1. Faculty of Science, School of Sciences, Natabua Campus Lautoka
BIO706 Embryology Lecture 22: Plant Reproductive Biology - II

2. Plant Reproductive Biology
What is it?
Study of sexual and asexual reproduction
Pollination mechanisms
Gene flow
Genetic variation
Propagule dispersal
Why study it?
Insight into adaptive significance & homology of systematic characters
Insight into delimitation of species and subspecies.

3. Sexual Reproduction Non-seed plants Seed plants:
Pollination - transfer of pollen from microsporangia to stigma (angiosperms) or ovule (gymnosperms)
Wind pollination - ancestral (all gymnosperms)
Animal pollination - derived for angiosperms
Some angiosperms secondarily wind pollinated
Fertilization - fusion of sperm and egg embryo (new sporophyte)

4. Strategy of animal pollination: Attractant & Reward
Visual
perianth
stamens (e.g., Myrtaceae, Mimosoideae)
staminodes (e.g., Zingiberaceae, Cannaceae)
corona (e.g., Narcissus)
inflorescence
Olfactory - usually from perianth
sweet smell – e.g. honey bee pollinated flowers
rotten (foul/fetid) - e.g., fly pollinated flowers

5. Strategy of animal pollination: Attractant & Reward
Nectar
Pollen
Waxes
Resins
or “Trick” instead of a “Treat”
Insect trapped (Aristolochia) or drowned (Nymphaea sp.)
Mimicry: E.g., fooling male insect into “mating” with orchid

6. Pollination Mechanisms
INSECT (entomophily)
Bees (melittophily/hymenopterophyly)
Flowers: showy, colorful, fragrant, with:
nectar guides
landing platforms
Butterflies (psychophily) flowers: showy, colorful, fragrant
no nectar guides
long tubes or spurs

7. Pollination Mechanisms
Moths (phalaenophily):
large, white, fragrant
no nectar guides
usually tubes or spurs

8. Pollination Mechanisms
Flies (sapromyiophily)
maroon / brown in color
foul smelling (like rotting flesh)

9. Pollination Mechanisms
Birds (ornithophily):
red (often, not always)
tubular (often)

10. Pollination Mechanisms
Bats (cheiropterophily):
nocturnal anthesis
large, colorful or white
produce copious nectar or pollen

11. Pollination Mechanisms
Wind (anemophily):
flowers small, numerous, often unisexual
perianth absent or non-showy
flowers often produced in mass

12. Pollination Mechanisms
Water (hydrophily):

13. Outbreeding versus Inbreeding vs. in-between
include
Outbreeding versus Inbreeding vs. in-between

14. Outbreeding = outcrossing / allogamy / xenogamy: How is it promoted?
Breeding systems
Outbreeding = outcrossing / allogamy / xenogamy:
How is it promoted?
1) Plant sex: dioecy (incl. gynodioecy, androdioecy, trioecy)

15. Breeding systems Outbreeding = outcrossing / allogamy / xenogamy:
2) Difference in timing of floral parts = dichogamy
protandry - male first
protogyny - female first

16. heterostyly: different style/stigma & correlated anther heights
Breeding systems
Outbreeding = outcrossing / allogamy / xenogamy:
3) Spatial separation of anthers and stigmas = hercogamy
heterostyly: different style/stigma & correlated anther heights

17. enantiostyly: left & right-handed flowers
Outbreeding = outcrossing / allogamy / xenogamy:
3) Spatial separation of anthers and stigmas = hercogamy
enantiostyly: left & right-handed flowers

18. movement hercogamy: trigger mechanisms
Outbreeding = outcrossing / allogamy / xenogamy:
3) Spatial separation of anthers and stigmas = hercogamy
movement hercogamy: trigger mechanisms

19. movement hercogamy: e.g., stigma movement
Outbreeding = outcrossing / allogamy / xenogamy:
3) Spatial separation of anthers and stigmas = hercogamy
movement hercogamy: e.g., stigma movement
Diplacus [Mimulus] aurantiacus (Phyrmaceae)

20. Folding of style best explained as adaptation to reduce interference in bird pollination

21. Outbreeding = outcrossing / allogamy / xenogamy: 4) Self-incompatibility
Genetically determined, inability for fertilization to occur between gametes derived from one individual.

22. Inbreeding = selfing
autogamy (w/in 1 flower) & geitonogamy (between fls. of 1 indiv.)
Selective advantage: ensures propagule production
Disadvantage: reduced to absent genetic variability
Allo-autogamy: both outcrossing & inbreeding
e.g., Viola, Clarkia: two flower types:
chasmogamous flowers - normal, open
cleistogamous flowers - remain closed

24. Fruit/seed dispersal
Wind - samaras, winged seeds
Water - e. g., Cocos nucifera (Arecaceae)
Explosive dehiscence
Self (Autochory, e. g., Arachis hypogaea)
Animal

25. Vegetative reproduction: ramets Rhizomes Bulbs, bulbels Corms, cormels
Asexual Reproduction
Vegetative reproduction: ramets
Rhizomes
Bulbs, bulbels
Corms, cormels
Plantlets

26. Agamospermy - seed production without fertilization
Asexual Reproduction
Agamospermy - seed production without fertilization
Parthenogenesis (diploid egg)
Adventive polyembryony (non-egg diploid cell)

27. Hybridization in plants

28. Polyploidy – evolution of multiple sets of chromosomes; major mechanism of speciation.

29. Hybridization in plants
Common
Can produce sterile, vegetatively reproducing species (e. g., certain cacti)

30. Testing for breeding mechanisms
A B C D
1) Control
2) Caged, self-pollinated
3) Caged, left alone
4) Emasculated, caged
5) Caged, emascul., outcrossed
What is the breeding mechanisms for species A, B, C, D?

31. Pollen tube growth through style tissue

32. Courtesy Michael G. Simpson, internet sources and relevant book chapters Questions are welcome