Transfer of the recessive crossability allele kr1 from Chinese Spring into the winter wheat variety Martonvásári 9

Summary The recessive of crossability allele kr1 was transferred from the spring wheat variety Chinese Spring (CS) into the winter wheat variety Martonvásári 9 (Mv9) by backcrossing the Mv9 × CS hybrids with Mv9. The Mv9 variety possesses dominant Kr1 alleles and is heterogeneous at the kr2 locus, so that some individual plants carry recessive kr2 alleles. The selection of plants possessing the recessive kr alleles from the (Mv9 × CS)Mv9 BC₁ generation was carried out according to the seed set achieved when pollinated with rye (Secale cereale L. cv. Mercator). The partial dominance of the Kr alleles made it possible to differentiate between plants heterozygous at the Kr1 locus and Kr1Kr1 homozygous dominant plants. Two selfed consecutive progenies were tested by pollination with rye to select the homozygous recessive kr1kr1kr2kr2 plants and to check the result of the selection after each backcross.As a result of three backcrosses with Mv9 and two selfings after each backcross the selected progenies had 61.6% seed set with rye tested on sixty individual plants. These data confirm that after the third backcross the selected Mv9 kr1 line carries necessive crossability alleles Kr1 and Kr2, but the genotype is 93.75% Mv9.