The production of synthetic polyploids for plant breeding is compromised by high levels of mixoploids and low numbers of solid polyploid regenerants during in vitro induction. Somatic embryogenesis could potentially contribute to the maximization of solid polyploid production due to the single cell origin of regenerants. In the present study, a novel procedure for establishing homogeneous tetraploid embryogenic cell lines in Magnolia officinalis has been established. Embryogenic cell aggregate (ECA) about 100–200 μm across, and consisting of dozens of cells, regenerated into a single colony of new ECAs and somatic embryos following colchicine treatment. Histological analysis indicated that the few cells that survived some colchicine regimes still regenerated to form a colony. In some colonies, 100% tetraploid somatic embryos were obtained without mixoploid formation. New granular ECA from single colonies with 100% tetraploid somatic embryos were isolated and cultured individually to proliferate into cell lines. These cell lines were confirmed to be homogeneous tetraploid by flow cytometry. Many tetraploid somatic embryos and plantlets were differentiated from these cell lines and the stability of ploidy level through the somatic embryogenesis process was confirmed by flow cytometry and chromosome counting. The establishment of homogeneous polyploid cell lines, which were presumed to represent individual polyploidization events, might expand the phenotypic variations of the same duplicated genome and create novel breeding opportunities using newly generated polyploid plantlets.

The seed microbiome of crop wild relatives is a potential reservoir of beneficial traits that potentially improve their host plant resilience to fluctuating environments and pathogenic threats. Herein, we studied the seed microbiome of three species of the medicinal genus Panax (P. vietnamensis, P. japonicas, and P. stipuleanatus) collected from seven locations in Southwest China. We used qPCR and metabarcoding high-throughput sequencing to target both endophytic bacteria and fungi. Seed bacterial absolute abundance (1.1 × 109∼1.0 × 107 gene copy numbers per gram seed) was substantially higher than that of fungi (7.6 × 105∼3.7 × 102). Host plant genotype was the main driver of seed microbiome composition for both bacteria and fungi. Panax growing hypothermal environments significantly shaped their seed endophytic bacterial but not fungal microbiota. The three Panax species’ seeds harbored unique microbes [averaged ∼150 amplicon sequence variants (ASVs)], sharing only 12 bacterial ASVs (half affiliated to Halomonas) and four fungal ASVs. Network analysis showed that the Panax seed endophytic bacteria tend to form inter-weaved functional modules that are majorly connected by core members from the genus Halomonas, Pseudomonas, and Pantoea. These genera have been associated with nutrient cycling, plant, disease suppression, and tolerance to environmental fluctuation. Together, these novel insights may shade light on the ecological strategies of wild Panax plants adaptation to their thermal environment by possessing abundant beneficial seed endophytic bacteria.