Influence of Lead on Morphology and Genetic Composition of Pleurotus tuber-regium

Abstract

Aims: Lead is a heavy metal pollutant that persists in the environment, has no biological function, and is potentially toxic to microorganisms. The study examined the effect of lead on the morphology and genetic profile of Pleurotus tuber-regium, an edible mushroom. Study Design: Experimental study design. Place and Duration of Study: Bells University of Technology between December 2017 and August 2018. Methodology: P. tuber-regium sclerotium was planted in loamy soils polluted with PbO (50, 80, and 100 mg/kg). The effect of the lead was assessed by recording time for mushroom emergence, fresh fruitbody weight, stipe and pileus diameter, % protein, %ash, and molecular profile of mushrooms harvested from polluted soils against a control. Extracted DNA was amplified with ITS1 and ITS4 universal primers; amplicons were visualized with a UV Bio-Rad illuminator. Results: Lead had varied influences on the morphometry. The fruitbody emergence was fastest in polluted soils and significantly different from the control. Fruiting occurred after 13.23±0.76, 5.41±0.88, 9.33±0.75 and 11.01±1.06 days in 0, 50, 80 and 100 mg/kg Pb polluted soils respectively. The fresh weight, stipe, and pileus diameter were significantly different at 50 mg/kg compared to the control. The range in values was 8.57±0.75 – 15.21±0.85g, 9.30±0.89 - 14.40±0.99mm, and 3.33±0.75 - 9.60±0.57cm respectively. The %protein and %ash contents were higher in mushrooms from polluted soils. Lead accumulated in polluted soils but the bioaccumulation coefficient was low. DNA profile showed variations in amplicon sizes. Conclusion:  The study revealed that continuous exposure of Pleurotus tuber-regium to lead caused varied morphological and genetic changes. It led to increased fresh weight, stipe diameter, pileus diameter, and variation in DNA amplicons. The implication is that lead could cause variations in the morphology and genetic composition of P. tuber-regium.