Screening for rust resistance in cool season legumes: complementation of field and growth chamber studies with histology, genomics and proteomics

Trabajo presentado en la 2nd General Meeting of COST FA1306 (The quest for tolerant varieties - Phenotyping at plant and cellular level. PhenomenALL), celebrada en Copenhagen del 18 al 20 de abril de 2016.

Rusts are major biotic constraints of legumes worldwide. Breeding for resistance is regarded as the most cost efficient method for rust control. Preferred resistance for breeders for decades has been complete resistance, which is usually controlled by single genes. The draw back is the easy breakdrown by development and spread of new races of the pathogen. This has reaised an increasing concern on durability and in the search of more durable types of resistance. The situation is a bit different in cool season legumes. In contrast with the better studied common bean in which complete monogenic resistance has been identified and is efficiently used in breeding, only incomplete resistance of complex inheritance has been described in faba bean, pea, chickpea and lentil and several of their associated QTLs have been mapped. However, the relatively large distance between the QTLs and their associated molecular markers hampers their efficient use for MAS. However rust resistance breeding is not only slow due to the difficulty and the relatively low investment on genomics of the legume crops, but also, and mainly because of the little knowledge on the mechanisms of resistance operative and on the biology of the rust pathogens. Comprehensive studies on host status and virulence of the various rust species are often missing, and in most of the examples listed above, there is little agreement on the existence of races and on their distribution. Also, available information on levels of resistance and on the responsible mechanisms is often incomplete. Only after significant input to improve existing knowledge on biology of the causal agents and in phenotyping plant responses, will resistance breeding be efficiently accelerated. Phenotyping on rust resistance performed at Cordoba will be presented and critically discussed.

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