A wide collection of wild emmer accessions to discover novel resistance genes to yellow rust

MATTHEW MARTIN; VIVIANA ECHENIQUE; RAFFAELLA BATTAGLIA; ANNA MARIA MASTRANGELO; ELISABETTA MAZZUCOTELLI; BRIAN STEFFENSON; FRANCESCA DESIDERIO; ESRA CAKIR; LUIGI CATTIVELLI; OADI MATNY; PABLO RONCALLO; DELFINA BARABASCHI; HAKAN OZKAN

Saskatoon

Congreso; 1st International Wheat Congress; 2019

University of Saskatchewan

The stripe or yellow rust (YR) disease, caused by Puccinia striiformis f. sp. tritici (Pst), severely threatens grain yield. Unusual and severe epidemics of YR were observed in several continents in 2017 and years before, including not endemic geographic area, as a consequence of climate changes. Urgent is the exploration of new genetic variability to discover novel resistance genes. Alleles of the wild emmer wheat (T. dicoccoides), progenitor of the domesticated durum wheat, have been introgressed in cultivated wheat and showed to positively contribute to biotic and abiotic stress tolerance, yield components and quality. Among a wide collection of wild emmer accessions established c/o CREA-Genomics and Bioinformatics Research Centre, 285 lines have been genotyped using the Axiom 35K array, obtaining about 12000 poly-high resolution SNPs. The collection includes accessions originated from all Fertile Crescent countries, thus it represents all environments where wild emmer naturally occurs. The assessment of genetic diversity and population structure identified two well-defined groups, mostly corresponding to the two known races, as well as subgroups, according to the originating geographic area. LD decay was also assessed and verified to be fast as expected for a wild species. To identify wild emmer sources of resistance to YR, the collection has been phenotyped in controlled conditions for reaction to three YR isolates (Pstv14, Pstv37, Pstv40), and in open field in Southern Italy for two years. The GWAS identified a number of resistance loci widespread into the genome. These QTLs, together with those identified in other tetraploid wheat panels, were projected on the durum reference genome (cv Svevo), thus evidencing the overlapping with known genes as well as novel resistance loci to be introgressed in durum varieties. The QTLs were also projected to the wild emmer reference genome (Zavitan) to identify candidate genes.