Friday

1. Friday Present a plant stressor, what is known about it, and why it might affect plant 2˚ compounds in an ~ 10 minute presentation. Alternative: present another good plant/stressor response to study and why we should choose it over the ones already chosen.

2. John Austin: Maria Chinikaylo: effect of atrazine herbicide on glutathione in corn Cassia Cole: Christina Gambino: predation on caffeine coffee plant Andrew Hasuga: ozone Kelvin Mejia: High soil salinity Alexis Morgan: Sulfur deprivation on garlic Catherin Morocho: Ozone? Smog? Heavy metals? Predation? Heat? Tom Nawrocki: Jared Nicholoff: David Pupaza: Fungal attack Kyle Schimmel: Nathan Seabridge: sulfur deprivation on onions Kenneth Werkheiser: Agrobacterium tumefaciens Matt Yatison: UV radiation Michael Yucha: Cold Stress Atrazine? Cold? Shaking?Nutrient deprivation? Bacteria? Nematodes?

3. Natural Products >100,000 types; 3 main groups >30,000 terpenoids: made from isoprene units >12,000 Alkaloids: derived from amino acids: contain N >8,000 phenolics: contain phenol ring

4. Other natural products • ~ 100 cyanogenic glycosides • Release cyanide when plant is damaged • Found in seeds of apricots, cherries, other fruits Laetrile

5. Other natural products • > 100 glucosinolates: contain S and N • Mainly found in Brassicaceae (crucifers) • Made from modified amino acids bonded to glucose • Function in defense

6. Other natural products The genus Allium produces sulfoxides derived from cysteine When plants are damaged they are converted to pungent volatiles

7. Seeds • Seeds are unique feature of plants • Plant dispersal units • Must survive unfavorable conditions until they reach • suitable place (and time) to start next generation • Are dormant; dehydration is key • Germinate when conditions are right

8. Seed Development • Maturation: cell division ± ceases, but cells still expand • Activate new genes for making storage compounds • Storage compounds are key for seedlings and crops • Proteins, lipids & carbohydrates but vary widely • Many 2˚ metabolites

9. Seed Development • Next prepare for desiccation as ABA made by embryo (+endosperm) increases • Make proteins & other molecules (eg trehalose) that help tolerate desiccation • Next dehydrate (to 5% moisture content) and go dormant

10. Seed Development • Coat-imposed dormancy (maternal effect) • Preventing water uptake. • Mechanical constraint • Interference with gas exchange • Retaining inhibitors (ABA) • Inhibitor production (ABA) • Embryo dormancy (Zygotic effect)

11. Seed germination • Seeds remain dormant until sense appropriate conditions: • Water • Temperature: some seeds require vernalization = prolonged cold spell • Many require light: says photosynthesis is possible • often small seeds with few reserves

12. Seed germination • Seeds remain dormant until sense appropriate conditions: • Many require light: says that they will soon be able to photosynthesize: often small seeds with few reserves • Hormones can also trigger (or stop) germination • ABA blocks it • GA stimulates it

13. Seed germination • Seeds remain dormant until sense appropriate conditions: • Many require light: says that they will soon be able to photosynthesize: often small seeds with few reserves • Hormones can also trigger (or stop) germination • ABA blocks it • GA stimulates it • Germination is a two step process • Imbibition

14. Seed germination • Germination is a two step process • Imbibition is purely physical: seed swells as it absorbs water until testa pops. • Even dead seeds do it.

15. Seed germination • Germination is a two step process • Imbibition is purely physical: seed swells as it absorbs water until testa pops. • Even dead seeds do it. • Seeds with endosperm pop testa first, then endosperm

16. Seed germination • Germination is a two step process • Imbibition is purely physical: seed swells as it absorbs water until testa pops. • Even dead seeds do it. • Seeds with endosperm pop testa first, then endosperm • Separate processes: can pop testa but not endosperm

17. Seed germination • Germination is a two step process • Imbibition is purely physical: seed swells as it absorbs water until testa pops. • Even dead seeds do it. • Seeds with endosperm pop testa first, then endosperm • Separate processes: can pop testa but not endosperm • Testa and endosperm have different genotypes!

18. Seed germination • Germination is a two step process • Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it. • Seeds with endosperm pop testa first, then endosperm • Next embryo must start metabolism and cell elongation

19. Seed germination • Germination is a two step process • Imbibition is purely physical: seed swells as it absorbs water until testa pops. Even dead seeds do it. • Next embryo must start metabolism and cell elongation • This part is sensitive to the environment, esp T & pO2

20. Seed germination • Germination is a two step process • Next embryo must start metabolism and cell elongation • This part is sensitive to the environment, esp T & pO2 • Hormones also play a complex role

21. Seed germination • Germination is a two step process • Next embryo must start metabolism and cell elongation • This part is sensitive to the environment, esp T & pO2 • Hormones also play a complex role • GA, Ethylene and BR all stimulate

22. Seed germination • Germination is a two step process • Next embryo must start metabolism and cell elongation • This part is sensitive to the environment, esp T & pO2 • Hormones also play a complex role • GA, Ethylene and BR all stimulate • ABA blocks

23. Seed germination • Germination is a two step process • Next embryo must start metabolism and cell elongation • This part is sensitive to the environment, esp T & pO2 • Once radicle has emerged, vegetative growth begins

24. Vegetative growth • Once radicle has emerged, vegetative growth begins • Juvenile plants in light undergo photomorphogenesis

25. Vegetative growth • Once radicle has emerged, vegetative growth begins • Juvenile plants in light undergo photomorphogenesis • Juvenile plants in dark undergo skotomorphogenesis • Seek light: elongate hypocotyl, don’t unfold cotyledons

26. Vegetative growth • Once radicle has emerged, vegetative growth begins • Juvenile plants in light undergo photomorphogenesis • Expand cotyledons, start making leaves & photosynthetic apparatus

27. Vegetative growth • Once radicle has emerged, vegetative growth begins • Juvenile plants in light undergo photomorphogenesis • Expand cotyledons, start making leaves & photosynthetic apparatus • Initially live off reserves, but soon do net photosynthesis

28. Vegetative growth • Once radicle has emerged, vegetative growth begins • Initially live off reserves, but soon do net photosynthesis • Add new leaves @ SAM in response • to auxin gradients • Add new branches from axillary • buds lower down stem if apical • dominance wanes

29. Vegetative growth • Once radicle has emerged, vegetative growth begins • Add new leaves @ SAM in response to auxin gradients • Add new branches from axillary • buds lower down stem if apical • dominance wanes • Roots grow down seeking • water & nutrients

30. Vegetative growth • Once radicle has emerged, vegetative growth begins • Add new leaves @ SAM in response to auxin gradients • Roots grow down seeking water & nutrients • 1˚ (taproot) anchors plant • 2˚ roots absorb nutrients

31. Vegetative growth • Once radicle has emerged, vegetative growth begins • Add new leaves @ SAM in response to auxin gradients • Roots grow down seeking water & nutrients • 1˚ (taproot) anchors plant • 2˚ roots absorb nutrients • Continue to add cells • by divisions @ RAM

32. Vegetative growth • Roots grow down seeking water & nutrients • Continue to add cells by divisions @ RAM • Form lateral roots in maturation zone in response to nutrients & auxin/cytokinin

33. reproductive phase • Eventually switch to reproductive phase & start flowering • Are now adults!

34. reproductive phase • Eventually switch to reproductive phase & start flowering • Are now adults! • Triggered by FT protein: moves from leaves to shoot apex in phloem to induce flowering!

35. Transition to Flowering • Adults are competent to flower, but need correct signals • Very complex process! • Can be affected by: • Daylength • T (esp Cold) • Water stress • Nutrition • Hormones • Age

36. reproductive phase • Are now adults! • Very complex process! • Time needed varies from days to years

37. reproductive phase • Eventually switch to reproductive phase & start flowering • Are now adults! • Time needed varies from days to years. • Shoot apical meristem now starts making new organ: flowers, with many new structures & cell types

38. Senescence Shoot apical meristem now starts making new organ: flowers, with many new structures & cell types Eventually petals, etc senesce = genetically programmed cell death: controlled by specific genes

39. Senescence Eventually petals, etc senesce = genetically programmed cell death: controlled by specific genes Also seen in many other cases: deciduous leaves in fall, annual plants, older trees

40. Senescence Induce specific senescence-associated genes ; eg DNAses, proteases, lipases Also seen during xylem formation: when cell wall is complete cell kills itself

41. Senescence Also seen during xylem formation: when cell wall is complete cell kills itself Also seen as wound response: hypersensitive response Cells surrounding the wound kill themselves

42. Senescence Also seen during xylem formation: when cell wall is complete cell kills itself Also seen as wound response: hypersensitive response Cells surrounding the wound kill themselves Some mutants do this w/o wound -> is controlled by genes!

43. Light regulation of Plant Development • Plants use light as food and information • Use information to control development

44. Light regulation of Plant Development • Plants use light as food and information • Use information to control development • germination

45. Light regulation of Plant Development • Plants use light as food and information • Use information to control development • Germination • Photomorphogenesisvsskotomorphogenesis

46. Light regulation of Plant Development • Plants use light as food and information • Use information to control development • Germination • Photomorphogenesisvsskotomorphogenesis • Sun/shade & shade avoidance

47. Light regulation of Plant Development • Germination • Morphogenesis • Sun/shade & shade avoidance • Flowering

48. Light regulation of Plant Development • Germination • Morphogenesis • Sun/shade & shade avoidance • Flowering • Senescence

49. Light regulation of growth Plants sense Light quantity

50. Light regulation of growth Plants sense Light quantity Light quality (colors)