Multiplicative vs. arbitrary gene action in heterosis.

Schnell, F. W.; Cockerham, C. Clark

doi:10.1093/genetics/131.2.461

Cited by 114 publications

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“…Epistatic interactions hypothesis emphasizes the favorable alleles in the role of heterosis gain. For any site, the effect can be produced by additive dominant or over-dominance ( Minvielle, 1987 ; Schnell and Cockerham, 1992 ; Frascaroli et al, 2007 ). It should be noted that heterosis in self-pollinated species (e.g., rice) may involve different genetic interactions from heterosis in cross-pollinated species (e.g., maize), so both dominant and epistatic hypotheses may be related ( Garcia et al, 2008 ).…”

Section: Introductionmentioning

confidence: 99%

Transcriptome Reveals Allele Contribution to Heterosis in Maize

Sun

Zhao³

et al. 2021

Front. Plant Sci.

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Heterosis, which has greatly increased maize yields, is associated with gene expression patterns during key developmental stages that enhance hybrid phenotypes relative to parental phenotypes. Before heterosis can be more effectively used for crop improvement, hybrid maize developmental gene expression patterns must be better understood. Here, six maize hybrids, including the popular hybrid Zhengdan958 (ZC) from China, were studied. Maize hybrids created in-house were generated using an incomplete diallel cross (NCII)-based strategy from four elite inbred parental lines. Differential gene expression (DEG) profiles corresponding to three developmental stages revealed that hybrid partial expression patterns exhibited complementarity of expression of certain parental genes, with parental allelic expression patterns varying both qualitatively and quantitatively in hybrids. Single-parent expression (SPE) and parent-specific expression (PSE) types of qualitative variation were most prevalent, 43.73 and 41.07% of variation, respectively. Meanwhile, negative super-dominance (NSD) and positive super-dominance (PSD) types of quantitative variation were most prevalent, 31.06 and 24.30% of variation, respectively. During the early reproductive growth stage, the gene expression pattern differed markedly from other developmental stage patterns, with allelic expression patterns during seed development skewed toward low-value parental alleles in hybrid seeds exhibiting significant quantitative variation-associated superiority. Comparisons of qualitative gene expression variation rates between ZC and other hybrids revealed proportions of SPE-DEGs (41.36%) in ZC seed DEGs that significantly exceeded the average proportion of SPE-DEGs found in seeds of other hybrids (28.36%). Importantly, quantitative gene expression variation rate comparisons between ZC and hybrids, except for transgressive expression, revealed that the ZC rate exceeded the average rate for other hybrids, highlighting the importance of partial gene expression in heterosis. Moreover, enriched ZC DEGs exhibiting distinct tissue-specific expression patterns belonged to four biological pathways, including photosynthesis, plant hormone signal transduction, biology metabolism and biosynthesis. These results provide valuable technical insights for creating hybrids exhibiting strong heterosis.

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Section: Introductionmentioning

confidence: 99%

Transcriptome Reveals Allele Contribution to Heterosis in Maize

Sun

Zhao³

et al. 2021

Front. Plant Sci.

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“…Four hypotheses were proposed to explain this; the dominance hypothesis which postulates that the increase in vigor after crossing results from the combination of different dominant alleles contributed by each parent [1]. The heterozygosis hypothesis attributes the increase in vigor to the existence of loci at which the heterozygous state is superior to either homozygotes [2,3]; the pseudo-overdominance hypothesis that attributes the hybrid vigor to the effect of tightly linked genes with favorable dominant alleles in repulsion phase in the parental lines resulting in an apparent overdominance when combined in the hybrid [4]and epistasis hypothesis which explains the increased vigor in the light of the interaction of favorable alleles from two parents at different loci that show additive, dominant and/or overdominant action [5]. Among these hypotheses, heterozygosis gained prominence.…”

Section: Introductionmentioning

confidence: 99%

Heterosis and Heterotic Grouping among Tropical Maize Germplasm

Akinwale¹

2021

Cereal Grains - Volume 2

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Maize (Zea mays L.) is the most important staple cereal cultivated in sub-Saharan Africa but its productivity is considerable low due to several factors. Development and deployment of maize hybrids have been reported as one of the crucial options in achieving sustainable maize production in sub-Saharan Africa. Information on the heterotic response among available genetic materials in a breeding program is valuable before commencement of any hybrid development program. Unlike the temperate germplasm, maize tropical germplasm is characterized with wide genetic base and genetic complexities and thus, proper organization of the pools, populations, varieties and inbreds that can serve as parental materials for hybrid development through identification of a distinct heterotic groups and patterns among tropical germplasm becomes very essential. This paper reviewed past research efforts at characterizing heterotic response among tropical maize genetic materials with a view to point out merits and demerits in the methods used and future direction towards achieving sustainable hybrid cultivation and enhancing food security in the sub-region.

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“…Few previous theoretical studies prove the contribution of epistasis for heterosis. Assuming combined multiplicative action of two additive genes, Minvielle (1987) and Schnell and Cockerham (1992) concluded that dominance is not necessary for heterosis. Additionally, Schnell and Cockerham (1992) showed that the multiplicative action of more genes increase the contribution of dominance, but not epistasis, to heterosis.…”

Section: Introductionmentioning

confidence: 99%

“…Assuming combined multiplicative action of two additive genes, Minvielle (1987) and Schnell and Cockerham (1992) concluded that dominance is not necessary for heterosis. Additionally, Schnell and Cockerham (1992) showed that the multiplicative action of more genes increase the contribution of dominance, but not epistasis, to heterosis. Cockerham and Zeng (1996) and Garcia et al (2008) modelled epistatic linked QTLs.…”

Section: Introductionmentioning

confidence: 99%

The impact of epistasis in the heterosis and combining ability analyses

Viana

2021

Preprint

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The current theoretical knowledge concerning the influence of epistasis on heterosis is based on simplified multiplicative model. The objective of this study was to assess the impact of epistasis in the heterosis and combining ability analyses, assuming additive model, hundreds of genes, linkage disequilibrium (LD), dominance, and seven types of digenic epistasis. We developed the quantitative genetics theory for supporting the simulation of the individual genotypic values in nine populations, the selfed populations, the 36 interpopulation crosses, 180 doubled haploids (DHs) and their 16,110 crosses, assuming 400 genes in 10 chromosomes of 200 cM. Epistasis only affects population heterosis if there is LD. Only additive x additive and dominance x dominance epistasis can affect the components of the heterosis and combining ability analyses of populations. Both analyses can lead to completely wrong inferences regarding the identification of the superior populations, the populations with greater differences of gene frequencies, and the populations with maximum variability, when the number of interacting genes and the magnitude of the epistatic effects are high. There was a decrease in the average heterosis by increasing the number of epistatic genes and the magnitude of their epistatic effects. The same results are generally true for the combining ability analysis of DHs. Surprisingly, the combining ability analyses of subsets of 20 DHs showed no significant average impact of epistasis on the identification of the most divergent ones, even assuming a high number of epistatic genes and great magnitude of their effects. However, a significant negative effect can occur.Statements and DeclarationsThe author has no relevant financial or non-financial interests to disclose. The author has no competing interests to declare that are relevant to the content of this article. The author certifies that he has no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. The author has no financial or proprietary interests in any material discussed in this article.

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Multiplicative vs. arbitrary gene action in heterosis.

Cited by 114 publications

References 0 publications

Transcriptome Reveals Allele Contribution to Heterosis in Maize

Transcriptome Reveals Allele Contribution to Heterosis in Maize

Heterosis and Heterotic Grouping among Tropical Maize Germplasm

The impact of epistasis in the heterosis and combining ability analyses

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