Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/2016
Publication Date: 2/12/2016
Citation: Thompson, A.L., Smiley, R.W., Paulitz, T.C., Garland Campbell, K.A. 2016. Identification of dual-resistance to Pratylenchus neglectus and P. thornei in Iranian landrace accessions of wheat. Crop Science. 56(2):654-672. Interpretive Summary: Root-lesion nematodes are soil-borne pathogens that challenge wheat production around the world. It has been estimated that these nematodes reduce wheat profits by $69 billion each year in Australia and $51 billion each year in the Pacific Northwest. There are currently few options available for wheat growers to manage the nematode populations and reduced economic losses. Breeding cultivars that are resistant to the nematodes is considered the best strategy to reduced populations. Resistance is rare so identifying sources in wheat is important for breeding efforts. In this paper we identified 32 sources of resistance in landrace accessions from Iran. We also characterized these accessions for other useful traits including stripe rust resistance, growing requirements (photoperiod and vernalization) market class, and grain quality. This research shows these accessions have diversity that could be useful for wheat breeders to integrate variation as well as nematode resistance into wheat cultivars.
Technical Abstract: The pathogenic nematode species Pratylenchus neglectus and P. thornieii cause severe yeid losses in wheat (Triticum aestivum). Our objectives 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 in 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, SNP, and known vernalization markers and hierarchical cluster analysis was used to identify relatedness among accessions. Thirty-two accessions were identified as resistant and/or moderately resistant to both Pratylenchus species. Four of these accessions also had moderate adult plant resistance to stripe rust in the field. The range of mean agronomic traits over locations was 53-105 cm for plant height; 46-84 days for post planting days to heading; and 151-728 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. This diversity within this subset could be useful for wheat breeders to integrate genetic variation and resistance to both major pathogenic Pratylenchus spp.