Plant Breeding & Genetics PSS 1411 Amber Bates Why Breed Plants? Higher yields Greater vigor Alter plant growth habits Improve pest resistance Increase stress tolerance Improve flower color, shape, and size Improve foliar characteristics Increased nutritional value Better Flavor Two Types of Breeding Conventional ? sexual propagation to transfer genes into a new individual Nonconventional- physically incorporate into the genetic system of another plant Phenotype = genotype + environment Phenotype ? physical characteristic (trait) Genotype ? genes Father of Modern Genetics Gregor Mendel (1822-1884) Garden Peas Traits he studied were only controlled by one gene Heritability Fundamental unit of heredity is a gene Alternate forms of a gene are alleles Homozygous Heterozygous Tt Tt Tt Tt F1 hybrid F2 Tt Tt Tt Tt Plant Breeding Inheritance Quantitative Inheritance ? more than one gene responsible for trait Qualitative ? only one gene Dominance Recessive Complete dominance RR x rr = red Incomplete dominance RR x rr = pink Codominance RR x rr = red with white spots Breeding Programs Must be familiar with organism Must have variety Must be able to make decisions Organization design Planning and control Team behavior Steps in a Breeding Program Objectives Germplasm Selection Evaluation Certification and cultivar release Heterosis vs. Inbreeding Hybrid vigor Why is that important? F1 seeds are more expensive because of production techniques Inbreeding Not prefered Inbreeding depression Seedless Fruit Have crosses that result in female sterility Often done by crossing plants with different chromosome numbers Sometimes makes male sterility as well Asexually Propagated Plant Breeding Induce artificial mutations Biotechnology
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