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VALIDACIÓN DE MARCADORES MOLECULARES LIGADOS AL GEN S H 3 DE RESISTENCIA CONTRA LA ROYA EN INTRODUCCIONES DE LA COLECCIÓN COLOMBIANA DE CAFÉ

Leaf rust is the most important coffee (Coffea arabica L.) disease in producing countries. In order to face this disease, resistant varieties derived from Timor Hybrid have been developed in America. In Colombia, these varieties are made up of lines with different resistance genes combinations issued from this hybrid. Thanks to this diversity, such varieties have remained resistant to leaf rust for more than 25 years. However, the pathogen evolution obliges to keep a strategy based on the resistance genes diversity. The SH3 gene from Coffea liberica is a good candidate for this purpose. Recent development of molecular markers linked to this gene has opened the possibility to efficiently identify the genotypes that carry it. The aim of this study was to validate ten PCR-specific markers over 52 accessions to the Colombian Coffee Collection characterized by having different introgression degrees from C. liberica. Our results revealed that two out of the ten markers allowed reliable discrimination of genotypes carrying the SH3 gene. Furthermore, the presence of the selected markers significantly coincided with a high rust resistance recorded in the field. Therefore, we propose the use of these markers for early selection of rust resistant genotypes in the framework of gene pyramiding strategy involving not only the S H 3 but the resistance genes from the Timor hybrid. This accumulation of new resistance genes represents the most reliable approach towards development of future varieties with truly durable resistance.