Transferring a new Fusarium head blight resistance locus FhbRc1 from Roegneria ciliaris into wheat by developing alien translocation lines.

A new FHB resistance locus FhbRc1 was identified from the R. ciliaris chromosome 7S and transferred into common wheat by developing alien translocation lines. Fusarium head blight (FHB) caused by multiple Fusarium species is a globally destructive disease of common wheat. Exploring and utilization of resources with FHB resistance are the most effective and environmentally beneficial approach for the disease control. Roegneria ciliaris (Trin.) Nevski (2n = 4x = 28, SSYY), a tetraploid wheat wild relative, possesses high resistance to FHB. In the previous study, a complete set of wheat-R. ciliaris disomic addition (DA) lines were evaluated for FHB resistance. DA7S had stable FHB resistance, which was confirmed to be derived from alien chromosome 7S. We tentatively designated the resistant locus as FhbRc1. For better utilization of the resistance in wheat breeding, we developed translocations by inducing chromosome structural aberrations using iron irradiation and the homologous pairing gene mutant ph1b. Totally, 26 plants having various 7S structural aberrations were identified. By marker analysis, a cytological map of 7S was constructed and 7S was dissected into 16 cytological bins. Seven alien chromosome aberration lines, which all had the bin 7S-1 on the long arm of 7S, showed enhanced FHB resistance. Thus, FhbRc1 was mapped to the distal region of 7SL. A homozygous translocation line T4BS·4BL-7SL (NAURC001) was developed. It showed improved FHB resistance, while had no obvious genetic linkage drag for the tested agronomic traits compared with the recurrent parent Alondra's. When transferring the FhbRc1 into three different wheat cultivars, the derived progenies having the translocated chromosome 4BS·4BL-7SL all showed improved FHB resistance. This revealed the potential value of the translocation line in wheat breeding for FHB resistance.