After 10 years of evaluation in different locations with high levels of incidence of disease, a group of sugarcane somaclones derived from callus tissues was selected for eyespot resistance. Resistance evaluations of four somaclones were performed under field and laboratory conditions. The results confirmed the superiority of two somaclones, one resistant and one tolerant to eyespot disease. Restriction analysis of mitochondrial DNA revealed that the two somaclones had a difl'erent DNA organization which distinguished them both from each other and from the donor plant; the restriction profile was similar however to that of the resistant control done. Restriction patterns of a third somaclone, also resistant, were similar to those of the donor plant. Difl"erences among the somaclones were also evident when using a maize ribosomal DNA probe.

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Sugarcane leaves and calli from highly susceptible and resistant varieties to eyespot disease were used to evaluate the Drechslera sacchari toxin effect at different concentrations and incubation times by measuring electrolyte leakage. This expression of disease resistance was observed not only in the leaf but also in the callus. Furthermore, the growth of resistant calli MS medium supplemented with DS toxin, was higher when compared to the susceptible ones. The possibility of obtaining resistant somaclones is confirmed.

Black Sigatoka caused by Mycosphaerella fijiensisMorelet is the most dangerous and devastating disease of banana around the world. Disease control is carried out by integrating cultural, genetic and chemical measures. Mycosphaerella musicola has been replaced by M. fijiensis wherever Black Sigatoka has been introduced in America and elsewhere, and remains as a significant problem at sites located at relatively high altitudes. To optimize fungicide applications for disease management a presymptomatic quantification of fungal proteins in leaves is desirable. In this study, we describe the generation of a mouse monoclonal antibody (Mab) reactive to a high-molecular weight antigens from M. fijiensis mycelial single ascospore in vitro culture, but not reactive to mycelial antigens from M. musicola, M. musae and M. minima single ascospore cultures. A rabbit-specific polyclonal antibody against the same M. fijiensis antigen, reactive also to fungal secreted proteins, was able to discriminate naturally M. fijiensis infected from healthy leaves as well as other concomitant fungi. The Mab was used as a capturing reagent and the polyclonal preparation as a second antibody for a triple antibody enzymelinked immunosorbent assay able to quantify mycelial protein antigens in a range of 10-40 lg ⁄ ml and differentiate it from healthy banana leaf extracts. The aim of this study was the analytical setting up of a Mab-based immunoassay for the quantification of mycelial and secreted proteins of M. fijiensis. It is intended for the further establishment and optimization of an asymptomatic leaf assay for an improved forecast and warning system applied to Black Sigatoka disease management.

Two methods arc proposed tO' e^"aluate rust and eye spot disease resistance in sugarcane using biodiemical criteria.Eye spot disease resistance is easily evaluated by a fast conductimetric bioassa)' of high sensitivity", ff desired, the conductimetric values mav be converted into grades of field resistance by means of a regression graph based on standard varieties. The main advantages of this method art it's complete objectivity, reproducibility and independence of climatic conditions.It was also found that susceptibility of sugarcane to rust can be recognized xery early in the infection process by a striking increment of peroxidase activity. The simplicity of this enzyme reaction, which can easily be automated and the speed of detection during infection are discussed as an option for rust resistance evaluation.