CONICET | Buscador de Institutos y Recursos Humanos

Potato (Solanum tuberosum) is one of the most important widespread hosts of Ralstonia solanacearum. This pathogen has the ability to produce symptomless latent infections which facilitates its global dissemination, hindering bacterial wilt disease control (1). In Uruguay is conducted a national potato breeding program focused on the development of germplasm with resistance to R. solanacearum. The strategy adopted involves the introduction of resistance from the wild native species S. commersonii andS. chacoense, widely distributed and adapted to our environmental conditions (2). Screening for selection of resistant genotypes involves symptom evaluation and detection of latent infection in asymptomatic plants by a BIO-multiplex-PCR assay. Different responses to R. solanacearum infection were observed including susceptible, tolerant (asymptomatic but with latent infection), and resistant genotypes. The overall aim of this work is to generate knowledge about the process of R.solanacearum infection and resistance mechanisms present in potato germplasm. Seven advanced clones with different responses to R. solanacearum infection were selected and colonization, dissemination and multiplication patterns were compared. A high aggressive R.solanacearum strain (UY031,IIB1) was genetically modified to constitutively generate fluorescence from asynthetic GFP stably inserted in the chromosome. This reporter strain was used to allow a direct and precise visualization of fluorescent cells in plant tissues by confocal microscopy. Typical symptoms of bacterial wilt were correlated with the presence of bacteria in high concentrations in xylem vessels and in asymptomatic plants the bacteria were detected only in roots. This study was complemented by evaluation of different plant defense responses including callose and lignine deposition, ROS production and loss of ions using ion leakage method.