Endophytic Microbes Are Tools to Increase Tolerance in Plants Against Arsenic Stress.

Seed microbiota is becoming an emergent area of research. Host plant microbial diversity is increasingly well described, yet relatively little is known about the stressors driving plant endomicrobiota at the metaorganism level. The present work examines the role of horizontal and vertical transmission of bacterial microbiota in response to abiotic stress generated by arsenic. Horizontal transmission is achieved by bioaugmentation with the endophyte , while vertical transmission comes maternal inheritance from seeds. To achieve this goal, all experiments were conducted with two species. is tolerant to arsenic (As), whereas , being phylogenetically close to , was not previously described as As tolerant. The core bacterial endophytes are composed of genera , , , , and and family across different environmental conditions. All these operational taxonomic units (OTUs) coexisted from seeds to the development of the seedling, independently of As stress, or bioaugmentation treatment and species. colonized efficiently both species, driving the endomicrobiota structure of with a stronger effect than As stress. Despite the fact that most of the OTUs identified inside seeds and seedlings belonged to rare microbiota, they represent a large bacterial reservoir offering important physiological and ecological traits to the host. traits co-regulated with , and the associated microbiota improved the host response to As stress. NGS-Illumina tools provided further knowledge about the ecological and functional roles of plant endophytes.