Ch 38 and 39 Reproduction, Biotechnology, Hormones

1. Ch 38 and 39 Reproduction, Biotechnology,Hormones

4. A-Sexual REproduction Fragmentation: Pieces develop into a whole offspring Vegetative Reproduction: New plants come from mature fragments, tough Apomixis: (Dandelions) Produce seeds w/o fertilization or pollination – makes mature seeds

5. A-Sexual Benefits • No need for a pollinator (sparsely distributed) • Identical offspring • Typically stronger offspring (come from mature fragments) Disadvantages - Identical offspring

6. Sexual Benefits • Large number of offspring to overcome odds of fragile seeds • Varied offspring to withstand env. Changes • Further seed dispersal • Dormant seeds until favorable conditions avail. Disadvantages - Fragile seeds (disease, predators)

7. Totipotent Cells • You can be anything you want to be! • Especially in meristems • House plants, shoot cuttings • Creates a mass of dividing, undifferentiated, totipotent cells at the cut end • Can also be grafted onto a new plant! • Might both have their own beneficial features • Resist pathogens, quality of fruit Asexual propagation

8. Figure 38.14 Biotechnology • Transgenic: Engineered to express a gene from another species BT Corn?!?

9. Genetically modified rice Ordinary rice Figure 38.15 Figure 38.16 Golden Rice • Increasing quality of the rice, malnutrition Has helped children with Vitamin A deficiency (blindness) – Increased beta carotene

10. Health Concerns • May transfer allergens from a gene source to a plant used for food • Effect nontarget organisms – Monarch Butterflies • Transgene Escape – Crop/Weed hybridization, creating superweeds

11. A very Confused Potato A look at hormones and plant response

12. Dodder Plant • Vampire Plant: Parasitic, non-flowering • Attaches to and feeds off of host (Tomato) • Attracted by the scent of the host (chemical signals)

13. Adaptations enhance survival • Etiolation: Growth in complete/partial darkness • Weak stems • Pale Leaves • Yellow Color • Benefit for underground plants that don’t need expanded leaves or extensive root system to combat transpiration

14. And then there was light… • De-etiolation • The plant undergoes profound change • Stem elongation • Leaves and roots expand • Producing chlorophyll

15. Cell Signaling 1) Reception- signals are detected by receptors • Proteins that change in response to specific stimuli • Phytochrome, Cytoplasm, Functions in light detection (de-etiolation) • Other: Hormone Signals • Other: Environmental Triggers 2) Transduction- secondary messengers • Transfer and amplify signals that cause specific responses • Ca2+ and cGMP

16. 3) Response • Leads to a regulation of one or more cellular or enzymatic activities • Post-Translational modification • Transcriptional regulation Ultimately switch genes on and off to regulate proteins

18. Auxin and Phototropism • Phototropism: Directs shoot growth towards sunlight • Dark side elongates faster than the light side to allow the plant to bend Location: Accumulates in meristem region (shoot tips), Developing seeds and fruits

19. Auxin and pattern formation • Carries information about development, size and environment • How does my branch look? • Dormant plant reduces auxin transport capacity and the expression of genes

20. Control of apical dominance

21. Gib • Location: Meristems and Seeds • Stimulate stem elongation and leaf growth • Fruit growth • Work with Auxin Spray used commercially, seedless grapes Larger More spacing at notes

22. Gib and Germination • Signals seed to break dormancy • Stimulates synthesis of amylase to breakdown stored sugars

23. Abscisic acid • SLOWS GROWTH!!!! • High levels of ABA during seed dormancy • Closes stomata during drought Affects calcium messengers causing K channels of guard cells to open… Water is lost…. Turgor pressure is lost… Stomata close Location: All parts of the plant

24. PHotoperiodism

25. Ethylene • Response to stress (drought, pressure, injury, infection) • A change in the balance of auxin and ethylene controls leaf abscission • The process that occurs in autumn when a leaf falls

26. Abscission

27. Ethylene and Fruit Ripening • Attract animals, Seed dispersal • Done commercially, transporting produce

28. Cytokinins

29. Midnight Noon Circadian RhythmsPlants Oscillate during the day Many legumes • Lower their leaves in the evening and raise them in the morning Figure 39.21

30. Gravitropism • Roots Down • Shoots Up

31. (a) Unstimulated (b) Stimulated Side of pulvinus with flaccid cells Leafletsafterstimulation Side of pulvinus with turgid cells Pulvinus(motororgan) Vein (c) Motor organs 0.5 m See Growth in response to touch, Vines Thigmotropism • Result from mechanical perturbation • Ex: Rubbing the stems of young plants a couple of times daily, Results in plants that are shorter than controls

32. Stress and Defense! • Environmental stresses adversely effect plant’s survival, growth, and reproduction • Crop yields in agriculture • Luckily equipped with many natural defenses • Toxins • Needle shaped cells crystals in cells, irritant • Hard to chew • Recruit predatory animals defend against herbivores