Exploring Plant Development, Cell Genetics, and Energy Processes

1. Phytoremediation • Plant products • Biofuels • Effects of seed spacing on seed germination • Effects of nutrient deprivation • Effects of stresses • Climate/CO2 change • Non-coding RNAs • Biotechnology • Plant movements: flytraps, mimosa, soybeans • Carnivorous plants • Stress responses/stress avoidance • Plant signaling (including neurobiology) • Flowering? • Hormones? • Plant pathology? • Plant tropisms and nastic movements • Root growth responses • Metal toxicity? • Circadian rhythms? • Effects of magnetic fields? • Effects of different colors of light on plant growth?

2. Plant Development • Cell division = growth • Determination = what cell can become • Differentiation = cells become specific types • Pattern formation • Morphogenesis: organization into tissues & organs

3. Plant Development umbrella term for many processes • Embryogenesis • Seed dormancy and germination • Seedling Morphogenesis • Transition to flowering, fruit and seed formation Many responses to environment

4. Unique features of plant development • Meristems: plants have perpetually embryonic regions, and can form new ones • No germ line! Cells at apical meristem become • flowers: allows Lamarckian evolution! • Different parts of the same 2000 year old tree have different DNA & form • different gametes

5. Cell walls Carbohydrate barrier surrounding cell Protects & gives cell shape 1˚ wall made first • mainly cellulose • Can stretch! 2˚ wall made after growth stops • Inside 1˚ wall

6. Endomembrane system Organelles derived from the ER 1) ER 2) Golgi 3) Vacuoles 4) Plasma Membrane 5) Nuclear Envelope 6) Endosome 7) Oleosomes

7. VACUOLES Vacuoles are subdivided: lytic vacuoles are distinct from storage vacuoles!

8. Endomembrane System Oleosomes: oil storage bodies derived from SER Surrounded by lipid monolayer! • filled with lipids: no internal hydrophobic effect!

9. Peroxisomes Fn: • destroy H2O2, other O2-related poisons • change fat to CH2O (glyoxysomes) • Detoxify & recycle photorespiration products • Destroy EtOH (made in anaerobic roots)

10. Mitochondria • matrix contains DNA, RNA and ribosomes • Genomes vary from 100,000 to 2,500,000 bp, but only 40-43 genes • Sometimes mutate to cause cytoplasmic male sterility • Reproduce by fission

11. Mitochondria • matrix contains DNA, RNA and ribosomes • Genomes vary from 100,000 to 2,500,000 bp, but only 40-43 genes • Sometimes mutate to cause cytoplasmic male sterility • Reproduce by fission • IM is 25% cardiolipin, a bacterial phospholipid

12. Mitochondria • matrix contains DNA, RNA and ribosomes • Genomes vary from 100,000 to 2,500,000 bp, but only 40-43 genes • Sometimes mutate to cause cytoplasmic male sterility • Reproduce by fission • IM is 25% cardiolipin, a bacterial phospholipid • Genes most related to Rhodobacteria

13. Mitochondria Fn : cellular respiration -> oxidizing food & supplying energy to cell Also make many important biochemicals

14. Mitochondria Fn : cellular respiration -> oxidizing food & supplying energy to cell Also make important biochemicals & help recycle PR products

15. Mitochondria Fn : cellular respiration -> oxidizing food & supplying energy to cell Also make important biochems & help recycle PR prods • Have extra oxidases: burn off excess NADH or NADPH? • Can’t kill plants with cyanide because of alternative oxidase!

16. Mitochondria • Fn : cellular respiration • -> oxidizing food & supplying energy to cell • Also make important biochems & help recycle PR prods • Have extra oxidases • Do lots of extra biochemistry

17. endosymbionts • Peroxisomes • Mitochondria • Plastids

18. Plastids • Present in all plant cells, but take many forms • Chloroplasts do photosynthesis • Amyloplasts store starch • Chromoplasts store pigments • Leucoplasts are found in roots

19. Chloroplasts • Bounded by 2 membranes • 1) outer envelope • 2) inner envelope

20. Chloroplasts • Interior = stroma • Contains thylakoids • membranes where light • rxns of photosynthesis occur • mainly galactolipids

21. Chloroplasts Interior = stroma Contains thylakoids • membranes where light rxns of photosynthesis occur • mainly galactolipids Contain DNA, RNA, ribosomes

22. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes

23. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes Closest relatives = cyanobacteria

24. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes Closest relatives = cyanobacteria Divide by fission

25. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes Closest relatives = cyanobacteria Divide by fission Fns: Photosynthesis

26. Chloroplasts Fns: Photosynthesis & starch synth Photoassimilation of N & S

27. Chloroplasts Fns: Photosynthesis & starch synth Photoassimilation of N & S Fatty acid & some lipid synth

28. Chloroplasts Fns: Photosynthesis & starch synth Photoassimilation of N & S Fatty acid & some lipid synth Synth of ABA, GA, many other biochem

29. Chloroplasts & Mitochondria Contain eubacterial DNA, RNA, ribosomes Inner membranes have bacterial lipids Divide by fission Provide best support for endosymbiosis theory

30. Endosymbiosis theory (Margulis) Archaebacteria ate eubacteria & converted them to symbionts

31. Endosymbiosis theory (Margulis) Archaebacteria ate eubacteria & converted them to symbionts

32. Endosymbiosis theory (Margulis) Archaebacteria ate eubacteria & converted them to symbionts

33. cytoskeleton network of proteins which give cells their shape also responsible for shape of plant cells because guide cell wall formation left intact by detergents that extract rest of cell

34. Cytoskeleton Actin fibers (microfilaments) ~7 nm diameter Form 2 chains of polar actin subunits arranged in a double helix

35. Actin fibers polar subunits arranged in a double helix • Add to + end • Fall off - end • Fn = movement

36. Actin fibers Very conserved in evolution

37. Actin fibers Very conserved in evolution Fn = motility Often with myosin

38. Actin fibers Very conserved in evolution Fn = motility Often with myosin: responsible for cytoplasmic streaming

39. Actin fibers Very conserved in evolution Fn = motility Often with myosin: responsible for cytoplasmic streaming, Pollen tube growth & movement through plasmodesmata

40. Actin fibers Often with myosin: responsible for cytoplasmic streaming, Pollen tube growth & movement through plasmodesmata

41. Actin fibers Often with myosin: responsible for cytoplasmic streaming, Pollen tube growth & movement through plasmodesmata

42. Intermediate filaments Protein fibers 8-12 nm dia (between MFs & MTs) form similar looking filaments Conserved central, rod-shaped -helical domain

43. Intermediate filaments 2 monomers form dimers with parallel subunits Dimers form tetramers aligned in opposite orientations & staggered

44. Intermediate filaments 2 monomers form dimers with parallel subunits Dimers form tetramers Tetramers form IF

45. Intermediate filaments 2 monomers form dimers with parallel subunits Dimers form tetramers Tetramers form IF Plants have several keratins: fn unclear

46. Intermediate filaments 2 monomers form dimers with parallel subunits Dimers form tetramers Tetramers form IF Plants have several keratins: fn unclear No nuclear lamins! Have analogs that form similar structures

47. Microtubules Hollow, cylindrical; found in most eukaryotes outer diameter - 24 nm wall thickness - ~ 5 nm Made of 13 longitudinal rows of protofilaments

48. Microtubules Made of abtubulin subunits polymerize to form protofilaments (PF) PF form sheets Sheets form microtubules

49. Microtubules Protofilaments are polar -tubulin @ - end -tubulin @ + end all in single MT have same polarity

50. Microtubules In constant flux polymerizing &depolymerizing Add to  (+) Fall off  (-)