Novel marine yeast strains as plant growth-promoting agents improve defense in wheat (Triticum aestivum) against Fusarium oxysporum

Abstract

Yeasts are multilateral opportunistic plant symbionts that can cause intrinsic changes in the metabolism of host plants, thereby increasing plant growth and activating plant defense against various diseases. Although yeasts isolated from soil and plants have been evaluated as biological control agents, the search for new antagonists continues. Marine yeasts can be an option for the selection of new plant promoters and antagonistic agents. The objective of the present study was selected to demonstrate the potential of two marine yeast strains isolated from Red Sea water to award beneficial agronomic quality to promote wheat growth and induce defense mechanism against Fusarium oxysporum and its ability to produce zearalenone. These yeast strains were identified based on the genotypic identification as Candida orthopsilosis and Rhodotorula mucilaginosa, and their sequences were deposited in the GenBank database under the accession number MN784461 and MN784463, respectively. The results of in vitro assay showed great inhibition on mycelial growth and zearalenone production level. Also, wheat seeds primed with the two yeast strains in the presence and absence of Fusarium displayed early seedling emergence and enhanced growth compared with wheat treated by Fusarium only and untreated wheat (control). Also, under greenhouse conditions, C. orthopsilosis and R. mucilaginosa revealed remarkable improvement in the wheat growth parameters and resistance against Fusarium oxysporum and led to a complete inhibition of zearalenone production in treated wheat roots and spikes compared to those treated by Fusarium only. Our findings demonstrated the contribution of tested marine yeasts in the increase in metabolites accumulation.