Gibberellins Producing Endophytic Fungus Porostereum spadiceum AGH786 Rescues Growth of Salt Affected Soybean

Abstract

In the pursuit of sustainable agriculture through environment and human health friendly practices, we evaluated the potential of a novel gibberellins (GAs) producing basidiomycetous endophytic fungus Porostereum spadiceum AGH786, for alleviating salt stress and promoting health benefits of soybean. Soybean seedlings exposed to different levels of NaCl stress (70 and 140 mM) under greenhouse conditions, were inoculated with the AGH786 strain. Levels of phytohormones including GAs, JA and ABA, and isoflavones were compared in control and the inoculated seedlings to understand the mechanism through which the stress is alleviated. Gibberellins producing endophytic fungi have been vital for promoting plant growth under normal and stress conditions. We report P. spadiceum AGH786 as the ever first GAs producing basidiomycetous fungus capable of producing six types of GAs. In comparison to the so for most efficient GAs producing Gibberella fujikuroi, AGH786 produced significantly higher amount of the bioactive GA3. Salt-stressed phenotype of soybean seedlings was characterized by low content of GAs and high amount of ABA and JA with reduced shoot length, biomass, leaf area, chlorophyll contents, and rate of photosynthesis. Mitigation of salt stress by AGH786 was always accompanied by high GAs, and low ABA and JA, suggesting that this endophytic fungus reduces the effect of salinity by modulating endogenous phytohormones of the seedlings. Additionally, this strain also enhanced the endogenous level of two isoflavones including daidzen and genistein in soybean seedlings under normal as well as salt stress conditions as compared to their respective controls. P. spadiceum AGH786 boosted the NaCl stress tolerance and growth in soybean, by modulating seedlings endogenous phytohormones and isoflavones suggesting a valuable contribution of this potent fungal biofertilizer in sustainable agriculture in salt affected soils.

Aspergillus niger CSR3 regulates plant endogenous hormones and secondary metabolites by producing gibberellins and indoleacetic acid

“…Production of phytohormones is a key attribute enabling endophytes to promote plant growth by improving the ability of the host to tolerate and overcome different abiotic and biotic environmental stresses (Ma et al 2016;Hamayun et al 2017;Khan et al 2017;Sandhya et al 2017). Therefore, to determine the phytohormones i.e.…”

“…For instance, concentration of GAs and IAA varied in the culture of the same fungus grown on various nutrients and pH (Waqas et al 2014). Furthermore, production of GA by various endophytic fungi has been reported as the most significant characteristic of PGPF (Zhang et al 2016;Hamayun et al 2017).…”

Preussia sp. BSL-10 producing nitric oxide, gibberellins, and indole acetic acid and improving rice plant growth

“…Furthermore, Penicillium funiculosum, Aspergillus fumigatus sp. LH02 (Khan et al 2011), Porostereum spadiceum AGH786 (Hamayun et al 2017), and Aspergillus clavatus Y2H0002 (You et al 2015) have been recently revealed to produce various kinds of gibberellins in their growth cultures. The current study suggests the existence of gibberellin biosynthesis where the end-product is GA 4 not GA 3 in Preussia sp.…”

Microbial small molecules – weapons of plant subversion

“…However, endophytes such as Porostereum spadicium have been shown to produce GAs that enhanced the ability of soybean to tolerate salt stress. 73 Similarly, soybean roots inoculated with a specic strain of Aspergillus fumigatus exhibited increased shoot length, increased shoot and leaf biomass, and photosynthetic rates under salt stress compared to noninoculated plants. 74 Exhaustive reviews on the history of gibberellin research, its biological mechanisms, and the ability of plant-associated microbes to produce GAs were published recently by Hedden and Sponsel, 72 and Khan et al 75 There is however only limited knowledge on GA biosynthesis in plantassociated bacteria.…”