Characterization of the endophytic bacteria from in vitro cultures of Dendrocalamus asper and Bambusa oldhamii and assessment of their potential effects in in vitro co-cultivated plants of Guadua chacoensis (Bambusoideae, Poaceae)

Bamboos (Bambusoideae, Poaceae) are multiple-purpose perennial grasses, which display a growing production chain in Brazil. One of the main bottlenecks is high-quality supplying of plantlets, then requiring efficient mass propagation methods, such as micropropagation. Contamination by microorganisms is recurrent in bamboo in vitro cultures, although some of those manifestations are considered endophytes harboring plant growth promotion potential. The isolation of endophytic bacteria from in vitro cultures of Dendrocalamus asper and Bambusa oldhamii was performed to assess their potential growth-promoting effect in co-cultivation with in vitro plants of Guadua chacoensis, an economically promising bamboo species. Among the total bacterial collection (32 isolates), all of them showed growth-promotion potential as indole compounds-producers. Sequences of 16S rRNA genes from eight selected isolates were newly generated, and the BLASTn similarity test recovered four bacterial genera (Bacillus, Brevibacillus, Serratia, and Atlantibacter) and six species. The co-cultivation experiment was carried out with three isolates selected based on their low- (Ba16), medium- (Ba03), and high-yield (Ba24) production of indole compounds, and Bayesian inferences strongly supported them as Bacillus subtilis, Serratia marcescens, and Brevibacillus parabrevis, respectively. The co-cultivation with three bacterial isolates, and their dilution levels, did not influence shoot or root growth and, however, did not cause apparent impairment for G. chacoensis in vitro cultures. Taken together, the isolation of endophytic microorganisms from field-growth bamboo clump and its co-cultivation with in vitro cultures of bamboos is possible, encouraging a continuous discovery and improvement of micropropagation techniques.

Automated summary

The study isolated endophytic bacteria from in vitro cultures of bamboo and found that these bacteria may have potential growth-promoting effects, providing possibilities for continuous improvement of bamboo micropropagation techniques.