Development of beneficial fungal consortia and their assessment in mitigating Cadmium stress in plants

Abstract

Cadmium (Cd) is an environmental threat and a hazardous contaminant to soil health and the safety of human life from food chain entry. Intense plant exposure to Cd inhibits plant growth and lowers the biomass and life vital physiological activities. Myco-remediation is a new concept in Pakistan. In this study, we investigate the potential of Trichoderma and Metarhizium fungal strains to assist in mitigating Cd stress in maize (Zea mays). Cd tolerance on agar and broth assays were screened in eight fungal strains including commercial and lab isolated Trichoderma and Metarhizium. Cd removal efficiencies were tested in selected strains that showed Cd removal performances, in particular Trichoderma lixii SPB9 and Metarhizium brunneum ARSEF 4556. Compatibility between fungal strains was evidenced through co-culturing experiments to optimize remediation potential without antagonistic effects. Specific fungal treatment alleviates Cd induced stress and increases growth over untreated controls in terms of physiological parameters, including shoot and root biomass, chlorophyll content and Photosystem II activity. Arguing that MAPK genes MAPK2, MAPK3, and MAPK6 may play a role in stress signaling, gene expression analysis of MAPK genes showed enhanced response to Cd. Results show that some fungal consortia can alleviate Cd toxicity but at low concentration providing an ecofriendly remedy for Cd contaminated soils. Moreover, in future, we can further investigate the role of Trichoderma in Cd toxicity and their bioaccumulation study.