Basal angiosperms, and plant breeding systems Angiosperm phylogeny Soltis et al., 2011 Ranunculaceae' Monocots' Magnoliids' ANITA'grade'
Basal angiosperms Angiosperm phylogeny A N A ANITA grade Amborella Nymphaeaceae Illicium Trimenia Austrobaileya 1 cotyledon tricolpate pollen Nymphaeaceae 8 genera, 70 species (Nymphaea) http://botany.csdl.tamu.edu/flora/tfplab/lilyp.gif Nymphaea spp. Victoria sp., Amazon water lily
Nymphaeaceae 8 genera, 70 species (Nymphaea) Habit: Aquatic Stems: Air canals Leaves: Long petioles, submerged or floating to emergent Nymphaeaceae Symmetry: radial Perianth parts: 4-12 tepals, free; petal-like staminodes Stamens: 3-many, laminar Pistils: 1-many (1-many carpels/pistil) Ovary position: superior or inferior Fruit type: aggregate of nuts, or follicle, berry, fleshy capsule
Basal angiosperms Angiosperm phylogeny 1 cotyledon tricolpate pollen Magnoliaceae 2 genera, 220 species (Liriodendron, Magnolia) Magnolia x soulangeana Liriodendron tulipifera
Magnoliaceae 2 genera, 220 species (Liriodendron, Magnolia) Habit: Trees or shrubs Evergreen or deciduous Leaves: Alternate, simple, entire (lobed in Liriodendron) Ethereal oils Magnoliaceae Symmetry: radial Perianth parts: 6-many tepals, free Stamens: many, laminar Pistils: many simple pistils = many free carpels Ovary position: superior Fruit type: aggregate of follicles (Magnolia), or samara (Liriodendron)
Basal angiosperms Flowers of early angiosperms Insect-pollinated Radially symmetric Perfect Floral parts: Several to many Spirally arranged Distinct (unfused) Stamens laminar Pistils simple Ovaries superior Basal angiosperms Angiosperm phylogeny 1 cotyledon tricolpate pollen
Angiosperm phylogeny Basal eudicots Eudicots (Tricolpates) Rosids Asterids 47 genera, 2,000 species Ranunculaceae
47 genera, 2,000 species Ranunculaceae Habit: Usually herbaceous Leaves: Usually alternate (often all basal), simple to dissected to compound Usually lacking stipules Symmetry: radial or bilateral Perianth parts: 5 sepals, 5 petals (or 4-many tepals), free Stamens: many Pistils: usually 5-many, simple Ovary position: superior Fruit type: usually aggregate, sometimes a berry Ranunculaceae
Plant breeding systems Plants vs. Animals non-mobile mobile body plan = modular body plan = fixed bisexual unisexual sex = dynamic sex = fixed Asexual reproduction Vegetative reproduction: does not involve flowers Agamospermy (apomixis) Flowers produced No fertilization Embryo produced clonally
Asexual reproduction Advantages Locally adapted offspring Less reproductive effort Reproductive assurance Disadvantages Little genetic variability Narrow range of environmental tolerance Limited dispersal (except agamospermy) Sexual reproduction Cross pollination Self pollination Self pollination Self pollination: pollen transfer within an individual plant Self fertilization: fertilization of egg by sperm of same individual plant
Sexual reproduction: selfing Self pollination: pollen transfer within an individual plant Self fertilization: fertilization of egg by sperm of same individual plant Sexual reproduction: selfing Advantages Double genetic contribution to offspring Locally adapted offspring Less reproductive effort Reproductive assurance Disadvantages Inbreeding depression Little genetic variability Narrow range of environmental tolerance
Sexual reproduction: outcrossing Self-compatible (SC) Capable of self-fertilization Ovule may be fertilized by pollen from the same plant, or from different plants Self-incompatible (SI) Only capable of cross-fertilization Ovule cannot be fertilized with pollen from the same plant Class discussion breeding systems How might you discover Will seed whether be set? an unknown plant reproduces by self-fertilization, cross-fertilization, or agamospermy? Asexual reproduction You may perform any of the following experiments to determine whether seed is set: Pollinator exclusion Remove stamens before pollen is released Artificial self-pollination Artificial cross-pollination Pollinator exclusion Emasculation Artificial self-pollination Artificial cross-pollination What do you predict will happen in each case? Sexual reproduction Agamospermy SC SI
Functions promoting outcrossing in plants Temporal separation of male and female Protandry Protogyny Pollen released before stigma is receptive Stigma receptive before pollen is released Functions promoting outcrossing in plants Spatial separation of male and female Heterostyly Monoecy/dioecy Within flowers Between flowers
Sexual reproduction: outcrossing Advantages High genetic diversity Avoid expression of deleterious recessive alleles Broad range of environmental tolerance Disadvantages Reproduction less likely Dependent on pollinator Dependent on population density