Genetic diversity and association mapping for agromorphological and grain quality traits of a structured collection of Spanish durum wheat

Durum wheat (Triticum turgidum L. subsp. durum) is a crop of strategic importance in the Mediterranean area. However, the massive introduction of homogeneous and more productive modern cultivars have contributed to greatly reduce its genetic diversity. Wheat landrace collections contain a wide genetic diversity and constitute an easily transferable and valuable source of genetic variation for agronomical, morphological, adaptive and quality traits. A durum wheat collection of Spanish landraces comprising accessions of the three main inter-fertile subspecies (durum, turgidum and diccocon) was evaluated in a previous work using several molecular marker systems. The genetic diversity and agromorphological traits were correlated with geographic and climatic features. The broad variation found for all the evaluated traits underlined the large genetic variability of the collection (Ruiz et al. 2012). These study allowed the creation of the Spanish durum wheat core collection (Ruiz et al. 2013). Association mapping was performed for 18 agromorphological and grain quality traits in a collection of 183 Spanish landraces. A total of 85 stable MTAs (marker?trait associations) were identified for agromorphological and quality parameters, some of them common among subspecies and others subspecies-specific. For all the traits, MTAs explaining more than 10?% of the phenotypic variation were found in any of the three subspecies. The validation of several adaptive and quality trait MTAs by combining the association mapping with an analysis of the signature of selection, identifying the putative gene function of the marker, or by coincidences with previous reports, showed that this approach was successful for the detection of MTAs and the high potential of the collection to identify marker?trait associations. Novel MTAs not previously reported, some of them subspecies specific, have been described and provide new information about the genetic control of complex traits (Giraldo et al. 2016).The genetic characterisation and association studies of different wheat germplasm sets will provide researchers comprehensive information of the tetraploid wheat gene pool and the tools to improve the characterisation and utilisation of this germplasm.