O slideshow foi denunciado.
Utilizamos seu perfil e dados de atividades no LinkedIn para personalizar e exibir anúncios mais relevantes. Altere suas preferências de anúncios quando desejar.
Evolutionary
Transitions from C3 to
C4 plantsSUBMITTED BY: HAFSA ARSHAD
ROLL NUMBER: BBOF17M006
Submitted to: SIR ZAFAR IQBAL
2
DEPARTMENT OF BOTANY
UNIVERSITY OF SARGODHA
Plant Evolutionary
History
Life began in water
The earliest plants were aquatic
• Since plants evolved to live without
wat...
Plants
adaptations
 Most adaptations involve in some
sort of trade off.
 For plants the trade off with
photosynthesis is...
5
 The openings on leaves is called
stomata.
 This is where 𝐶𝑂2 and 𝑂2 can enter
and exit the plant.
 Water is also los...
6
 Those plants whose first product of
photosynthesis is 3 carbon compound.
 About 85% of plant species are 𝑪 𝟑 plants.
...
7
In 𝑪 𝟑 plants, the bundle sheet cells do
not contain chloroplast
Carbon dioxide fixation takes place
only at one place...
8
 𝑪 𝟑 photosynthesis is the major of
three pathways for carbon fixation by
plants.
 During hot days they close their
st...
9
 And send it to the Calvin cycle
instead of 𝐶𝑂2
 Peroxisomes and mitochondria split
the new compound and release 𝐶𝑂2
...
10
 Photorespiration uses ATP but
don’t make ATP.
 Photorespiration makes no
sugar
 Photorespiration decreases
photosyn...
11
 Photorespiration may be an evolutionary leftover
 In early atmosphere, with little 𝑂2 it didn’t matter if
rubisco ha...
12
o They include cereals, grains, wheat,
rice. Barley, oats, peanuts, cotton,
sugar beets, tobacco, spinach,
soybeans and...
13
 The plant whose first product of
photosynthesis is 4 carbon compound is
called C4 plant.
 Those plants which undergo...
14
 In 𝐶4 plants the bundle sheet cells
contain chloroplasts.
 Carbon dioxide fixation takes place
twice (one in mesophy...
15
Why plant use C4 mechanism ?
 Some plants which live in drought, at high temperature and
nitrogen and carbon dioxide l...
16
Why plant use C4 mechanism ?
 Fixation of oxygen starts the process of photorespiration instead of
carboxylation of su...
17
KRANZ ANATOMY
Their vascular bundles are surrounded by the two ring cells
 Inner ring
Contain bundle sheath cells (bun...
18
ADVANTAGES OF KRANZ ANATOMY
Main function of Kranz
anatomy is:
• To provide a site in which
CO2 concentrated around
rub...
19
MECHANISM OF C4 PLANTS
FIRST STEP:
Conversion of (PEP) into oxalo-acetic acid
 In this step CO2 react with phosphoenol...
20
MECHANISM OF C4 PLANTS
2nd STEP:
Conversion of OAA into Malate
 In this step oxaloacetic acid is converted into Malate...
21
MECHANISM OF C4 PLANTS
3rd STEP:
Conversion of Malate into pyruvic acid
 In this step malate is transported into bundl...
22
MECHANISM OF C4 PLANTS
4th STEP:
Conversion of pyruvic acid into PEP
 In this step pyruvic acidreacts with ATP and reg...
23
C4 MECHANISM
24
 𝐶4 photosynthesis is an adaptation for
plants living in hot, arid climate
 Some plants that live in hot, dry climate...
25
 𝐶4 plants have
adaptations that allow
them to minimize the
effect of photorespiration.
𝐶4 Adaptations
26
 They have an alternate
means of fixing carbon.
 𝐶4 plants fix carbon out in
the cytoplasm before it
enters the Calvi...
27
 They have special type of
leaf anatomy
 They tolerate high
temperatures.
 They show response to
high light intensit...
28
 The large cells present
around the vascular
bundle of the 𝐶4 pathway
plants are known as
bundle sheath cells.
 The l...
29
𝑪 𝟒 Plants undergo
𝑪 𝟒 cycle which is
also known as
Hatch And Slack
cycle.
Hatch and slack cycle
30
 1st step is binding 𝐶𝑂2 to PEP (Phosphoenolpyruvate) by enzyme PEP
carboxylase to make a 4-C compound
 PEP has a hig...
31
 They have greater productivity in biomass.
 Despite having Oxaloacetic acid as the first 𝐶𝑂2 fixation product
they u...
32
 𝐶4 plants thrive in hot
climate where stomata
will be closed often
 Some important 𝐶4
plants are sugarcane,
corn, tr...
33
This adaptation allows 𝐶4 plants
to keep a high concentration of
𝐶𝑂2 in the photosynthetic cells,
preventing from build...
34
They include black mustard seed,
watercress, lettuce, cabbage,
maize, sorghum, millets, switch-
grass, broccoli, caulif...
COMPARISON
𝑪 𝟑 Plants
 Photosynthesis occur in mesophyll
tissues
• The carbon dioxide accepter is
RuBisco
• KRANZ anatomy...
COMPARISON
𝑪 𝟑 Plants
 The optimum temperature is 20 -
25°C.
 Photo-respiratory loss is high.
 Photosynthetic rate is l...
𝑪 𝟑 Plants 𝑪 𝟒 Plants
Most plants Tropical grasses like
corn, sugarcane
Fix carbon in Calvin cycle –
attach 𝐶𝑂2 to RuBP
Fi...
38
CARBON FIXATION
 C4 pathway is certainly more efficient than C3 pathway in
sense of carbon fixation.
 The enzyme resp...
39
Why is C3 photosynthesis inefficient
 C3 plants have disadvantage that in hot dry conditions their
photosynthetic effi...
40
Leaf Anatomy Of 𝐶3 & 𝐶4 Plants
41
𝐶3 & 𝐶4 cycles
42
Significance of 𝑪 𝟒 Plants
43
 In 𝑪 𝟒 plants, it increase the
photosynthetic yield two to three
times more than 𝑪 𝟑 plant...
THANK YOU!
Email
hafsaranjha.botanist@gmail.com
Próximos SlideShares
Carregando em…5
×

Evolutionary transitions from c 3 to c 4 plants

C3 and C4 plants transitions adaptations of C3 plants to C4 plants
what are C3 and C4 plants

  • Seja o primeiro a comentar

  • Seja a primeira pessoa a gostar disto

Evolutionary transitions from c 3 to c 4 plants

  1. 1. Evolutionary Transitions from C3 to C4 plantsSUBMITTED BY: HAFSA ARSHAD ROLL NUMBER: BBOF17M006
  2. 2. Submitted to: SIR ZAFAR IQBAL 2 DEPARTMENT OF BOTANY UNIVERSITY OF SARGODHA
  3. 3. Plant Evolutionary History Life began in water The earliest plants were aquatic • Since plants evolved to live without water, they had a hard time dealing with dehydration 3
  4. 4. Plants adaptations  Most adaptations involve in some sort of trade off.  For plants the trade off with photosynthesis is that they lose water to the environment through transpiration. 4
  5. 5. 5  The openings on leaves is called stomata.  This is where 𝐶𝑂2 and 𝑂2 can enter and exit the plant.  Water is also lost through stomata.  Plants often close stomata in very hot days, and also 𝐶𝑂2 intake cuts off. A little plant anatomy
  6. 6. 6  Those plants whose first product of photosynthesis is 3 carbon compound.  About 85% of plant species are 𝑪 𝟑 plants.  The term 𝑪 𝟑 photosynthesis is ancestral pathway for carbon fixation.  It occurs in all taxonomic plant groups.  The term 𝑪 𝟑 photosynthesis is based on the observations that the first product of photosynthesis is a 3-carbon molecule.  In this way such plants are known as 𝑪 𝟑 plants. 𝐶3 Plants
  7. 7. 7 In 𝑪 𝟑 plants, the bundle sheet cells do not contain chloroplast Carbon dioxide fixation takes place only at one place. 𝐶3 Plants
  8. 8. 8  𝑪 𝟑 photosynthesis is the major of three pathways for carbon fixation by plants.  During hot days they close their stomata part way and produce little sugar. 𝐶3 Mechanism
  9. 9. 9  And send it to the Calvin cycle instead of 𝐶𝑂2  Peroxisomes and mitochondria split the new compound and release 𝐶𝑂2  This is called photorespiration.  s the 𝐶𝑂2 is used up by plant, rubisco fix 𝑂2 instead
  10. 10. 10  Photorespiration uses ATP but don’t make ATP.  Photorespiration makes no sugar  Photorespiration decreases photosynthesis output.
  11. 11. 11  Photorespiration may be an evolutionary leftover  In early atmosphere, with little 𝑂2 it didn’t matter if rubisco had an affinity for 𝑂2  Today with so much 𝑂2 in the atmosphere, it is inevitable that some 𝑂2 will be fixed in the environment. So why would any plant do this…
  12. 12. 12 o They include cereals, grains, wheat, rice. Barley, oats, peanuts, cotton, sugar beets, tobacco, spinach, soybeans and most trees are 𝑪 𝟑 plants. o Most lawn grasses rye and fescue are 𝑪 𝟑 plants. 𝐶3 Crop Plants
  13. 13. 13  The plant whose first product of photosynthesis is 4 carbon compound is called C4 plant.  Those plants which undergo 𝐶4 photosynthesis are known as 𝐶4 plants.  𝐶4 photosynthesis occur in more advanced plant taxa and specially common among dicots(most trees and shrubs).  𝐶4 plants evolved independently in a hot, dry environment where their stomata must be partially closed during the day. 𝐶4 Plants
  14. 14. 14  In 𝐶4 plants the bundle sheet cells contain chloroplasts.  Carbon dioxide fixation takes place twice (one in mesophyll cells, second in bundle sheath cells).  In 𝐶4 photosynthesis the initial photosynthetic product is 4-carbon molecule. 𝐶4 Plants
  15. 15. 15 Why plant use C4 mechanism ?  Some plants which live in drought, at high temperature and nitrogen and carbon dioxide limitation environment, they use C4 mechanism  Because C4 plants fix more carbon dioxide as compared to C3 plants due to having KRANZ anatomy  C4 plants lose 277 molecules of water to fix per molecule of CO2 as compared to c3 use 833 molecules of water approximately at 30°C  They also avoid photorespiration process  C4 enzyme fix carbon more efficiently as compared to C3 plants who also fix oxygen during carbon fixation process
  16. 16. 16 Why plant use C4 mechanism ?  Fixation of oxygen starts the process of photorespiration instead of carboxylation of substrate, substrate oxidize and as a result loss and start the process of photorespiration.  This process occur due to the dual activity of rubisco present in C3 plants such as oxygenase and carboxylase activity.
  17. 17. 17 KRANZ ANATOMY Their vascular bundles are surrounded by the two ring cells  Inner ring Contain bundle sheath cells (bundle sheath cells contain starch rich chloroplast lacking grana)  Outer ring Contain mesophyll cells
  18. 18. 18 ADVANTAGES OF KRANZ ANATOMY Main function of Kranz anatomy is: • To provide a site in which CO2 concentrated around rubisco • And avoiding photorespiration mechanism
  19. 19. 19 MECHANISM OF C4 PLANTS FIRST STEP: Conversion of (PEP) into oxalo-acetic acid  In this step CO2 react with phosphoenol pyruvic acid to form oxaloacetic acid  This reaction takes place in the presence of enzyme phosphoenol pyruvate carboxylase
  20. 20. 20 MECHANISM OF C4 PLANTS 2nd STEP: Conversion of OAA into Malate  In this step oxaloacetic acid is converted into Malate  This reaction is catalyzed by malate dehydrogenase.
  21. 21. 21 MECHANISM OF C4 PLANTS 3rd STEP: Conversion of Malate into pyruvic acid  In this step malate is transported into bundle sheath cell. In bundle sheath cells it is converted into pyruvic acid by releasing CO2
  22. 22. 22 MECHANISM OF C4 PLANTS 4th STEP: Conversion of pyruvic acid into PEP  In this step pyruvic acidreacts with ATP and regenerate phosphoenol pyruvate.  This reaction takes place in the presence of pyruvate orthophosphate dikinase.
  23. 23. 23 C4 MECHANISM
  24. 24. 24  𝐶4 photosynthesis is an adaptation for plants living in hot, arid climate  Some plants that live in hot, dry climates maintain low oxygen levels in their leaves by keeping stomata closed to prevent water loss.  𝐶4 plants have special leaf anatomy with prominent bundle sheath cells surrounding the leaf veins. 𝐶4 Adaptations
  25. 25. 25  𝐶4 plants have adaptations that allow them to minimize the effect of photorespiration. 𝐶4 Adaptations
  26. 26. 26  They have an alternate means of fixing carbon.  𝐶4 plants fix carbon out in the cytoplasm before it enters the Calvin Cycle
  27. 27. 27  They have special type of leaf anatomy  They tolerate high temperatures.  They show response to high light intensities.
  28. 28. 28  The large cells present around the vascular bundle of the 𝐶4 pathway plants are known as bundle sheath cells.  The leaves which have such anatomy are said to have KRANZ anatomy. Bundle Sheath Cells
  29. 29. 29 𝑪 𝟒 Plants undergo 𝑪 𝟒 cycle which is also known as Hatch And Slack cycle. Hatch and slack cycle
  30. 30. 30  1st step is binding 𝐶𝑂2 to PEP (Phosphoenolpyruvate) by enzyme PEP carboxylase to make a 4-C compound  PEP has a high affinity of 𝐶𝑂2 and none for 𝑶 𝟐  The 4-Carbon compound enters the photosynthetic cells.  𝑪𝑶 𝟐 is released from PEP and Calvin cycle continues as normal 𝐶4 Plant Adaptation s
  31. 31. 31  They have greater productivity in biomass.  Despite having Oxaloacetic acid as the first 𝐶𝑂2 fixation product they use 𝑪 𝟑 pathway or Calvin cycle as the main biosynthetic pathway  𝐶4 plants have twice as the photosynthetic capacity as 𝐶3 plants and can cope with higher temperature, less water and available nitrogen.
  32. 32. 32  𝐶4 plants thrive in hot climate where stomata will be closed often  Some important 𝐶4 plants are sugarcane, corn, tropical grasses
  33. 33. 33 This adaptation allows 𝐶4 plants to keep a high concentration of 𝐶𝑂2 in the photosynthetic cells, preventing from building of 𝑶 𝟐 instead of 𝐶𝑂2
  34. 34. 34 They include black mustard seed, watercress, lettuce, cabbage, maize, sorghum, millets, switch- grass, broccoli, cauliflower, turnip etc. 𝐶4 Crop Plants
  35. 35. COMPARISON 𝑪 𝟑 Plants  Photosynthesis occur in mesophyll tissues • The carbon dioxide accepter is RuBisco • KRANZ anatomy is absent • The 1st stable compound formed is 3C compound called 3- phosphoglyceric acid (PGA). 𝑪 𝟒 Plants  Photosynthesis occurs both in mesophyll and bundle sheath cells.  The carbon dioxide acceptor is PEP carboxylase.  KRANZ anatomy is present  The 1st stable compound is 4- carbon Oxaloacetic acid (OAA) 35
  36. 36. COMPARISON 𝑪 𝟑 Plants  The optimum temperature is 20 - 25°C.  Photo-respiratory loss is high.  Photosynthetic rate is low.  They are more adapted to environment with more carbon dioxide. 𝑪 𝟒 Plants  The optimum temperature is 35 – 44°C.  Photorespiration does not takes place.  Photosynthetic rate is comparatively high  They are more adapted to environment with more oxygen. 36
  37. 37. 𝑪 𝟑 Plants 𝑪 𝟒 Plants Most plants Tropical grasses like corn, sugarcane Fix carbon in Calvin cycle – attach 𝐶𝑂2 to RuBP Fix carbon in cytoplasm - attach 𝐶𝑂2 to PEP Enzyme - Rubisco Enzyme – PEP-ase Most energy efficient method Less efficient Lose water through photorespiration Lose less water Comparison of 𝐶3 & 𝐶4 Plants 37
  38. 38. 38 CARBON FIXATION  C4 pathway is certainly more efficient than C3 pathway in sense of carbon fixation.  The enzyme responsible for this step is rubisco  In C4 plants the inner cells get only carbon dioxide in the form of malate.  This avoid the oxygenation process and hence makes the pathway more efficient
  39. 39. 39 Why is C3 photosynthesis inefficient  C3 plants have disadvantage that in hot dry conditions their photosynthetic efficiency suffers because of processes called photorespiration.  When CO2 concentration in chloroplast drops below about 50ppm, the catalyst rubisco helps to fix carbon begin to fix oxygen instead
  40. 40. 40 Leaf Anatomy Of 𝐶3 & 𝐶4 Plants
  41. 41. 41 𝐶3 & 𝐶4 cycles
  42. 42. 42
  43. 43. Significance of 𝑪 𝟒 Plants 43  In 𝑪 𝟒 plants, it increase the photosynthetic yield two to three times more than 𝑪 𝟑 plants  In 𝑪 𝟒 plants, it performs a high rate of photosynthesis even when the stomata are nearly closed.  It increases the adaptability of 𝑪 𝟒 Plants to high temperature and light intensities.  They can grow very well in saline soils because of presence of 𝑪 𝟒 organic acid.
  44. 44. THANK YOU! Email hafsaranjha.botanist@gmail.com

×