Plant-endophytic bacteria interactions associated with root and leaf microbiomes of Cattleya walkeriana and their effect on plant growth

Using root and leaf microbiomes that prevail in different Cattleya walkeriana orchid agroecosystems, i.e., associated with the natural habitat, greenhouse, and in vitro cultivation, we performed the isolation of endophytic bacteria for bioprospecting of the mechanisms promoting plant and enzymatic growth. However, practically nothing is known about or use of its bacterial community. A total of 67 endophytic bacteria were isolated, and all showed biological nitrogen fixation capacity; 55.2% produced indole-3-acetic acid, 86.6% solubilized phosphate, and 74.6% solubilized zinc; 13.4% produced siderophores; and 71.6% had some enzymatic activity (protease, cellulase, and pectinase). The endophytes Paenibacillus taichungensis, Enterobacter sp., Rhizobium sp., Paenibacillus sp., Pseudomonas sp., and Paenibacillus pabuli were inoculated in acclimatizing seedlings obtained by micropropagation of C. walkeriana and have a potential use/role as plant growth promoters, as well as in morphological changes, nutrient uptake also resulting in increased antioxidant enzyme activity and non-enzymatic antioxidants. These results increase our understanding of the inner biome of C. walkeriana and suggest that this orchid is highly dependent on bacterial symbionts during its cycle. The isolated bacterial strains also have high potential as bioinoculant to improve nutrient acquisition and overall growth, contributing to a more sustainable.