Characterization of the Asian soybean rust (phakopsora pachyrhizi) in Corrientes province, Argentina

MARÍA G. CABRERA, ROBERTO E. ÁLVAREZ, MARÍA A. CÚNDOM, SUSANA A. GUTIÉRREZ AND E. GALDEANO

Nashville, TN, USA

Simposio; National Soybean Rust Symposium; 2005

The Soybean Rust agent (Phakopsora pachyrhizi Sydow) has been known to reduce yields on the total soybean production, in the world. The aim of this work was to characterize to soybean rust agent on morphomethrical and molecular study, as its present in the Corrientes province, in Argentina. Samples were collected of different plots during the 2204-05 growing season. Were specially considered the sampled leaflets of leaves from the lower one-third of the canopy. The number of rust lesions on leaves affected and uredinia per lesion were measured on the undersides of leaflets with 30× magnification. Morphomethrical characteristics of anamorph were observed. Molecular characterization by Polymerase Chain Reaction (PCR) was realized by DNA extraction from strains of disease leaves and field populations with Doyle & Doyle assay (1990), and specific primers for P. pachyrhizi were utilized (Frederik et al 2002). Anamorph and rudimental teleomorph states were observed. Uredinia were observed on petioles and soybean pods. The uredinia number per lesion was 1 to 6 (8) and 1547 to 3405 lesions per leaflets (according to leaflets size) were observed. The average size of urediniospores (n = 110) was 20-32 × 14-25 µm. Finally, micrographs with Scanning Electron Microscope were obtained. Key words: Asian Rust - Soybean - Morfomethrical Characteristics - PCR - Corrientes