Breeding self-fertile SM and МS of sugar beet lines and selecting best ones for breeding and economic valuable attributes

The aim of the researches was to breed new combination valuable self-fertile (Sf) sterility maintainers (FS) and their mail sterility (МS) analogues (а) as well as to select the new outbred SfМS line-testers (t), with a complex of valuable traits. It was established, that the share of self-pollinated plants varied from 62.0 up to 80.0 % in self-fertile hybrid generation. The lowest parameters were noted for hybrids-synthetics with the donor D3 M3 Sf for both recipients (64,4 and 62.0 % respectively). The offspring of the donor D1 G5 Sf380 showed a larger part of self-pollinated plants – from 76.2 % with the recipient R1 FS1 and 74.7 % with – R2 FS2 . Breeding for better seed pollination level was conducted. Analyzing crossings of the candidates for SfFS, with their МSа and МSt with the subsequent study of the offspring (F1 F2 ) МS of plants was carried out in conditions of strict isolation in order to estimate their sterility maintainers ability. F3 generations have received at weakened inbreeding, in group isolators and F4 on the isolated sites for free flight of pollen. At 100 % fertility of the candidates in SfFS and their МS 55 with 95–98% sterility, the hybrid generation had sterility and monogerm of 99–100 %. To all selection-valuable attributes the Only 25 % of the studied materials with МS new SfFS and their simple hybrids had satisfactory parameters. As for other numbers, formed with hybrids with МS hybrid and outbred FS of O type (МSt×SfFS), significant deviations in the "sterility" trait 92–58 % were noted. The best new materials were studied in sort testing for their efficiency estimation. SfFS candidates had good parameters for "sugar contents" trait – 19.18 %, while the standard had 19.01 %. The study of parameters МSа and МSt of lines with subsequent by selection perspective was important for successful hybrids breeding. The collection of the initial forms of Verhnyatska RSS was enlarged with new SfFS and their MS lines which is a source of valuable traits of the future parent components of hybrids as a result of the breeding. Key words: sugar beet, monogerm, pollinator, fertility, selection, hybrid, productivity.

Demographic determinants of biometric heritability

The response of quantitative characters to selection depends on their transmission from parents to offspring. A common estimate of this transmission is the biometric heritability defined as the slope of the regression of offspring phenotype on same-aged mid-parent phenotype (i.e. the ratio of the phenotypic parent-offspring covariance over the parental phenotypic variance). This slope is often interpreted as the percentage of phenotypic variation due to additive genetic effects after accounting for confounding factors such as environment, litter or parental effects. However, researchers seldom account for the possible influence of selection on this estimate. Here we study the effect on biometric heritability of fertility and viability selection, as well as phenotype ontogeny (growth) and inheritance from parents to offspring. We present exact formulas for the elasticities of biometric heritability in age-phenotype-structured integral projection models (IPMs), and illustrate these for two iteroparous long-lived species. We find that both viability and fertility selection can strongly affect heritability, mediated by growth and inheritance. Generally, demographic processes that result in parents reproducing at large phenotypes, regardless of their own birth phenotype, decrease heritability. Analysed at equilibrium, our models imply that a heritable character can show no response to selection, if parental phenotypes affect offspring phenotypes and if phenotypes develop with age. Our results further highlight the importance of accounting for demographic processes when estimating heritability.

Identification of molecular markers on bovine chromosome 18 associated to calving interval in a Brangus-Ibagé cattle herd

In the detection phase of a bovine marker assisted selection program, this paper investigated the genetic variability of three microsatellites on the chromosome 18 (BTA 18). The possible associations between genotypes or alleles of these markers versus weight at first calving and a lifetime calving interval (as indicators of reproductive performance) were evaluated in a beef cattle herd (5/8 Aberdeen Angus x 3/8 Nelore). Eleven alleles were detected in TGLA227 and ILSTS002 and three in BMS3004, the most frequent being TGLA227*79, ILSTS002*133, ILSTS002*135 and BMS3004*129. Polymorphic information content ranged from 0.41 to 0.84, while heterozygosity ranged from 49% to 86%, with an average value of 77%. The association analyses performed between genotype classes for the genetic markers versus weight at first calving indicated no significant result. Also, no correlation was observed between calving interval (CI) and TGLA227 genotypes. However, positive associations were detected between ILSTS002 and BMS3004 and CI. Animals carrying at least one ILSTS002*135 allele presented a CI about 39 days longer than the individuals with other genotypes; animals heterozygous for BMS3004 presented a CI about 35 days shorter than the homozygous. On these grounds, it can be concluded that these markers can be useful as an aid to fertility selection, in this herd.