Endophytic and rhizospheric bacterial consortia from Peganum harmala alleviate lead phytotoxicity and enhance durum wheat growth in heavy metal-contaminated soils.

Heavy metal contamination poses a serious threat to agricultural sustainability, particularly in arid regions where soil and crop quality are easily compromised. This study evaluated the potential of indigenous plant growth-promoting rhizobacteria (PGPR) consortia, isolated from Peganum harmala L., to improve wheat (Triticum durum Desf.) growth and bioremediate lead-contaminated soils. Sixteen characterized strains, possessing both PGPR and heavy metal resistance traits were grouped into three consortia (SCA, SCB, and S(CA × CB)) derived from rhizosphere, endosphere, and mixed origins. Each consortium was inoculated separately onto wheat grown in soils containing 800 ppm lead (Pb). Results demonstrated significant improvements across treatments compared to the control: germination rates reached up to 100%; aerial fresh weight, total soluble sugars, phenolics, and flavonoids all increased markedly (up to 78.3, 61.0, 33.1, and 50.6%, respectively). Root system architecture, protein, and sugar contents also showed notable enhancements. These findings highlight the dual function of these indigenous consortia, as agents of both plant growth promotion and efficient bioremediation. Our work provides a practical, ecofriendly framework for restoring heavy metal-affected soils and optimizing crop productivity using tailored microbiological treatments.