PP1701a.jpg.

Slides:



Advertisements
Similar presentations
Julia Rausenberger Zentrum für Biosystemanalyse Universität Freiburg
Advertisements

Light Receptors and Pathogens
Light regulation of plant development
Plant Tropism and Defenses Lights important affect on plants – Photosynthesis… conversion of CO2 & H2O to energy containing carbon compounds and O2 – Phototropism…
Biological Rhythms Endogenous: Endogenous: internal body clock Exogenous: Exogenous: controlled by environmental stimuli Most rhythms are endogenous but.
Plant Responses to Stimuli Tropism = change in growth pattern in response to an environmental stimulus –Phototropism = response to light Auxin is produced.
Photomorphogenesis (control of growth & development by light) Environmental signals (light, temperature and gravity) are important signals for plant development.
Lectures in Plant Developmental Physiology, 2 cr. Department of Biological and Environmental Sciences Plant Biology Viikki Biocenter Spring 2006.
Growth Responses and Regulation of Growth
CHAPTER 8 Metabolic Respiration Overview of Regulation Most genes encode proteins, and most proteins are enzymes. The expression of such a gene can be.
Plant Biology MSc course Plants and their Environment 2007
MCB 186 CIRCADIAN BIOLOGY The cellular-molecular mechanism of the circadian clock DRUGS Lecture #3 October 18, 2006 J. W. Hastings.
Plant Responses to Signals IV Photomorphogenesis Circadian Rhythms Gravitropism
Brassinosteroid mutants show dwarf phenotypes Brassinosteroid signal transduction goes through kinases.
Skotomorphogenesis Seed germination Genes and enzymes Embryo and Seed development Plant life cycle Photomorphogenesis Photoreceptors Phytochrome Cells.
Cells and cell growth Membranes and cell walls Fertilization and embryogenesis Seed development and dormancy Germination Water transport Water relations.
Photomorphogenesis Skotomorphogenesis (etiolation)
Role of Phytochromes in Shade Avoidance Ecophysiological and Molecular aspects.
Plant-environment interaction 1: How do plants respond to light? Lecture 1: The phytochrome pathways Photomorphogenesis -- The light-induced developmental.
Phytochrome and flowering. When is the right time to flower? Unreliable indicators of time of year –Temperature –Moisture –Light levels Reliable: length.
Light and plant development
Plant Responses to Signals IV Photomorphogenesis Circadian Rhythms Gravitropism
The blue light signaling pathways
Plant Responses to Signals IV Photomorphogenesis Circadian Rhythms Gravitropism
Germination of lettuce seeds (photoreversibility)
Photomorphogenesis: responding to light
Photomorphogenesis Skotomorphogenesis (etiolation)
Plant Development Chapter 31 Part Adjusting the Direction and Rates of Growth  Tropisms Plants adjust the direction and rate of growth in response.
Plant Growth & Development
Plant timing responses. Like animals, plants have both exogenous and endogenous factors that control rhythms. Circadian rhythms shown by plants include:
Photomorphogenesis: plant responses to light Plant Phys and Biotech Biology 3470 Lecture 6, Tues. 24 Jan 2006 Text Chapter 17 Rost et al., “Plant biology”,
Christian Fleck Center for Biological Systems Analysis
Corn and mustard seedlings grown either in the light or the dark
CHAPTER 39 PLANT RESPONSES TO INTERNAL AND EXTERNAL SIGNALS Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Section C: Plant.
Plant Responses to Signals IV Photomorphogenesis Circadian Rhythms Gravitropism
How do light signals control nuclear genes for leaf & plastid development? Can divide into 3 basic steps (or parts): 1.Receiving the signal (photoreceptors)
Chapter 39: Plant Responses to Internal and External Signals Jay Swan Cincinnati, Ohio.
Plants must be able to respond to ever-changing environment –How is growth regulated? –When should reproductive structures develop? –When should germination.
Travismulthaupt.com Chapter 39 Plant Responses to Internal and External Signals.
 Set up a prism in class to create a rainbow from sunlight. Ask students to explain the “rainbow.” Position the prism under incandescent and fluorescent.
Plant Responses Chapter 39.
bringing-big-changes-to-forests, Arabidopsis 2.Fast plant 3. Sorghum 4. Brachypodium distachyon.
Plants. Transport in plants Vascular vessels- – Xylem – water & minerals up to leaves – Phloem – water & food – up & down to parts of plant (products.
Seeds – Part 3 1. Dormancy b.) Primary: dormancy that is initiated during seed development i. Exogenous 1) Physical – e.g., seed coat, fruit parts Scarification.
Tropic responses Directional movements by growth in response to a directional stimulus.
Biological clock An innate mechanism in living organisms that controls the periodicity or rhythm of various physiological functions or activities. Circadian.
Chapter 17. Phytochrome and Light Control of Plant Development.
Chapter 39 Plant Responses: Long-Day and Short Day Plants Essential Idea: Reproduction in flowering plants is influenced by the biotic and abiotic environment.
Plant biofuel related Novel biofuel
Light regulation of growth
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 36 Plant Growth and Development.
Chapter VII Plant Photomorphogenensis
Plant Timing Responses
Neuronal Control of Behavior
Seed germination Seeds remain dormant until sense appropriate conditions: Many require light: says that they will soon be able to photosynthesize: often.
Help needed for the Art & Science Day at the Chester Street Elementary school 110 Chester St, Kingston 12- 3:30 on Tuesday, March 22.
The biological measurement of the relative lengths of day and night
Plant Control Systems It’s a Hormonal Thing!.
Plant Responses to Internal and External Signals
Linkage of ubiquitin system between plant and mammalian
Volume 8, Issue 3, Pages (March 2015)
Chapter 39- The Response in Plants to Internal and External Stimuli
Photoperiodism: The Coincidental Perception of the Season
Volume 11, Issue 4, Pages (April 2018)
The Phytochrome System
The biological measurement of the relative lengths of day and night
The Chapter 31 Test has been postponed until April 3
Light regulation of Plant Development
Plant defense responses Hypersensitive response
Phytochrome has 2 forms Red-absorbing phytochrome
Presentation transcript:

PP1701a.jpg

PP1701b.jpg

PP1701c.jpg

PP1701d.jpg

PHYTOCHROME AND PHOTOMORPHOGENESIS A blue protein pigment with a molecular mass of about 125 kDa. Mediates photomorphogenesis responses to red (660 nm) and far-red (730 nm) light.

PP17T010.jpg

PP1702a.jpg

PP1702b.jpg

PP1702c.jpg

PP1702d.jpg

PP1702e.jpg

PHYTOCHROME CAN INTERCONVERT BETWEEN Pr AND Pfr FORMS Red light Pr Pfr Far-red light

PP17030.jpg

PHOTOSTATIONARY STATE - Red Light When Pr molecules absorb red light, most are converted to Pfr. Since Pfr molecules can also absorb red light (see absorption spectrum), some of the Pfr molecules are converted back to Pr. Thus after saturating irradiation with red light, only about 85% conversion of Pr to Pfr occurs.

PHOTOSTATIONARY STATE - Far-red light When Pfr molecules are exposed to far-red light, nearly all the molecules are converted to the Pr form. Since Pr molecules absorb almost no far-red light, there is almost no back reaction from Pr to Pfr. Thus, after saturating far-red light there is about 97% conversion of Pfr to Pr.

Pfr is the Physiologically Active Form of Phytochrome (Is phytochrome response due to build-up of Pfr or tp the loss of Pr?) In general, the magnitude of the physiological response to red light is proportional to the amount of Pfr produced. In some cases the magnitude of the response is proportional to the ration of Pfr to pr, or of Pfr to Ptot. Phytochrome deficient (hy) Arabidopsis mutants have long hypocotyls in both darkness and white light. If the red light response were due to a lack of Pr, we would expect the opposite to be true, i.e. the hypocotyls would be short in both darkness and white light.

PHYTOCHROME IS A DIMER COMPOSED OF TWO POLYPEPTIDES PP17050.jpg

Synthesized in plastids PP17040.jpg

Two Types of Phytochrome Have Been identified Type I a) About 9X more abundant in dark-grown tissues. b) The Pfr form is rapidly degraded. c) The Pfr form feed-back inhibits its own synthesis. Type II a) Present in in equal amounts with Type I phytochrome in light-grown tissues. b) The Pfr form is not degraded. c) Synthesis of Type II phytochrome is not feed-back inhibited by Pfr.

Phytochrome is Encoded By a Multigene Family 1. Arabidopsis has five structurally related phytochrome genes: PHYA, PHYB, PHYC, PHYD, and PHYE. 2. PHYA is the only Type I phytochrome 3. PHYB - PHYE are all Type II phytochromes.

Types I and II Phytochromes are Regulated Differently Red 1. PHYA mRNA Pr Pfr Response Far-red Ubiquitin + ATP Degradation Degradation Red 2. PHYB-E mRNA Pr Pfr Response Far-red

PP17060.jpg

PHYTOCHROME RESPONSES VARY IN LAG TIME LAG TIME - THE TIME BETWEEN THE STIMULUS AND THE OBSERVED RESPONSE A. PHYTOCHROME RESPONSES MAY BE RAPID (A FEW MINUTES) OR LONG TERM (SEVERAL WEEKS).

PHYTOCHROME RESPONSES VARY IN THE AMOUNT OF LIGHT REQURIED A. FLUENCE - TOTAL NUMBER OF PHOTONS IMPINGING ON A UNIT SURFACE AREA (micromoles/m2) VLFR - VERY LOW FLUENCE RESPONSE LFR - LOW FLUENCE RESPONSE B. IRRADIANCE - FLUENCE RATE; NUMBER OF PHOTONS IMPINGING ON UNIT SURFACE AREA PER UNIT TIME (micromoles/m2/s) 1. HIR - HIGH IRRADIANCE RESPONSE

PHYTOCHROME RESPONSES VARY IN THEIR RECIPROCITY LAW OF RECIPROCITY - FLUENCE = FLUENCE RATE X TIME (micromoles/m2) = (micromoles/m2/sec) X (sec) B. According to the Law of Reciprocity, treating plants with a brief duration of high fluence rate (bright) light will five the same response as treating them with a long duration of low fluence rate (dim) light. C. Reciprocity applies to most photochemical reactions, like the exposure of film.

PP17070.jpg

PP17080.jpg

PP17T020.jpg

PP17090.jpg

PP17100.jpg

PP17T040.jpg

ECOLOGICAAL FUNCTIONS OF PHYTOCHROME: SHADE AVOIDANCE PHYTOCHROME HELPS PLANTS TO ADAPT TO CHANGING LIGHT CONDITIONS BY SENSING THE RATIO OF RED AND FAR-RED LIGHT

PP17T030.jpg

ECOLOGICAAL FUNCTIONS OF PHYTOCHROME: SHADE AVOIDANCE PHYTOCHROME HELPS PLANTS TO AVOID SHADING BY OTHER PLANTS BY SENSING THE RATIO Pfr/Ptotal A GREATER PROPORTION OF FAR-RED LIGHT CONVERTS MORE Pfr TO Pr, AND THE Pfr/Ptotal RATIO DECREASES. ONLY “SUN PLANTS’ EXHIBIT SHADE AVOIDANCE. “SHADE PLANTS” ARE ADAPTED TO SHADING, AND THEREFORE DO NOT EXHIBIT SHADE AVOIDANCE.

PP17110.jpg

PHYTOCHROME REGULATES CIRCADIAN RHYTHMS CIRCADIAN RHYTHM = APPROXIMATELY A DAY PERIOD = TIME BETWEEN SUCCESSIVE PEAKS OR TROUGHS IN A CYCLE ENDOGENOUS RHYTHM = UNAFFECTED BY EXTERNAL STIMULI; REGULATED BY INTERNAL FACTORS OSCILLATOR = BIOLOGICAL CLOCK MECHANISM TEMPERATURE COMPENSATION = RHYTHM UNAFFECTED BY TEMPERATURE ENTRAINMENT = ABILITY OF A STIMULUS (TYPICALLY LIGHT) TO RESET OR SYNCHRONIZE THE RHYTHM.

PP17130.jpg

PP17140.jpg

THE CIRCADIAN OSCILLATOR INVOLVES A TRANSCRIPTIONAL NEGATIVE FEEDBACK LOOP PP17180.jpg

DIFFERENT PHYTOCHROMES HAVE DIFFERENT ECOLOGICAL FUNCTIONS PHYTOCHROME B MEDIATES THE RESPONSE TO CONTINUOUS RED OR WHITE LIGHT PHYTOCHROME A IS REQUIRED FOR THE RESPONSE TO CONTINUOUS FAR-RED LIGHT PHYA AND PHYB CAN HAVE MUTUALLY ANTAGONISTIC EFFECTS

PP17151.jpg

PP17152.jpg

PP17160.jpg

PHYTOCHROME REGULATES GENE EXPRESSION THE STIMULATION AND REPRESSION OF GENE TRANSCRIPTION BY LIGHT CAN BE VERY RAPID (~5 MINUTES). THESE RAPID CHANGES INVOLVE DIRECT ACTIVATION OF TRANSCRIPTION FACTORS BY ONE OR MORE SIGNAL TRANSDUCTION PATHWAYS. SOME OF THE EARLY GENE PRODUCTS ARE TRANSCRIPTION FACTORS WHICH ACTIVATE THE EXPRESSION OF OTHER GENES. EXPRESSION OF THE EARLY GENES, CALLED PRIMARY RESPONSE GENES, IS INDEPENDENT OF PROTEIN SYNTHESIS AND INVOLVES ACTIVATION OF PRE-EXISTING TRANSCRIPTION FACTOR PROTEINS

Secondary response gene Primary response gene PP17170.jpg

PHYTOCHROME MOVES INTO THE NUCLEUS phyA-GFP, continuous FR light phyB-GFP, continuous white light PP1719.jpg

PP17200.jpg

Phytochrome is a Serine/Threonine Protein Kinase Cyanobacterial phytochrome is part of a two-component system signal transduction pathway Cyanobacterial phytochrome is a histidine kinase Eukaryotic phytochrome is a serine/threonine kinase.

PP17211.jpg

PP17212.jpg

PP17221.jpg

PP17222.jpg