The Wheat Seed Microbiome as a Model for Understanding the Transmission of Beneficial Plant-Associated Bacteria.

Beneficial plant-microbe interactions are fundamental to plant nutrition, growth, stress tolerance and disease resistance. However, because microorganisms are not encoded by the plant genome, the mechanisms by which microbial associations persist across generations remain unresolved. In this review, we examine the emerging evidence that seeds function not only as reproductive structures but also as reservoirs of microorganisms that may facilitate the maintenance and transmission of selected microbial partners. We synthesize current knowledge of seed microbiome diversity, ecological functions and assembly processes, highlighting the roles of maternal, floral, pollen-mediated and environmental transmission, together with host selection and microbial interactions. We then evaluate evidence that seed-borne microorganisms contribute to plant microbiome assembly and may support the multigenerational persistence of beneficial taxa. Using wheat as a model system, we explore how domestication and host genetic control have shaped microbial communities, assess evidence for recurrent the seed-borne presence of specific bacterial taxa, propose a candidate wheat seed bacterial meta-core based on taxa repeatedly detected across independent studies, and highlight Pantoea as a candidate lineage showing evidence of within-generation persistence and multigenerational transmission across generations. Finally, we discuss the conceptual and methodological challenges that currently limit our understanding of microbiome inheritance as a general biological principle and explore how this knowledge may guide future microbiome-assisted crop improvement. Together, these findings position seeds as key ecological and evolutionary hubs through which beneficial plant-microbe interactions may persist and potentially be inherited across generations.