Background: To combat salinity, plants need easily accessible, safe and sustainable mechanisms for optimum growth. Recently, endophytes proved to be the promising candidates that helped the host plant to thrive under stress conditions. Therefore, the aim was to discover endophytic strain(s) and their mechanism of action to alleviate salt stress in maize.
Results: Keeping the diverse role of endophytes in view, 9 endophytic fungi from the spines of Euphorbia milli L. were isolated. Among the isolated fungal isolates, isolate FH1 was selected for further study on the basis of high antioxidant activity and capability to produce high indole-3-acetic acid (IAA), indole-3-acetamide (IAM), phenol and flavonoid contents. The 18S rDNA sequence homology and phylogenetic analysis of the fungal isolate FH1 revealed to be Yarrowia lipolytica. Furthermore, the inoculation of Y. lipolytica FH1 had significantly promoted plant growth attributes in treated maize as compared to positive (salt stress) and negative (salt stress free) controls. Likewise, differences in chlorophyll, carotenes, electrolyte leakage, leaf relative water, peroxidase, catalase, ABA, IAA and proline contents were observed between treated maize and controls. Interestingly, Y. lipolytica FH1 inoculated plants showed lower endogenous ABA and higher endogenous IAA contents.
Conclusion: From the results, we have concluded that Y. lipolytica inoculation has promoted the growth of maize plants through controlled metabolism and hormonal secretions (ABA and IAA) under salinity stress. Because of the fact, Y. lipolytica can be tried as an eco-friendly bio-fertilizer to achieve optimum crop productivity under saline conditions.
Keywords: Abscisic acid; Flavonoids; Indole-3-acetic acid; Maize; Phenols; Salt stress; Y. lipolytica FH1.