Development and Cytomolecular Identification of Monosomic Alien Addition and Substitution Lines of Triticale (× Wittmack) With 2S Chromosome Conferring Leaf Rust Resistance Derived From Boiss.

Alien chromosome introgression has become a valuable tool to broaden the genetic variability of crop plants via chromosome engineering. This study details the procedure to obtain monosomic addition and monosomic substitution lines of the triticale carrying 2S chromosome from Boiss., which harbors + leaf and stripe rust-resistant gene loci, respectively. Initially, × artificial amphiploids (2 = 6 = 42 chromosomes, UUSSRR) were crossed with triticale cv. "Sekundo" (2 = 6 = 42, AABBRR) in order to obtain fertile offspring. Cyto-molecular analyses of five subsequent backcrossing generations revealed that 2S chromosome was preferentially transmitted. This allowed for the selection of monosomic 2S addition (MA2S) lines of triticale. Finally, the 2S(2R) substitution plants were obtained by crossing MA2S with the nullisomic (N2R) plants of triticale. The presence of 2S chromosome in subsequent generations of plants was evaluated using SSR markers linked to + loci. Disease evaluation of the monosomic 2S(2R) substitution plants for the reaction to leaf and stripe rust infection were carried out under controlled conditions in a growth chamber. The results showed significant improvement of leaf rust resistance severity of monosomic substitution plants compared with control ("Sekundo"). In contrast, the introgression of the + loci did not lead to improvement of stripe rust resistance. In summary, the creation of monosomic addition and monosomic substitution lines of triticale is the starting point for the precise and guided transfer of + loci. The results showed that the developed materials could be exploited for the development of triticale varieties with resistance to leaf rust.