Phytochrome.ppt
- 1. PRESENTATION ON THE TOPIC- ▪GUIDED BY- ▪DR PANKAJ BORGOHAIN ▪ASSISTANT PROFESSOR ▪DEPT OF BOTANY GAUHATI UNIVERSITY PRESENTED BY- NAME-SATABDI CHETRY PAPER CODE-BOT-2036 ROLL NO-PS-231-807- 0041 DEPT OF BOTANY GAUHATI UNIVERSITY
- 2. ❑INTRODUCTION ❑HISTORY AND DISCOVERY ❑FORMS OF PHYTOCHROME ❑CHEMICAL STRUCTURE ❑ TYPES OF PHYTOCHROME ❑MODE OF ACTION ❑PHYTOCHROME MEDIATED RESPONSES
- 3. Phytochrome is a photoreceptor ,a pigment that responsible for photomorphogenesis. Its absorbs red (650-750)nm and far red light (710- 850)nm . Biochemically it is a protein with a bilin chromophore. They are almost ubiquitous in green plants . Its regulate growth and development process like induction of flowering ,seed germination ,stem elongation etc.
- 4. ❑The phytochrome pigment was discovered by Harry Borthwick and Sterling Hendricks at the U.S. Department of Agriculture plant Industry Station in Beltsville, Maryland during a period from the late 1940s to the early 1960s . ❑They discoverd that red light was very effective for promoting germination or triggering flower responses.
- 5. By using spectograph (An apparatus for photographing or recording spectra)
- 6. ❑It exist in two forms Pr (650-680 nm) and Pfr (700- 740) form ,both are interconvertable.
- 7. The Pr form - Absorbs at a peak of 665 nm. Is the form synthesized in dark-grown seedings. When Pr absorbs red light ,it is converted to the Pfr form. The Pfr form- The Pfr form is the active form that initiates biological responses. Absorbs at a peak of 730 nm When Pfr absorbs far red light,it is converted to the Pr form. Prf can also spontaneously revert to the Pr form in the dark over time =dark reversion .
- 8. Pr form Pfr form ❑ Being inactive,it doesn’t show phytochrome mediated responses. ❑ It has an absorption maximum in red region (about 680 nm) ❑ It is found difused throughout the cytosol. ❑ It is converted into Pfr form in presence of red light. ❑ Being active,it shows phytochrome mediated responses. ❑ It has an absorption maximum in far red region(about 730 nm) ❑ Its usually found in discrete area of cytosol. ❑ It is converted into Pr form in presence of far red light .
- 10. Phytochrome Is a Dimer Composed of Two Polypeptides. Native phytochrome is a soluble protein It occurs as a dimer made up of two equivalent subunits- chromophore & apoprotein. Together, the apoprotein and its chromophore make up the holoprotein. In higher plants the chromophore of phytochrome is a linear tetrapyrrole termed phytochromobilin.
- 12. Phytochrome protein are encoded by phytochrome gene family termed as PHY TYPE-1 PHYTOCHROME Phytochrome is light sensitive ,so in light the transcription of PHY gene inhibited ,mRNA degradation and proteolysis takes place.TYPE- 1 phytochrome mainly function in dark. Example- PHY A TYPE-2 PHYTOCHROME Phytochrome is light stable,so present in both light grown and dark grown plants.Type-2 phytochrome mainly function in light. Example-PHY B,PHY C,PHY D& PHY E
- 13. COP 1- CONSITUTIVEPHOTOMORPHOGENIC 1,is a E3 Ubiqutin ligase ,which are involved in targetting proteins for 26s proteasome-mediated degradation. It inhibit the photomorphogenesis is in darfi by degrading the Phtochrome inducing factor(PIFs) In the darfi ,COP1 IS present in the nucleus,but in the light it is only found in the cytoplasm. HY5 - HY5 is a transcription factor that is a fiey regulator of photomorphogenesis in phytochrome pathway.In the light ,the level of HY5 protein increases and in the darfi ,it declines.
- 15. 1.Photoperiodism. 2.Seed germination 3.Elongation of leaf,petiole&stem. 4.Hypocotyl hook unfolding. 5.Pollen germination 6.Nyctinastic movements.
- 16. ❑Phytochromes are versatile photoreceptors essential for plant adaptation to their environment. ❑Understanding their structure and functions provides insights into plant growth and development, with implications for agriculture, horticulture, and environmental management. ❑Phytochromes serve as indispensable mediators of plant responses to light cues, orchestrating a myriad of developmental processes vital for plant survival and adaptation
- 17. ❑Phytochrome photosensory signalling networks. Nature Reviews Molecular Cell Biology, 3(2), 85-93.Rockwell, N. C., Su, Y. S., & Lagarias, J. C. (2006). ❑VK .JAIN Plant physiology ❑https:// www.slideshare.net/slideshow/phytochrome- 54535931/54535931 ❑Taiz, E., & Ziegler, I. M. (Year). Plant Physiology and Development (Edition). Sunderland, MA: Sinauer Associates