Identification of Resistance to Pratylenchus neglectus and Pratylenchus thornei in Iranian Landrace Accessions of Wheat

The pathogenic nematodes Pratylenchus neglectus (Rensch, 1924) Filipjev and Schuurmans Stekhoven, 1941 and Pratylenchus thornei Sher and Allen, 1953 cause severe yield losses in wheat (Triticum aestivum L.). The objectives in this study were to assay a collection of Iranian landrace accessions collected from 12 provinces in Iran to identify novel sources of resistance to both species and to characterize agronomic traits critical for consideration in wheat breeding. Seventy-eight accessions were assayed for dual resistance to parasitic nematodes P. neglectus and P. thornei in controlled environment assays. Field trials conducted in Pullman, WA, and Pendleton, OR, evaluated stripe rust (Puccinia striiformis f. sp. tritici) resistance, days to heading, grain volume weight, plant height, seed protein content, seed kernel characterization, glume tenacity, and pubescence. The accessions were assayed with simple-sequence repeat (SSR), single-nucleotide polymorphism (SNP), and known vernalization markers for hierarchical cluster analysis to identify relatedness among accessions. Thirty-two accessions were identified as resistant or moderately resistant to both Pratylenchus species. Six were identified with moderate adult plant resistance to stripe rust in the field. The range of mean agronomic traits over locations was 53 to 105 cm for plant height, 46 to 84 d for post planting days to heading, and 151 to 728 kg m(-3) for grain volume weight. The genetic cluster analysis identified three clusters based on the number of rare polymorphisms in the subset. The nematode resistance was distributed over the three clusters. The diversity within this subset could be useful for wheat breeders to integrate genetic variation and resistance to both Pratylenchus spp.