Relationship between hybrid performance and genetic variation in self-fertile and self-sterile sugar beet pollinators as estimated by SSR markers

Sugar beet hybrid varieties are produced through the crosses between male sterile lines and the multigerm pollinators. The uniformity of pollinators used for hybrid crosses depends on the presence of self-sterility (S ^s ) and self-fertility (S ^f ) genes. The aim of the study was to analyze correlation between hybrid performance and genetic distance or heterozygosity of the sugar beet pollinators. Twelve diploid pollinators classified as self-sterile (S ^s ) or self-fertile (S ^f ) and two cytoplasmic male sterile (CMS) lines were crossed in line × tester scheme, producing 24 F₁ hybrids. The parents and the hybrids were evaluated for root yield and quality traits, from which F₁ performance, combining abilities, mid-parent and high-parent heterosis were calculated. Parental genetic distance and diversity of the pollinators were estimated by SSR markers and, together with GCA and F₁ performance, correlated with the heterosis effects. The S ^f hybrids had better GCA and higher values of root yield, root weight, and root circumference than the S ^s hybrids. Heterosis was recorded in more combinations with the S ^f than with the S ^s pollinators. Parameters of genetic diversity were higher in the S ^s (Na = 3.125; Ne = 2.341; He = 0.555) than in the S ^f pollinators (Na = 3.000; Ne = 2.188; He = 0.510). Genetic distance between the tested pollinators and the CMS lines was low (0.072–0.224) indicating that the genetic base of the investigated germplasm was narrow. Correlation of the heterosis effects with GD and heterozygosity was detected only for the root yield traits.