Dynamics of hybrid necrosis genes in Russian cultivars of common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Study of necrosis genotypes of 72 Russian cultivars of winter common wheat has confirmed a tendency towards “washing off“ of genotypes with the Ne1 gene. Fifty-six percent of cultivars have the genotype ne1ne1Ne2Ne2, and 44% have the genotype ne1ne1ne2ne2; i.e., they are free of hybrid necrosis genes. The results of the study indicate that the diversity of the original ancestors in the groups of cultivars with the ne1ne1Ne2Ne2 and ne1ne1ne2ne2 genotypes is almost the same. This determines the instability of the tendency towards a higher prevalence of the ne1ne1Ne2Ne2 genotype in recent years. The changes in the diversity of the original ancestors with time have shown an increase in the diversity index. These processes may somewhat decrease the rate of genetic erosion caused by the fact that the Ne1Ne1ne2ne2 falls out of breeding. The routes of transmission of necrosis gene alleles from ancestors to descendants have been traced using extended pedigrees, and this information has been used to identify the probable donors and sources of hybrid necrosis gene alleles. In most cases, the cultivars Mironovskaya 808 and Krasnodarskaya 39 are the putative sources of the Ne2 allele (60.6 and 27.3% of all cases, respectively). The old cultivar Gostianum 237 from Saratov oblast is the putative source of the Ne2 allele in the cultivar Krasnodarskaya 39. The cultivars Bezostaya 1 and Odesskaya 51 (whose pedigree also includes Bezostaya 1) are the donors of the recessive genotype ne1ne1ne2ne2 in 93.5% of cases. The old Ukrainian cultivar Ukrainka is the most frequent source of recessive alleles. The strength of the Ne2 allele has been estimated in 36 cultivars. The results indicate that modifier genes affect the expression of tumor necrosis genes.