Estabelecimento in vitro de Handroanthus impetiginosus (Mart. ex Dc.) Mattos (Bignoniaceae) e estudo da incidência de oídio (Oidium sp.) em plântulas obtidas in vitro

• Autor(a) principal: Mamedes, Talita Cristina
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/7505
• topic: Ipê roxo; Cerrado; Cultura de tecidos; Tissue culture; Ipê roxo; Cerrado; GENETICA::GENETICA VEGETAL

Handroanthus impetiginosus (Mart. ex DC.) Mattos is widely distributed woody species in Brazil. It has economic importance for its use as wood, medicinal, ecological and ornamental tree. There is great variation in the production of fruits and seeds over the years, many of the seeds are attacked by fungi and insects, and finally, the remaining intact seeds lose viability very quickly. Techniques of plant tissue culture can increase the rate of germination in woody species. The cultivation in nutrient medium under aseptic conditions, provides great production of seedlings in reduced time and space and at any time of year. Furthermore, in vitro propagation acts as a tool in the identification of microorganisms, studying their relationships and interactions with the host plant at genetic, cellular and physiological levels. The aim of this study was to establish a protocol for in vitro propagation of H. impetiginosus developed in three steps: decontamination and seed germination, induction of new shoots and roots. The protocol was based on direct organogenesis using plant material from seedlings germinated in vitro. For in vitro germination, seed surface contamination was controlled using 2 min. in 70% ethanol and 10 min. sodium hypochlorite with 2 % active chlorine. The germination rate was 99 % on MS medium. Induction and multiplication of new shoots were carried out with the aid of growth regulators 6 - benzylaminopurine (BAP) and naphthalene acetic acid (NAA) in different combinations. The results showed that for explants of H. impetiginosus all the tested amounts of BAP and NAA have the ability to regenerate shoots, callus and adventitious roots, it is necessary to improve the regeneration protocol to obtain greater number of new shoots. For in vitro rooting, cuttings responded positively to 6.0 mg L - 1 butyric acid (IBA), with 92 % rooting. However, the methods of decontamination of seeds did not control fungi of the genus Oidium. In order to identify the fungus and study the fungus - host relationship in H. impetiginosus cuts were made in vitro leaf fragments and the anatomical structure analyzed by optical microscope and scanning electron microscope. After the emergence of Oidium sp. on seedlings developed in vitro, methods of seeds disease control were tested for germination using different times and concentrations of ethanol, sodium hypochlorite, Chlorothalonil + tiophanate Methyl (systemic fungicid ) and Neem oil assessing the incidence and severity of each disease treatment. No treatment was effective in the control of powdery mildew, indicating the need for further studies. However, reduction of severity was observed in seeds treated with 70 % ethanol and sodium hypochlorite (2% active chlorine) and Neem oil immersion to 1.5 % for 10 minutes.