Enhancing Phosphorus Uptake and Mitigating Lead Stress in Maize Using the Rhizospheric Fungus Talaromyces purpureogenus PH7

Abstract

Modern agriculture faces significant environmental challenges due to toxic contaminants like lead (Pb), which infiltrate the food chain and pose severe risks to all living organisms, including humans. Bioremediation, utilizing microorganisms to mitigate contamination, offers a sustainable and cost-effective solution. In this study, a fungal strain, PH7, was isolated from the rhizosphere of Parthenium hysterophorus and identified as Talaromyces purpureogenus through genetic analysis of ITS 1 and ITS 4 rRNA regions. Preliminary screenings revealed its ability to solubilize phosphate and produce key plant growth regulators, including indole acetic acid (IAA) and salicylic acid (SA), alongside beneficial metabolites like phenolics, sugars, proteins, lipids, and flavonoids. The strain demonstrated substantial Pb tolerance, up to 800 µg/g, while enhancing the antioxidant defense system in liquid culture. Under 500 µg/g Pb stress, maize (Zea mays L.) exhibited a significant reduction in root length (29.2%), shoot length (30.4%), fresh weight (24.5%), and dry weight (53.5%). However, treatment with T. purpureogenus markedly improved these parameters, along with chlorophyll and carotenoid levels. The treated plants also showed enhanced antioxidant activity, including elevated levels of enzymatic and nonenzymatic antioxidants. These findings highlight the dual role of T. purpureogenus as a bioremediant and biofertilizer, capable of restoring Pb-contaminated soils and enhancing agricultural productivity and plant health.