Fig. 5

Seed-borne bacteria spread to next-generation seedlings upon germination. A The axenic system for rice cultivation. The entire device was autoclaved, and the rice caryopses and grains planted inside were surface-sterilized. B qPCR showing bacterial abundance in internal caryopsis (caryopsis), internal grain (grain), endosphere of seedling shoot (shoot) or root (root). Seedlings germinated from grain or caryopsis cultivated with grain or SynCom contain abundant bacteria within shoots and roots, while seedlings from sterilized caryopsis contain few bacteria. The circles indicate planting methods: surface-sterilized caryopsis on axenic medium (left), surface-sterilized grain on axenic medium (middle), alternate planting of caryopsis and grain on axenic medium (middle), and surface-sterilized caryopsis on SynCom-containing medium (right). Bacterial abundance in caryopses and grains calculated with log₁₀[bacterial cells]/seed, in seedlings with log₁₀[bacterial cells]/g fresh weight. ns, not significant; ****, p < 0.0001. Data from 12 seed samples. C SEM or confocal laser scanning microscope (CLSM) showing GFP-labeled Pantoea eucrina SY1 (PeSY1-GFP). Scale bar, 3 μm. D Inoculation schema of PeSY1-GFP into rice plants under axenic conditions. E PeSY1-GFP colonization in longitudinal and cross-sections of seedling roots. Images examined at 14 days after planting using a Leica TCS SP8 confocal microscope