Identifying Nematode Resistant Quantitative Trait Loci in Wheat

Root lesion nematodes (RLN) (Pratylenchus thornei and P. neglectus) are characterized soil borne pathogens of wheat that invade and feed on root host cells.   Common signs of root lesion nematode damage are lesions on the roots, root girdling and lack of lateral root branching.  In the Pacific Northwest (PNW) these species of nematode were found in 95% of sampled fields and were estimated to cause between 37% and 50% yield loss in spring wheat.  Resistance to both Pratylenchus sp. had been found in a wheat landrace accession from Iran, AUS28451, and was used to develop a mapping population. Recent findings indicate lignin as the potential mechanism of resistance for AUS28451 and was also evaluated in this population.  Quantitative trait loci (QTL) analysis using WinQTL cartographer 2.5 software found two major QTL’s for nematode resistance located on chromosomes 1B and 5A.  Other significant QTL were found on chromosomes 2B, 4A and 7A.  Pratylenchus thornei resistant QTL had also previously been mapped to chromosomes 1B, 2B and 7A in other Middle Eastern landrace accessions.  Significant lignin QTL were mapped to chromosomes 2B, 3A, 4A, 6A and 7A.  Overlapping significant QTL sharing markers for both traits were found on chromosomes 4A and 7A.