A novel approach for begonias micropropagation by inflorescence explants

Uma nova abordagem para micropropagação de begônias por explantes de botões florais

Abstract

Begonias grown in greenhouses are susceptible to devastating disease caused by pathogenic bacteria and fungi, decreasing the quality of propagated material. Plant tissue culture provides an alternative for rapid propagation of healthy Begonia material. The present study was undertaken to develop the protocol of micropropagation of three Begonia species and one hybrid from inflorescence explants. Male flower buds with part of pedicel restricted to 1 mm have been cultured in vitro on 6 variants of modified N6 media. Adventitious shoot organogenesis has been shown to occur from both pedicel and receptacle tissues under the action of any type of cytokinin applied, whereas BA and 2-iP triggered mainly the direct organogenesis, while TDZ proceeding morphogenic events through the stage of callus formation. For the culture establishment in vitro the most effective was the medium, supplemented with 1.5 µM 2-iP + 0.54 µM NAA with the addition of 40 mg L^-1 adenine sulfate, contributed to the highest shoot regeneration from floral explants of all begonias studied. Histological analysis of adventitious buds pathways approved that their induction occurs under the treatment directly from the subepidermal cells. Morphological analysis performed after plantlets adaptation to the greenhouse conditions showed no morphological or bloom variations in the progeny, derived from the begonias inflorescence. The suggested technique considered as a practical step toward obtaining the uniform planting material for the propagation of economically valuable Begonia plants.

Keywords:
begonias; floral explants; morphogenesis in vitro