The Reproductive Systems of Davidson’s Plum (Davidsonia jerseyana, Davidsonia pruriens and Davidsonia johnsonii) and the Potential for Domestication
Yasmina Sultanbawa, Fazal Sultanbawa in Australian Native Plants, 2017
Hybridisation has long been recognised as an important component of plant domestication (Stebbins, 1950) and is extremely valuable in crop plants, because it can provide novel genotypes and hybrid vigour. Hybrid vigour, or heterosis, describes the situation where the phenotypic performance of hybrid offspring is superior to that of their parents. Cross-pollination experiments could be undertaken to see if hybridisation is possible between Davidsonia species. Advantages could include, for example, producing novel genotypes by increasing heterozygosity in D. jerseyana. However, caution would need to be applied because gene flow from hybrids to their wild relatives is not uncommon in other species (Ellstrand et al., 1999) and therefore, if hybridisation was successful in Davidsonia species, accidental gene flow from hybrids to natural populations could further threaten the endangered species. Fortunately, this is actually unlikely to occur, because the reproductive barriers present between the Davidsonia species are likely to preclude gene flow.
The Impacts of Modern Agriculture on Plant Genetic Diversity
Bill Pritchard, Rodomiro Ortiz, Meera Shekar in Routledge Handbook of Food and Nutrition Security, 2016
The evolution of agriculture in the past century, moving from subsistence farming and traditional practices with low inputs in limited land to intensive agriculture based on specialized mechanization and high chemical inputs, did not happen by chance. Steady population growth put pressure on available food, which has been argued as needing to double in less than 50 years to meet global demands (Tilman et al. 2011). Early deliberate crop improvement was based on a narrow genetic base and selection methods that rendered limited genetic progress: intra-specific diversity was produced through homologous recombination of chromosomes. Around the mid-twentieth century, breeding of a few crops used the hybridization of distantly related species (inter-specific diversity) to broaden genetic diversity. Contemporary developments included the use of cytoplasmic male sterility in inbred lines and the discovery of heterosis for the production of hybrids from selected inbred parents. In the twenty-first century, advanced techniques promise to increase significantly the rate of genetic improvement (Phillips 2010), often widening the use of genetic diversity, at the very least trying to surpass what conventional techniques can give of themselves and at a much higher speed. Related, but conceptually different, developments have also greatly affected genetic diversity in modern agriculture. These are, among others, those referred to further below in the social area, e.g., the role of consumers, and in the legal area, i.e., the protection of cultivars and their components.
The Phase I–II Paradigm
Ying Yuan, Hoang Q. Nguyen, Peter F. Thall in Bayesian Designs for Phase I–II Clinical Trials, 2017
One may consider a phase I–II design to be like a Labradoodle, which is obtained by cross-breeding a Labrador Retriever with a Poodle. Labradoodles enjoy the desirable quality of heterosis, or hybrid vigor, since they have greater genetic diversity and hence better overall health than either of their parents. Hybrid clinical trial designs, if carefully constructed, enjoy similar advantages over the simpler designs that motivated them. The analogy is not strict, however, since both Labradors and Poodles both are fine canine breeds, whereas the most commonly used phase I or phase II clinical trial designs suffer from logical and ethical flaws, as we demonstrated in Chapter 1.
Assessment of natural variability in leaf morphological and physiological traits in maize inbreds and their related hybrids during early vegetative growth
Published in Egyptian Journal of Basic and Applied Sciences, 2019
Farag Ibraheem, Eman M. El-Ghareeb
Maize growth, development, and productivity are shaped by genetic constitution of maize genotypes and their consequences on gene expression. In addition, critical environmental conditions such as soil fertility and climatic changes-related parameters such as alterations in temperature, CO2 emission, rainfalls, and drought stress can significantly affect maize growth and productivity [14]. Previous studies revealed significant differences in many growth- and physiology-related traits among parental maize inbreds and their hybrids. Hybrids usually exhibit better plant growth vigor, physiological adaptation and overall field performance than their parental inbreds and such improved performance of hybrids is attributed to heterosis (hybrid vigor) [15,16]. The impact of heterosis on plant growth and productivity can be equivalent to that of adequate fertilization [17]. The extent of heterosis is greatly influenced by the genetic diversity between their parental inbreds where greater genetic difference induces stronger heterosis [3,18,19]. In maize, heterosis is usually discussed in terms of grain yield. However, other phenotypic traits such as root growth and development, plant height, leaf features, leaf/stem biomass, flowering time and ear height can also exhibit heterosis [20–23].
A semi-parametric Bayesian approach for detection of gene expression heterosis with RNA-seq data
Published in Journal of Applied Statistics, 2023
Ran Bi, Peng Liu
Heterosis, also called hybrid vigor, describes the phenotypic improvement of a hybrid offspring over its two inbred parents. Heterosis was documented by [7] and has been widely utilized in growing agricultural crops, such as rice [30], to increase development rates and grain yields. In China, hybrid rice is estimated to be planted on more than 50% of the rice farmland, and produces 10–20% more than inbred varieties [6]. However, the mechanism of heterosis is not yet well studied [5].
Related Knowledge Centers
- Genetic Drift
- Genetic Variation
- Inbreeding Depression
- Mendelian Inheritance
- Phenotypic Trait
- Zygosity
- Hybrid
- NON-Mendelian Inheritance
- Fitness
- Outbreeding Depression