Caracterização morfológica e molecular de cultivares de bananeira

Abstract

Banana genetic breeding at Embrapa Cassava and Tropical Fruits has carried out great efforts in trying to obtain banana cultivars resistant to most pests and diseases and with good agronomic characteristics, once most of the existing cultivars are tall in height and susceptible to most diseases. In this attempt, great financial and intellectual efforts are required for the obtainment of new hybrids that present desirable characteristics. With the creation of the Cultivar Protection Law, the right to protect a cultivar being released, with the emission of a Cultivar Certificate, was instituted. Therefore, the characterization of new genotypes becomes necessary in order to minimize the risk of unlawful acquirement of cultivars being released. The actual characterization being accepted, is the one based in morphological descriptors, even though the isoenzime pattern has also been used. The characterization of the genotypes with morphological and isoenzimatic descriptors, present some limitations, for they are influenced by the environment and therefore, the use of DNA descriptors acting directly in the plant genome presents another tool to overcome these problems. The objective of the present work was to use two types of descriptors: morphological and molecular (RAPD and SSR) in thediscrimination of banana cultivars being recommended by Embrapa Cassava and Tropical Fruits. The morphological descriptors were made up of 12 quantitative and sixty-one qualitative characteristics. For the molecular characterization, 48 RAPD primers and 34 microsatellite primers were used. The results concluded that the application of the qualitative and quantitative descriptors showed a broad genetic variability between the genotypes studied, but the Preciosa, Pacovan Ken and Garantida cultivars presented little perceptible differences, being perceptible only at DNA level. The descriptors based on microsatellites were superior to the others due to their repeatability and high discriminating power, enabling the definition of molecular patterns for some of the cultivars evaluated. With the selected primers in addition to the ones indicated, the creation of a molecular data bank for varietal identification takes its first steps.