6/25/2023 0 Comments Hybrid vigor definitionHybridization plays an important role in the emergence of new species by providing a myriad of novel interactions giving rise to new phenotypes, thereby helping to colonize unoccupied ecological niches. Therefore, identifying the underlying mechanism of hybrid vigor is of great interest. Moreover, hybrid vigor has been extensively exploited for increasing productivity in agriculture. Hybrids and heterosis have fascinated evolutionary biologists since Darwin and continue to fascinate modern day geneticists. This phenomenon, known as heterosis, has been observed in all eukaryotic kingdoms, namely plants, animals, and fungi. Hybrids between related species or strains often display traits that are superior to their parents, in particular in relation to growth vigor. We propose that heterosis results from incompatibilities that perturb regulatory mechanisms, which evolved to protect cells against damage or prepare them for future challenges by limiting cell growth. Our results define a budding yeast hybrid that is perturbed in multiple regulatory processes but still shows a clear growth heterosis. These growth-affecting alleles were condition-dependent, and differed greatly from alleles that reduced the growth of the S. cerevisiae alleles whose deletion reduced growth of the hybrid. A systematic genetic screen identified hundreds of S. Phenotypically, the hybrid progresses more rapidly through cell cycle checkpoints, relieves the repression of respiration in fast growing conditions, does not slow down its growth when presented with ethanol stress, and shows increased signs of DNA damage. We describe a budding yeast hybrid that grows faster than both its parents under different environments. Still, only fragmented knowledge is available on genes and processes contributing to heterosis. In this view, the superior performance of the hybrid is attributed to heterozygote combinations that compensate for deleterious mutations accumulating in each individual genome, or lead to new, over-dominating interactions with improved performance. Heterosis is typically viewed as the opposite of hybrid incompatibility. The merging of genomes in inter-specific hybrids can result in novel phenotypes, including increased growth rate and biomass yield, a phenomenon known as heterosis.
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