Heterosis in plants. Heterosis Meaning, Genetic Basis, and Effect in Animals 2022-10-04
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Heterosis, also known as hybrid vigor, refers to the improved performance of a hybrid organism compared to its parent species. In plants, this can manifest as increased growth, larger fruit size, increased disease resistance, and improved stress tolerance. Heterosis is a valuable trait in agriculture, as it allows for the production of crops with higher yields and improved quality.
The phenomenon of heterosis is thought to be caused by the masking of negative recessive traits in the hybrid offspring. In many cases, a hybrid plant will inherit one dominant and one recessive trait from each parent. If the dominant trait is beneficial, it will be expressed in the hybrid, while the recessive trait will be masked and not expressed. This can lead to an overall improvement in the plant's traits, as the negative recessive traits are not present.
There are several ways in which heterosis can be utilized in plant breeding. One common method is through the use of inbred lines, which are plants that have been carefully bred over several generations to be genetically similar. When two inbred lines are crossed, the resulting hybrid offspring will often exhibit heterosis. This is because the inbreeding process leads to an accumulation of recessive traits, which are then masked in the hybrid offspring.
Another way to utilize heterosis is through the use of hybrid seeds. These seeds are produced by crossing two distinct parent plants, and the resulting hybrid offspring is often more vigorous and productive than either parent. Hybrid seeds are widely used in commercial agriculture, as they can lead to higher crop yields and improved quality.
While heterosis can provide many benefits in plant breeding, it is important to note that it is not always a reliable trait. In some cases, hybrid offspring may not exhibit heterosis, or may even exhibit inferior traits compared to their parent species. This is because the expression of traits in plants is often complex and influenced by many factors, including the environment and the specific genetic makeup of the plant.
Overall, heterosis is a valuable trait in plant breeding that can lead to improved growth, increased disease resistance, and higher crop yields. By utilizing techniques such as inbred lines and hybrid seeds, plant breeders can take advantage of this phenomenon to produce crops with improved characteristics.
Heterosis
A similar concept proposed by Stephen Goff suggests that hybrids achieve greater cellular energy efficiency by selectively regulating transcription and translation of the more stable, energy-efficient alleles in hybrids. Seedling emergence was faster in the hybrid and potence ratios indicated dominance for increased leaf number, area and mass, and stem mass. High grain weight, etc. Hybrid vigour and growth rates in a maize cross and its reciprocal. All possible modes of gene action are observed in a global comparison of gene expression in a maize F1 hybrid and its inbred parents. For further crop improvement, understanding the extent and pattern of variability, particularly genetic variability, present in a population of a given crop is critical.
Heterosis Meaning, Genetic Basis, and Effect in Animals
In simplest terms, this hypothesis suggests that at each locus the dominant allele has a favourable effect, while the recessive allele has an unfavourable effect. Exploitation of hybrid vigour in the improvement of crop plants,fruits and vegetables. The impacts of general combining ability GCA and Specialized Combining Ability SCA are highly useful genetic parameters for determining the next phase of breeding projects. Traditionally, homozygous lines are generated by multiple more than seven cycles of self-pollination to obtain homozygosity in almost all genes. Genetic diversity and heterosis. The term heterosis was first used by Shull in 1914. Genet Mol Biol25: 179-183.
After the leaves were detached, W. The biometric measurements included cob length, cob diameter, core length, core diameter, number of rows of grain, number of grains in a row, mass of grain from the cob, weight of one thousand grains, and yield. Cis-transcriptional variation in maize inbred lines B73 and Mo17 leads to additive expression patterns in the F1 hybrid. Differential gene expression in egg cells and zygotes suggests that the transcriptome is restructed before the first zygotic division in tobacco. Heterosis refers to improved or altered performance observed in F1 hybrid organisms when compared to their parents. The results show that the cytosine methylation level in the maintainer line was lower than in the CMS lines.
Earliness is highly desirable in many cases, particularly in vegetables. For instance, in some species highly homozygous, modern inbred lines perform better than highly heterozygous hybrids developed some decades ago. After germination, seedling root traits including lateral root density, primary root length or seminal root number display differences as early as a few days after germination Heterosis is observed for A seedling root traits, such as lateral-root density, primary-root length and seminal-root number, B plant height and C cob size of the F1-hybrid offspring center in comparison to both parental inbred lines left and right. This theory is called by various names such as stimulation of heterozygosis, cumulative action of divergent alleles, single gene heterosis, super-dominance and over-dominance. By 1930, breeders successfully introduced the first commercial hybrid varieties in the United States, and by the early 1940s, every commercial operator in the country was planting hybrid maize. The ANGUSTIFOLIA gene of Arabidopsis, a plant CtBP gene, regulates leaf-cell expansion, the arrangement of cortical microtubules in leaf cells and expression of a gene involved in cell-wall formation.
J Genet 4: 83. In this direction, estimating heterosis for yield-related traits could well be useful for examining the most beneficial hybrid mix with the exploitation of top-quality hybrid. Once one goes beyond first generation purebred to purebred, you lose the heterosis effect, which is the goal for most hybrid breeders. The relationship of heterosis and genetic divergence in maize. In the case of Hybridization might promote offspring fitness via a greater tolerance to environmental stressors due to heterosis and higher levels of phenotypic plasticity.
Combining ability and heterosis in plant improvement
In: Coors J G, Pandey S, eds. Genetic Basis of Heterosis : There are two main theories to explain the genetic cause of heterosis. In: Gowen JW ed Heterosis. The degree of inbreeding is measured by the inbreeding coefficient. There are number of findings that support potential links between epigenetic regulation and heterosis in model and crop plants, including the potential for DNA methylation, histone modification, and small RNAs to influence heterotic effects in F1 hybrids.
Heterosis in plants: Manifestation in early seed development and prediction approaches to assist hybrid breeding
It is well established that the incidence and magnitude of heterosis has positive association with the presence and magnitude of non-allelic interaction. An explanation for this, one that is not necessarily in conflict with the dominance model, is that linkage of loci representing deleterious and beneficial alleles might substantially hamper the enrichment of favorable alleles. The commercial value of a hybrid would be determined mostly by how well it performed in relation to the best commercial variety of the crop species in question. Some evidence on type of gene action involved in yield heterosis in maize. In addition to the absence of inbreeding depressing, present in inbreed and purebred dogs in general, there is some remote inbreeding in any breed. . The overdominance model attributes the superiority of hybrids to heterozygosity itself and hence allelic interactions at multiple loci.
ADVERTISEMENTS: A Dominance Hypothesis : This hypothesis was proposed by Davenport and further expanded by others. The following factors are important in the commercial exploitation of heterosis: 1. Molecular Level: ADVERTISEMENTS: Heterosis is manifested in increased rate of DNA reduplication, transcription and translation influencing the formation of genetic information, enzymatic activity, other regulatory mechanisms and also hybrid protein molecule formation. Agron J 44: 462-466. Perspectives: 90 years ago: the beginning of hybrid maize. Expression profile comparisons between inbred lines and hybrids revealed complex transcriptional networks specific for different developmental stages and tissues mainly in maize Zea mays , rice Oryza sativa and Arabidopsis Arabidopsis thaliana. In: Lamkey K R, Staub J E, eds.
