Abstract:
Environmental variance is not dependent on the genotype and therefore subject to change. It is
governed by some degree of genetic control. This study aimed to characterize genetic variability
parameters and factors influencing on leavening ability of baker's yeast to determine the factors
governing fermentation performance. To do so, three parental strains of Saccharomyces
cerevisiae and two hybrid genotypes were used. Genetic variability parameters for the weight of
fermented bread dough were assessed over the time of fermentation. The biomass weight of
yeast strains and their hybrids was shown as follows: H1> H2> P1> P3> P2. This indicated more
viability of hybrid yeast cells leading to generating high quantities of carbon dioxide. Hybrid
genotypes exhibited heterogeneity at 8 g sucrose leading to evolution toward sugar stress.
Heterosis obtained reflected the optimum range of divergence in gene expression in changing
environments. Fermentation performance appeared phenotypic coefficient of variance (PCV)
slightly higher than the correspondence genotypic coefficient of variance (GCV). This indicated
the influence of environmental factors on fermentation activity. So, fermentation performance
exhibited low heritability coupled with low and moderate genetic advance as a percent of the
mean. This arises from the low values of genotypic variance. So, the fermentation performance
was governed by non-additive gene action. The heterosis tool will be of great value for
improving this trait followed by a selection of good quality genotypes. These, therefore, superior
hybrid genotypes have a potential value in bread bread-making industry. |
