Basal angiosperms, and plant breeding systems Today s lecture Nymphaeaceae Magnoliaceae Ranunculaceae Video Breeding systems Class exercise
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
Ranunculaceae 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 Class exercise pollination video (cont. from last week) We will watch two short video segments on pollination biology in Nymphaeaceae. During the videos, think about: What is the function of the differences in flower timing (male vs. female)? Why do plants exhibit strategies to promote outcrossing?
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 (vegetative reproduction) Sexual reproduction Self-compatible (SC) Capable of self-fertilization or cross-fertilization Self-incompatible (SI) Only capable of crossfertilization Ovule cannot be fertilized with pollen from same plant SUCCESSFUL POLLINATION SUCCESSFUL FERTILIZATION
Sexual reproduction: selfing Pollen transfer within an individual plant = self-pollination Fertilization of egg by sperm of same individual plant = selffertilization (autogamy) Cleistogamy Cleistogamous flowers are inconspicuous Self-pollinate and self-fertilize in bud A plant may produce both cleistogamous and chasmogamous flowers 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-incompatibility (SI): inability of a fertile hermaphrodite flower to produce zygotes after selfpollination. Biochemical reaction inhibits fertilization Governed by S-locus: Sexual reproduction: review Selfing SC Mostly annuals Few, inconspicuous flowers Similar maturation of reproductive parts Anthers near stigma Style included All fruits mature Low pollen:ovule ratio Outcrossing SI or SC Mostly woody perennials Numerous large, showy flowers Differential maturation of reproductive parts Anthers far from stigma Stigma well-exserted Only some fruits mature High pollen:ovule ratio
Class exercise breeding systems How might you discover whether an unknown plant is self-compatible, self-incompatible, or agamospermic? 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 What do you predict will happen in each case? Functions promoting outcrossing in plants Temporal separation of male and female (dichogamy) Protandry Pollen released before stigma is receptive Common in insectpollinated plants Protogyny Stigma receptive before pollen is released Less common than protandry
Functions promoting outcrossing in plants Spatial separation of male and female (herkogamy) Within flowers Between flowers Eg., heterostyly Eg., monoecy, dioecy Functions promoting outcrossing in plants Spatial separation of male and female Heterostyly 2-3 floral morphs: length of style and filament vary Only pollinations between different floral morphs are successful.
Functions promoting outcrossing in plants Spatial separation of male and female Unisexual flowers Imperfect flowers are either staminate or carpellate Monoecy Plants bisexual Common in large, windpollinated plants Dioecy Plants unisexual