Breeding & Genetics

Overview

Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular techniques.

Plant breeding started with sedentary agriculture and particularly the domestication of the first agricultural plants, a practice which is estimated to date back 9,000 to 11,000 years. Initially early farmers simply selected food plants with particular desirable characteristics, and employed these as progenitors for subsequent generations, resulting in an accumulation of valuable traits over time. Gregor Mendel's experiments with plant hybridization led to his establishing laws of inheritance. Once this work became well known, it formed the basis of the new science of genetics, which stimulated research by many plant scientists dedicated to improving crop production through plant breeding. Modern plant breeding is applied genetics, but its scientific basis is broader, covering molecular biology, cytology, systematics, physiology, pathology, entomology, chemistry, and statistics (biometrics).

Classical Breeding

Classical plant breeding uses deliberate interbreeding (crossing) of closely or distantly related individuals to produce new crop varieties or lines with desirable properties. Plants are crossbred to introduce traits/genes from one variety or line into a new genetic background. For example, a mildew-resistant pea may be crossed with a high-yielding but susceptible pea, the goal of the cross being to introduce mildew resistance without losing the high-yield characteristics. Progeny from the cross would then be crossed with the high-yielding parent to ensure that the progeny were most like the high-yielding parent, (backcrossing). The progeny from that cross would then be tested for yield and mildew resistance and high-yielding resistant plants would be further developed. Plants may also be crossed with themselves to produce inbred varieties for breeding. Classical breeding relies largely on homologous recombination between chromosomes to generate genetic diversity. The classical plant breeder may also make use of a number of in vitro techniques such as protoplast fusion, embryo rescue or mutagenesis (see below) to generate diversity and produce hybrid plants that would not exist in nature.

Traits that breeders have tried to incorporate into crop plants in the last 100 years include:

  • Increased quality and yield of the crop
  • Increased tolerance of environmental pressures (salinity, extreme temperature, drought)
  • Resistance to viruses, fungi and bacteria
  • Increased tolerance to insect pests
  • Increased tolerance of herbicides
Projects
2009
Development of cultivars with improved nutritional profile and agronomic characters are among the major objectives in field pea breeding at the Crop Development Centre (CDC).In this project, 169 pea accessions of the cultivated pea Pisum sativum, wild relative species P. fulvum and several wild sub-species accessions (subspp. abyssinicum, arvense, and elatius) collected from eastern Europe, Russia and Canada were screened for their nutritional profile including total starch, amylose, amylopectin, fiber and protein by wet chemistry and/or near infrared (NIR) methods, and for reaction to ascochyta blight under controlled and/or field conditions.
2009
Lentil is an economically important pulse crop for Canada produced mainly for the export market. In conventional breeding programs, several segregating generations must be grown in order to reach a certain level of homozygosity that allows the selection of traits of interest. In contrast, double-haploid (DH) technology produces instant homozygosity and thus can significantly reduce the time required for developing new varieties. The efficiency of the lentil breeding program will also be improved through the reduction in the population size required for screening.
2009
The project has three phases: In the first phase, chickpea genotypes were evaluated in the growth chambers for their flowering response under both long (16 h) and short days (10 h) and 22 0C and 16 0C day and night temperatures. Variability among the genotypes in their flowering response under either long or short days was identified. In the second phase of the study eight selected chickpea genotypes with extreme responses to photoperiod will be evaluated to determine the timing and duration of the photoperiod sensitive phase and the time of floral initiation and to establish whether photoperiod sensitivity ends at floral initiation or if it extends further into the phases of flower development. These same eight genotypes will be further characterized in a factorial combination of two photoperiods: 10 h and 16 h and three temperatures regimes: 16/8 0C, 20/12 0C and 24/16 0C (day/night). This study allows us to determine flowering response of chickpea genotypes grown in a range of thermal regimes combined with either long or short days. In the third phase of the study, chickpea RILs derived from a cross between ICCV 96029 and CDC Frontier and their parents will be used for mapping genes for early flowering, photoperiod insensitivity and reaction to ascochyta blight.
2009
Approximately 60-80% of total phosphorus is stored in crop seeds as phytate. Phytate is not readily available to humans and non-ruminant livestock because of their lack of phytase enzyme. The low-phytate lines had similar seedling emergence counts, vine length, lodging score, and mycosphaerella blight score when compared with CDC Bronco. The low-phytate lines had somewhat later days to flowering and days to maturity, and somewhat lower grain yield and seed weight than CDC Bronco. Harvested seeds of the low-phytate lines had substantially higher inorganic phosphorus (1.21-1.28 mg/g) concentration than CDC Bronco (0.24-0.25 mg/g) and the other normal-phytate cultivars.
2009
Double haploids are plants developed from either a male or female gamete, n=1 cell, and therefore are completely homozygous at all loci. Because all traits are visible within one generation, this methodology adds speed and efficiency to breeding programs. The goal of our research is to improve all aspects of the field pea anther culture protocol including: increasing the number of immature pollen grains initiated to become embryogenic, improving the regeneration of haploid embryos, and regenerating plants from those embryos.
2009
Ninety-six Lentil Association mapping panel (LAM) lines were run on the Lc1536 Lentil Illumina Golden Gate assay.
2009
Ninety-six Lentil Association mapping panel (LAM) lines were run on the Lc1536 Lentil Illumina Golden Gate assay.
2009
Ninety-six Lentil Association mapping panel (LAM) lines were run on the Lc1536 Lentil Illumina Golden Gate assay.
2009
Ninety-six USDA lines were run on the Lc1536 Lentil Illumina Golden Gate assay.
2009
Ninety-six USDA lines were run on the Lc1536 Lentil Illumina Golden Gate assay.

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