A novel assembly of Thinopyrum ponticum genes into the durum wheat genome: pyramiding Fusarium head blight resistance onto recombinant lines previously engineered for other beneficial traits from the same alien species

Abstract

Favoured by climate changes, Fusarium head blight (FHB) has recently become a threat also in unusual environments, including those where durum wheat is largely cultivated. Since current durum wheat cultivars are mostly susceptible to FHB, new germplasm is needed, capable of maintaining yield capacity and grain quality under the disease pressure. To achieve this goal, a sustainable approach relies on transfer of resistance from related Triticeae species by means of chromosome engineering. We resorted to this cytogenetic strategy, efficiently complemented with advanced selection systems, to transfer into durum a QTL for FHB resistance (here, temporarily designated Fhb-7el 2 ) previously mapped on the 7el 2 L arm of the wild Thinopyrum ponticum. A bread wheat 7DS.7el 2 L translocation line was employed as donor of Fhb-7el 2 in crosses with previously developed durum wheat 7AS.7AL-7el 1 L recombinant genotypes, carrying genes for rust diseases (Lr19 ? Sr25) as well as for quality-and yieldcontributing traits, deriving from a different Th. ponticum accession. In pentaploid F 1 s, the largely homologous 7el 1 L and 7el 2 L arms showed considerable reduction in pairing and recombination frequency as compared to what observed in a parallel experiment we carried out in a hexaploid context. Nevertheless, pyramiding into durum of target genes/QTL from the two Th. ponticum accessions was successfully achieved. The selected 7el 1 L ? 7el 2 L tetraploid lines exhibited 70-85 % reduction in FHB severity following Fusarium inoculation, and a parallel decrease in fungal biomass in kernels of infected spikes. Similar effects were detected in bread wheat lines carrying the same target gene assembly on 7DL instead of 7AL. Preliminary evidence of good agronomic performance of the novel 7el 1 L ? 7el 2 L recombinant lines paves the way for their straightforward exploitation in breeding.

Harnessing Genetic Diversity of Wild Gene Pools to Enhance Wheat Crop Production and Sustainability: Challenges and Opportunities

“…Blasco [41]. In this context, a further different picture emerged, again likely influenced by the background genotype.…”

“…As shown in Figure 5, the work of Forte et al [41] enabled a higher map resolution than previously achieved [64], separating this SDR from a more proximal one, containing the PSR129 marker, associated, in turn, to 7el 1 L-linked SD effects in various studies and materials (both bread and durum wheat recombinant lines, see [36] for a review). Within the 7el 2 L SDR, it seems of interest to note the presence of a wheat EST (Expressed Sequence Tag), namely BF200943, for whose nucleotide sequence a BLAST search (https://blast.ncbi.nlm.nih.gov/Blast.cgi) indicated a high homology with a protein product belonging to the mitogen-activated protein kinase (MAPK) cascades of several Triticeae species.…”

“…Similarly, and in this case exploiting the high degree of homology relating two group 7 chromosomes (named 7el 1 and 7el 2 ) of different Th. ponticum accessions, the Lr19 gene (located on the 7el 1 L arm) was pyramided, both in bread wheat [39][40][41] and in durum wheat [41], with Fhb-7el2, a major QTL for resistance to Fusarium head blight (FHB) mapped on 7el 2 L (recently renamed Fhb7 [42]). …”

Engineered Durum Wheat Germplasm with Multiple Alien Introgressions: Agronomic and Quality Performance

“…segment, distally located on the 7AL arm [35,39]. Since the size of the alien block introgressed in all the quoted cases remains within tolerable amounts by the recipient genome, such recombinant genotypes represent promising materials for use in breeding and cultivation.…”

Production and Molecular Cytogenetic Characterization of a Durum Wheat-<b><i>Thinopyrum elongatum</i></b> 7E Disomic Addition Line with Resistance to Fusarium Head Blight

“…ponticum (7AgL) into a durum wheat background, yield and other agronomic characteristics were enhanced. Forte et al [2014] developed complex genotypes that included the addition of chromosome 7el 1 L + 7el 2 L to a tetraploid wheat background. These lines showed 70-85% reduction in FHB severity following Fusarium inoculation and a parallel decrease in fungal biomass in kernels of infected spikes.…”