The Global Durum Wheat Panel: An international effort to identify and exchange beneficial alleles

Authors: MAZZUCOTELLI, ELISABETTA - Crea - Research Centre For Genomics And Bioinformatics; SCIARA, GIUSEPPE - University Of Bologna, Italy; MASTRANGELO, ANNA-MARIA - Crea-Research Centre For Cereal And Industrial Crops; DESIDERIO, FRANCESCA - Crea - Research Centre For Genomics And Bioinformatics; Xu, Steven; Faris, Justin; HAYDEN, MATHEW - Agriculture Victoria; TRICKER, PENNY - University Of Adelaide; OZKAN, HAKAN - Cukurova University; ECHENIQUE, VIVIANA - National University Of The South

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2020
Publication Date: 12/21/2020
Citation: Mazzucotelli, E., Sciara, G., Mastrangelo, A., Desiderio, F., Xu, S.S., Faris, J.D., Hayden, M.J., Tricker, P.J., Ozkan, H., Echenique, V. 2020. The Global Durum Wheat Panel: An international effort to identify and exchange beneficial alleles. Frontiers in Plant Science. 11:569905. https://doi.org/10.3389/fpls.2020.569905.
DOI: https://doi.org/10.3389/fpls.2020.569905

Interpretive Summary: A collection of unique lines that represent global genetic diversity is an excellent resource for genetic studies and breeding for crop improvement. A global core collection of durum wheat, an important cereal specifically for making pasta products, has not previously been established. To facilitate durum wheat improvement, the Expert Working Group on Durum Wheat Genetics and Breeding of the Wheat Initiative assembled a global durum wheat panel (GDP) of 1,011 lines obtained from various gene banks and breeding programs globally. The GDP consists of a wide representation of modern and historic durum wheat cultivars along with a selection of wild relatives and durum wheat progenitors to maximize diversity. The GDP collection represents 94-97% of the original durum wheat diversity. It was found that the breeding programs from Italy, France and Central Asia provided the highest level of genetic diversity among the modern durum wheat lines, and breeding programs from Europe had the largest sets of unique genes. The molecular data and seed of the GDP collection from this study have been made publicly available. The GDP collection will facilitate international collaboration in the durum wheat community and lead to the identification and utilization of beneficial genes by breeding programs.

Technical Abstract: Representative, broad, and diverse collections are a primary resource to dissect genetic diversity and meet pre-breeding and breeding goals through the identification of beneficial alleles for target traits. From 2,500 tetraploid wheat accessions obtained via the collaborative effort of the Expert Working Group on Durum Wheat Genetics and Breeding of the Wheat Initiative, a Global Durum wheat Panel (GDP) of 1,011 genotypes was assembled to represent 94-97% of the original durum wheat diversity. The GDP consists of a wide representation of modern Triticum turgidum ssp. durum germplasm and landraces, along with a selection of wild emmer and primitive tetraploid wheats to maximise diversity. Genetic diversity and population structure within the GDP collection were investigated using the wheat iSelect 90K SNP array. Among modern durum accessions, breeding programs from Italy, France and Central Asia provided the highest level of genetic diversity, with only a moderate decrease in genetic diversity observed across nearly 50 years of breeding (1970 to 2018). Breeding programs from Europe had the largest sets of unique alleles. Within the GDP accessions, LD was lower in the landraces (0.4 Mbp) than in modern germplasm (1.8 Mbp) at r2 = 0.5. ADMIXTURE analysis defined a minimum of 13 distinct genetic clusters (k), which could be attributed to the known breeding programs. Chromosome regions putatively subjected to strong selection pressure were identified from fixation index (Fst) and diversity reduction index (DRI) metrics in pairwise comparisons defined by decades and the breeding program. Clusters of putative selection sweeps (PSW) were identified as co-localizing with major loci controlling phenology (Ppd and Vrn), plant height (Rht) and quality (gliadins and glutenins), underlining the role of the corresponding genes as driving elements of modern breeding. Public seed availability and deep genetic characterization of the GDP make this collection ideal to identify and map useful genetic diversity at loci of interest to any breeding program.