Custom script for feature extraction from Genbank files

Microbes are thought to be distributed and circulated around the world,
but the connection between marine and terrestrial microbiomes is largely
unknown. We use Plantibacter, a representative plant-associated genus, as
our research model to show the global distribution and adaptation of
plant-related bacteria in plant-free environments, especially in the
remote Southern Ocean and the deep Atlantic Ocean. The marine isolates and
their plant-associated relatives shared over 98% whole-genome average
nucleotide identity (ANI), indicating recent divergence and ongoing
speciation from plant-related niches to marine environments. Comparative
genomics revealed that the marine strains acquired new genes via
horizontal gene transfer from non-Plantibacter species and refined
existing genes through positive selection to improve adaptation to new
habitats. Meanwhile, marine strains retained the ability to interact with
plants, such as modifying root system architecture and promoting
germination. Plantibacter species were further found to be widely
distributed in marine environments, revealing an unrecognized phenomenon
that plant-associated microbiomes have colonized the ocean, which could
serve as a reservoir for plant growth-promoting microbes. This study
demonstrates the presence of an active reservoir of terrestrial plant
growth-promoting bacteria in remote marine systems and advances our
understanding of the microbial connections between plant-associated and
plant-free environments at the genome level.