Methods of creating substituted lines for hybrid selection of sugar beet: plants of the species Beta vulgaris L. with new sterile cytoplasm of Beta patula L

Purpose. Due to changing climatic conditions and the spread of new viral diseases, an important issue in beet growing is the expansion of plasma ulture using new sterile cytoplasm from wild species of the genus Beta L. as an alternative to Owen’s S-cytoplasm. The goal of this work was to obtain new breeding genotypes based on new cytoplasm. Methods. Cytological, biotechnological. field and laboratory. Results. Availability of recombination in the locus of grafted genes of one-year and two-year development cycles B+b- and hypocotyl colour R+r- was determined using the method of analytical crosses. Earlier we have proved the positive effect of sterility maintainer Beta vulgaris Nxxzz in replacement of the sterility maintainer genome based on our results on the selection of hypocotyl of green color r-rand two-year development cycle b-b- in the interspecific hybrids F2 obtained under the hybridization scheme Beta maritima L: ♀B1C maritima / ♂ Beta vulgaris Nxxzz (Роїк М. В., 2013). In the case of interspecific hybrids, in the conditions of sterile cytoplasm Beta patula L., only backcross offspring of the third cycle of saturating crosses were identified by one- and two-year developmental cycles. Seed bearing plants of BC3S patula of a two-year development cycle were characterized by spreading stems, multi-seeded fruits (3, 4 seeds) and sterile anthers. At the same time, monogermity and a two-year development cycle were restored against the background of sterile cytoplasm of Beta patula L. only among the seed bearing plants of the fourth cycle of saturating crosses. Recombinant genotypes with a red hypocotyl colour and a two-year development cycle BC4S patula R+r- were characterized by multigermity, chimericalness by sterility of CMS‑1 and CMS‑0 type and single- and multi-stem morphological types of anthers. The expression of CMS nuclear genes in the newly replaced BC5S patula lines was marked by high sterility rates of the CMS‑0 type; however, the fertility rates required additional rejection of multigerm seed plants. This is an indicator of the complex structure of the fertility locus in wild Beta patula L. and the special response of the nuclear genome of the sterility maintainers to the new cytoplasmic background. Experimental triploid hybrids with the new introductory sterile cytoplasm Beta patula L. were determined by high sugar content and dry matter content up to 29%. Conclusions. Alloplasmic lines based on the cytoplasm of the wild species Beta patula L are created. Their sugar content at the level of experimental triploid hybrids was 19.5% and 20.5% with a dry matter content of 25% —29%. Alloplasmic lines with a new BCC Beta patula L. recommended for use in the selection process of sugar beets.