Challenges in Exploiting Introgression Stocks Carrying Segments from Wild Relatives in Durum Wheat improvement

Genes introgressed from wild relatives via translocated segments have been a source of valuable genetic variability in bread wheat and their recent availability in durum backgrounds opened the way for their utilization in this crops’ improvement, albeit with certain challenges. We evaluated the potential use in breeding of 3 such introgression stocks, two harboring a segment from L. ponticum, carrying the Lr19/Sr25 rust resistance genes as well as a yellow pigment locus, and one with the translocation from T. speltoides, carrying rust resistance gene Lr47. A series of Near-Isogenic Lines (NILs) in four different, rust susceptible, backgrounds were developed and tested for yield potential, some yield components and quality attributes, under full and reduced irrigation, in 2012 and 2013. The presence of the L. ponticum translocation resulted either in yield decrease or increase, depending of the NIL and background under full irrigation but was always associated with a decreased performance under drought. Reduced yield was associated with reduced kernel weight under both conditions and not with differences in biomass. The translocation was generally positive or neutral for gluten strength and always highly favorable for yellow pigment content. The T. speltoides translocation was usually negative for yield under both conditions and had variable effects on quality. Clearly, gene introgression via these stocks needs to be conducted with a systematic attempt to either unlink the desired gene(s) from negative effects possibly carried on the same translocated segments or compensate for the loss of important wheat genes displaced by the translocations.