The lead (Pb) contamination is a serious risk to the agricultural productiveness and food security by affecting the metabolism of plants, halting photosynthesis, and causing oxidative stress. This research examined how the rhizospheric fungus Aspergillus terreus (isolate F2) could minimize the adverse effects of Pb phytotoxicity on the growth and physiology of red bean (Phaseolus vulgaris L.) under greenhouse conditions. The plants were cultivated in soil with 25 and 75 ppm of lead acetate and inoculated with a suspension of A. terreus spores in a completely randomized block trial (three replicas). Lead stress caused significant retardation of plant growth, with reductions of up to 43% in shoot length and up to 37% in dry weight at the higher Pb concentration (75 ppm), while root length and fresh weight declined by up to 24% and 34%, respectively. The photosynthetic pigments-chlorophyll a, chlorophyll b, carotenoids, and xanthophylls-declined by approximately 24-58% under Pb stress, with the greatest reductions observed for chlorophyll b and carotenoids at 75 ppm Pb. Increase in secondary metabolites (flavonoids and phenolics) was a form of stress response, and soluble sugars became considerably reduced. Lipid and proline levels were high in the Pb stress, proving oxidative damage and osmoregulatory processes. Inoculation of A. terreus considerably reverted these effects, and growth parameters, pigment levels, and metabolic balance were returned. Lactophenol cotton blue staining and light microscopy were used to confirm that the root sections were colonized by fungi. The isolate was molecularly determined through ITS rDNA sequencing and phylogenetic analysis using MEGA-11. Multivariate techniques [principal component analysis (PCA), hierarchical clustering, Pearson correlation, and treatment profile radar charting] verified the total treatment group separation of all 15 measured variables with PC1 and PC2 explaining 73.3% of total variance; chlorophyll a, fresh weight, and soluble sugars were the best distinguishing variables. These results reveal that A. terreus is an ideal bioinoculant in the reduction of Pb phytotoxicity and a viable and environmentally friendly approach to bioremediation of heavy metal-contaminated farm soils. These results indicate that A. terreus is an effective bioinoculant for alleviating Pb-induced physiological and biochemical stress in Phaseolus vulgaris L.; however, as Pb concentrations in plant tissue and soil were not measured, direct evidence of Pb immobilization or removal remains to be established in future studies.


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