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Julin N Maloof - One of the best experts on this subject based on the ideXlab platform.
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Network Analysis Reveals a Role for Salicylic Acid Pathway Components in Shade Avoidance.
Plant physiology, 2018Co-Authors: Kazunari Nozue, Upendra K. Devisetty, Saradadevi Lekkala, Patricia Mueller-moulé, Aurélie Bak, Clare L. Casteel, Julin N MaloofAbstract:Plants have sophisticated mechanisms for sensing neighbor Shade. To maximize their ability to compete for light, plants respond to Shade through enhanced elongation and physiological changes. The Shade Avoidance response affects many different organs and growth stages, yet the signaling pathways underlying this response have mostly been studied in seedlings. We assayed transcriptome changes in response to Shade across a 2-d time course in the wild type and 12 Arabidopsis (Arabidopsis thaliana) mutants. The resulting temporal map of transcriptional responses to Shade defines early and late responses in adult plants, enabling us to determine connections between key signaling genes and downstream responses. We found a pervasive and unexpectedly strong connection between Shade Avoidance and genes related to salicylic acid, suggesting salicylic acid signaling to be an important Shade Avoidance growth regulator. We tested this connection and found that several mutants disrupting salicylic acid levels or signaling were defective in Shade Avoidance. The effect of these mutations on Shade Avoidance was specific to petiole elongation; neither hypocotyl nor flowering time responses were altered, thereby defining important stage-specific differences in the downstream Shade Avoidance signaling pathway. Shade treatment did not change salicylic acid levels, indicating that the mediation of Shade Avoidance by salicylic acid is not dependent on the modulation of salicylic acid levels. These results demonstrate that salicylic acid pathway genes also are key components of petiole Shade Avoidance.
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YUCCA auxin biosynthetic genes are required for Arabidopsis Shade Avoidance.
PeerJ, 2016Co-Authors: Patricia Müller-moulé, Andreah D Wallace, Kazunari Nozue, Melissa L Pytlak, Christine M Palmer, Michael F Covington, Stacey L Harmer, Julin N MaloofAbstract:Plants respond to neighbor Shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization of PHYTOCHROME INTERACTING FACTOR proteins and subsequent induction of YUCCA auxin biosynthetic genes. To investigate the role of YUCCA genes in phytochrome-mediated elongation, we examined auxin signaling kinetics after an end-of-day far-red (EOD-FR) light treatment, and found that an auxin responsive reporter is rapidly induced within 2 hours of far-red exposure. YUCCA2, 5, 8, and 9 are all induced with similar kinetics suggesting that they could act redundantly to control Shade-mediated elongation. To test this hypothesis we constructed a yucca2, 5, 8, 9 quadruple mutant and found that the hypocotyl and petiole EOD-FR and Shade Avoidance responses are completely disrupted. This work shows that YUCCA auxin biosynthetic genes are essential for detectable Shade Avoidance and that YUCCA genes are important for petiole Shade Avoidance.
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Tomato phyE Is Required for Shade Avoidance in the Absence of phyB1 and phyB2.
Frontiers in plant science, 2016Co-Authors: Amanda Schrager-lavelle, Leslie A. Herrera, Julin N MaloofAbstract:The phytochrome (phy) family of red and far-red photoreceptors provides plants with critical information about their surrounding environment and can signal downstream developmental and physiological changes. Neighboring plants compete for limited light resources, and their presence is detected by the phytochrome photoreceptors as a reduced ratio of red: far-red light. One common response to Shade is increased elongation of petioles and internodes to compete with their neighbors. While the phytochrome family, phyB in particular, has been well studied in Arabidopsis, information about the other phytochrome family members is limited, especially in sympodial crop plants such as tomato, that have a very different architecture from that of the model plant. To study the tomato phytochrome family we took advantage of several existing mutants and generated an artificial miRNA (amiRNA) line to target SlPHYE, the remaining phytochrome B subfamily member with no currently available mutant line. Here, we characterize internode elongation and Shade Avoidance phenotypes of the SlPHYE amiRNA line (PHYE amiRNA). In addition, higher order phytochrome subfamily B mutants were generated with the PHYE amiRNA line to investigate the role of SlphyE within the phyB subfamily. We find that the PHYE amiRNA line has no detectable phenotype on its own, however in higher order combinations with SlphyB1 and/or SlphyB2 there are notable defects in Shade Avoidance. Most notably, we find that the triple mutant combination of SlPHYE amiRNA, SlphyB1, and SlphyB2 has a phenotype that is much stronger than the SlphyB1 SlphyB2 double, showing constitutive Shade Avoidance and little to no response to Shade. This indicates that SlphyE is required for the Shade Avoidance response in the absence of SlphyB1 and SlphyB2.
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YUCCA auxin biosynthetic genes are required for Arabidopsis Shade Avoidance
2016Co-Authors: Patricia Müller-moulé, Andreah D Wallace, Kazunari Nozue, Melissa L Pytlak, Christine M Palmer, Michael F Covington, Stacey L Harmer, Julin N MaloofAbstract:Plants respond to neighbor Shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization of PHYTOCHROME INTERACTING FACTOR proteins and subsequent induction of YUCCA auxin biosynthetic genes. To investigate the role of YUCCA genes in phytochrome-mediated elongation we examined auxin signaling kinetics after an end-of-day far-red (EOD-FR) light treatment, and found that an auxin responsive reporter is rapidly induced within 2 hours of far-red exposure. YUCCA2, 5, 8, and 9 are all induced with similar kinetics suggesting that they could act redundantly to control Shade-mediated elongation. To test this hypothesis we constructed a yucca2,5,8,9 quadruple mutant and found that the hypocotyl and petiole EOD-FR and Shade Avoidance are completely disrupted. This work shows that YUCCA auxin biosynthetic genes are essential for detectable Shade Avoidance and that YUCCA genes are important for petiole Shade Avoidance.
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YUCCA auxin biosynthetic genes are required for Arabidopsis Shade Avoidance
2016Co-Authors: Patricia Müller-moulé, Andreah D Wallace, Kazunari Nozue, Melissa L Pytlak, Christine M Palmer, Michael F Covington, Stacey L Harmer, Julin N MaloofAbstract:Plants respond to neighbor Shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization of PHYTOCHROME INTERACTING FACTOR (PIF) proteins and subsequent induction of YUCCA auxin biosynthetic genes. To investigate the role of YUCCA genes in Shade Avoidance we examined auxin signaling kinetics and found that an auxin responsive reporter is rapidly induced within 2 hours of Shade exposure. YUCCA2, 5, 8, and 9 are all induced with similar kinetics suggesting that they could act redundantly to control Shade-mediated elongation. To test this hypothesis we constructed a yucca2,5,8,9 quadruple mutant and found that the hypocotyl and petiole Shade Avoidance is completely disrupted. This work shows that YUCCA auxin biosynthetic genes are essential for detectable Shade Avoidance and that YUCCA genes are important for petiole Shade Avoidance.
Keara A. Franklin - One of the best experts on this subject based on the ideXlab platform.
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PRR proteins of the circadian clock call time on Shade Avoidance
Proceedings of the National Academy of Sciences of the United States of America, 2020Co-Authors: Keara A. FranklinAbstract:Light limitation represents a significant threat to plant survival. Shade-intolerant species have, therefore, evolved mechanisms to detect and avoid shading by neighbors. Plants detect the proximity and density of neighboring vegetation by monitoring alterations in light quality (1). Phytochrome photoreceptors detect changes in the ratio of red (R) to far-red light (FR), with phytochrome B performing a dominant role. R is absorbed by living vegetation and used for photosynthesis, whereas the majority of FR is transmitted through and reflected within canopies. R:FR is, therefore, reduced proportionally with increasing depth of canopy (1). Early perception of encroaching Shade enables plants to rapidly elongate stems and elevate leaves to overtop competitors and avoid light limitation. Such responses are termed Shade Avoidance and can promote survival in mixed stands (1). Shade Avoidance is regulated by a group of transcription factors named PHYTOCHROME INTERACTING FACTORS (PIFs), with PIF4, PIF5, and PIF7 performing dominant roles (2⇓–4). These PIFs collectively promote synthesis of the growth-promoting hormone auxin (4, 5). In sunlight (high R:FR), phytochrome B becomes activated … [↵][1]1Email: kerry.franklin{at}bristol.ac.uk. [1]: #xref-corresp-1-1
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UV-B antagonises Shade Avoidance and increases levels of the flavonoid quercetin in coriander ( Coriandrum sativum )
Scientific reports, 2017Co-Authors: Donald P. Fraser, Ashutosh Sharma, Taryn Fletcher, Simon Budge, Chris Moncrieff, Antony N. Dodd, Keara A. FranklinAbstract:Despite controlling a diverse array of regulatory processes in plants, UV-B wavelengths (280-315 nm) are attenuated by common greenhouse materials such as glass and polycarbonate and are therefore depleted in many commercial growing environments. In this study, we analysed the architecture, pigment accumulation and antioxidant capacity of coriander (Coriandrum sativum, also known as cilantro) plants grown with and without supplementary UV-B (1.5 µmol m-2 s-1). We demonstrate that UV-B limits stem elongation responses to neighbour proximity perception (Shade Avoidance), promoting a more compact plant architecture. In addition, UV-B increased leaf quercetin content and total antioxidant capacity. Arabidopsis thaliana mutants deficient in flavonoid biosynthesis were not impaired in Shade Avoidance inhibition, suggesting that UV-B-induced flavonoid synthesis is not a component of this response. Our results indicate that UV-B supplementation may provide a method to manipulate the architecture, flavour and nutritional content of potted herbs whilst reducing the deleterious impacts of dense planting on product quality.
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Photoreceptor crosstalk in Shade Avoidance.
Current opinion in plant biology, 2016Co-Authors: Donald P. Fraser, Scott Hayes, Keara A. FranklinAbstract:Plants integrate a variety of environmental signals to determine the threat of competitor shading and use this information to initiate escape responses, termed Shade Avoidance. Photoreceptor-mediated light signals are central to this process. Encroaching vegetation is sensed as a reduction in the ratio of red to far-red wavebands (R:FR) by phytochromes. Plants Shaded within a canopy will also perceive reduced blue light signals and possibly enriched green light through cryptochromes. The detection of canopy gaps may be further facilitated by blue light sensing phototropins and the UV-B photoreceptor, UVR8. Once sunlight has been reached, phytochrome and UVR8 inhibit Shade Avoidance. Accumulating evidence suggests that multiple plant photoreceptors converge on a shared signalling network to regulate responses to Shade.
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UV-B detected by the UVR8 photoreceptor antagonizes auxin signaling and plant Shade Avoidance
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Scott Hayes, Christos N. Velanis, Gareth I. Jenkins, Keara A. FranklinAbstract:Plants detect different facets of their radiation environment via specific photoreceptors to modulate growth and development. UV-B is perceived by the photoreceptor UV RESISTANCE LOCUS 8 (UVR8). The molecular mechanisms linking UVR8 activation to plant growth are not fully understood, however. When grown in close proximity to neighboring vegetation, Shade-intolerant plants initiate dramatic stem elongation to overtop competitors. Here we show that UV-B, detected by UVR8, provides an unambiguous sunlight signal that inhibits Shade Avoidance responses in Arabidopsis thaliana by antagonizing the phytohormones auxin and gibberellin. UV-B triggers degradation of the transcription factors PHYTOCHROME INTERACTING FACTOR 4 and PHYTOCHROME INTERACTING FACTOR 5 and stabilizes growth-repressing DELLA proteins, inhibiting auxin biosynthesis via a dual mechanism. Our findings show that UVR8 signaling is closely integrated with other photoreceptor pathways to regulate auxin signaling and plant growth in sunlight.
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temperature dependent Shade Avoidance involves the receptor like kinase erecta
Plant Journal, 2013Co-Authors: Dhaval Patel, Scott Hayes, Manojit Basu, Imre Majláth, Flora M. Hetherington, Timothy J. Tschaplinski, Keara A. FranklinAbstract:Plants detect the presence of neighbouring vegetation by monitoring changes in the ratio of red (R) to farred (FR) wavelengths (R:FR) in ambient light. Reductions in R:FR are perceived by the phytochrome family of plant photoreceptors and initiate a suite of developmental responses termed the Shade Avoidance syndrome. These include increased elongation growth of stems and petioles, enabling plants to overtop competing vegetation. The majority of Shade Avoidance experiments are performed at standard laboratory growing temperatures (>20°C). In these conditions, elongation responses to low R:FR are often accompanied by reductions in leaf development and accumulation of plant biomass. Here we investigated Shade Avoidance responses at a cooler temperature (16°C). In these conditions, Arabidopsis thaliana displays considerable low R:FR-mediated increases in leaf area, with reduced low R:FR-mediated petiole elongation and leaf hyponasty responses. In Landsberg erecta, these strikingly different Shade Avoidance phenotypes are accompanied by increased leaf thickness, increased biomass and an altered metabolite profile. At 16°C, low R:FR treatment results in the accumulation of soluble sugars and metabolites associated with cold acclimation. Analyses of natural genetic variation in Shade Avoidance responses at 16°C have revealed a regulatory role for the receptor-like kinase ERECTA.
Ronald Pierik - One of the best experts on this subject based on the ideXlab platform.
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A Gas-and-Brake Mechanism of bHLH Proteins Modulates Shade Avoidance.
Plant physiology, 2020Co-Authors: Sara Buti, Chrysoula K. Pantazopoulou, Kasper Van Gelderen, Valérie A.c. Hoogers, Emilie Reinen, Ronald PierikAbstract:Plants detect proximity of competitors through reduction in the ratio between red and far-red light that triggers the Shade Avoidance syndrome, inducing responses such as accelerated shoot elongation and early flowering. Shade Avoidance is regulated by PHYTOCHROME INTERACTING FACTORs, a group of basic helix-loop-helix (bHLH) transcription factors. Another (b)HLH protein, KIDARI (KDR), which is non-DNA-binding, was identified in de-etiolation studies and proposed to interact with LONG HYPOCOTYL IN FAR-RED1 (HFR1), a (b)HLH protein that inhibits Shade Avoidance. Here, we established roles of KDR in regulating Shade Avoidance in Arabidopsis (Arabidopsis thaliana) and investigated how KDR regulates the Shade Avoidance network. We showed that KDR is a positive regulator of Shade Avoidance and interacts with several negative growth regulators. We identified KDR interactors using a combination of yeast two-hybrid screening and dedicated confirmations with bimolecular fluorescence complementation. We demonstrated that KDR is translocated primarily to the nucleus when coexpressed with these interactors. A genetic approach confirmed that several of these interactions play a functional role in Shade Avoidance; however, we propose that KDR does not interact with HFR1 to regulate Shade Avoidance. Based on these observations, we propose that Shade Avoidance is regulated by a three-layered gas-and-brake mechanism of bHLH protein interactions, adding a layer of complexity to what was previously known.
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Reducing Shade Avoidance can improve Arabidopsis canopy performance against competitors
Plant cell & environment, 2020Co-Authors: Chrysoula K. Pantazopoulou, Franca J. Bongers, Ronald PierikAbstract:Plants that grow in high density communities activate Shade Avoidance responses to consolidate light capture by individuals. Although this is an evolutionary successful strategy, it may not enhance performance of the community as a whole. Resources are invested in Shade responses at the expense of other organs and light penetration through the canopy is increased, allowing invading competitors to grow better. Here we investigate if suppression of Shade Avoidance responses would enhance group performance of a monoculture community that is invaded by a competitor. Using different Arabidopsis genotypes, we show that suppression of Shade-induced upward leaf movement in the pif7 mutant increases the pif7 communal performance against invaders as compared to a wildtype canopy. The invaders were more severely suppressed and the community grew larger as compared to wild-type. Using computational modeling, we show that leaf angle variations indeed strongly affect light penetration and growth of competitors that invade the canopy. Our data thus show that modifying specific Shade Avoidance aspects can improve plant community performance. These insights may help to suppress weeds in crop stands. This article is protected by copyright. All rights reserved.
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The bHLH network underlying plant Shade‐Avoidance
Physiologia plantarum, 2020Co-Authors: Sara Buti, Scott Hayes, Ronald PierikAbstract:Shade is a potential threat to many plant species. When Shade-intolerant plants detect neighbours, they elongate their stems and leaves in an effort to maximise their light capture. This developmental programme, known as 'Shade-Avoidance' is tightly controlled by specialised photoreceptors and a suite of transcriptional regulators. The basic helix-loop-helix (bHLH) family of transcription factors are particularly important for Shade-induced elongation. In recent years, it has become apparent that many members of this family heterodimerise and that together they form a complex regulatory network. This review summarises recent work into the structure of the bHLH network and how it regulates elongation growth. In addition to this, we highlight how photoreceptors modulate the function of the network via direct interaction with transcription factors. It is hoped that the information integrated in this review will provide a useful theoretical framework for future studies on the molecular basis of Shade-Avoidance in plants.
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the bhlh network underlying plant Shade Avoidance
Physiologia Plantarum, 2020Co-Authors: Sara Buti, Scott Hayes, Ronald PierikAbstract:Shade is a potential threat to many plant species. When Shade-intolerant plants detect neighbours, they elongate their stems and leaves in an effort to maximise their light capture. This developmental programme, known as 'Shade-Avoidance' is tightly controlled by specialised photoreceptors and a suite of transcriptional regulators. The basic helix-loop-helix (bHLH) family of transcription factors are particularly important for Shade-induced elongation. In recent years, it has become apparent that many members of this family heterodimerise and that together they form a complex regulatory network. This review summarises recent work into the structure of the bHLH network and how it regulates elongation growth. In addition to this, we highlight how photoreceptors modulate the function of the network via direct interaction with transcription factors. It is hoped that the information integrated in this review will provide a useful theoretical framework for future studies on the molecular basis of Shade-Avoidance in plants.
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Reducing Shade Avoidance can improve Arabidopsis canopy performance against competitors
2019Co-Authors: Chrysoula K. Pantazopoulou, Franca J. Bongers, Ronald PierikAbstract:AbstractThe loss of crop yield due to weeds is an urgent agricultural problem. Although herbicides are an effective way to control weeds, more sustainable solutions for weed management are desirable. It has been proposed that crop plants can communally suppress weeds by shading them out. Shade Avoidance responses, such as upward leaf movement (hyponasty) and stem or petiole elongation, enhance light capture of individual plants, increasing their individual fitness. The shading capacity of the entire crop community might, however, be more effective if aspects of Shade Avoidance are suppressed. Testing this hypothesis in crops is hampered by the lack of well-characterized mutants. We therefore investigated if Arabidopsis competitive performance at the community level against invading competitors is affected by the ability to display Shade Avoidance. We tested two mutants: pif4pif5 that has mildly reduced petiole elongation and hyponasty and pif7 with normal elongation but absent hyponasty in response to Shade. Although pif4pif5 performed similar to wildtype, we found that pif7 showed significantly increased canopy biomass and suppression of invading competitors as compared to its wildtype. Our data thus show that modifying specific Shade Avoidance aspects has potential for plant community performance. This may help to suppress weeds in crop stands.HighlightHyponastic response in canopies facilitates light penetration and weed growth. Inhibition of this response to neighbors increased canopy biomass, canopy closure and suppression of competitors.
Kazunari Nozue - One of the best experts on this subject based on the ideXlab platform.
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Network Analysis Reveals a Role for Salicylic Acid Pathway Components in Shade Avoidance.
Plant physiology, 2018Co-Authors: Kazunari Nozue, Upendra K. Devisetty, Saradadevi Lekkala, Patricia Mueller-moulé, Aurélie Bak, Clare L. Casteel, Julin N MaloofAbstract:Plants have sophisticated mechanisms for sensing neighbor Shade. To maximize their ability to compete for light, plants respond to Shade through enhanced elongation and physiological changes. The Shade Avoidance response affects many different organs and growth stages, yet the signaling pathways underlying this response have mostly been studied in seedlings. We assayed transcriptome changes in response to Shade across a 2-d time course in the wild type and 12 Arabidopsis (Arabidopsis thaliana) mutants. The resulting temporal map of transcriptional responses to Shade defines early and late responses in adult plants, enabling us to determine connections between key signaling genes and downstream responses. We found a pervasive and unexpectedly strong connection between Shade Avoidance and genes related to salicylic acid, suggesting salicylic acid signaling to be an important Shade Avoidance growth regulator. We tested this connection and found that several mutants disrupting salicylic acid levels or signaling were defective in Shade Avoidance. The effect of these mutations on Shade Avoidance was specific to petiole elongation; neither hypocotyl nor flowering time responses were altered, thereby defining important stage-specific differences in the downstream Shade Avoidance signaling pathway. Shade treatment did not change salicylic acid levels, indicating that the mediation of Shade Avoidance by salicylic acid is not dependent on the modulation of salicylic acid levels. These results demonstrate that salicylic acid pathway genes also are key components of petiole Shade Avoidance.
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YUCCA auxin biosynthetic genes are required for Arabidopsis Shade Avoidance.
PeerJ, 2016Co-Authors: Patricia Müller-moulé, Andreah D Wallace, Kazunari Nozue, Melissa L Pytlak, Christine M Palmer, Michael F Covington, Stacey L Harmer, Julin N MaloofAbstract:Plants respond to neighbor Shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization of PHYTOCHROME INTERACTING FACTOR proteins and subsequent induction of YUCCA auxin biosynthetic genes. To investigate the role of YUCCA genes in phytochrome-mediated elongation, we examined auxin signaling kinetics after an end-of-day far-red (EOD-FR) light treatment, and found that an auxin responsive reporter is rapidly induced within 2 hours of far-red exposure. YUCCA2, 5, 8, and 9 are all induced with similar kinetics suggesting that they could act redundantly to control Shade-mediated elongation. To test this hypothesis we constructed a yucca2, 5, 8, 9 quadruple mutant and found that the hypocotyl and petiole EOD-FR and Shade Avoidance responses are completely disrupted. This work shows that YUCCA auxin biosynthetic genes are essential for detectable Shade Avoidance and that YUCCA genes are important for petiole Shade Avoidance.
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YUCCA auxin biosynthetic genes are required for Arabidopsis Shade Avoidance
2016Co-Authors: Patricia Müller-moulé, Andreah D Wallace, Kazunari Nozue, Melissa L Pytlak, Christine M Palmer, Michael F Covington, Stacey L Harmer, Julin N MaloofAbstract:Plants respond to neighbor Shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization of PHYTOCHROME INTERACTING FACTOR proteins and subsequent induction of YUCCA auxin biosynthetic genes. To investigate the role of YUCCA genes in phytochrome-mediated elongation we examined auxin signaling kinetics after an end-of-day far-red (EOD-FR) light treatment, and found that an auxin responsive reporter is rapidly induced within 2 hours of far-red exposure. YUCCA2, 5, 8, and 9 are all induced with similar kinetics suggesting that they could act redundantly to control Shade-mediated elongation. To test this hypothesis we constructed a yucca2,5,8,9 quadruple mutant and found that the hypocotyl and petiole EOD-FR and Shade Avoidance are completely disrupted. This work shows that YUCCA auxin biosynthetic genes are essential for detectable Shade Avoidance and that YUCCA genes are important for petiole Shade Avoidance.
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YUCCA auxin biosynthetic genes are required for Arabidopsis Shade Avoidance
2016Co-Authors: Patricia Müller-moulé, Andreah D Wallace, Kazunari Nozue, Melissa L Pytlak, Christine M Palmer, Michael F Covington, Stacey L Harmer, Julin N MaloofAbstract:Plants respond to neighbor Shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization of PHYTOCHROME INTERACTING FACTOR (PIF) proteins and subsequent induction of YUCCA auxin biosynthetic genes. To investigate the role of YUCCA genes in Shade Avoidance we examined auxin signaling kinetics and found that an auxin responsive reporter is rapidly induced within 2 hours of Shade exposure. YUCCA2, 5, 8, and 9 are all induced with similar kinetics suggesting that they could act redundantly to control Shade-mediated elongation. To test this hypothesis we constructed a yucca2,5,8,9 quadruple mutant and found that the hypocotyl and petiole Shade Avoidance is completely disrupted. This work shows that YUCCA auxin biosynthetic genes are essential for detectable Shade Avoidance and that YUCCA genes are important for petiole Shade Avoidance.
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Shade Avoidance Components and Pathways in Adult Plants Revealed by Phenotypic Profiling
PLoS genetics, 2015Co-Authors: Kazunari Nozue, Upendra K. Devisetty, Saradadevi Lekkala, An V. Tat, Matthew Robinson, Maxwell R. Mumbach, Yasunori Ichihashi, Julin N MaloofAbstract:Shade from neighboring plants limits light for photosynthesis; as a consequence, plants have a variety of strategies to avoid canopy Shade and compete with their neighbors for light. Collectively the response to foliar Shade is called the Shade Avoidance syndrome (SAS). The SAS includes elongation of a variety of organs, acceleration of flowering time, and additional physiological responses, which are seen throughout the plant life cycle. However, current mechanistic knowledge is mainly limited to Shade-induced elongation of seedlings. Here we use phenotypic profiling of seedling, leaf, and flowering time traits to untangle complex SAS networks. We used over-representation analysis (ORA) of Shade-responsive genes, combined with previous annotation, to logically select 59 known and candidate novel mutants for phenotyping. Our analysis reveals shared and separate pathways for each Shade Avoidance response. In particular, auxin pathway components were required for Shade Avoidance responses in hypocotyl, petiole, and flowering time, whereas jasmonic acid pathway components were only required for petiole and flowering time responses. Our phenotypic profiling allowed discovery of seventeen novel Shade Avoidance mutants. Our results demonstrate that logical selection of mutants increased success of phenotypic profiling to dissect complex traits and discover novel components.
Jorge J. Casal - One of the best experts on this subject based on the ideXlab platform.
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Shade Avoidance responses become more aggressive in warm environments.
Plant cell & environment, 2020Co-Authors: Sofía Romero-montepaone, Sofía Poodts, Patrick Fischbach, Romina Sellaro, Matias D. Zurbriggen, Jorge J. CasalAbstract:When exposed to neighbour cues, competitive plants increase stem growth to reduce the degree of current or future Shade. The aim of this work is to investigate the impact of weather conditions on the magnitude of Shade Avoidance responses in Arabidopsis thaliana. We first generated a growth rate database under controlled conditions and elaborated a model that predicts daytime hypocotyl growth as a function of the activity of the main photosensory receptors (phytochromes A and B, cryptochromes 1 and 2) in combination with light and temperature inputs. We then incorporated the action of thermal amplitude to account for its effect on selected genotypes, which correlates with the dynamics of the growth-promoting transcription factor PHYTOCHROME-INTERACTING FACTOR 4. The model predicted growth rate in the field with reasonable accuracy. Thus, we used the model in combination with a worldwide data set of current and future whether conditions. The analysis predicted enhanced Shade Avoidance responses as a result of higher temperatures due to the geographical location or global warming. Irradiance and thermal amplitude had no effects. These trends were also observed for our local growth rate measurements. We conclude that, if water and nutrients do not become limiting, warm environments enhance the Shade Avoidance response.
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Shade-Avoidance responses become more aggressive in warm environments
2019Co-Authors: Sofía Romero-montepaone, Sofía Poodts, Patrick Fischbach, Romina Sellaro, Matias D. Zurbriggen, Jorge J. CasalAbstract:AbstractWhen exposed to neighbour signals, competitive plants increase the growth of the stem to reduce the degree of current or future Shade. Plants can experience similar neighbour cues under different weather conditions and the aim of this work is to investigate the impact of daily average temperature and irradiance and thermal amplitude on the magnitude of Shade-Avoidance responses in Arabidopsis thaliana. For this purpose, we first generated a growth database and elaborated under controlled conditions a model that predicts hypocotyl growth during the photoperiod as a function of the light-modulated activity of the main photo-sensory receptors (phytochromes A and B, cryptochromes 1 and 2), temperature-modulated activity of phytochrome B and an independent temperature input. Thermal amplitude (lower temperatures during the morning and afternoon that at midday) reduced growth of genotypes with normally fast morning growth, and this effect was incorporated to the model. Thermal amplitude also decreased the abundance of the growth-promoting transcription factor PHYTOCHROME-INTERACTING FACTOR 4. The model predicted growth in the field through different seasons with reasonable accuracy. Then, we used the model in combination with a worldwide dataset of current and future whether conditions. The analysis predicted enhanced Shade-Avoidance responses as a result of higher temperatures due to the geographical location or global warming. Irradiance and thermal amplitude had no effects. These trends were also observed for our local growth measurements. We conclude that, if water and nutrients do not become limiting, warm environments enhance the Shade Avoidance response.
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Multiple links between Shade Avoidance and auxin networks.
Journal of experimental botany, 2017Co-Authors: María José Iglesias, Matias D. Zurbriggen, Romina Sellaro, Jorge J. CasalAbstract:Auxin has emerged as a key player in the adjustment of plant morphology to the challenge imposed by variable environmental conditions. Shade-Avoidance responses, including the promotion of stem and petiole growth, leaf hyponasty, and the inhibition of branching, involve an intimate connection between light and auxin signalling. Low activity of photo-sensory receptors caused by the presence of neighbouring vegetation enhances the activity of PHYTOCHROME INTERACTING FACTORs (PIFs), which directly promote the expression of genes involved in auxin biosynthesis, conjugation, transport, perception, and signalling. In seedlings, neighbour signals increase auxin levels in the foliage, which then moves to the stem, where it reaches epidermal tissues to promote growth. However, this model only partially accounts for Shade-Avoidance responses (which may also occur in the absence of increased auxin levels), and understanding the whole picture will require further insight into the functional significance of the multiple links between Shade and auxin networks.
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Convergence of CONSTITUTIVE PHOTOMORPHOGENESIS 1 and PHYTOCHROME INTERACTING FACTOR signalling during Shade Avoidance
The New phytologist, 2016Co-Authors: Manuel Pacín, Mariana Semmoloni, Martina Legris, Scott A. Finlayson, Jorge J. CasalAbstract:Shade-Avoidance responses require CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) but the mechanisms of action of COP1 under Shade have not been elucidated. Using simulated Shade and control conditions, we analysed: the transcriptome and the auxin levels of cop1 and phytochrome interacting factor 1 (pif1) pif3 pif4 pif5 (pifq) mutants; the dynamics of ELONGATED HYPOCOTYL 5 (HY5) and LONG HYPOCOTYL IN FAR-RED (HFR1) proteins; and the epistatic relationships between cop1 and pif3, pif4, pif5, hy5 and hfr1 mutations in Arabidopsis thaliana. Despite severely impaired Shade-Avoidance responses, only a few genes that responded to Shade in the wild-type failed to do so in cop1. Shade enhanced the convergence between cop1 and pifq transcriptomes, mainly on Shade-Avoidance marker genes. Shade failed to increase auxin levels in cop1. Residual Shade Avoidance in cop1 was not further reduced by the pif3, pif4 or pif5 mutations, suggesting convergent pathways. HFR1 stability decreased under Shade in a COP1-dependent manner but Shade increased HY5 stability. The cop1 mutant retains responses to Shade and is more specifically impaired in Shade Avoidance. COP1 promotes the degradation of HFR1 under Shade, thus increasing the ability of PIFs to control gene expression, increase auxin levels and promote stem growth.
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a constitutive Shade Avoidance mutant implicates tir nbs lrr proteins in arabidopsis photomorphogenic development
The Plant Cell, 2006Co-Authors: Ana Faigonsoverna, Franklin G Harmon, Leonardo Storani, Elizabeth Karayekov, Roberto J Staneloni, Walter Gassmann, Jorge J. Casal, Marcelo J YanovskyAbstract:In plants, light signals caused by the presence of neighbors accelerate stem growth and flowering and induce a more erect position of the leaves, a developmental strategy known as Shade-Avoidance syndrome. In addition, mutations in the photoreceptors that mediate Shade-Avoidance responses enhance disease susceptibility in Arabidopsis thaliana. Here, we describe the Arabidopsis constitutive Shade-Avoidance1 (csa1) mutant, which shows a Shade-Avoidance phenotype in the absence of Shade and enhanced growth of a bacterial pathogen. The csa1 mutant has a T-DNA inserted within the second exon of a Toll/Interleukin1 receptor–nucleotide binding site–leucine-rich repeat (TIR-NBS-LRR) gene, which leads to the production of a truncated mRNA. Arabidopsis plants transformed with the truncated TIR-NBS-LRR gene recapitulate the mutant phenotype, indicating that csa1 is a dominant-negative mutation that interferes with phytochrome signaling. TIR-NBS-LRR proteins have been implicated in defense responses in plants. RPS4, the closest homolog of CSA1, confers resistance to Pseudomonas syringae and complements the csa1 mutant phenotype, indicating that responses to pathogens and neighbors share core-signaling components in Arabidopsis. In Drosophila melanogaster and Caenorhabditis elegans, TIR domain proteins are implicated in both development and immunity. Thus, the dual role of the TIR domain is conserved across kingdoms.
