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A developed procedure to differentiate banana cultivars based on foliar resistance or susceptibility to Fusarium oxysporum f. sp. Cubense strain 1 infection was validated, attending to a phenotypical parameter (lesion area) and biochemical markers (free or cell wall-bound phenols, malondialdehyde and the rest of aldehydes, and proteins). Estimates were established from a data matrix considering the effects of fungus culture filtrates on leaves from eighteen cultivars. As part of the program for genetic improvement, an unprecedented discriminate analysis for differentiating resistant genotypes was carried out. Two discriminant functions were formulated for resistant and susceptible phenotypes, respectively. Every plant included in the matrix was evaluated according to both functions, reaching a 94.4 % of accuracy for assigning the corresponding phenotype (68 from 72). This is the first report on validating a method for differentiating banana resistance against the attack of the Fusarium oxysporum f. sp. Cubense strain 1 fungus, based on applying fungus culture filtrates on banana leaves. This method constitutes a useful tool for increasing the selection efficiency ex vitro irrespective of environmental or seasonal conditions for disease development. [ABSTRACT FROM AUTHOR]

En investigaciones previas se desarrolló un procedimiento para la diferenciación foliar de la resistencia y susceptibilidad de cultivares de banano a Fusarium oxysporum f. sp. cubense raza 1. En este estudio se incluyen evaluaciones de otros indicadores, tales como componentes bioquímicos. El análisis del discriminante para la diferenciación de la resistencia y susceptibilidad de cultivares de banano, utilizado en el programa de mejoramiento genético, constituye un aspecto novedoso en este trabajo. Tal estimación se realizó a partir de una matriz de datos que incluyó el efecto del filtrado del cultivo del hongo (área de la lesión y niveles de fenoles libres y ligados a las paredes celulares, aldehídos, excepto malondialdehído, y proteínas) en hojas de dieciocho cultivares. Tras el análisis discriminante, se obtuvieron dos funciones, una para los clones resistentes y otra para los susceptibles. Se evaluó cada planta de la matriz, según las funciones discriminantes y estas se clasificaron en resistentes o susceptibles al 94.4% de los casos (68 de 72 plantas). Por primera vez se propone un método para la diferenciación de la resistencia del banano a Fusarium oxysporum f. sp. cubense raza 1, mediante la aplicación de filtrados del cultivo del hongo en sus hojas. Este método constituye una herramienta útil para incrementar la eficiencia de la selección en condiciones ex vitro, sin tener en cuenta las condiciones ambientales ni la época del año favorables para el desarrollo de la enfermedad. [ABSTRACT FROM AUTHOR]

Panama disease, caused by Fusarium oxysporum f. sp. cubense, is considered a destructive disease of economic importance in the genus Musa. The culture filtrates of the pathogen have been used to differentiate cultivars, but have not identified metabolites involved in the differential response. The aim of this study was to purify phytotoxic metabolites present in the culture filtrate of Fusarium oxysporum f. sp. cubense GCV [01210] Race 1 for further chemical characterization. We used a culture filtrate of 15 days of incubation. The phytotoxic activity was tested with a leaf bioassay on the susceptible cultivar 'Gros Michel' and resistant 'FHIA 01'. The organic extract was extracted and fractionated. It was partitioned with organic solvents of rising polarity and found the complexity of each of the fractions by TLC. The metabolites were purified by flash column chromatography. Two compounds were purified from the culture filtrate of the pathogen which not only differed in color (blue and pale yellow), but also in polarity. Fractions B (containing blue compound) and E (containing yellow compound) produced significant differences in lesion area between resistant and susceptible cultivar. These results are not conclusive but, it is the basis for the identification of compounds involved in the differential response of Musa spp. cultivars to the culture filtrate of Fusarium oxysporum f. sp. cubense. [ABSTRACT FROM AUTHOR]