TRANSMISSION OF RALSTONIA SOLANACEARUM IN TOMATO SEED
AND TRUE POTATO SEED (TPS). C. Borda (1); E. Saenz (1); P.
Aley; L. Gutarra (2) and S. Priou (2)
(1) University of São Paulo, São Paulo,
Brazil and (2) International Potato Center, Lima, Peru.
Abstract: Bacterial wilt caused by the soilborne bacterium R. solanacearum, is one of
the most destructive bacterial diseases of economically important crops.
Tomato seed and mesocarp extracts were inoculated with different
concentrations of R. solanacearum race 3/biovar II (10 to 10^8 ufc/ml in tenfold
serial dilutions) and incubated at room temperature for 6, 12, 24 and 48
hours with constant agitation (150 r.p.m.) previously incubated at 40C for 2
hours. After enrichment, the extracts were analyzed in plated on medium
SMSA, ELISA and double-PCR to repeat the methodology with TPS and
potato mesocarp. The method developed in tomato seed inoculated was
applied to samples of tomato seed and mesocarp obtained from plants with
bacterial wild symptoms from field infested and plants inoculated in
greenhouse with R. solanacearum, were analyzed to check the effectiveness
of the detection method. Different infected plant parts (roots, stem and fruit)
were examined to confirm the presence of the pathogen. The analyses
demonstrated the method effectiveness and that R. solanacearum is a
bacterial that infects tomato seed. Finally, it was examined samples of TPS
and mesocarp of two resistant varieties and two susceptible varieties of
potato, obtained from plants with bacterial wild symptoms from fields
infected. The analyzes demonstrated that neither TPS nor mesocarp from
wild plants of 4 varieties harbor R. Solanacearum. Support: CIP