Resistance test to Uromyces appendiculatus through pathogen inoculation in common bean detached leaves - DOI: 10.4025/actasciagron.v31i2.7029

Abstract

A new methodology of inoculating Uromyces appendiculatus in tests aimed at evaluation of common bean resistance to rust is proposed. The common bean lines Golden Gate Wax (gene Ur-6) and Ouro Negro (gene Ur-ON) were crossed to obtain a F₂ population, which was inoculated with race 29-3 of U. appendiculatus. Race 29-3 is incompatible with ‘Ouro Negro’ and compatible with ‘Golden Gate Wax’. Primary leaves of ten-days-old F₂ plants were detached and inoculated by immersion into an inoculum suspension. Immediately following immersion, each F₂ leaf was placed in a Petri dish containing a filter paper previously moistened with distilled water. These dishes were incubated in a BOD at 20°C, under a 12h daily light regime. The humidity in the dishes was maintained by addiction of 1.5 mL of distilled water in filter paper, under a three days regime. As control, the remaining primary leaves of ten-days-old F₂ plants were inoculated using the conventional inoculation method. Both inoculation methods were efficient in evaluating the reaction of the common bean to U. appendiculatus. The resistance/susceptibility screening of the F₂ population confirmed the monogenic dominant nature of the rust resistance controlled by the Ur-ON gene in both methods.