Whole-genome and microbial diversity analyses reveal mechanism of GY8 for enhancing cadmium removal rate of duckweed

Abstract

The enhancement of heavy metal remediation efficiency by endophytes in hyperaccumulators has been widely demonstrated. However, research on the influence of endophytes on cadmium (Cd) remediation efficiency of hyperaccumulating duckweed remains limited. In this study, a Cd-resistant endophyte, Agrobacterium fabrum GY8 (GY8), was identified, which increased Cd removal rate of duckweed to 93%. And, colonization of GY8 enhanced duckweed growth rates (up to 117.78%) and alleviated Cd-induced oxidative damage by activating key antioxidant enzymatic pathways. Further investigation revealed that GY8 facilitated phytoremediation through reducing Cd accumulation within duckweed organelles and transforming bioavailable NaCl-extractable Cd into stable HCl-extractable complexes. Whole-genome sequencing identified genes of GY8 associated with Cd resistance and plant growth promotion, including those involved in glutathione metabolism, sulfur cycling, ABC transporter systems, and phenylpropanoid biosynthesis pathways. Microbial diversity analyses confirmed the successful colonization and predominance of GY8 within duckweed. The results provide innovative insights into the mechanisms of endophytes enhancing the Cd removal rate of duckweed, offering theoretical basis for the development of plant-microbe remediation strategies for heavy metal contamination.