Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

phytochrome

•Download as PPTX, PDF•
•
sardar bahadur khan women university quetta
sardar bahadur khan women university quetta

This document provides an overview of phytochrome, a photoreceptor pigment found in plants. It discusses the two forms of phytochrome (Pr and Pfr), their absorption of different wavelengths of light, and their roles in regulating plant growth and development processes like seed germination, flowering, and circadian rhythms. It also mentions other plant photoreceptors like cryptochrome and their functions. Key processes that phytochrome is involved in include photomorphogenesis, photoperiodism, and the circadian clock in plants.

1 of 60
phytochrome
Beautiful quotation • A father’s goodness is higher than the mountain, A mother’s goodness is deeper than the sea.
Presented by Kulsoom PirJan baloch
Topic : Phytochrome
Sub topics 1… introduction of Phytochrome 7…Biosynthesis of phytochrome 2…Forms of phytochrome 8…photoperiodism 3…Discovery of phytochrome 9…Circadian clock in plants 4…photomorphogenesis 10… phytochrome system. 5…cryptochrome 6…Phytochrome concentration in plants
Introduction of phytochrome • Phytochrome is a photoreceptor, a pigment that plants, and some bacteria and fungi, use to detect light • It is sensitive to light in the red and far-red region of the visible spectrum. • In other word a blue-green pigment found in many plants, in which it regulates various developmental processes.
Introduction cont.. • Many flowering plants use it to regulate the time of flowering based on the length of day and night (photoperiodism) and to set circadian rhythms. • It also regulates other responses including the germination of seeds(photoblasty), elongation of seedlings, the size, shape and number of leaves etc •
phytochrome cont.. • This pigment has a regulatory role in all phases of plant growth and development (photomorphogenesis) and is apparently ubiquitous in all taxonomic groups of eukaryotic plants with the exception of fungi.
phytochrome cont… Light, in addition to providing the energy which drives photosynthesis,also acts as a regulatory environmental stimulus. Many light-controlled plant responses are now believed to be mediated by the photoreceptor, phytochrome.
Phytochrome cont.. • Other plant photoreceptors include cryptochromes, phototropins, and UVR8, which are sensitive to light in the blue and ultra-violet regions of the spectrum.
Forms of phytochrome • phytochrome has two different chemical structures that are inter-convertible. The forms are named by the color of light that they absorb maximally • Pr is a blue form that absorbs red light and Pfr is a blue-green form that absorbs far-red light
phytochrome
Forms of phytochrome conti.. • The phytochrome molecule is the photoreceptor for red light responses. It exists in two forms, Pr and Pfr. • Phytochrome is a family of proteins with a small covalently-bound pigment molecule •Phytochrome proteins occur as a dimer of two identical polypeptides,
phytochrome
phytochrome
Forms of phytochrome conti.. •When the chromophore absorbs light, there is a slight change in its structure. •The pigment is called the chromophore. It is a linear tetrapyrrole.(4pyrrol ring)
phytochrome
phytochrome
Forms of phytochrome cont… • The Pr form: •Absorbs at a peak of 660nm •Is the form synthesized in dark-grown seedlings. •When Pr absorbs red light, it is converted to the Pfr form
Forms conti.. • The Pfr form: •Absorbs at a peak of 730 nm. •The Pfr form is the active form that initiates biological responses. •When Pfr absorbs far red light, it is converted to the Pr form.
phytochrome
phytochrome
What is strange about these pigments ???? When these pigments absorbed light (photon), they change chemically into the OTHER form. The two forms of phytochrome differ in their absorption spectra.
phytochrome
Discovery • The phytochrome pigments was discovered by sterling hendricks and harry borthwick at the agricultural research center in maryland during a period from the late 1940s to the early 1960s . • By using spectrograph( an apparatus for photographing or recording spectra)
phytochrome
Plant pigment – phytochrome • A plant pigment is any type of colored substance produced by a plant. In general, any chemical compound which absorbs visible radiation between about 380 nm (violet) and 760 nm (ruby-red) is considered a pigment. • There are many different plant pigments, and they are found in different classes of organic compounds.
Plant pigment – phytochrome • Plant pigments give color to leaves, flowers, and fruits and are also important in controlling photosynthesis, growth, and development. • Phytochrome is a blue-green plant pigment which regulates plant development, including seed germination, stem growth,leaf expansion, pigment synthesis, and flowering.
phytochrome
photomorphogenesis • The process by which plant development is controlled by light is called photo- morphogenesis , typically photomorphogenic responses are most obvious in germinating seedlings but light affects plant development in many ways throughout all stages of development
phytochrome
Photomorphogenesis cont… • Light has profound effects on the development of plants . • Most striking effects of light are observed when a germinating seedling emerges from the soil and exposed to light for first time . • Normally the seedling radicle ( root) emerge first from the seed,
Photomorphogenesis cont.. • And shoot appears as the root becomes established . Later , with growth of the shoot ( particularly when it emerge into the light) there is increased secondary root formation and branching . • Simply it’s a coordinated progression of developmental responses ..
Photomorphogenesis cont.. • In this phenomena where the root affects the growth of the shoot and vice versa , to a large degree , the growth responses are hormones mediated.
Photomorphogenesis cont…
Analysis of Photomorphogenesis • Plants exhibit different growth habits in dark and light • In the dark they have elongated stems, undifferentiated chloroplasts and unexpanded leaves. This is called skotomorphogenesis. • Photomorphogenesis (light grown) involves the inhibition of stem elongation, the differentiation of chloroplasts and accumulation of chlorophyll, and the expansion of leaves.
Analysis of photomorphogenesis • Thus the same stimulus causes opposite effects on cell elongation in leaves and stems. Photomorphogenesis can be induced by red, far red and blue light. • You know that a pigment absorbs light and is altered electronically . • results in a change in other chemicals in the immediate environment to drive photosynthesis.
Analysis of photomorphogenesi cont…. • Chlorophyll is not the only important pigment, you learned about antenna pigments too. Today we are examining a pigment that fundamentally alters plant behavior. It is phytochrome. • Now the seed germination laboratory exercise with lettuce demonstrates a classic phytochrome effect.
Analysis of photomorphogenesis cont… • The seeds germinate better in red light and fail in far-red light compared to control seeds in kept in darkness.
phytochrome
phytochrome
cryptochromes The word cryptochrome is derived frome greek word crypto = hidden , chrome = colours • Cryptochromes are photoreceptors that regulates entrainment by light of the circadian clock in plants and animals .
Cryptochrome cont… • They also act as integral parts of the central circadian oscillator in animals brains and as receptors controlling photomorphogenesis in response to blue or UV light in plants. • Cryptochromes are flavoprotein photo- receptors first identified in Arabidopsis thaliana
Crypto… • Cryptochrome play key roles in growth and development . • A plant pigment that absorbs mainly blue and uv light and also involved in various plant responses to light. • Including phototropism and hypocotyl elongation
phytochrome
Cryptochrome absorbed blue light…..
Phytochrome concentrations vary within the plant…….
Biosynthesis of phytochrome.. • Phytochrome is produced in different parts of the cell and assembled from those parts. • The phytochrome binding protein is coded in nuclear genes, transcribed in the nucleus and translated on cytosolic ribosomes. • The phytochrome chromophore is produced in the plastid. These are assembled in the cytosol.
Biosynthesis of phytochrome.. • phytochrome has been found to be associated with plastids in terms of final destination. • The phytochrome protein includes a kinase domain that, after exposure to red light (i.e. when the chromophore is in Pfr form), allows the protein to phosphorylate itself. This way the autophosphorylation of phytochrome protein activates it.
phytochrome
photoperiodism • the response of an organism to seasonal changes in day length. • Many flowering plants (angiosperms) use a photoreceptor protein, such as phytochrome or cryptochrome,to sense seasonal changes in night length, or photoperiod, which they take as signals to flower.
phytochrome
Phytochrome system… • The phytochrome system acts as a biological light switch. It monitors the level, intensity, duration, and color of environmental light. • The biologically-inactive form of phytochrome (Pr) is converted to the biologically-active form Pfr under illumination with red light. Far-red light and darkness convert the molecule back to the inactive form.
Phytochrome system cont.. • Pfr can slowly revert to Pr in the dark or break down over time. and then physiological response induced by red light is reversed. The active form of phytochrome (Pfr) can directly activate other molecules in the cytoplasm, or it can be trafficked to the nucleus, where it directly activates or represses specific gene expression.
phytochrome
phytochrome
Circadian clock in plants.. • Circadian rhythms govern many plant processes, including movements of organs such as leaves and petals, stomata opening, stem elongation, sensitivity to light of floral induction, metabolic processes such as respiration and photosynthesis and expression of a large number of different genes.
phytochrome
refrences • Yang X, Kuk J, Moffat K (2009). "Crystal structure of P. aeruginosa bacteriaphytochrome PaBphP photosensory core domain mutant Q188L". Proc. Natl. Acad. Sci. U.S.A. 106: 15639–15644. • Walker TS, Bailey JL. Two spectrally different forms of the phytochrome chromophore extracted from etiolated oat seedlings. Biochem J. 1968 Apr;107(4):603–605.
phytochrome

More Related Content

phytochrome

  • 2. Beautiful quotation • A father’s goodness is higher than the mountain, A mother’s goodness is deeper than the sea.
  • 5. Sub topics 1… introduction of Phytochrome 7…Biosynthesis of phytochrome 2…Forms of phytochrome 8…photoperiodism 3…Discovery of phytochrome 9…Circadian clock in plants 4…photomorphogenesis 10… phytochrome system. 5…cryptochrome 6…Phytochrome concentration in plants
  • 6. Introduction of phytochrome • Phytochrome is a photoreceptor, a pigment that plants, and some bacteria and fungi, use to detect light • It is sensitive to light in the red and far-red region of the visible spectrum. • In other word a blue-green pigment found in many plants, in which it regulates various developmental processes.
  • 7. Introduction cont.. • Many flowering plants use it to regulate the time of flowering based on the length of day and night (photoperiodism) and to set circadian rhythms. • It also regulates other responses including the germination of seeds(photoblasty), elongation of seedlings, the size, shape and number of leaves etc •
  • 8. phytochrome cont.. • This pigment has a regulatory role in all phases of plant growth and development (photomorphogenesis) and is apparently ubiquitous in all taxonomic groups of eukaryotic plants with the exception of fungi.
  • 9. phytochrome cont… Light, in addition to providing the energy which drives photosynthesis,also acts as a regulatory environmental stimulus. Many light-controlled plant responses are now believed to be mediated by the photoreceptor, phytochrome.
  • 10. Phytochrome cont.. • Other plant photoreceptors include cryptochromes, phototropins, and UVR8, which are sensitive to light in the blue and ultra-violet regions of the spectrum.
  • 11. Forms of phytochrome • phytochrome has two different chemical structures that are inter-convertible. The forms are named by the color of light that they absorb maximally • Pr is a blue form that absorbs red light and Pfr is a blue-green form that absorbs far-red light
  • 13. Forms of phytochrome conti.. • The phytochrome molecule is the photoreceptor for red light responses. It exists in two forms, Pr and Pfr. • Phytochrome is a family of proteins with a small covalently-bound pigment molecule •Phytochrome proteins occur as a dimer of two identical polypeptides,
  • 16. Forms of phytochrome conti.. •When the chromophore absorbs light, there is a slight change in its structure. •The pigment is called the chromophore. It is a linear tetrapyrrole.(4pyrrol ring)
  • 19. Forms of phytochrome cont… • The Pr form: •Absorbs at a peak of 660nm •Is the form synthesized in dark-grown seedlings. •When Pr absorbs red light, it is converted to the Pfr form
  • 20. Forms conti.. • The Pfr form: •Absorbs at a peak of 730 nm. •The Pfr form is the active form that initiates biological responses. •When Pfr absorbs far red light, it is converted to the Pr form.
  • 23. What is strange about these pigments ???? When these pigments absorbed light (photon), they change chemically into the OTHER form. The two forms of phytochrome differ in their absorption spectra.
  • 25. Discovery • The phytochrome pigments was discovered by sterling hendricks and harry borthwick at the agricultural research center in maryland during a period from the late 1940s to the early 1960s . • By using spectrograph( an apparatus for photographing or recording spectra)
  • 27. Plant pigment – phytochrome • A plant pigment is any type of colored substance produced by a plant. In general, any chemical compound which absorbs visible radiation between about 380 nm (violet) and 760 nm (ruby-red) is considered a pigment. • There are many different plant pigments, and they are found in different classes of organic compounds.
  • 28. Plant pigment – phytochrome • Plant pigments give color to leaves, flowers, and fruits and are also important in controlling photosynthesis, growth, and development. • Phytochrome is a blue-green plant pigment which regulates plant development, including seed germination, stem growth,leaf expansion, pigment synthesis, and flowering.
  • 30. photomorphogenesis • The process by which plant development is controlled by light is called photo- morphogenesis , typically photomorphogenic responses are most obvious in germinating seedlings but light affects plant development in many ways throughout all stages of development
  • 32. Photomorphogenesis cont… • Light has profound effects on the development of plants . • Most striking effects of light are observed when a germinating seedling emerges from the soil and exposed to light for first time . • Normally the seedling radicle ( root) emerge first from the seed,
  • 33. Photomorphogenesis cont.. • And shoot appears as the root becomes established . Later , with growth of the shoot ( particularly when it emerge into the light) there is increased secondary root formation and branching . • Simply it’s a coordinated progression of developmental responses ..
  • 34. Photomorphogenesis cont.. • In this phenomena where the root affects the growth of the shoot and vice versa , to a large degree , the growth responses are hormones mediated.
  • 36. Analysis of Photomorphogenesis • Plants exhibit different growth habits in dark and light • In the dark they have elongated stems, undifferentiated chloroplasts and unexpanded leaves. This is called skotomorphogenesis. • Photomorphogenesis (light grown) involves the inhibition of stem elongation, the differentiation of chloroplasts and accumulation of chlorophyll, and the expansion of leaves.
  • 37. Analysis of photomorphogenesis • Thus the same stimulus causes opposite effects on cell elongation in leaves and stems. Photomorphogenesis can be induced by red, far red and blue light. • You know that a pigment absorbs light and is altered electronically . • results in a change in other chemicals in the immediate environment to drive photosynthesis.
  • 38. Analysis of photomorphogenesi cont…. • Chlorophyll is not the only important pigment, you learned about antenna pigments too. Today we are examining a pigment that fundamentally alters plant behavior. It is phytochrome. • Now the seed germination laboratory exercise with lettuce demonstrates a classic phytochrome effect.
  • 39. Analysis of photomorphogenesis cont… • The seeds germinate better in red light and fail in far-red light compared to control seeds in kept in darkness.
  • 42. cryptochromes The word cryptochrome is derived frome greek word crypto = hidden , chrome = colours • Cryptochromes are photoreceptors that regulates entrainment by light of the circadian clock in plants and animals .
  • 43. Cryptochrome cont… • They also act as integral parts of the central circadian oscillator in animals brains and as receptors controlling photomorphogenesis in response to blue or UV light in plants. • Cryptochromes are flavoprotein photo- receptors first identified in Arabidopsis thaliana
  • 44. Crypto… • Cryptochrome play key roles in growth and development . • A plant pigment that absorbs mainly blue and uv light and also involved in various plant responses to light. • Including phototropism and hypocotyl elongation
  • 48. Biosynthesis of phytochrome.. • Phytochrome is produced in different parts of the cell and assembled from those parts. • The phytochrome binding protein is coded in nuclear genes, transcribed in the nucleus and translated on cytosolic ribosomes. • The phytochrome chromophore is produced in the plastid. These are assembled in the cytosol.
  • 49. Biosynthesis of phytochrome.. • phytochrome has been found to be associated with plastids in terms of final destination. • The phytochrome protein includes a kinase domain that, after exposure to red light (i.e. when the chromophore is in Pfr form), allows the protein to phosphorylate itself. This way the autophosphorylation of phytochrome protein activates it.
  • 51. photoperiodism • the response of an organism to seasonal changes in day length. • Many flowering plants (angiosperms) use a photoreceptor protein, such as phytochrome or cryptochrome,to sense seasonal changes in night length, or photoperiod, which they take as signals to flower.
  • 53. Phytochrome system… • The phytochrome system acts as a biological light switch. It monitors the level, intensity, duration, and color of environmental light. • The biologically-inactive form of phytochrome (Pr) is converted to the biologically-active form Pfr under illumination with red light. Far-red light and darkness convert the molecule back to the inactive form.
  • 54. Phytochrome system cont.. • Pfr can slowly revert to Pr in the dark or break down over time. and then physiological response induced by red light is reversed. The active form of phytochrome (Pfr) can directly activate other molecules in the cytoplasm, or it can be trafficked to the nucleus, where it directly activates or represses specific gene expression.
  • 57. Circadian clock in plants.. • Circadian rhythms govern many plant processes, including movements of organs such as leaves and petals, stomata opening, stem elongation, sensitivity to light of floral induction, metabolic processes such as respiration and photosynthesis and expression of a large number of different genes.
  • 59. refrences • Yang X, Kuk J, Moffat K (2009). "Crystal structure of P. aeruginosa bacteriaphytochrome PaBphP photosensory core domain mutant Q188L". Proc. Natl. Acad. Sci. U.S.A. 106: 15639–15644. • Walker TS, Bailey JL. Two spectrally different forms of the phytochrome chromophore extracted from etiolated oat seedlings. Biochem J. 1968 Apr;107(4):603–605.