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Chromosome techniques: Theory and practice

About: The article was published on 1965-01-01 and is currently open access. It has received 423 citations till now.
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Journal ArticleDOI
TL;DR: It is demonstrated that speed breeding in fully enclosed, controlled-environment growth chambers can accelerate plant development for research purposes, including phenotyping of adult plant traits, mutant studies and transformation.
Abstract: The growing human population and a changing environment have raised significant concern for global food security, with the current improvement rate of several important crops inadequate to meet future demand1. This slow improvement rate is attributed partly to the long generation times of crop plants. Here, we present a method called ‘speed breeding’, which greatly shortens generation time and accelerates breeding and research programmes. Speed breeding can be used to achieve up to 6 generations per year for spring wheat (Triticum aestivum), durum wheat (T. durum), barley (Hordeum vulgare), chickpea (Cicer arietinum) and pea (Pisum sativum), and 4 generations for canola (Brassica napus), instead of 2–3 under normal glasshouse conditions. We demonstrate that speed breeding in fully enclosed, controlled-environment growth chambers can accelerate plant development for research purposes, including phenotyping of adult plant traits, mutant studies and transformation. The use of supplemental lighting in a glasshouse environment allows rapid generation cycling through single seed descent (SSD) and potential for adaptation to larger-scale crop improvement programs. Cost saving through light-emitting diode (LED) supplemental lighting is also outlined. We envisage great potential for integrating speed breeding with other modern crop breeding technologies, including high-throughput genotyping, genome editing and genomic selection, accelerating the rate of crop improvement.

639 citations


Cites methods from "Chromosome techniques: Theory and p..."

  • ...The two remaining anthers were stained following the Feulgen procedure [31]....

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Journal ArticleDOI
TL;DR: The study confirms the genotoxic potential of TiO(2) nanoparticles in both plant and human lymphocytes.

397 citations


Cites methods from "Chromosome techniques: Theory and p..."

  • ...Slides were prepared from each of the root meristem following the squash technique of Sharma and Sharma (1980), and coded to prevent observer bias....

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Journal ArticleDOI
TL;DR: Computer software is developed that generates and manipulates graphical genotypes, a concept that should be useful in whole genome selection for polygenic traits in plant and animal breeding programs and in the diagnosis of heterogenously based genetic diseases in humans.
Abstract: With the advent of high density restriction fragment length polymorphism (RFLP) maps, it has become possible to determine the genotype of an individual at many genetic loci simultaneously. Often, such RFLP data are expressed as long strings of numbers or letters indicating the genotype for each locus analyzed. In this form, RFLP data can be difficult to interpret or utilize without complex statistical analysis. By contrast, numerical genotype data can also be expressed in a more useful, graphical form, known as a “graphical genotype”, which is described in detail in this paper. Ideally, a graphical genotype portrays the parental origin and allelic composition throughout the entire genome, yet is simple to comprehend and utilize. In order to demonstrate the usefulness of this concept, graphical genotypes for individuals from backcross and F2 populations in tomato are described. The concept can also be utilized in more complex mating schemes involving two or more parents. A model that predicts the accuracy of graphical genotypes is presented for hypothetical RFLP maps of varying marker spacing. This model indicates that graphical genotypes can be more than 99% correct in describing a genome of total size, 1000 cM, with RFLP markers located every 10 cM. In order to facilitate the application of graphical genotypes to genetics and breeding, we have developed computer software that generates and manipulates graphical genotypes. The concept of graphical genotypes should be useful in whole genome selection for polygenic traits in plant and animal breeding programs and in the diagnosis of heterogenously based genetic diseases in humans.

321 citations


Cites background from "Chromosome techniques: Theory and p..."

  • ...In addition to showing the relative sizes and shapes of chromosomes, karyotypes can frequently be used to indicate the presence of inversion, translocation, or aneuploidy in a genome (Sharma and Sharma 1980)....

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Journal ArticleDOI
TL;DR: Somatic polyembryogenesis was evoked in cells from an embryonal–suspensor mass whose nuclei were color–coded by a double–staining method for estimates of yield based on the initial properties of embryogenic and nonembryogenic cell masses.
Abstract: Plantlets of loblolly pine were regenerated and converted to soil by somatic polyembryogenesis (SPE). SPE was evoked in cells from an embryonal–suspensor mass whose nuclei were color–coded by a double–staining method. Color–coding with cell suspension cultures distinguished a free–nuclear stage, initial physiological states and the ultimate fate of each cell for estimates of yield based on the initial properties of embryogenic and nonembryogenic cell masses. Somatic embryos were encapsulated and stored in an alginate gel or in liquid nitrogen.

308 citations

Journal ArticleDOI
TL;DR: It is suggested that the probability of gene flow from transgenic B. napus to R. raphanistrum to S. arvensis or E. gallicum is very low (<2–5 × 10–5) and transgenes can disperse in the environment via wild B. rapa in eastern Canada and possibly via commercial B.Rapa volunteers in western Canada.
Abstract: The frequency of gene flow from Brassica napus L. (canola) to four wild relatives, Brassica rapa L., Raphanus raphanistrum L., Sinapis arvensis L. and Erucastrum gallicum (Willd.) O.E. Schulz, was assessed in greenhouse and/or field experiments, and actual rates measured in commercial fields in Canada. Various marker systems were used to detect hybrid individuals: herbicide resistance traits (HR), green fluorescent protein marker (GFP), species-specific amplified fragment length polymorphisms (AFLPs) and ploidy level. Hybridization between B. rapa and B. napus occurred in two field experiments (frequency approximately 7%) and in wild populations in commercial fields (approximately 13.6%). The higher frequency in commercial fields was most likely due to greater distance between B. rapa plants. All F1 hybrids were morphologically similar to B. rapa, had B. napus- and B. rapa-specific AFLP markers and were triploid (AAC, 2n = 29 chromosomes). They had reduced pollen viability (about 55%) and segregated for both self-incompatible and self-compatible individuals (the latter being a B. napus trait). In contrast, gene flow between R. raphanistrum and B. napus was very rare. A single R. raphanistrum × B. napus F1 hybrid was detected in 32,821 seedlings from the HR B. napus field experiment. The hybrid was morphologically similar to R. raphanistrum except for the presence of valves, a B. napus trait, in the distorted seed pods. It had a genomic structure consistent with the fusion of an unreduced gamete of R. raphanistrum and a reduced gamete of B. napus (RrRrAC, 2n = 37), both B. napus- and R. raphanistrum-specific AFLP markers, and had <1% pollen viability. No hybrids were detected in the greenhouse experiments (1,534 seedlings), the GFP field experiment (4,059 seedlings) or in commercial fields in Quebec and Alberta (22,114 seedlings). No S. arvensis or E. gallicum × B. napus hybrids were detected (42,828 and 21,841 seedlings, respectively) from commercial fields in Saskatchewan. These findings suggest that the probability of gene flow from transgenic B. napus to R. raphanistrum, S. arvensis or E. gallicum is very low (<2–5 × 10–5). However, transgenes can disperse in the environment via wild B. rapa in eastern Canada and possibly via commercial B. rapa volunteers in western Canada.

266 citations