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
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.
2009
A set of 1107 legume cross species orthologous sequences (COS) were amplified from Lens culinaris (CDC Redberry and Eston) and L. ervoides (L01-827a and IG 72815). Sequences were aligned and SNPs identified. A subset of 110 KASP assays were designed for use in L. culinaris. An Illumina GoldenGate array of 768 SNPs was designed for use in L. ervoides or interspecies hybrid populations between Lc and Le.
2008 to 2009
Mixture of eight cultivars with varying seed phenotypes: Indian Head, Commando, CDC LeMay, CDC Robin, and breeding lines 1899T-50 and 1788-4 (CDC, Univ. Saskatchewan, Saskatoon, Canada) All developmental stages of seeds and very young fertilized pods were harvested from mature plants, and divided into the following lots: very young fertilized ovaries, young ovules, enlarging seeds, cotyledons of fully filled seed, seed coats of fully filled seeds. cDNA library was made from a mixture of equal amounts of mRNA extracted from each of the above tissues.

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