorium reilianum, Sphaceloma manihoticola and Agaricus bisporus have been identified to either produce GAs during their growth or contain Gas biosynthesis gene clusters. Scolecobasidium tshawytschae has been known to produce indole-3-acetic acid and indole-3-lactate. Until now, 21 different endophytic fungal species have been identified for their potential to produce GAs in axenic cultures. These endophytes were isolated from the rhizospheric continuum of the endophyte plant environment. All the isolated endophytes have the potential to produce GA1,GA3,GA4,GA7,GA9 and GA12 which suggest that these endophytes might have GAs biosynthesis pathways similar to plants.
