Prompted by recent changes in climate trends, cropping areas, and management practices, head blight (FHB), a threatening disease of cereals worldwide, is also spreading in unusual environments, where bread wheat (BW) and durum wheat (DW) are largely cultivated. The scarcity of efficient resistance sources within adapted germplasm is particularly alarming for DW, mainly utilized for human consumption, which is therefore at high risk of kernel contamination by health-dangerous mycotoxins (e.g., deoxynivalenol = DON). To cope with this scenario, we looked outside the wheat primary gene pool and recently transferred an exceptionally effective FHB resistance QTL () from 7EL chromosome arm onto a 7elL arm segment, containing additional valuable genes (including for leaf rust resistance and for yellow pigment content), distally inserted onto 7DL of BW lines. Two such lines were crossed with two previously developed DW- recombinants, having 7elL distal portions on 7AL arms. Genomic hybridization (GISH) analysis showed homologous pairing, which is enabled by 7elL segments common to the BW and DW recombinant chromosomes, to occur with 42-78% frequency, depending on the shared 7elL amount. Aided by 7EL/7elL-linked markers, 7EL+7elL tetraploid recombinant types were isolated in BC progenies to DW of all cross combinations. Homozygous 7EL+7elL recombinant plants and null segregates selected in BCF progenies were challenged by spike inoculation to verify the efficacy in DW. Infection outcomes confirmed previous observations in BW, with >90% reduction of disease severity associated with presence . its absence. The same differential effect was detected on seed set and weight of inoculated spikes, with genotypes lacking having ∼80% reduction compared with unaffected values of carriers. In parallel, DON content in flour extracts of resistant recombinants averaged 0.67 ppm, a value >800 times lower than that of susceptible controls. Furthermore, as observed in BW, the same also provided the novel DW recombinants with resistance to crown rot (∼60% symptom reduction) as from seedling infection with . Through alien segment stacking, we succeeded in equipping DW with a very effective barrier against different diseases and other positive attributes for crop security and safety.
PMID: 31695716 [PubMed]