Basal Angiosperms. Plant Breeding Systems

Transcription

1 Basal Angiosperms Plant Breeding Systems

2 Announcements Herbarium Tour today during lab. Lab Quiz 2 next Monday. Keying practice this Friday, 3-5 pm, HCK 246.

3 Phylogeny of angiosperms Basal angiosperms Angiosperms Parallel venation scattered vascular bundles 1 cotyledon Tricolpate pollen ANITA grade Amborella Nymphaeaceae Illicium Trimenia Austrobaileya vessels (Jansen et al. 2007)

4 Phylogeny of angiosperms Basal angiosperms Angiosperms Parallel venation scattered vascular bundles 1 cotyledon Tricolpate pollen Nymphaeales is a monophyletic group including Nymphaeaceae, Barclayaceae, and Cabombaceae vessels (Jansen et al. 2007)

5 Nymphaeaceae (Water lily family)

6 Nymphaeaceae (Water lily family) 8 genera, 70 species (Nymphaea, Nuphar, Victoria) Habit: Ben Legler Stems: Textbook DVD WSJ Leaves:

7 Nymphaeaceae (Water lily family) Inflorescence: Flowers: Sex of plant: Ben Legler

8 Nymphaeaceae (Water lily family) Flower symmetry: Perianth parts: # of stamens: # of pistils/flower: # of carpels/pistil: Textbook DVD KRR & DLN Ovary position:

9 Nymphaeaceae (Water lily family) Fruit type: Textbook DVD KRR & DLN Textbook DVD JRA

10 Phylogeny of angiosperms Basal angiosperms Angiosperms Parallel venation scattered vascular bundles 1 cotyledon Tricolpate pollen Magnoliids is a monophyletic group including Magnoliaceae, Lauraceae, Piperaceae and several other families vessels (Jansen et al. 2007)

11 Magnoliaceae (Magnolia family) Magnolia X soulangeana Textbook DVD KRR

12 2 genera, 220 species (Liriodendron, Magnolia) Magnoliaceae (Magnolia family) Habit: Magnolia grandiflora Textbook DVD WSJ Leaves: Liriodendron tulipifera Textbook DVD WSJ

13 Magnoliaceae (Magnolia family) Inflorescence: Flowers: Magnolia grandiflora Textbook DVD WSJ Sex of plant: Liriodendron tulipifera Textbook DVD WSJ

14 Magnoliaceae (Magnolia family) Flower symmetry: Perianth parts: # of stamens: Textbook DVD KRR # of pistils/flower: # of carpels/pistil: Ovary position: Textbook DVD KRR

15 Magnoliaceae (Magnolia family) Fruit type: Textbook DVD SMK & KRR Textbook DVD KRR

16 Early Angiosperm Flower Insect-pollinated Radially symmetric Floral parts numerous, Perianth of tepals Perfect flower Laminar stamens spirally arranged and free Gynoecium of simple pistils, and superior ovaries Textbook DVD KRR Ben Legler

17 Phylogeny of angiosperms Basal angiosperms Angiosperms Parallel venation scattered vascular bundles 1 cotyledon Tricolpate pollen vessels (Jansen et al. 2007)

18 Phylogeny of Eudicots (or Tricolpates) Basal eudicots Eudicots (or Tricolpates) Ranunculales is a monophyletic group including Ranunculaceae, Berberidaceae, Papaveraceae, and 4 other families. (Jansen et al. 2007)

19 Ranunculaceae (Buttercup family) Yaowu Yuan Aquilegia Yaowu Yuan Ranunculus

20 Ranunculaceae (Buttercup family) 47 genera, 2000 species (Anemone, Clematis, Delphinium, Helleborus, Ranunculus) Habit: Leaves: Textbook DVD KRR

21 Ranunculaceae (Buttercup family) Inflorescence: Flowers: Jim Riley Sex of plant:

22 Ranunculaceae (Buttercup family) Flower symmetry: Perianth parts: # of stamens: Yaowu Yuan # of pistils/flower: # of carpels/pistil: Ovary position: Yaowu Yuan

23 Ranunculaceae (Buttercup family) Fruit type: Textbook DVD KRR Textbook DVD KRR & DLN

24 Papaveraceae s.s. (Poppy family) (Hoot et al. 1997)

25 Papaveraceae s.s. (Poppy family) Textbook DVD CSC Eschscholzia californica California poppy Papaver rhoeas

26 23 genera, 240 species (Argemone, Eschscholzia, Papaver) Papaveraceae s.s. (Poppy family) Habit: Stems: Leaves: Textbook DVD WSJ

27 Papaveraceae s.s. (Poppy family) Inflorescence: Flowers: Sex of plant: Yaowu Yuan

28 Papaveraceae s.s. (Poppy family) Flower symmetry: Perianth parts: # of stamens: Textbook DVD DLN # of pistils/flower: # of carpels/pistil: Ovary position: Yaowu Yuan

29 Papaveraceae s.s. (Poppy family) Fruit type: Yaowu Yuan Textbook DVD KRR

30 PLANT BREEDING SYSTEMS Diversity and Evolution of Reproduction in Angiosperms

31 Plants vs. Animals Flowering plants are generally hermaphroditic. Use intermediary agents. Can reproduce asexually & sexually. Less rigidly controlled development. Alternation of generations. Plant breeding systems are rarely fixed & static!

32 Asexual Reproduction Reproduction of genetically identical individuals from a single parent plant. Main type: vegetative reproduction. No meiosis, no fertilization, and no recombination.

33 Modes of Vegetative Reproduction Rhizomes underground shoots Tillers aboveground shoots Bulblets little bulbs Bulbils inflorescence veg buds Cuttings

34 Advantages of Asexual Reproduction Parent plants well-adapted to local environment will have offspring with a competitive advantage. Less reproductive effort. Colonization with limited dispersal. Reproductive assurance in limited cross-pollination.

35 Disadvantages of Asexual Reproduction Little if any new genetic variability. Genetically uniform populations. Very narrow population niche width. No capabilities for travel, dormancy, and establishment that seeds exhibit.

36 Sexual Reproduction Production of offspring through meiosis and fertilization. Offspring genetically different from parents due to recombination = genetic diversity. Plants can be both asexual and sexual, with a variety of forms.

37 SUCCESSFUL POLLINATION SUCCESSFUL FERTILIZATION

38 Hermaphroditic Flowers Self-compatible (SC) Capable of self-fertilization or cross-fertilization Self-incompatible (SI) Only capable of crossfertilization Inability of hermaphroditic plant to produce zygotes w/ self pollen

39 Self-fertilization Pollen transfer within or among flowers of same individual ~20% of angiosperms are habitual selfers ~40% of angiosperms can self-fertilize

40 Advantages of Self-fertilization Reproductive assurance. Selectively advantageous by transmitting both sets of genes to offspring. Well-adapted genotypes preserved. Only single colonizing individual needed. Cost-saving on male expenditure.

41 Disadvantages of Self-fertilization Decreases genetic variability. Inability to adapt to changing conditions. Increases inbreeding depression. Reduces heterozygosity and increases homozygosity of deleterious alleles. Loss of vigour in offspring!

42 Loss of Heterozygosity from Selfing Aa x Aa A a 1/4 AA 1/2 Aa 1/4 aa A a AA Aa Aa aa A selfed heterozygote will yield offspring that are 50% heterozygous.

43 Loss of Heterozygosity from Selfing Proportion of heterozygotes is 1/2 in each successive generation. F1: 50% of offspring heterozygous from original parent (Aa). F2: 25% F3: 12.5% F4: 6.2% F5: 3.1% F6: 1.5%

44 Disadvantages of Self-fertilization Decreases genetic variability. Inability to adapt to changing conditions. Increases inbreeding depression. Reproductive inefficiency.

45 Self-incompatibility (SI) Inability of a fertile hermaphrodite flower to produce zygotes after self-pollination. Involves a biochemical reaction in the stigma or style to reject self pollen or prevent pollen tube growth. Genetically controlled by S-locus. opposite S alleles attract like S alleles repel

46 Selfers vs. Outcrossers SC Mostly annuals Small flowers (few) Unscented flowers Nectaries & nectar guides absent Similar maturation of reproductive parts Anthers near stigma Style included All fruits mature Low pollen:ovule ratio SI or SC Mostly woody perennials Large showy flowers (many) Scented flowers Nectaries & nectar guides present Differential maturation of reproductive parts Anthers far from stigma Stigma well-exserted Only some fruits mature High pollen:ovule ratio

47 Cleistogamy (CL) Flowers never open and only capable of self-fertilization in bud. Inconspicuous, bud-like apetalous flowers that form directly into seed capsules. 488 species, across 212 genera and 49 families. Violaceae, Fabaceae, Poaceae

48 Cleistogamy (CL) Mixed mating systems -can produce both CL and open flowers on an individual. CL fls are a back-up in case pollinators scarce. CL occur after normal flowering period. open fls early spring and CL fls later in season.

49 Strategies to Prevent Self-fertilization

50 Physical Separation of Reproductive Parts (Herkogamy) Within flowers Among flowers

51 Heterostyly Flowers in different individuals of the same species having 2 or 3 different style lengths With stamen lengths varying inversely 25 families of angiosperms, over 18 orders, and 155 genera.

52 Distyly 2 floral morphs. Thrum flower long filaments w/ short styles Pin flower short filaments w/ long styles Only pollinations between different floral morphs are successful. E.g.: Primulaceae, Boraginaceae

53 Tristyly 3 floral morphs Style long, stamens short and medium Style medium, stamens short and long Style short, stamens medium and long Only 3 families!

54 Temporal Separation of Reproductive Parts (Dichogamy) Protandry Anthers release pollen before stigma receptive Common in insectpollinated plants

55 Temporal Separation of Reproductive Parts Protogyny Stigma receptive before pollen release (Dichogamy) Less common than protandry

56 Physical Separation of Reproductive Parts Unisexual flowers Staminate and carpellate flowers Monoecy Dioecy

57 Selective Pressures for Unisexuality Outcrossing requirement. Gender resource allocation. Physical interference between male & female function.

58 Monoecy Common in large windor water-pollinated plants. Betulaceae, Fagaceae, Cyperaceae, etc. Common in temperate regions. Self-pollination possible but less likely.

59 Dioecy 6% of angiosperms Common in tropical regions and oceanic islands Gen small fl size 100% outcrossing, but inefficient Sometimes controlled by sex chromosomes

60 Polygamous Flowers Both bisexual and unisexual fls on the same plant or in the same population. Androdioecy = bisexual and staminate individuals in a population. Andromonoecy = bisexual and staminate flowers on same individual. Gynodioecy = bisexual and carpellate individuals in a population. Gynomonoecy = bisexual and carpellate flowers on same individual.

61 Evolution of Breeding Systems Ancestral angiosperms were SC & hermaphroditic. SI has evolved many times. Physical and temporal separation have evolved many times. Dioecy has evolved many times and through different pathways. Breeding systems not fixed and often mixed!