Especificidade patogênica de Fusarium oxysporum, em bananeira e outras espécies cultiváveis

Abstract

CAPÍTULO 1 = Banana (Musa spp.) is one of major fruit crop in Brazil and worldwide and responsible for generating significant income in agriculture. However, as all crop species, it is affected by pest such as the Panama disease caused by the fungus Fusarium oxysporum f. sp. cubense - FOC, the most important disease of culture, and responsible for economic losses caused to banana growers. The most appropriate strategy for the management of this disease is the use of resistant varieties, but currently new pathogen variants have threatened the viability of the crops in the medium to long term. Thus, this study aimed to investigate the pathogenicity of specific isolates and other FOC formae speciales F. oxysporum on other hosts such as lettuce, cotton, cowpea, castor bean, Passion fruit and tomato; by cross inoculation, in order to establish a knowledge of the specificity and host range. Ten isolates of FOC and seven isolates of different hosts with two inoculation methodologies were used: Root immersion in conidial suspension - MIR; Sand-corn meal infested with the fungus - MAFI. In the cross-inoculation experiment, FOC isolates prompted typical symptoms of Fusarium wilt for the vast majority of cultures evaluated; and isolates from different hosts caused wilt symptom and vascular discoloration in banana, regardless of inoculation method. Thus, based on the results obtained it can be seen nonspecific interactions FOC and other crops, and different formae speciales infecting banana varieties, plantain indicating that can be affected by different variants of F. oxysporum and other plant species can be affected by FOC, which theoretically is a forma specialis exclusively of Musaceas. CAPÍTULO 2 = Fusarium oxysporum f. sp. cubense (FOC), is the causal agent of the Panama disease, being very important to the banana (Musa spp.) producing regions throughout the world for its destructive potential on the culture. A high genetic diversity of FOC isolates were evidenced on previous studies, and the presence of isolates genetically related to other formae speciales than 'FOC’, was also notices. Thus, this study aimed to investigate the specificit of pathogenicity of FOC and others F. oxysporum from other hosts such as lettuce (Lactuca sativa); cotton (Gossypium hirsutum); cowpea (Vigna unguiculata), castor bean (Ricinus communis), passion fruit (Passiflora edulis Sims f. flavicarpa Deneger) colonization and tomato (Solanum lycopersicum) by cross inoculation. Ten isolates of FOC and seven isolates of F. oxysporum from different hosts were inoculated using two methods: Immersion of roots in conidial suspension and sand-corn meal infested with the fungus. The isolates studied showed typical symptoms of the disease in all cultures in at least one method of inoculation. Based on the results is possible to noticed that the banana can be affected by different variants of F. oxysporum and other plant species may be affected by FOC, which theoretically is a forma specialis exclusively of Musaceas.