Diversidade e bioprospecção de bactérias endofíticas associadas à Cattleya walkeriana e promoção de crescimento durante aclimatização

Abstract

Micropropagated seedlings of the Cattleya walkeriana orchid require a long acclimatization period. Studies of the interaction between endophytic-orchid that is capable of fixing atmospheric nitrogen, synthesizing indole, solubilizing inorganic phosphates and producing proteolytic activity can be useful during this ex vitro process. The goal of this study was to evaluate the number and diversity of the composition of endophytic bacteria associated with the different places of cultivation of Cattleya walkeriana in nature, in agricultural cultivation (greenhouse), and in vitro asymbiotic conditions, as well as, to evaluate the different mechanisms for promoting plant growth. In this regard, endophytic bacteria from Cattleya walkeriana leaves and roots were isolated and identified from three cultivation environments. A greater number of isolated endophytic of the orchid was found in nature, around 42% when compared to other cultivation environments, about 33% in agricultural environment and 25% in vitro. The diversity of endophytic bacteria was identified, and it belongs to the genres: Achromobacter, Acinetobacter, Bacillus and Enterobacter. The potential for promoting plant growth was evaluated in 33 endophytic bacteria associated with Cattleya walkeriana, all of which are diazotrophic bacteria and, comparatively, 90% were able to produce indoleacetic acid, 78.8% and 30.3% solubilized calcium phosphate and oxide zinc in vitro, respectively, and 54.5% showed the capacity for proteolytic activity. The results obtained may offer a contribution to a better understanding of the interaction of microorganisms associated with Cattleya walkeriana and the beneficial growth-promoting characteristics for more effective management.