Plant growth and development [compatibility mode]


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Plant growth and development [compatibility mode]

  1. 1. Plant growth and developmentg p GrowthGrowth Irreversible increase in size, results from cell division and cell enlargement Morphogenesis Development of formp Development Sum of all of the changes that PROGRESSIVELY elaborate an organism’s body
  2. 2. Nutritional requirementsq CO2CO2 Mineral nutrients- essential chemical elements absorbed from the soil in the form of inorganic ionsabsorbed from the soil in the form of inorganic ions H20* mineralsminerals
  3. 3. Essential nutrients Required for a plant to grow from a seed andRequired for a plant to grow from a seed and complete the life cycle No other elem can replace itNo other elem can replace it It has a direct or indirect action in plt metab 17 essential nutrients17 essential nutrients Macronutrients - 9 Micronutrients – 8Micronutrients – 8 e
  4. 4. Macronutrients Required in large amounts Produces the body of the plant Carrying out essential physiological processes 9 macronutrients (CHONPSKCaMg)9 macronutrients (CHONPSKCaMg) 1. CARBON 2. HYDROGEN 3. OXYGEN 4. NITROGEN 5. PHOSPHORUS 6. SULFUR 7. POTASSIUM 8. CALCIUM 9. MAGNESIUM
  5. 5. 1 CARBON - CO21. CARBON CO2 2. HYDROGEN - H2O 3 OXYGEN CO3. OXYGEN - CO2 CHO j f l ’ i d-major component of plant’s organic compounds
  6. 6. ELEMENT FORM AVAILABLE IN PLANTS MAJOR FUNCTIONS Nitrogen NO3 - , NH4 + Component of nucleic acids, proteins, hormones, and coenzymes Sulfur SO4 -2 Component of proteins, coenzymes Phosphorus H2PO4 -, HPO4 2- Component of nucleic acid, phospholipids, ATP,Phosphorus H2PO4 , HPO4 Component of nucleic acid, phospholipids, ATP, several coenzymes Potassium K+ Cofactor that functions in protein synthesis; majorPotassium K Cofactor that functions in protein synthesis; major solute in water balance; operation of stomata Calcium Ca2+ Stability of cell walls, maintaining membraneCalcium Ca Stability of cell walls, maintaining membrane structure and permeability; enzyme cofactor, regulating stimulus response Magnesium Mg2+ Enzyme activator; component chlorophyllMagnesium Mg Enzyme activator; component chlorophyll
  7. 7. Micronutrients Required in very small amounts Usually cofactors for enzymes; can be recycled 8 micronutrients I1. Iron 2. Chlorine 3. Copper 4. Manganese 5. Zinc 6 Molybdenum6. Molybdenum 7. Boron 8. Nickel
  8. 8. ELEMENT AVAILABLE FORM IN PLANTS MAJOR FUNCTIONS Chlorine Cl- Essential in water splitting; water balanceC o e C sse a wa e sp g; wa e ba a ce Iron Fe 3+; Fe 2+ Activator of some enzymes; form parts of h d f hl h llcytochromes and nitrogenase; for chlorophyll synthesis Boron H2BO3- For chlorophyll synthesis; may be involved in nucleic acid synthesis CHO transport and membraneacid synthesis, CHO transport and membrane integrity Manganese Mn2+ Activator of some enzymes; active in the formation of amino acids’ required in water splitting; integrityof amino acids required in water splitting; integrity of chloroplast membrane Zinc Zn2+ Activator of some enzymes; formation of chlorophyll Copper Cu2+, Cu+ Activator of some enzymes involved in redox reactions; component of lignin-biosynthetic enzymes Molybdenum MoO 2- Nitrogen fixation and nitrate reductionMolybdenum MoO4 2 Nitrogen fixation and nitrate reduction Nickel Ni2+ Cofactor for an enzyme that functions in nitrogen metabolism
  9. 9. Mineral Deficiencyy 1. Function1. Function Chlorosis- yellowing of leaves Deficiency in Mg or FeDeficiency in Mg or Fe 2. Mobility Mg highly mobileMg- highly mobile Symptoms of deficiency show up 1st in older organs F i bilFe- immobile Symptoms of deficiency show up in younger organs
  10. 10. Assignmentg Make a list of deficiency symptoms of essentialMake a list of deficiency symptoms of essential elements
  11. 11. The role of soil bacteria in nitrogen t itinutrition
  12. 12. Plant hormones coordinate growth, development and responses to stimuliresponses to stimuli HormoneHormone Greek word “to excite” A small molecule that carries information from theA small molecule that carries information from the cell where it was produced to a particular target cells, causing a change in response to internal needscells, causing a change in response to internal needs or external stimuli Minute concentrations are requiredMinute concentrations are required Reaction to hormone: not on amounts but on relative concentration compared to other hormonesconcentration compared to other hormones
  13. 13. Signal-transduction pathwayg p y
  14. 14. Auxin Major site: shoot apical meristem Can be found also in embryo of seed young leavesCan be found also in embryo of seed, young leaves Movement: Polar transport: unidirectional Natural auxin: Indoleacetic acid (IAA)Na u a au : do eace c ac d ( ) Higher conc inhibit cell elongation (due to synthesis of ethylene- inhibitor of plant growth) Synthetic auxins: Naphthaleneacetic acid (NAA) 2 4 di hl h ti id (2 4 D) h bi id2,4-dichlorophenoxyacetic acid (2,4 D)- herbicide Agent Orange
  15. 15. Auxin Major function:Major function: cell elongation root growth (adventitious roots)root growth (adventitious roots) differentiation and branching Fruit development (seeds synthesize auxin)p ( y ) Apical dominance Phototropism and gravitropismp g p
  16. 16. Acid growth hypothesisg yp
  17. 17. Cytokininy Stimulate cytokinesis or cell divisionStimulate cytokinesis or cell division Discovered from coconut milk
  18. 18. Cytokininy Sites: growing tissues in roots, embryos and fruitsSites: growing tissues in roots, embryos and fruits Major functions Cell division and differentiationCell division and differentiation Counteracting apical dominance Delaying aging of leavesDelaying aging of leaves
  19. 19. Role of cytokinin and auxiny
  20. 20. Gibberellins Cell elongation and seed germination Derived its name from Gibberella, a fungus Site: apical meristems; young leaves and embryos bolting
  21. 21. Gibberellins Major functions: Stem elongation GA – facilitate movement of expansins into correct position in cell wallin cell wall Reverse dwarfism Seed germinationg Stimulate production of alpha-amylase Juvenility Promotes flowering Biennials flower in their first year F i f i i i f f iFruit formation -- increases size of fruits
  22. 22. Abscisic Acid Terpenoid hormoneTerpenoid hormone Sites: leaves, stems, roots and green fruit Slows growthSlows growth seed dormancy Dormant buds inhibits cell division of vascular cambiumDormant buds, inhibits cell division of vascular cambium Stress hormones Closes stomataCloses stomata Water shortage can stress the root system production of ABA transported to leavesproduction of ABA transported to leaves
  23. 23. Ethyleney Gaseous formGaseous form Initiated by high concentrations of AUXIN ripening fruits nodes of stems senescent leaves andripening fruits, nodes of stems, senescent leaves and flowers
  24. 24. Ethyleney Major functionsMajor functions Represses growth in length while stimulating expansion in widthexpansion in width Ethylene production: stimulated by touch, wind or any damageany damage Growth maneuver: triple response 1 Slowing of stem or root elongation1. Slowing of stem or root elongation 2. Thickening of root or stem 3. Curving to grow horizontally3. Curving to grow horizontally
  25. 25. Ethyleney Major functions:Major functions: Abscission of leaves Senescence/ agingSenescence/ aging Progression of irreversible change that eventually leads to deathto death Related to fruit ripening and leaf abscission Fruit ripeningFruit ripening Chlorophyll degradation Softening of fruitSoftening of fruit
  26. 26. Brassinosteroids Newly discoveredy Steroid First discovered in Brassica, which includes cabbage Bind to receptor protein the plasma membrane Act like auxin Stimulate cell division and elongation in stems Cause differentiation of xylem cells Pollen tube growthPollen tube growth Slow root growth Delay leaf abscissionDelay leaf abscission
  27. 27. Additional phytohormonesp y Polyaminesy Cell division and synthesis of DNA, RNA, and proteins Root initiation and tuber formation Development of embryos, flowers and fruit Jasmonic acid Fatty acid Inhibits growth of seeds, pollen and roots P t l ti f t i i dPromotes accumulation of proteins in seeds Stimulates formation of flower, fruit and seed Plant defensePlant defense
  28. 28. Growth responses I T iI. Tropisms Growth response that result in curvature of plant OWA AWA forgans TOWARD or AWAY from stimuli Negative and positive tropism hA. Phototropism B. Gravitropism ThC. Thigmotropism D. Heliotropism H d iE. Hydrotropism F. Chemotropism
  29. 29. A. Phototropism - lightp g Influenced by IAAInfluenced by IAA Movement of auxin to darker sidedarker side Ensures that leaves & stem will intercept lightstem will intercept light for photosyn
  30. 30. B. Gravitropism itgravity Controlled by Ca &y IAA Results in stems growing up while roots grow down Ensures that roots will encounter water & minerals
  31. 31. C. Thigmotropism – touchg p Involves ethyleney Release of ethylene inhibits growth ong the side that touches an object Allows plts to climb obj. inc. plts chances of intercepting light for photosyn
  32. 32. Growth responses II N ti tII. Nastic movements direction of response independent of direction ofdirection of response independent of direction of stimulus Seismonasty – a nastic movement resulting fr contactSeismonasty a nastic movement resulting fr contact or mech disturbances such as shaking
  33. 33. Growth responses II N ti tII. Nastic movements SeismonastySeismonasty
  34. 34. Nyctinasty- sleeping movements nastic response caused daily rhythms of light & dark
  35. 35. Growth responses III Ph t i diIII. Photoperiodism Photoperiod- relative lengths of night and dayPhotoperiod relative lengths of night and day Response to changes in the photoperiod Detected by phytochrome and cryptochromesDetected by phytochrome and cryptochromes Short day plants- poinsettias Long day plants cloverLong day plants- clover Day neutral plants- corn, impatiens