Micropropagação de espécies de helicônia, caracterização morfológica e identificação molecular de bactérias contaminantes

Abstract

The Heliconia genus has increasing participation in the tropical floriculture, used mainly as cut flower and for landscape. The use of micropropagation in the process of heliconia production can improve product quality and productivity, providing large-scale and efficient plant multiplication, independently of the season, clonal multiplication of hybrids and other valuable plants, consequently with a more uniform production and possibility of a shorter period for harvesting. However, the success of the micropropagation process depends on various factors, such as the explant establishment in vitro, culture medium and a suitable substrate for acclimatization, which were studied in this work. Bacterial contamination is one of the difficulties for the in vitro establishment of heliconia explants. The results showed that Heliconia bihai cv. Peach Pink, H. ortotricha Candy Cane and H. ortotricha L. Anderss. cv. Total Eclipse responded differently to the descontamination treatments used. The use of full strength of MS (Murashige; Skoog, 1962) medium supplemented with 2,5 mg/L BAP and 0,10 mg/L ANA was the best for the in vitro culture of H. ortrotricha cv. Candy Cane, providing good multiplication rates, with well developed plants. H. ortotricha Candy Cane acclimatization showed better results in substrate mixtures containing Plant Max® Horticulture + Coconut fiber and Plant Max® Horticulture + Rind of carbonized rice with better rates of survival, better development of the aerial parts and root system development. For identification of the contaminantes, 100 bacteria isolates were obtained from contaminated culture media and leaves of greenhouse plants and submitted to morphological and molecular analyses to characterization for Amplified Ribosomal DNA Restriction Analysis (ARDRA) and identification for partial 16S rRNA gene sequencing. The bacterial isolates obtained from the leaves in TSA and R2A culture media had been only four species in the three heliconia cultivars, and were identified as Arthrobacter sp., Xanthomonas sp., Burkholderia sp. and Rhizobium sp.. In culture media contaminated Burkholderia sp. was evidenced in cultures of H. ortotricha Candy Cane and H. ortotricha L. Anderss. cv. Total Eclipse and Burkholderia sp. and Rhizobium sp. in H. bihai cv. Peach Pink. The bacterial contaminants observed during the in vitro establishment of heliconia explants originated from the endophytic community of the plants which were used as explant sources.