Unveilling the potential of Portuguese common bean varieties to genetic improvement: rust and fusarium wilt resistance

Trabajo presentado en la V Meeting Asociación Española de Leguminosas, AEL (Eucarpia International Symposium on Protein Crops), celebrada en Pontevedra del 4 al 7 de mayo de 2015.Common bean (Phaseolus vulgaris L.) is the worldwide most important food legume, being an excellent source of proteins, fiber, minerals (iron and zinc) and vitamins. In addition to its health benefits it is an environmentally friendly resource because of the capability of fixing atmospheric nitrogen as a result of the endosymbiotic association with the soil bacteria Rhizobium. However, due yield instability caused by biotic and abiotic stresses, this crop is underused in Europe. Therefore, it is essential to genetically improve common bean varieties in order to attain more stable, reliable and sustainable local production. A collection of 130 Portuguese common bean landraces, resulting from more than five centuries of adaptation and mass selection by farmers, was screened for resistance to rust and fusarium wilt under controlled conditions. The diseases caused by these two very different fungi (an airborne and a soilborne, respectively) are among the most important constraints to the bean production and quality being intimately related to yield loss. Rust infection type and disease severity were analyzed 12 days after inoculation using a 0-4 scale (Stakman et al., 1962). The most frequent infection type observed was 4, indicative of a compatible plant-pathogen interaction, with no macroscopically visible hypersensitivity. Disease severity values varied greatly, from