Work

Cadmium tolerance of Rhizopus microsporus and its alleviating effect on cadmium stress in chili peppers

Year: 2026

Type: article

Abstract: Cadmium (Cd) accumulation in crops depends not only on root accumulation but also on Cd transport to aboveground parts, especially leaves and edible portions. Therefore, microbial resources capable of altering Cd distribution within plants deserve more attention than those merely enhancing tolerance. However, research on fungal-mediated Cd redistribution remains limited. In this study, a Cd-tolerant fungus was isolated from Cd-rich mining slag soil and identified as Rhizopus microsporus (RM). RM formed dense visible mycelia under 200 mg/L Cd 2 + , whereas no visible colony was observed at 400 mg/L Cd 2+ , indicating that its Cd tolerance threshold was between 200 and 400 mg/L Cd 2+ , The strain exhibits antagonistic activity against Phytophthora capsici , and shows growth-promoting traits (phosphate solubilization, IAA, siderophore production). SEM-EDS revealed rough hyphal surfaces and Cd accumulation under Cd stress. Transcriptome analysis identified 867, 745, and 636 differentially expressed genes at 2, 6, and 12 h of Cd stress, respectively, with enriched pathways related to amino acid metabolism, nucleotide metabolism, transmembrane transport, NADH dehydrogenase activity, and glycolysis, suggesting Cd tolerance involves energy metabolism and transmembrane regulation. Hydroponic experiments showed that Cd stress inhibited seedling growth, reduced chlorophyll content, and promoted Cd accumulation in all tissues. RM inoculation did not consistently reduce oxidative indicators (malondialdehyde, catalase, Superoxide dismutase, acid phosphatase), but significantly lowered leaf Cd accumulation from 217.34 mg/kg (Cd alone) to 38.21 mg/kg (a 5.69-fold reduction), and promoted recovery of chlorophyll content, plant height, root length, and biomass. These findings suggest that RM enhances pepper adaptability to Cd stress primarily by reshaping Cd distribution within the plant rather than simply inhibiting oxidative damage.

Source: Environmental Technology & Innovation

DOI: 10.1016/j.eti.2026.104980