QTL for resistance to root lesion nematode (Pratylenchus thornei) from a synthetic hexaploid wheat source

Abstract

A whole genome average interval mapping approach identified eight QTL associated with P. thornei resistance in a DH population from a cross between the synthetic-derived wheat Sokoll and cultivar Krichauff. Pratylenchus thornei are migratory nematodes that feed and reproduce within the wheat root cortex, causing cell death (lesions) resulting in severe yield reductions globally. Genotypic selection using molecular markers closely linked to Pratylenchus resistance genes will accelerate the development of new resistant cultivars by reducing the need for laborious and expensive resistance phenotyping. A doubled haploid wheat population (150 lines) from a cross between the synthetic-derived cultivar Sokoll (P. thornei resistant) and cultivar Krichauff (P. thornei moderately susceptible) was used to identify quantitative trait loci (QTL) associated with P. thornei resistance. The resistance identified in the glasshouse was validated in a field trial. A genetic map was constructed using Diversity Array Technology and the QTL regions identified were further targeted with simple sequence repeat (SSR) and single-nucleotide polymorphism (SNP) markers. Six significant and two suggestive P. thornei resistance QTL were detected using a whole genome average interval mapping approach. Three QTL were identified on chromosome 2B, two on chromosome 6D, and a single QTL on each of chromosomes 2A, 2D and 5D. The QTL on chromosomes 2BS and 6DS mapped to locations previously identified to be associated with Pratylenchus resistance. Together, the QTL on 2B (QRlnt.sk-2B.1-2B.3) and 6D (QRlnt.sk-6D.1 and 6D.2) explained 30 and 48 % of the genotypic variation, respectively. Flanking PCR-based markers based on SSRs and SNPs were developed for the major QTL on 2B and 6D and provide a cost-effective high-throughput tool for marker-assisted breeding of wheat with improved P. thornei resistance.

Genome-wide association study in hexaploid wheat identifies novel genomic regions associated with resistance to root lesion nematode (Pratylenchus thornei)

“…This value indicates that despite the complexity of the trait which mainly owes to environmental conditions significant genetic effects were still observed and measured in the present study. Although in previous studies comparatively higher heritability for this nematode was also observed ranging from 0.83 to 0.97 36,44,45 . Dababat et al 42 detected very high heritability values, 0.95, 0.97 and 0.97 for Heterodera avenae, P. neglectus and P. thornei, respectively.…”

Constitutive and Induced Expression of Total Phenol and Phenol Oxidases in Wheat Genotypes Ranging in Resistance/Susceptibility to the Root-Lesion Nematode Pratylenchus thornei

“…Rahman et al recently identified key enzymes of phenylpropanoids, such as phenyl ammonium lyase and chalcone synthase, as candidate genes in QTL regions on chromosomes 2BS and 6DS for resistance to P. thornei in the synthetic derived wheat line Sokoll [43]. Initial QTL mapping studies reported the co-location of resistance to P. thornei in Sokoll on chromosomes 2BS and 6DS with QTL for resistance to P. thornei in CPI133872 [14,19]. However, more recent mapping studies have identified kompetitive allele specific PCR (KASP) markers that select for the CPI133872-derived resistance, but do not select for Sokoll-derived resistance, suggesting that P. thornei resistance in these synthetic hexaploid wheat genotypes is controlled by different genes [44] and therefore with possibly different resistance mechanisms.…”

“…No wheat genotype completely prevents the 2 of 17 reproduction of P. thornei. Hexaploid wheat genotypes (2n = 6x = 42) with high levels of resistance to P. thornei have been identified, including GS50a, a selection from the susceptible wheat cultivar, Gatcher [11], West Asian and North African wheat landraces [12], Iranian wheat landraces [13], and synthetic hexaploid wheat genotypes [10,14,15]. Furthermore, resistance to P. thornei has also been identified in tetraploid (2n = 4x = 28, Triticum turgidium subsp.…”

“…Zwart et al found that the inheritance of resistance in wheat is additive and polygenic [18]. Several quantitative trait loci (QTL) linked to P. thornei resistance have been identified in the aforementioned germplasm [14,15,19,20]. However, investigations into the mechanisms of resistance conferred by the quantitative trait loci (QTL) in wheat against P. thornei are limited.…”

Resistance to Cereal Cyst Nematodes in Wheat and Barley: An Emphasis on Classical and Modern Approaches

“…This provides the basis of QTL mapping for nematode resistance which normally involves at least a couple years to develop mapping populations and gene discovery based on the genetic background of only two parental genotypes. Recently, 3 QTL linked to the genomic regions associated with resistance against Pratylechus thorni have been identified on chromosomes 2B and 6D in wheat, validating the robustness of these QTL as useful sources of resistance in different genetic backgrounds [74]. Wheat genotypes resistant to H. avenae in one region of a same country could be highly susceptible to isolates of H. avenae from other regions.…”