Community Profiling of Seed Endophytes from the Pb-Zn Hyperaccumulator Noccaea caerulescens and Their Plant Growth Promotion Potential

Endophytes within plants are known to be crucial for plant fitness, and while their presence and functions in many compartments have been studied in depth, the research on seed endophytes is still limited. This work aimed to characterize the seed endophytic and rhizospheric bacterial community of two Noccaea caerulescens Pb-Zn hyperaccumulator populations, growing on two heavy-metal-polluted sites in Belgium. Cultured representatives were evaluated for their potential to enhance seed germination and root length of the model species Arabidopsis thaliana. The results indicated that the community structure within the seed is conserved between the two locations, comprising mainly of Proteobacteria (seeds), and Actinobacteria in the bulk soil. Root length of A. thaliana was significantly increased when inoculated with Sphingomonas vulcanisoli. The results of this paper offer insights into the importance of the selection of the core seed endophytic microbiome and highlight the precarious symbiotic relationship they have with the plant and seed.

Automated summary

This study characterized the bacterial communities in the seeds and rhizosphere of two Noccaea caerulescens Pb-Zn hyperaccumulator populations in Belgium. The results showed that the seed endophytic community structure was consistent between the two locations, mainly composed of Proteobacteria, while Actinobacteria dominated in the bulk soil. Inoculating Sphingomonas vulcanisoli significantly increased the root length of Arabidopsis thaliana. These findings highlight the importance of selecting the core seed endophytic microbiome and emphasize their precarious symbiotic relationship with the plant and seed.