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Genetic identification of loci for Hessian fly resistance in durum wheat

Bassi, F. M., Brahmi, H., Sabraoui, A., Amri, A., Nsarellah, N., Nachit, M. M., Al-Abdallat, A., Chen, M. S., Lazraq, A., El Bouhssini, M.
Molecular breeding 2019 v.39 no.2 pp. 24
Mayetiola destructor, Triticum turgidum subsp. dicoccon, Triticum turgidum subsp. durum, biotypes, chromosome mapping, cultivars, disease outbreaks, durum wheat, genes, genetic resistance, introgression, loci, marker-assisted selection, pests, quantitative trait loci, telomeres, Northern Africa
Durum wheat (Triticum durum Desf.) is a major crop of North Africa. Here, its production is affected by Hessian fly (Mayetiola destructor, HF) epidemics. Genetic resistance against this pest exist, but its molecular basis remains unclear. Here, a panel of 159 modern durum lines were exposed to the Moroccan HF biotype. Association mapping studies revealed three major loci conferring resistance. QH.icd-2A was identified at LOD of 24.1 on the telomeric end of 2AL, and it is believed to represent a novel locus derived from T. dicoccum. QH.icd-5B was identified on 5BS at LOD of 9.5, and it appears as overlapping with H31. QHara.icd-6B was identified at LOD of 54.5. This locus confers resistance to five Moroccan released cultivars, including ‘Faraj’. A mapping population (MP) was obtained by crossing ‘Faraj’ and a HF-susceptible cultivar ‘Gidara2’. Challenging this MP with the Moroccan and Great Plains HF biotypes revealed 1:1 segregation ratio fitting of a single gene. Quantitative trait locus (QTL) analysis confirmed a single locus at LOD of 35 and 25 for the two biotypes, respectively, corresponding to QHara.icd-6B. This locus spans a 7.7 cM interval, and it is derived via introgression from a resistant T. araraticum. One KASP marker (BS00072387) was validated for use in breeding on a separate set of elite lines, to show r² of 0.65 and accuracy of 0.98. Finally, field testing across sites did not identify any yield drag for QHara.icd-6B. The work presented here provides ideal tools to incorporate HF-resistant loci in durum cultivars via marker-assisted breeding.