Cadmium (Cd) is a highly toxic heavy metal that can greatly affect crops and pose a threat to food security. Plant growth-promoting rhizobacteria (PGPR) are capable of alleviating the harm of Cd to crops. In this research, a Cd-tolerant PGPR strain was isolated and screened from the root nodules of semi-wild soybeans. The strain was identified as Pseudomonas sp. strain KM25 by 16S rRNA. Strain KM25 has strong Cd tolerance and can produce indole-3-acetic acid (IAA) and siderophores, dissolve organic and inorganic phosphorus, and has 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Under Cd stress, all growth indicators of soybean seedlings were significantly inhibited. After inoculation with strain KM25, the heavy metal stress of soybeans was effectively alleviated. Compared with the non-inoculated group, its shoot height, shoot and root dry weight, fresh weight, and chlorophyll content were significantly increased. Strain KM25 increased the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities of soybean seedlings, reduced the malondialdehyde (MDA) content, increased the Cd content in the roots of soybeans, and decreased the Cd content in the shoot parts. In addition, inoculation treatment can affect the community structure of endophytic bacteria in the roots of soybeans under Cd stress, increasing the relative abundance of Proteobacteria, Bacteroidetes, Sphingomonas, Rhizobium, and Pseudomonas. This study demonstrates that strain KM25 is capable of significantly reducing the adverse effects of Cd on soybean plants while enhancing their growth.

Ragweed (Ambrosia artemisiifolia L.), an invasive species, is well-known for its rapid growth, strong reproductive potential, and high stress tolerance. The evolutionary distinctiveness and strong ecological adaptability of Ambrosia have enabled the endophytic fungi that coevolved with it to become valuable microbial resources. In this study, one of the endophytic fungi isolated from ragweed was named strain V3. Strain V3 was identified as Chaetomium sp. (Ascomycota) based on morphological characteristics and molecular analyses. The strain V3 promotes tomato growth by significantly increasing plant height, root length, the number of lateral roots, and chlorophyll content, effectively enhancing photosynthesis and consequently improving fruit yield. Meanwhile, compared to the control, tomato fruits inoculated with strain V3 exhibited significantly higher levels of vitamin C (VC) and lycopene, indicating a notable enhancement in fruit quality. Additionally, strain V3 is capable of producing phytohormones, including indole-3-acetic acid (IAA), gibberellin (GA₃), and zeatin, and of regulating the expression of tomato auxin response factor (ARF) genes. This study demonstrates that strain V3 has the potential to promote tomato plant growth.