1. Flowers and seeds

2. The plant kingdom ~ 275,000 flowering plants! Focus on angiosperms
Brief foray into gymnosperms and ferns
Apologies to the rest of the kingdom for lack of coverage
Tegeder and Ward,

3. Alternation of generations
The gametophytic (n) and sporophytic (2n) generations
Gametophyte
haploid
Sporophyte
diploid
or polyploid

4. Alternation of generations
The sporophytic generation may be diploid (2n = 2x) or polyploid (2n = _x)
V V
VAVAVBVB
VAVAVBVBVDVD
2n = 2x = 14
~30,000 genes
2n = 4x = 28
60,000 genes
2n = 6x = 42
90,000 genes
1 pair homologous chromosomes.
1 pair of the 7 pairs
of chromosomes.
The V locus and 2 possible alleles at the locus
2 pairs of homologous chromosomes
2 sets of homoeologous chromosomes
AABB
3 pairs of homologous chromosomes
3 sets of homoeologous chromosomes
AABBDD
A A B B
A A B B D D

5. Sexual reproduction in Angiosperms Advantages > disadvantages

6. Angiosperms 2n = 6x = 42 90,000 genes Polyploidy: frequent
VAVAVBVB
VAVAVBVBVDVD
2n = 2x = 14
~30,000 genes
2n = 4x = 28
60,000 genes
2n = 6x = 42
90,000 genes
VAVA

7. Reproductive organs and gamete formation Development of the female gametophyte
Reproductive structure: Ovule(s), style, stigma

8. Development of the female gametophyte
arizonabeetlesbugsbirdsandmore.blogspot.com
Pollinator attraction: Nectar, Color, Aroma
“Nectar contains water, sugars and amino acids to attract pollinators and defenders and is protected from nectar robbers and microorganisms by secondary compounds and antimicrobial proteins…More research is needed to understand how plants produce nectar, the most important mediator of their interactions with mutualistic animals.” Heil

9. Development of the female gametophyte
Pollinator attraction: Petunia species and pollinators.
Key roles for Myb transcription factors genes; ~ 200 different ones!
Bee-pollinated
P. integrifolia
Hummingbird-pollinated
P. exserta
Hawkmoth-pollinated P. axillaris
ANTHOCYANIN2 (AN2)
Activates anthocyanin biosynthesis
Functional
Nonsense mutations
ODORANT1 (ODO1)
Regulates methylbenzoate volatile
+ 10X volatile production
Baseline volatile production
Yuan et al

10. Development of the female gametophyte
Disseminator attraction
Blue rose
Tulipomania
Transgenic:
+ Delphinidin from pansy; - knock-down of 2 endogenous rose genes
Virus infection
Lesnaw and Ghabrial

11. Development of the female gametophyte
Megaspore mother cell (MMC) 
MMC undergoes meiosis
Of 4 megaspores produced 1 survives (most species)
Three post-meiotic mitoses 1 2 3

12. Development of the female gametophyte
The 8-nucleate embryo sac (1 egg, 2 synergids, 2 primary endosperm nuclei, 3 antipodals)
Source: yougems.reflectionsinfos.com
lima.ohio-state.edu

13. Development of the male gametophyte
Reproductive structures: Anthers; pollen within anthers

14. Development of the male gametophyte
Pollen mother cell (PMC) 
Meiosis gives a tetrad of microspores
Note, this is different than ♀
Meiosis 1
Meiosis 2

15. Development of the male gametophyte
The first mitosis gives vegetative and generative nuclei; at the second mitotic division, the generative nucleus gives 2 sperms.
mitosis
mitosis
mitosis
mitosis
mitosis
mitosis
mitosis
mitosis

16. The pollen pathway The stigma is the site of pollen recognition
Pollen germinates and the vegetative (tube nucleus) grows through the style to the ovule
The two sperm use the tube as conduit

17. The pollen pathway Corn silks and pollen

18. Double fertilization
One sperm fertilizes the egg to give the 2n embryo, the other fertilizes the polar nuclei to give the 3n endosperm
antipodals ♀ ♀ 3n
endosperm
polar
nuclei ♀ ♀ ♂ ♀ ♂ ♀
egg 2n
embryo
synergids

19. A review… Double fertilization in angiosperms: The Movie Nn
n n n
n n
MMC Nn OR
MMC Nn n N n N
N N N
N N
N N N n N Nn
sporophytic
generation
PMC Nn
n n
N N n N n N n N
n n
N N

20. After double fertilization….
….there are at least four independent and genetically distinct generations coexisting in the angiosperm seed:
maternal sporophyte diploid tissue
maternal gametophyte haploid tissue
offspring sporophyte diploid tissue
fusion of male (1) and female (2) gametophyte to form triploid tissue

21. The gymnosperms ~ 1,000 species
Tegeder and Ward,

22. Sexual reproduction in Gymnosperms
Advantages > disadvantages

23. Gymnosperms: Alternation of generations: 2n n Polyploidy: rare
Sequoia sempervirens – only known hexaploid (2n = 6x = 66)

24. Gymnosperms
Gamete formation Development of the male and female gametophyte
Male and female cones can also be
At different position on same tree
On separate trees

25. Gymnosperms No double fertilization No ovary
The female gametophyte: 4 megaspores (n,n,n,n) produced; 1 (n) forms functional megaspore. Slow growth (~ 15 months).
The male gametophyte:
~ 4 (n) cells/pollen grain
Pollen dispersal: usually wind-pollinated (pollen found in mid-Atlantic!)
Pollen tube (n) ; slow growth (~15 months!)
2 sperm (n,n): one fertilizes egg, other degenerates
The seed: ~ 2 years to mature. Nutritive tissues are haploid megagametophte (female); diploid embryo; seed coat (diploid female)

26. Gymnosperms The female gametophyte:
After meiosis, 1 of 4 megaspores (each of them n) becomes the egg
3 of 4 megaspores have structural functions or degenerate
Slow growth (~ 1 year)
The male gametophyte:
After meiosis, 4 microspores
Usually wind dispersal of pollen
Slow growth of pollen tube (~1 year)
2 sperm: one fertilizes egg, other degenerates

27. Gymnosperms No double fertilization No ovary The seed
~ 2 years to mature
Nutritive tissues are haploid megagametophte (female)
diploid embryo
seed coat (diploid female sporophyte)

28. The ferns and horsetails
~ 13,000
No seeds, no flowers
Spores!
Tegeder and Ward,

29. Sexual reproduction in ferns and horsetails Advantages > disadvantages

30. Ferns and horsetails
Alternation of generations: 2n and n are free-living: 2n n
Polyploidy: common

31. Ferns and horsetails Gametes: formation and fertilization

32. The comeback of the horsetails
Cool fern links
USFS
American Fern Society
Ferns - the secret life
Ferns - the movie
The comeback of the horsetails
weeds/weedspeciespage/horsetail/Equisetum_arvense_horsetail.html

33. Seeds

34. Seeds https://www.atlasobscura.com/places/judean-date-palm-methuselah

35. Seeds - looking ahead to Mendelian genetics+ = n
n n
N N N
N N
N N n
N n + = N
N N
N N N N n NN Nn nn + = N
N N
n n n
n n
n n N
n N + = n
n n
n n n
Note: At this point in the figure, were are focusing on an Angiosperm,
the antipodals and synergids are deleted and only the fertilized endosperm nuclei (now 3n)
and fertilized egg (now 2n) are shown. Only the fertilized egg is carried to the Punnett square.

37. Embryo genetics the focus, but remember the 3n endosperm (angiosperms)
Berner and Hoff :

38. Embryo genetics the focus, but remember xenia
“Because the endosperm is the bulk of what we see and eat when we consume sweet corn, sweet corn breeders must work with an unusual genetic effect called xenia. Xenia refers to observable effects that occur due to the influence of pollen. In sweet corn,
the two most important traits affected by pollen are kernel color and sweetness. For example, yellow kernel color is dominant to white, and if a white variety receives pollen from a yellow variety, yellow kernels will appear among the white ones.”

39. Embryo genetics the focus, but remember megagametophyte (gymnosperms)

40. Seeds and persistence