Asterids (Ericaceae, lamiids part I), parasitic plants Today s lecture

Transcription

1 Asterids (Ericaceae, lamiids part I), parasitic plants Today s lecture Video Ericaceae Class exercise Boraginaceae Apocynaceae Parasitic plants Video

2 Video plant-fungal mutualism As a class, we will watch part of David Attenborough s 1995 documentary The Private Life of Plants. During the video, think about: What sort of ecological interactions exist between organisms? Is symbiosis equally beneficial to all partners? Angiosperm phylogeny Soltis et al., 2011 Rosids Saxifragales Asterids Caryophyllales Ranunculaceae Monocots Magnoliids ANITA grade

3 Angiosperm phylogeny Basal eudicots Eudicots (Tricolpates) Rosids Asterids Asterids Asterids Core asterids Lamiids Campanulids Iridoid compounds Unitegmic ovules Tenuinucellate ovules

4 Ericaceae Textbook DVD KRR & DLN Rhododendron macrophyllum Pacific Rhododendron (WA State Flower) Ryan Miller Ericaceae Vaccinium spp.

5 Ericaceae 124 genera; 4,100 species Habit: Herbaceous to woody Often mycotrophic Leaves: Simple Often evergreen Variously arranged Ericaceae Ericaceae are often associated with mycorrhizal fungi and often mycotrophic. Mycotrophic = nutritionally dependent on fungi underground, which are themselves dependent on other green plants. Monotropa uniflora Indian-pipe

6 Ericaceae Symmetry: usually radial Perianth parts: 5 sepals, 5 petals Urn-shaped Stamens: Usually 10 terminal pores Pistils: 1 compound pistil (3-5 carpels) Ovary position: usually superior Fruit type: drupe, berry, capsule Ericaceae

7 Class exercise economic botany You have a recipe for a tasty pie. What are its ingredients? Try to describe as many plant components of the pie as you can, then compare notes with your group. Turn in your worksheet when you re done. Asterids Asterids Core asterids Lamiids Campanulids 2 fused carpels Stamens alternate w. petals Stamens epipetalous, corollas gamopetalous Iridoid compounds Unitegmic ovules Tenuinucellate ovules

8 Boraginaceae Boraginaceae s.s. Hydrophyllaceae 134 genera; 2,650 species Habit: Ours herbaceous Boraginaceae Leaves: Simple to compound Alternate Hispid hairs

9 Boraginaceae Inflorescence: Scorpoid or helicoid cyme = coiled inflorescence, bearing flowers along the upper side and straightening as the flowers mature. Helicoid cyme Scorpioid cyme Boraginaceae Symmetry: radial Perianth parts: 5 sepals, 5 petals corona Stamens: 5, included or exserted Pistils: 1 compound pistil (2 carpels) Ovary position: superior Fruit type: 4 nutlets, or capsule

10 Apocynaceae 355 genera; 3,700 species Habit: Ours herbaceous Milky latex Leaves: Simple, entire Often opposite Apocynaceae Catharanthus roseus

11 Apocynaceae Symmetry: radial Perianth parts: 5 sepals, 5 petals Stamens: 5 anthers often modified Pistils: 1 compound pistil (2 carpels; 2 ovaries) Ovary position: superior Fruit type: follicle, berry, drupe Apocynaceae stylar head 2 distinct ovaries Textbook DVD KRR & DLN Ryan Miller

12 Parasitic plants Monotropa hypopitys Cuscuta pentagona Most plants are autotrophs (producing their own food); parasitic plants are heterotrophs (feeding on other organisms). Parasitic plants Haustorium: a modified root which connects the parasite to the host.

13 Parasitic plants Phoradendron flavescens Hemiparasite: A parasite that is photosynthetic (during at least one stage of its life cycle), may be capable of living independently. Holoparasite: A non-photosynthetic parasite, always dependent on its host. Parasitic plants Obligate parasite: must attach to a host to complete its life cycle. Facultative parasite: does not require a host to complete its life cycle.

14 Parasitic plants Parasitic reduction syndrome Loss of chlorophyll plants no longer green Loss of leaves leaves reduced to scales Reduction in size no tall stems Loss of roots reduced to short projections with haustoria Loss of photosynthetic genes Rapid DNA divergence in genes that are not lost Parasitic plants Wolfe et al., Proc Natl Acad Sci USA 89(22): Wakasugi e et al., Pl. Mol. Biol. Reporter. 16: Epifagus virginiana 70 kb Nicotiana tabacum 156 kb

15 Parasitic plants Note the rapid divergence of chloroplast genes of parasites compared with their non-parasitic relatives. Stefanovic e et al., Am. J. Bot. 89(9): Parasitic plants Orobanchaceae ( Scrophulariaceae ) Boraginaceae Ericaceae Parasitism has evolved ~20 times independently in flowering plants. Orchidaceae

16 Video parasitic plants We will finish today s lecture by continuing to watch the portion of The Private Life of Plants that deals with plant symbioses. During the video, think about: What is the difference between mycotrophs like members of Ericaceae, and other parasites, like mistletoes?