The Mendelian Theory of Heredity and the Augmentation of Vigor

Bruce, Alexander Balmain

doi:10.1126/science.32.827.627-a

Cited by 331 publications

(196 citation statements)

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“…The greater phenotypic variation and lower fungal burden observed in the F1 progeny in comparison to the resistant CBA/J parental strain was not entirely unexpected, as heterosis is commonly seen upon crossing phenotypically divergent inbred strains and is most likely due to the absence of deleterious recessive homozygous genotypes. 43 Infection of a large CBAB6F2 population revealed a sex difference in pulmonary fungal burden that was not observed in the parental strains, with male CBAB6F2 having a lower mean CFU/ lung and a distinct phenotypic distribution compared to female CBAB6F2. Various experimental models of infection are influenced by the sex of the host.…”

Section: Discussionmentioning

confidence: 97%

Sex differences in the genetic architecture of susceptibility to Cryptococcus neoformans pulmonary infection

et al. 2008

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Cryptococcus neoformans is a major cause of fungal pneumonia, meningitis and disseminated disease in the immune compromised host. Here we have used a clinically relevant model to investigate the genetic determinants of susceptibility to progressive cryptococcal pneumonia in C57BL/6J and CBA/J inbred mice. At 5 weeks after infection, the lung fungal burden was over 1000-fold higher in C57BL/6J compared to CBA/J mice. A genome-wide scan performed on 210 male and 203 female (CBA/J Â C57BL/6J) F2 progeny using lung colony-forming units as a quantitative trait revealed a sex difference in genetic architecture with three loci (designated Cnes1-Cnes3) associated with susceptibility to cryptococcal pneumonia. Single locus analysis identified significant loci on chromosomes 3 (Cnes1) and 17 (Cnes2) with logarithm of the odds (LOD) scores of 4.09 (P ¼ 0.0110) and 7.30 (Po0.0001) that explained 8.9 and 15.9% of the phenotypic variance, respectively, in female CBAB6F2 and one significant locus on chromosome 17 (Cnes3) with a LOD score of 4.04 (P ¼ 0.010) that explained 8.6% of the phenotypic variance in male CBAB6F2 mice. Genome-wide pair-wise analysis revealed significant quantitative trait locus interactions in both the female and male CBAB6F2 progeny that collectively explained 43.8 and 19.5% of phenotypic variance in each sex, respectively.

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Section: Discussionmentioning

confidence: 97%

Sex differences in the genetic architecture of susceptibility to Cryptococcus neoformans pulmonary infection

et al. 2008

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“…The accumulation of reciprocal complementation over multiple loci yields a heterozygous hybrid with an overall larger number of favorable dominant alleles for more genes than in either of its parents, thereby outperforming them (Bruce, 1910). The only requirement of this model is a sufficient number of loci, each with some degree of dominance, which when additively summed can account for the heterosis.…”

Section: Introductionmentioning

confidence: 99%

“…As heterosis is conditioned by dominant effects, it is expected to be seen more often with fitness-related traits than with traits that respond well to selection (Semel et al, 2006). Despite the importance of this phenomenon for agriculture and research on the subject that dates back more than 100 years (Darwin, 1876;Bruce, 1910;Jones, 1917), our understanding of the genetic basis for the manifestation of heterosis is still incomplete (Lippman and Zamir, 2007;Charlesworth and Willis, 2009;Baranwal et al, 2012;Schnable and Springer, 2013).…”

Section: Introductionmentioning

confidence: 99%

Extensive heterosis in growth of yeast hybrids is explained by a combination of genetic models

et al. 2014

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Heterosis, also known as hybrid vigor, is the superior performance of a heterozygous hybrid relative to its homozygous parents. Despite the scientific curiosity of this phenotypic phenomenon and its significance for food production in agriculture, its genetic basis is insufficiently understood. Studying heterosis in yeast can potentially yield insights into its genetic basis, can allow one to test the different hypotheses that have been proposed to explain the phenomenon and allows better understanding of how to take advantage of this phenomenon to enhance food production. We therefore crossed 16 parental yeast strains to form 120 yeast hybrids, and measured their growth rates under five environmental conditions. A considerable amount of dominant genetic variation was found in growth performance, and heterosis was measured in 35% of the hybrid-condition combinations. Despite previous reports of correlations between heterosis and measures of sequence divergence between parents, we detected no such relationship. We used several analyses to examine which genetic model might explain heterosis. We found that dominance complementation of recessive alleles, overdominant interactions within loci and epistatic interactions among loci each contribute to heterosis. We concluded that in yeast heterosis is a complex phenotype created by the combined contribution of different genetic interactions.

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“…Two popular hypotheses, namely, dominance and overdominance, have stimulated interesting debates as to whether heterosis is caused by dominant complementation of slightly deleterious recessive alleles (Bruce, 1910;Jones, 1917;Xiao et al, 1995;Cockerham and Zeng, 1996) or by overdominant gene action in which genes have greater expression when they are heterozygous (Shull, 1908;East, 1936;Crow, 1948;Stuber et al, 1992;Mitchell-Olds, 1995). According to the former, highest performance should follow the maximum accumulation of dominant favorable genes from both parents in homozygous conditions.…”

Section: Introductionmentioning

confidence: 99%

Molecular marker genotypes, heterozygosity and genetic interactions explain heterosis in Arabidopsis thaliana

Syed

Chen

2004

Heredity

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The underlying mechanisms for hybrid vigor or heterosis are elusive. Here we report a population of recombinant inbred lines (RILs), derived from the two ecotypes, Col and Ler, which can serve as a permanent resource for studying the molecular basis of hybrid vigor in Arabidopsis. Using a North Carolina mating design III (NCIII), we determined the additive and dominant nature of gene action in this population. We detected heterosis among crosses of RILs with one of the two parents (Col and Ler) and analyzed genotypes and heterozygosities for RILs and test cross families (RILs crossed to Col and Ler) using a total of 446 published molecular markers. The performance of RILs and additive and dominant components in the test cross families were used to analyze QTLs for 16 traits, using QTL cartographer and composite interval mapping with 1,000 permutations for each trait. Our data suggest that locus-specific and/or genome-wide differential heterozygosity, including epistasis, plays an important role in the generation of the observed heterosis. Furthermore, the hybrid vigor occurred between two closely related ecotypes, and provides a general mechanism for novel variation generated between genetically similar materials. Heredity (2005) 94, 295-304.

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The Mendelian Theory of Heredity and the Augmentation of Vigor

Cited by 331 publications

References 0 publications

Sex differences in the genetic architecture of susceptibility to Cryptococcus neoformans pulmonary infection

Sex differences in the genetic architecture of susceptibility to Cryptococcus neoformans pulmonary infection

Extensive heterosis in growth of yeast hybrids is explained by a combination of genetic models

Molecular marker genotypes, heterozygosity and genetic interactions explain heterosis in Arabidopsis thaliana

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