Biochemical and morpho-anatomical analyses of strawberry vitroplants hyperhydric tissues affected by BA and gelling agents Análises bioquímicas e morfo-anat micas em vitroplantas de morangueiro hiper-hídricas afetadas pelo BA e agentes geleificantes

In vitro propagation has become an effective practice for large-scale production of strawberry plants. The objective of this study was to evaluate the hyperhydricity and the multiplication capacity of two strawberry varieties (Fragaria x ananassa Duch. 'Dover' and 'Burkley') propagated in vitro. Plants maintained in MS medium supplemented with 1.0 mg L-1 BA were individualized and transferred to the same medium solidified with Agar (6.5 g L-1) or Phytagel (2.5 g L-1) and BA at different concentrations (0; 0.5; 1.0; 2.0 and 3.0 mg L-1). Biochemical and anatomical analyses were carried out, as well as the analysis of the morphological hyperhydricity characteristics. The analysis of data showed: a) the increase in cytokinin concentration increased hyperhydricity frequency in both varieties; b) at concentrations up to 2.0 mg L-1 BA, the replacement of Agar by Phytagel induced a higher formation of hyperhydric shoots; and c) the addition of BA induced oxidative stress, which is characterized by increased antioxidant activity and lipid peroxidation, as well as alterations at the cellular level, such as malformation of stomata and epidermal cells. In conclusion, the culture medium containing 0.5 mg L-1 BA solidified with Agar provided lower hyperhydricity percentages in association with higher rates of shoot proliferation in strawberry. A propaga o in vitro tem se destacado como uma técnica efetiva na produ o em larga escala de plantas sadias de morangueiro. Neste trabalho estudamos a hiperhidricidade associado a capacidade de multiplica o in vitro na propaga o de duas variedades de morangueiro (Fragaria x ananassa Duch. "Dover" e "Burkley"). Plantas mantidas em meio de cultura MS, suplementadas com 1.0 mg L-1 de BA fora individualizadas e transferidas para o mesmo meio com ágar (6.5 g L-1) ou Phytagel (2,5 g L-1) e BA em diferentes concentra es (0; 0,5; 1,0; 2,0 e 3,0 mg L-1). Foram realizadas análises bioquímica e anat micas, além da caracteriza o morfológica do material hiper-hídrico. A análise dos dados mostrou: a) o incremento na concentra o de citocinina aumentou a freqüência de hiper-hidricidade para ambas as variedades; b) concentra es maiores que 2,0 mg L-1 de BA, com a substitui o do ágar pelo Phytagel induziu a maior forma o de ramos hiper-hídricos; e c) a adi o de BA induziu o estresse oxidativo, caracterizado pelo incremento da atividade antioxidante e peroxida o de lipídeos, bem como altera es a nível celular, como má forma o dos est matos e células epidérmicas. Concluindo, o meio de cultura contendo 0,5 mg L-1 de BA solidificad