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Chapter 5Chapter 5Seed SelectionSeed Selection
Self-pollination
• Fixed traits (homozygous) = “inbred”
Self-Pollination
Non-inbred
Inbred1x
Inbred2x
Cross-pollination
• Fixed traits (homozygous) = “inbred”
Controlled crosses
Controlled crosses
Controlled crosses
Cross-Pollination& hybrid vigor
B73 B73 x Mo17 Mo17
Cross-Pollination& hybrid vigor
B73 Mo17 B73 x Mo17
Avoiding self-pollination
• Pollen sterility - genetically engineered
CytoplasmicMale Sterility
Avoiding self-pollination
• Pollen sterility - genetically engineered Cytoplasmic Male Sterility
Avoiding self-pollination• Pollen sterility - genetically
engineeredCytoplasmic Male Sterility
Avoiding self-pollination• Pollen sterility - genetically
engineeredCytoplasmic Male Sterility
Sexual incompatibility
Sexual incompatibility
• Often found in the following plant families:– Solanaceae (nightshade family)– Rosaceae (rose family)– Scrophulariaceae (snapdragon family)– Fabaceae (bean family)– Poaceae (grass family)
Sexual incompatibility
• Examples in the rosaceae include:– Apples– Cherries– Plums
Sexual incompatibility
• Pollen prevented from reaching ovule.
• Pollen either does not germinate on the stigma or the pollen tube is prevented from traveling down the transmitting cells in the style
Sexual incompatibility
Normal pollen germination
Germinationprevented
Self-pollinating fruit trees
These include:
– Peaches
– Apricots
– Nectarines
Flower types for cross-pollination
• Dioecy (dioecious plants)– Example: Holly
Flower types for cross-pollination
• Dioecy (dioecious plants)– Example: Holly
Flower types for cross-pollination
• Monoecy (monoecious plants)– Example: Corn
Flower types for cross-pollination
• Dichogamy (monoecious plant flowering at different times)– Example: Squash
Male flower appears a few days earlier than female flower
Flower reproductive parts can be located away from each other
Ecotype
• A plant that has evolved in relation to its surrounding habitat
• Ex. Pseudotsuga menziesii– Coastal douglas fir– Rocky Mountain Douglas fir
Coastal Douglas fir
Rocky Mountain Douglas fir
Cline• A continuous variation in a species
• Ex. Acer rubrum (red maple)
Provenance
The geographic area
where a plant is
native to.
Controlling Genetic Variability
• Isolation
• Roguing
• Pure Stands
Controlling Genetic Variability
• Isolation
• Roguing
• Pure Stands
Controlling Genetic Variability
• Isolation
• Roguing
• Pure Stands
