Transcript Document
Light regulation of growth Light as signal about their environment vs light as food Plants sense 1. Light quantity 2. Light quality (colors) 3. Light duration 4. Direction it is coming from Must have photoreceptors that sense specific wavelengths Types of Phytochrome Responses 2 classes based on speed 3 classes based on fluence Different responses = Different phytochromes Phytochrome • Protein degradation is important for light regulation • Cop mutants are defective in specific types of protein degradation • COP1 helps target transcription factors for degradation • W/O COP1 they act in dark • In light COP1 is exported to cytoplasm so TF can act • Other COPs are part of protein deg apparatus (signalosome) Other Phytochrome Responses Circadian rhythms: >30% of genes • Once entrained, continue in constant dark or light! • Give plant headstart on photosynthesis, other processes that need gene expression • Or elongate at night! Other Phytochrome Responses Circadian rhythms: a –ve loop of transcription-translation • Light & TOC1 activate LHY & CCA1 at dawn • LHY & CCA1 repress TOC1 in day, so they decline too • At night TOC1 is activated (not enough LHY & CCA1) Circadian rhythms: a –ve loop of transcription-translation • Light & TOC1 activate LHY & CCA1 at dawn • LHY & CCA1 transcribe PRR7&PRR9, whose proteins block LHY & CCA1 transcription, LHY &CCA1 proteins are degraded Circadian rhythms: a –ve loop of transcription-translation • In evening TOC1 activates ELF 3 & LUX, who block PRR7&PRR9 expression • ZTL marks TOC1 for degradation, but in blue light GI binds ZTL & stops this ZTL marks TOC1 for degradation, but in blue light GI binds ZTL & stops this ZTL is both a blue-receptor and an E3 ubiquitin-ligase substrate Receptor! GI binds and also protects it from degradation in blue light ZTL marks TOC1 for degradation, but in blue light GI binds ZTL & stops this ZTL is both a blue-receptor and an E3 ubiquitin-ligase substrate Receptor! GI binds and also protects it from degradation in blue light Transcribed at constant rate, but [protein] 3x higher @ dusk ZTL is both a blue-receptor and an E3 ubiquitin-ligase substrate receptor! GI binds and also protects it from degradation in blue light Transcribed at constant rate, but [protein] 3x higher @ dusk In dark GI released, so ZTL Ubs TOC1 (unless it has Pi) but also gets degraded ZTL is both a blue-receptor and an E3 ubiquitin-ligase substrate receptor! GI binds and also protects it from degradation in blue light Transcribed at constant rate, but [protein] 3x higher @ dusk In dark GI released, so ZTL Ubs TOC1 (unless it has Pi) but also gets degraded FKF1 is a related blue receptor that controls flowering FKF1 is a related blue receptor that controls flowering CDF1 binds CO promoter & blocks transcription FKF1 is a related blue receptor that controls flowering CDF1 binds CO promoter & blocks transcription FKF1 absorbs blue photon& binds GI FKF1 is a related blue receptor that controls flowering CDF1 binds CO promoter & blocks transcription FKF1 absorbs blue photon& binds GI Complex enters nucleus, finds CDF1 & tags it with Ub FKF1 is a related blue receptor that controls flowering CDF1 binds CO promoter & blocks transcription FKF1 absorbs blue photon& binds GI Complex enters nucleus, finds CDF1 & tags it with Ub CO can now be transcribed & induces FT, etc Blue Light Responses Circadian Rhythms Blue Light Responses Circadian Rhythms Solar tracking Blue Light Responses Circadian Rhythms Solar tracking Phototropism Blue Light Responses Circadian Rhythms Solar tracking Phototropism Inhibiting stem elongation Blue Light Responses Circadian Rhythms Solar tracking Phototropism Inhibiting stem elongation Chloroplast movement Blue Light Responses Circadian Rhythms Solar tracking Phototropism Inhibiting stem elongation Chloroplast movement Stomatal opening Blue Light Responses Circadian Rhythms Solar tracking Phototropism Inhibiting stem elongation Chloroplast movement Stomatal opening Gene expression Blue Light Responses Circadian Rhythms Solar tracking Phototropism Inhibiting stem elongation Chloroplast movement Stomatal opening Gene expression Flowering in Arabidopsis Blue Light Responses Circadian Rhythms Solar tracking Phototropism Inhibiting stem elongation Chloroplast movement Stomatal opening Gene expression Flowering in Arabidopsis Responses vary in their fluence requirements Blue Light Responses Circadian Rhythms Solar tracking Phototropism Inhibiting stem elongation Chloroplast movement Stomatal opening Gene expression Flowering in Arabidopsis Responses vary in their fluence requirements & lag time Blue Light Responses Responses vary in their fluence requirements & lag time Stomatal opening is reversible by green light; others aren’t Blue Light Responses Responses vary in their fluence requirements & lag time Stomatal opening is reversible by green light; others aren’t Multiple blue receptors with different functions! Blue Light Responses Responses vary in their fluence requirements & lag time Stomatal opening is reversible by green light; others aren’t Multiple blue receptors with different functions! Identified genetically Blue Light Responses Responses vary in their fluence requirements & lag time Stomatal opening is reversible by green light; others aren’t Multiple blue receptors with different functions! Identified genetically, then clone the gene and identify the protein Blue Light Responses Responses vary in their fluence requirements & lag time Stomatal opening is reversible by green light; others aren’t Multiple blue receptors with different functions! Identified genetically, then clone the gene and identify the protein Cryptochromes repress hypocotyl elongation Blue Light Responses Identified genetically, then clone the gene and identify the protein Cryptochromes repress hypocotyl elongation Stimulate flowering Blue Light Responses Identified genetically, then clone the gene and identify the protein Cryptochromes repress hypocotyl elongation Stimulate flowering Set the circadian clock (in humans, too!) Blue Light Responses Identified genetically, then clone the gene and identify the protein Cryptochromes repress hypocotyl elongation Stimulate flowering Set the circadian clock (in humans, too!) Stimulate anthocyanin synthesis Blue Light Responses Identified genetically, then clone the gene and identify the protein Cryptochromes repress hypocotyl elongation Stimulate flowering Set the circadian clock (in humans, too!) Stimulate anthocyanin synthesis 3 CRY genes Blue Light Responses 3 CRY genes All have same basic structure: Photolyase-like domain binds FAD and a pterin (MTHF) that absorbs blue & transfers energy to FAD in photolyase (an enzyme that uses light energy to repair pyr dimers) Blue Light Responses 3 CRY genes All have same basic structure: Photolyase-like domain binds FAD and a pterin (MTHF) that absorbs blue & transfers energy to FAD in photolyase (an enzyme that uses light energy to repair pyr dimers) DAS binds COP1 & has nuclear localization signals Blue Light Responses 3 CRY genes All have same basic structure: Photolyase-like domain binds FAD and a pterin (MTHF) that absorbs blue & transfers energy to FAD in photolyase (an enzyme that uses light energy to repair pyr dimers) DAS binds COP1 & has nuclear localization signals CRY1 & CRY2 kinase proteins after absorbing blue Blue Light Responses 3 CRY genes CRY1 & CRY2 kinase proteins after absorbing blue CRY3 repairs mt & cp DNA! Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth • Triggers very rapid changes in membrane potential & growth Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth • Triggers very rapid changes in membrane potential & growth • Opens anion channels in PM Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth: light-stable • Triggers rapid changes in PM potential & growth • Opens anion channels in PM • Stimulates anthocyanin synthesis Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth: light-stable • Triggers rapid changes in PM potential & growth • Opens anion channels in PM • Stimulates anthocyanin synthesis • Entrains the circadian clock Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth: light-stable • Triggers rapid changes in PM potential & growth • Opens anion channels in PM • Stimulates anthocyanin synthesis • Entrains the circadian clock • Also accumulates in nucleus & interacts with PHY & COP1 to regulate photomorphogenesis, probably by kinasing substrates Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth: light-stable • Triggers rapid changes in PM potential & growth • Opens anion channels in PM • Stimulates anthocyanin synthesis • Entrains the circadian clock • Also accumulates in nucleus & interacts with PHY & COP1 to regulate photomorphogenesis, probably by kinasing substrates 2. CRY2 controls flowering Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth: light-stable 2. CRY2 controls flowering: little effect on other processes • Light-labile Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth 2. CRY2 regulates flowering: little effect on other processes • Light-labile 3. CRY3 enters cp & mito, where binds & repairs DNA Blue Light Responses 3 CRY genes 1. CRY1 regulates blue effects on growth 2. CRY2 controls flowering: little effect on other processes 3. CRY3 enters cp & mito, where binds & repairs DNA! Cryptochromes are not involved in phototropism or stomatal opening! Blue Light Responses Cryptochromes are not involved in phototropism or stomatal opening! Phototropins are! Blue Light Responses Phototropins are involved in phototropism & stomatal opening! Many names (nph, phot, rpt) since found by several different mutant screens Phototropins Many names (nph, phot, rpt) since found by several different mutant screens Mediate blue light-induced growth enhancements Phototropins Many names (nph, phot, rpt) since found by several different mutant screens Mediate blue light-induced growth enhancement & blue light-dependent activation of the plasma membrane H+-ATPase in guard cells Phototropins Many names (nph, phot, rpt) since found by several different mutant screens Mediate blue light-induced growth enhancement & blue light-dependent activation of the plasma membrane H+-ATPase in guard cells Contain light-activated serine-threonine kinase domain and LOV1 (light-O2-voltage) and LOV2 repeats Phototropins Many names (nph, phot, rpt) since found by several different mutant screens Mediate blue light-induced growth enhancement & blue light-dependent activation of the plasma membrane H+-ATPase in guard cells Contain light-activated serine-threonine kinase domain and LOV1 (light-O2-voltage) and LOV2 repeats LOV1 & LOV2 bind FlavinMonoNucleotide cofactors Phototropins Many names (nph, phot, rpt) since found by several different mutant screens Mediate blue light-induced growth enhancement & blue light-dependent activation of the plasma membrane H+-ATPase in guard cells Contain light-activated serine-threonine kinase domain and LOV1 (light-O2-voltage) and LOV2 repeats LOV1 & LOV2 bind FlavinMonoNucleotide cofactors After absorbing blue rapidly autophosphorylate & kinase other proteins Phototropins After absorbing blue rapidly autophosphorylate & kinase other proteins 1 result = phototropism due to uneven auxin transport Phototropins After absorbing blue rapidly autophosphorylate & kinase other proteins 1 result = phototropism due to uneven auxin transport Send more to side away from light! Phototropins After absorbing blue rapidly autophosphorylate & kinase other proteins 1 result = phototropism due to uneven auxin transport Send more to side away from light! PHOT 1 mediates LF Phototropins After absorbing blue rapidly autophosphorylate & kinase other proteins 1 result = phototropism due to uneven auxin transport Send more to side away from light! PHOT 1 mediates LF PHOT2 mediates HIR Phototropins 2nd result = stomatal opening via stimulation of guard cell PM proton pump Also requires photosynthesis by guard cells! Phototropins 2nd result = stomatal opening via stimulation of guard cell PM proton pump Also requires photosynthesis by guard cells & signaling from xanthophylls Phototropins 2nd result = stomatal opening via stimulation of guard cell PM proton pump Also requires photosynthesis by guard cells & signaling from xanthophylls npq mutants don’t make zeaxanthin & lack specific blue response Phototropins 2nd result = stomatal opening via stimulation of guard cell PM proton pump Also requires photosynthesis by guard cells & signaling from xanthophylls npq mutants don’t make zeaxanthin & lack specific blue response Basic idea: open when pump in K+ Phototropins 2nd result = stomatal opening via stimulation of guard cell PM proton pump Also requires photosynthesis by guard cells & signaling from xanthophylls npq mutants don’t make zeaxanthin & lack specific blue response Basic idea: open when pump in K+ Close when pump out K+ Phototropins Basic idea: open when pump in K+ Close when pump out K+ Control is hideously complicated! Phototropins Basic idea: open when pump in K+ Close when pump out K+ Control is hideously complicated! Mainly controlled by blue light Phototropins Basic idea: open when pump in K+ Close when pump out K+ Control is hideously complicated! Mainly controlled by blue light but red also plays role Phototropins Basic idea: open when pump in K+ Close when pump out K+ Control is hideously complicated! Mainly controlled by blue light but red also plays role Light intensity is also important Phototropins Mainly controlled by blue light, but red also plays role Light intensity is also important due to effect on [photosynthate] in guard cells Phototropins Mainly controlled by blue light, but red also plays role Light intensity is also important due to effect on [photosynthate] in guard cells PHOT1 &2 also help Phototropins Mainly controlled by blue light, but red also plays role Light intensity is also important due to effect on [photosynthate] in guard cells PHOT1 &2 also help Main GC blue receptor is zeaxanthin! Phototropins Mainly controlled by blue light, but red also plays role Light intensity is also important due to effect on [photosynthate] in guard cells PHOT1 &2 also help Main GC blue receptor is zeaxanthin! Reason for green reversal Phototropins Mainly controlled by blue light, but red also plays role Light intensity is also important due to effect on [photosynthate] in guard cells PHOT1 &2 also help Main GC blue receptor is zeaxanthin! Reason for green reversal water stress overrides light! Phototropins water stress overrides light: roots make Abscisic Acid: closes stomates & blocks opening regardless of other signals!