Community from Two Venezuelan Cultivars

Rice is currently the most important food crop in the world and we are only just 13 beginning to study the bacterial associated microbiome. It is of importance to perform screenings of 14 the core rice microbiota and also to develop new plant-microbe models and simplified 15 communities for increasing our understanding about the formation and function of its microbiome. 16 In order to begin to address this aspect, we have performed the isolation of bacterial strains from 17 the endorhizosphere of two rice cultivars from Venezuela. The validation of plant-growth 18 promoting bacterial activities in vitro has led us to select and characterize 15 isolates for in planta 19 studies such as germination test, endophytism ability and plant growth promotion. Consequently, 20 a set of 10 isolates was selected for the set-up of an endophytic consortium as a simplified model of 21 the natural rice bacterial endomicrobiota. Upon inoculation, the colonization and abundance of 22 each strain within the rice roots was tracked by a culture-independent technique in gnotobiotic 23 conditions in a 30 days period. Four strains belonging to Pseudomonas, Agrobacterium and Delftia 24 genera have shown a promising capacity for colonizing and coexistence in root tissues. On the 25 other hand, a bacterial community taxonomic profiling of the rhizosphere and the endorhizosphere 26 of both cultivars were obtained and are discussed. This study is part of a growing body of research 27 on core crops microbiome and simplified microbiomes, which strengthens the formation process of 28 the endophytic community leading to a better understanding of the rice microbiome. 29