Registration of six synthetic hexaploid wheat germplasm as sources of resistance to tan spot, stem rust, and stripe rust and adult plant resistance to leaf rust

Aegilops tauschii is the donor of D-genome of bread wheat (Triticum aestivum L.) as well as several agronomically desirable genes important for wheat improvement. The genetic transfers from Ae. tauschii to bread wheat are achieved either through direct crosses or indirectly through production of synthetic hexaploid wheat (SHW). Synthetic hexaploid wheat is produced by crossing tetraploid wheat (Triticum turgidum L.) with Ae. tauschii, followed by chromosome doubling of the F-1 hybrid by colchicine. Six Ae. tauschii accessions based on their seedling resistance to tan spot, stem rust, stripe rust and adult plant resistance to leaf rust and two tetraploid wheat genotypes (tetraPrelude and tetraThatcher) were used for the production of SHWs. The present report describes the production and evaluation of six new SHWs, TA4161-L1 (Reg. no. GP-1071, PI 700779), TA4161-L2 (Reg. no. GP-1072, PI 700780), TA4161-L3 (Reg. no. GP-1073, PI 700781), TA4161-L4 (Reg. no. GP-1074, PI 700782), TA4161-L5 (Reg. no. GP-1075, PI 700783), and TA4161-L6 (Reg. no. GP-1076, PI 700784), for seedling resistance to tan spot, stem rest, stripe rust, and adult plant resistance to leaf rust. The SHWs reported here with higher levels of resistance to race 1 of Pyrenospora tritici-repentis would be an excellent addition to the current collection of tan spot-resistant germplasm. The resistance to the three rusts was not expressed in the SHWs due to the presence of rust-suppressor factors in tetraploid parents. However, the SHWs will be good source material for new resistance genes to the three rusts in derivative lines upon breeding with nonsuppressive wheat genotypes as well as for the mapping of rust-suppressive factors.