301
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Iglesias MJ, Terrile MC, Casalongué CA. Auxin and salicylic acid signalings counteract the regulation of adaptive responses to stress. PLANT SIGNALING & BEHAVIOR 2011; 6:452-4. [PMID: 21358272 PMCID: PMC3142437 DOI: 10.4161/psb.6.3.14676] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 12/28/2010] [Indexed: 05/20/2023]
Abstract
In a previous publication, we performed a phenotypic characterization of Arabidopsis auxin receptor mutants grown under oxidative and salt stresses. In particular, the double mutant for TIR1 and AFB2 receptors, tir1 afb2 displayed increased tolerance against salinity measured as germination rate, root elongation and chlorophyll content. Here, it is reported that salicylic acid (SA)-treated tir1 afb2 mutant shows enhanced transcript level of a pathogenesis related gene, PR1. In addition, SA-mediated repression of auxin signaling was also demonstrated. All these findings allow us to suggest that down-regulation of auxin signaling may be a common mechanism within the plant adaptative response against both biotic and abiotic stresses.
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Affiliation(s)
- María José Iglesias
- Instituto de Investigaciones Biológicas, UE-CONICET-UNMDP, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
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302
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Agati G, Biricolti S, Guidi L, Ferrini F, Fini A, Tattini M. The biosynthesis of flavonoids is enhanced similarly by UV radiation and root zone salinity in L. vulgare leaves. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:204-12. [PMID: 20850892 DOI: 10.1016/j.jplph.2010.07.016] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 06/30/2010] [Accepted: 07/02/2010] [Indexed: 05/18/2023]
Abstract
Flavonoids have recently been suggested to have the potential to serve as antioxidants other than effective UV attenuators in photoprotection. Here, we tested the hypothesis that flavonoids accumulate in response to "excess light" in the presence or in the absence of UV radiation. In a UV exclusion experiment, we grew Ligustrum vulgare plants outdoors under 30% or 100% sunlight irradiance, by cutting-off the whole UV waveband. These plants were also exposed to UV irradiance or supplied with 125 mM NaCl at the root zone. Leaves of plants under 100% sunlight irradiance suffered from excess light, which was exacerbated greatly by root zone salinity stress. Salinity stress repressed the activities of antioxidant enzymes, particularly in full sunlight, and led to severe leaf oxidative damage. Dihydroxy B-ring-substituted flavonoids, namely quercetin 3-O- and luteolin 7-O-glycosides, accumulated steeply in response to sunlight irradiance in the absence of UV radiation. UV radiation and root zone NaCl increased, to a similar degree, the concentration of these flavonoids, which have a great potential to scavenge various forms of reactive oxygen. Treatment-induced changes in leaf phenylpropanoid concentration affected antioxidant activities to a greater extent than the UV-screening capacities of leaf extracts. Early responses to an abrupt increase in sunlight irradiance included a steep increase in the concentrations of quercetin derivatives and cyanidin 3-O-glucoside, with the latter negligibly absorbing in the UV-spectral region. In contrast, effective UV attenuators, such as hydroxycinnamates and monohydroxy B-ring flavonoids, were unresponsive to the light treatments. Overall, these findings lead to the hypothesis that flavonoids may have an important antioxidant function in photoprotection. This hypothesis is further corroborated by the large distribution of quercetin and luteolin derivatives in the vacuoles of mesophyll, not only in the corresponding compartments of epidermal cells, but also in full sunlight-treated leaves in the absence of UV radiation. Future experiments aimed at evaluating the relative contribution of flavonoids within the complex antioxidant defense systems operating in the leaf are needed to help conclusively address the relevance of their antioxidant functions in photoprotection.
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Affiliation(s)
- Giovanni Agati
- Istituto di Fisica Applicata Carrara, IFAC, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019 Sesto. F.no, Firenze, Italy
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303
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Ueda J, Miyamoto K, Uheda E, Oka M. Auxin transport and a graviresponse in plants: Relevance to ABC proteins. ACTA ACUST UNITED AC 2011. [DOI: 10.2187/bss.25.69] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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304
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Osawa H, Endo I, Hara Y, Matsushima Y, Tange T. Transient proliferation of proanthocyanidin-accumulating cells on the epidermal apex contributes to highly aluminum-resistant root elongation in camphor tree. PLANT PHYSIOLOGY 2011; 155:433-46. [PMID: 21045123 PMCID: PMC3075795 DOI: 10.1104/pp.110.166967] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 10/26/2010] [Indexed: 05/22/2023]
Abstract
Aluminum (Al) is a harmful element that rapidly inhibits the elongation of plant roots in acidic soils. The release of organic anions explains Al resistance in annual crops, but the mechanisms that are responsible for superior Al resistance in some woody plants remain unclear. We examined cell properties at the surface layer of the root apex in the camphor tree (Cinnamomum camphora) to understand its high Al resistance mechanism. Exposure to 500 μm Al for 8 d, more than 20-fold higher concentration and longer duration than what soybean (Glycine max) can tolerate, only reduced root elongation in the camphor tree to 64% of the control despite the slight induction of citrate release. In addition, Al content in the root apices was maintained at low levels. Histochemical profiling revealed that proanthocyanidin (PA)-accumulating cells were present at the adjacent outer layer of epidermis cells at the root apex, having distinctive zones for cell division and the early phase of cell expansion. Then the PA cells were gradually detached off the root, leaving thin debris behind, and the root surface was replaced with the elongating epidermis cells at the 3- to 4-mm region behind the tip. Al did not affect the proliferation of PA cells or epidermis cells, except for the delay in the start of expansion and the accelerated detachment of the former. In soybean roots, the innermost lateral root cap cells were absent in both PA accumulation and active cell division and failed to protect the epidermal cell expansion at 25 μm Al. These results suggest that transient proliferation and detachment of PA cells may facilitate the expansion of epidermis cells away from Al during root elongation in camphor tree.
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Affiliation(s)
- Hiroki Osawa
- Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
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305
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Monshausen GB, Miller ND, Murphy AS, Gilroy S. Dynamics of auxin-dependent Ca2+ and pH signaling in root growth revealed by integrating high-resolution imaging with automated computer vision-based analysis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 65:309-18. [PMID: 21223394 DOI: 10.1111/j.1365-313x.2010.04423.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Plants adapt to a changing environment by entraining their growth and development to prevailing conditions. Such 'plastic' development requires a highly dynamic integration of growth phenomena with signal perception and transduction systems, such as occurs during tropic growth. The plant hormone auxin has been shown to play a key role in regulating these directional growth responses of plant organs to environmental cues. However, we are still lacking a cellular and molecular understanding of how auxin-dependent signaling cascades link stimulus perception to the rapid modulation of growth patterns. Here, we report that in root gravitropism of Arabidopsis thaliana, auxin regulates root curvature and associated apoplastic, growth-related pH changes through a Ca2+-dependent signaling pathway. Using an approach that integrates confocal microscopy and automated computer vision-based image analysis, we demonstrate highly dynamic root surface pH patterns during vertical growth and after gravistimulation. These pH dynamics are shown to be dependent on auxin, and specifically on auxin transport mediated by the auxin influx carrier AUX1 in cells of the lateral root cap and root epidermis. Our results further indicate that these pH responses require auxin-dependent changes in cytosolic Ca2+ levels that operate independently of the TIR1 auxin perception system. These results demonstrate a methodology that can be used to visualize vectorial auxin responses in a manner that can be integrated with the rapid plant growth responses to environmental stimuli.
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306
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Dixon RA, Pasinetti GM. Flavonoids and isoflavonoids: from plant biology to agriculture and neuroscience. PLANT PHYSIOLOGY 2010; 154:453-7. [PMID: 20921162 PMCID: PMC2948995 DOI: 10.1104/pp.110.161430] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 06/30/2010] [Indexed: 05/19/2023]
Affiliation(s)
- Richard A Dixon
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401, USA.
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307
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Kitin P, Voelker SL, Meinzer FC, Beeckman H, Strauss SH, Lachenbruch B. Tyloses and phenolic deposits in xylem vessels impede water transport in low-lignin transgenic poplars: a study by cryo-fluorescence microscopy. PLANT PHYSIOLOGY 2010; 154:887-98. [PMID: 20639405 PMCID: PMC2949004 DOI: 10.1104/pp.110.156224] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Accepted: 07/16/2010] [Indexed: 05/17/2023]
Abstract
Of 14 transgenic poplar genotypes (Populus tremula × Populus alba) with antisense 4-coumarate:coenzyme A ligase that were grown in the field for 2 years, five that had substantial lignin reductions also had greatly reduced xylem-specific conductivity compared with that of control trees and those transgenic events with small reductions in lignin. For the two events with the lowest xylem lignin contents (greater than 40% reduction), we used light microscopy methods and acid fuchsin dye ascent studies to clarify what caused their reduced transport efficiency. A novel protocol involving dye stabilization and cryo-fluorescence microscopy enabled us to visualize the dye at the cellular level and to identify water-conducting pathways in the xylem. Cryo-fixed branch segments were planed in the frozen state on a sliding cryo-microtome and observed with an epifluorescence microscope equipped with a cryo-stage. We could then distinguish clearly between phenolic-occluded vessels, conductive (stain-filled) vessels, and nonconductive (water- or gas-filled) vessels. Low-lignin trees contained areas of nonconductive, brown xylem with patches of collapsed cells and patches of noncollapsed cells filled with phenolics. In contrast, phenolics and nonconductive vessels were rarely observed in normal colored wood of the low-lignin events. The results of cryo-fluorescence light microscopy were supported by observations with a confocal microscope after freeze drying of cryo-planed samples. Moreover, after extraction of the phenolics, confocal microscopy revealed that many of the vessels in the nonconductive xylem were blocked with tyloses. We conclude that reduced transport efficiency of the transgenic low-lignin xylem was largely caused by blockages from tyloses and phenolic deposits within vessels rather than by xylem collapse.
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Affiliation(s)
- Peter Kitin
- Laboratory for Wood Biology and Xylarium, Royal Museum for Central Africa, Tervuren, Belgium.
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308
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McLamore ES, Diggs A, Calvo Marzal P, Shi J, Blakeslee JJ, Peer WA, Murphy AS, Porterfield DM. Non-invasive quantification of endogenous root auxin transport using an integrated flux microsensor technique. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 63:1004-16. [PMID: 20626658 DOI: 10.1111/j.1365-313x.2010.04300.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Indole-3-acetic acid (IAA) is a primary phytohormone that regulates multiple aspects of plant development. Because polar transport of IAA is an essential determinant of organogenesis and dynamic tropic growth, methods to monitor IAA movement in vivo are in demand. A self-referencing electrochemical microsensor was optimized to non-invasively measure endogenous IAA flux near the surface of Zea mays roots without the addition of exogenous IAA. Enhanced sensor surface modification, decoupling of acquired signals, and integrated flux analyses were combined to provide direct, real time quantification of endogenous IAA movement in B73 maize inbred and brachytic2 (br2) auxin transport mutant roots. BR2 is localized in epidermal and hypodermal tissues at the root apex. br2 roots exhibit reduced shootward IAA transport at the root apex in radiotracer experiments and reduced gravitropic growth. IAA flux data indicates that maximal transport occurs in the distal elongation zone of maize roots, and net transport in/out of br2 roots was decreased compared to B73. Integration of short term real time flux data in this zone revealed oscillatory patterns, with B73 exhibiting shorter oscillatory periods and greater amplitude than br2. IAA efflux and influx were inhibited using 1-N-naphthylphthalamic acid (NPA), and 2-naphthoxyacetic acid (NOA), respectively. A simple harmonic oscillation model of these data produced a correlation between modeled and measured values of 0.70 for B73 and 0.69 for br2. These results indicate that this technique is useful for real-time IAA transport monitoring in surface tissues and that this approach can be performed simultaneously with current live imaging techniques.
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Affiliation(s)
- Eric S McLamore
- Birck-Bindley Physiological Sensing Facility, Purdue University, West Lafayette, USA
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309
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Organogenic nodule formation in hop: a tool to study morphogenesis in plants with biotechnological and medicinal applications. J Biomed Biotechnol 2010; 2010. [PMID: 20811599 PMCID: PMC2929504 DOI: 10.1155/2010/583691] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 06/14/2010] [Accepted: 06/28/2010] [Indexed: 11/18/2022] Open
Abstract
The usage of Humulus lupulus for brewing increased the demand for high-quality plant material. Simultaneously, hop has been used in traditional medicine and recently recognized with anticancer and anti-infective properties. Tissue culture techniques have been reported for a wide range of species, and open the prospect for propagation of disease-free, genetically uniform and massive amounts of plants in vitro. Moreover, the development of large-scale culture methods using bioreactors enables the industrial production of secondary metabolites.
Reliable and efficient tissue culture protocol for shoot regeneration through organogenic nodule formation was established for hop. The present review describes the histological, and biochemical changes occurring during this morphogenic process, together with an analysis of transcriptional and metabolic profiles. We also discuss the existence of common molecular factors among three different morphogenic processes: organogenic nodules and somatic embryogenesis, which strictly speaking depend exclusively on intrinsic developmental reprogramming, and legume nitrogen-fixing root nodules, which arises in response to symbiosis. The review of the key factors that participate in hop nodule organogenesis and the comparison with other morphogenic processes may have merit as a study presenting recent advances in complex molecular networks occurring during morphogenesis and together, these provide a rich framework for biotechnology applications.
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310
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Laffont C, Blanchet S, Lapierre C, Brocard L, Ratet P, Crespi M, Mathesius U, Frugier F. The compact root architecture1 gene regulates lignification, flavonoid production, and polar auxin transport in Medicago truncatula. PLANT PHYSIOLOGY 2010; 153:1597-607. [PMID: 20522723 PMCID: PMC2923893 DOI: 10.1104/pp.110.156620] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 05/28/2010] [Indexed: 05/21/2023]
Abstract
The root system architecture is crucial to adapt plant growth to changing soil environmental conditions and consequently to maintain crop yield. In addition to root branching through lateral roots, legumes can develop another organ, the nitrogen-fixing nodule, upon a symbiotic bacterial interaction. A mutant, cra1, showing compact root architecture was identified in the model legume Medicago truncatula. cra1 roots were short and thick due to defects in cell elongation, whereas densities of lateral roots and symbiotic nodules were similar to the wild type. Grafting experiments showed that a lengthened life cycle in cra1 was due to the smaller root system and not to the pleiotropic shoot phenotypes observed in the mutant. Analysis of the cra1 transcriptome at a similar early developmental stage revealed few significant changes, mainly related to cell wall metabolism. The most down-regulated gene in the cra1 mutant encodes a Caffeic Acid O-Methyl Transferase, an enzyme involved in lignin biosynthesis; accordingly, whole lignin content was decreased in cra1 roots. This correlated with differential accumulation of specific flavonoids and decreased polar auxin transport in cra1 mutants. Exogenous application of the isoflavone formononetin to wild-type plants mimicked the cra1 root phenotype, whereas decreasing flavonoid content through silencing chalcone synthases restored the polar auxin transport capacity of the cra1 mutant. The CRA1 gene, therefore, may control legume root growth through the regulation of lignin and flavonoid profiles, leading to changes in polar auxin transport.
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Affiliation(s)
| | | | | | | | | | | | | | - Florian Frugier
- Institut des Sciences du Végétal, CNRS, 91198 Gif sur Yvette cedex, France (C. Laffont, S.B., L.B., P.R., M.C., F.F.); Unité de Chimie Biologique, UMR 1318, AgroParisTech-INRA, Centre de Grignon, 78850 Thiverval-Grignon, France (C. Lapierre); Division of Plant Science, Research School of Biology, Australian Research Council Centre of Excellence for Integrative Legume Research, Australian National University, Canberra, Australian Capital Territory 0200, Australia (U.M.)
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311
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Victório CP, Arruda RDCDO, Lage CLS, Kuster RM. Production of Flavonoids in Organogenic Cultures of Alpinia Zerumbet. Nat Prod Commun 2010. [DOI: 10.1177/1934578x1000500815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Alpinia zerumbet plantlets were cultured in vitro in MS medium supplemented with growth regulators, including IAA, TDZ and BAP. Using high performance liquid chromatography (HPLC), the production of rutin, kaempferol-3- O-glucuronide, and kaempferol-3 -O-rutinoside was evaluated, based on leaf hydroalcoholic extracts of three-month-old plantlets. The relative concentration of phenolics from the hydroalcoholic extracts of plantlets cultured in control medium reached 100% compared with plantlets treated with growth regulators and donor plants (80%). The in vitro rutin production was more pronounced than the other flavonoids. While no direct relation between the content of phenolic compounds and increased flavonoid production was observed, the combination of IAA + TDZ enhanced the production of rutin (83.2 μg/g dried leaves) and kaempferol-3- O-glucuronide (29 μg/g dried leaves), compared with growth regulators used alone. Overall, these findings suggest the value of in vitro cultivation as a means of enriching phenolic and flavonoid production in medicinal plants.
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Affiliation(s)
- Cristiane P. Victório
- Laboratório de Fisiologia Vegetal, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Celso Luiz S. Lage
- Laboratório de Fisiologia Vegetal, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ricardo M. Kuster
- Laboratório de Fitoquímica, Núcleo de Pesquisas de Produtos Naturais, UFRJ, Rio de Janeiro, Brazil
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312
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Päsold S, Siegel I, Seidel C, Ludwig-Müller J. Flavonoid accumulation in Arabidopsis thaliana root galls caused by the obligate biotrophic pathogen Plasmodiophora brassicae. MOLECULAR PLANT PATHOLOGY 2010; 11:545-62. [PMID: 20618711 PMCID: PMC6640481 DOI: 10.1111/j.1364-3703.2010.00628.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Three different flavonoids-naringenin, quercetin and kaempferol-accumulate in root galls of Arabidopsis thaliana after infection with the obligate biotrophic pathogen Plasmodiophora brassicae. In addition, high-performance liquid chromatography and thin layer chromatography analysis indicated that these flavonoids and their glycosides were induced in galls rather than in healthy roots. The transcripts of selected genes involved in the biosynthesis of flavonoids were up-regulated during the time course of the disease. Some, such as chalcone synthase and chalcone isomerase, were up-regulated at both times investigated in this study, whereas up-regulation was observed only at later times for others, such as a flavonol synthase-like gene. Plants with mutations in different flavonoid biosynthesis genes were slightly more tolerant to clubroot at low infection pressure. However, flavonoid treatment of either leaves or roots did not reduce gall development. The possibility that flavonoids might influence auxin levels by regulating auxin transport or auxin degradation in roots was investigated by measuring auxin levels and response in roots of flavonoid-deficient mutants and the wild-type after inoculation with P. brassicae, as well as the antioxidative potential of flavonoids in the peroxidase-catalysed degradation of indole-3-acetic acid. In addition, the auxin transport rate from the shoots to the roots was measured in infected wild-type or flavonoid mutant plants compared with controls. In conclusion, our results indicate a role of flavonoids in the modulation of auxin efflux in root galls.
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Affiliation(s)
- Susanne Päsold
- Institute of Botany, Technische Universität Dresden, Zellescher Weg 20b, D-01062 Dresden, Germany
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313
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Agati G, Tattini M. Multiple functional roles of flavonoids in photoprotection. THE NEW PHYTOLOGIST 2010; 186:786-793. [PMID: 20569414 DOI: 10.1111/j.1469-8137.2010.03269.x] [Citation(s) in RCA: 375] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Affiliation(s)
- Giovanni Agati
- Istituto di Fisica Applicata 'Carrara', Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019, Sesto F.no, Firenze, Italy
| | - Massimiliano Tattini
- Istituto per la Protezione delle Piante, Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, I-50019, Sesto F.no, Firenze, Italy
- Present address: Dip. Scienze delle Produzioni Vegetali, del Suolo dell'Ambiente Agroforestale, sez. Coltivazioni Arboree, Università di Firenze, Viale delle Idee 30, I-50019, Sesto F.no, Firenze, Italy
- (Author for correspondence: tel +39 055 4574038; email )
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314
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Arabidopsis PIS1 encodes the ABCG37 transporter of auxinic compounds including the auxin precursor indole-3-butyric acid. Proc Natl Acad Sci U S A 2010; 107:10749-53. [PMID: 20498067 DOI: 10.1073/pnas.1005878107] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Differential distribution of the plant hormone auxin within tissues mediates a variety of developmental processes. Cellular auxin levels are determined by metabolic processes including synthesis, degradation, and (de)conjugation, as well as by auxin transport across the plasma membrane. Whereas transport of free auxins such as naturally occurring indole-3-acetic acid (IAA) is well characterized, little is known about the transport of auxin precursors and metabolites. Here, we identify a mutation in the ABCG37 gene of Arabidopsis that causes the polar auxin transport inhibitor sensitive1 (pis1) phenotype manifested by hypersensitivity to auxinic compounds. ABCG37 encodes the pleiotropic drug resistance transporter that transports a range of synthetic auxinic compounds as well as the endogenous auxin precursor indole-3-butyric acid (IBA), but not free IAA. ABCG37 and its homolog ABCG36 act redundantly at outermost root plasma membranes and, unlike established IAA transporters from the PIN and ABCB families, transport IBA out of the cells. Our findings explore possible novel modes of regulating auxin homeostasis and plant development by means of directional transport of the auxin precursor IBA and presumably also other auxin metabolites.
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315
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High molecular size humic substances enhance phenylpropanoid metabolism in maize (Zea mays L.). J Chem Ecol 2010; 36:662-9. [PMID: 20480387 DOI: 10.1007/s10886-010-9790-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 04/15/2010] [Accepted: 04/18/2010] [Indexed: 10/19/2022]
Abstract
A high molecular weight humic fraction (>3,500 Da) was characterized chemically by DRIFT and 1H NMR spectroscopy, and was applied to Zea mays L. plants to evaluate its effect on phenylpropanoid metabolism. The activity and gene expression of phenylalanine (tyrosine) ammonia-lyase (PAL/TAL), and the concentrations of phenolics and their amino acid precursors phenylalanine and tyrosine were assayed. Maximum induction of PAL/TAL activity and expression was obtained when the concentration of added humic substance was 1 mg C/l hydroponic solution. Phenylalanine and tyrosine significantly decreased (-16% and -22%, respectively), and phenolic compounds increased in treated plants. The effects of the humic substance could be ascribed partly to indoleacetic acid (27 nmol/mg C) in the humic fraction. Our results suggest that this humic fraction induces changes in phenylpropanoid metabolism. This is the first study that shows a relationship between humic substances and the phenylpropanoid pathway.
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316
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Roze LV, Chanda A, Linz JE. Compartmentalization and molecular traffic in secondary metabolism: a new understanding of established cellular processes. Fungal Genet Biol 2010; 48:35-48. [PMID: 20519149 DOI: 10.1016/j.fgb.2010.05.006] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 05/11/2010] [Accepted: 05/12/2010] [Indexed: 01/15/2023]
Abstract
Great progress has been made in understanding the regulation of expression of genes involved in secondary metabolism. Less is known about the mechanisms that govern the spatial distribution of the enzymes, cofactors, and substrates that mediate catalysis of secondary metabolites within the cell. Filamentous fungi in the genus Aspergillus synthesize an array of secondary metabolites and provide useful systems to analyze the mechanisms that mediate the temporal and spatial regulation of secondary metabolism in eukaryotes. For example, aflatoxin biosynthesis in Aspergillus parasiticus has been studied intensively because this mycotoxin is highly toxic, mutagenic, and carcinogenic in humans and animals. Using aflatoxin synthesis to illustrate key concepts, this review focuses on the mechanisms by which sub-cellular compartmentalization and intra-cellular molecular traffic contribute to the initiation and completion of secondary metabolism within the cell. We discuss the recent discovery of aflatoxisomes, specialized trafficking vesicles that participate in the compartmentalization of aflatoxin synthesis and export of the toxin to the cell exterior; this work provides a new and clearer understanding of how cells integrate secondary metabolism into basic cellular metabolism via the intra-cellular trafficking machinery.
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Affiliation(s)
- Ludmila V Roze
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI-48824, USA
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317
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Jia Z, Zou B, Wang X, Qiu J, Ma H, Gou Z, Song S, Dong H. Quercetin-induced H2O2 mediates the pathogen resistance against Pseudomonas syringae pv. Tomato DC3000 in Arabidopsis thaliana. Biochem Biophys Res Commun 2010; 396:522-7. [DOI: 10.1016/j.bbrc.2010.04.131] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 04/24/2010] [Indexed: 01/25/2023]
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318
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Managing phenol contents in crop plants by phytochemical farming and breeding-visions and constraints. Int J Mol Sci 2010; 11:807-57. [PMID: 20479987 PMCID: PMC2868352 DOI: 10.3390/ijms11030807] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 02/02/2010] [Accepted: 02/03/2010] [Indexed: 01/24/2023] Open
Abstract
Two main fields of interest form the background of actual demand for optimized levels of phenolic compounds in crop plants. These are human health and plant resistance to pathogens and to biotic and abiotic stress factors. A survey of agricultural technologies influencing the biosynthesis and accumulation of phenolic compounds in crop plants is presented, including observations on the effects of light, temperature, mineral nutrition, water management, grafting, elevated atmospheric CO(2), growth and differentiation of the plant and application of elicitors, stimulating agents and plant activators. The underlying mechanisms are discussed with respect to carbohydrate availability, trade-offs to competing demands as well as to regulatory elements. Outlines are given for genetic engineering and plant breeding. Constraints and possible physiological feedbacks are considered for successful and sustainable application of agricultural techniques with respect to management of plant phenol profiles and concentrations.
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319
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Zazímalová E, Murphy AS, Yang H, Hoyerová K, Hosek P. Auxin transporters--why so many? Cold Spring Harb Perspect Biol 2010; 2:a001552. [PMID: 20300209 PMCID: PMC2829953 DOI: 10.1101/cshperspect.a001552] [Citation(s) in RCA: 253] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Interacting and coordinated auxin transporter actions in plants underlie a flexible network that mobilizes auxin in response to many developmental and environmental changes encountered by these sessile organisms. The independent but synergistic activity of individual transporters can be differentially regulated at various levels. This invests auxin transport mechanisms with robust functional redundancy and added auxin flow capacity when needed. An evolutionary perspective clarifies the roles of the different transporter groups in plant development. Mathematical and functional analysis of elements of auxin transport makes it possible to rationalize the relative contributions of members of the respective transporter classes to the localized auxin transport streams that then underlie both preprogrammed developmental changes and reactions to environmental stimuli.
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Affiliation(s)
- Eva Zazímalová
- Institute of Experimental Botany AS CR, Rozvojová 263, CZ-165 02 Prague 6, Czech Republic.
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320
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Zhao J, Dixon RA. The 'ins' and 'outs' of flavonoid transport. TRENDS IN PLANT SCIENCE 2010; 15:72-80. [PMID: 20006535 DOI: 10.1016/j.tplants.2009.11.006] [Citation(s) in RCA: 269] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 11/18/2009] [Accepted: 11/22/2009] [Indexed: 05/18/2023]
Abstract
The sites of plant flavonoid biosynthesis, storage and final function often differ at the subcellular, cell, and even tissue and organ levels. Efficient transport systems for flavonoids across endomembranes and the plasma membrane are therefore required. However, a clear picture of the dynamic trafficking of flavonoids is only now beginning to emerge and appears to have many players. Here, we review current hypotheses for flavonoid transport, discuss whether these are mutually exclusive, highlight the importance of flavonoid efflux from vacuoles to the cytosol and consider future efforts to catch flavonoids 'in the act' of moving within and between cells. An improved understanding of transport mechanisms will facilitate the successful metabolic engineering of flavonoids for plant protection and human health.
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Affiliation(s)
- Jian Zhao
- Plant Biology Division, Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA
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321
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Impacts of Ultraviolet Radiation on Interactions Between Plants and Herbivorous Insects: A Chemo-Ecological Perspective. PROGRESS IN BOTANY 72 2010. [DOI: 10.1007/978-3-642-13145-5_12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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322
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Buer CS, Imin N, Djordjevic MA. Flavonoids: new roles for old molecules. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2010; 52:98-111. [PMID: 20074144 DOI: 10.1111/j.1744-7909.2010.00905.x] [Citation(s) in RCA: 361] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Flavonoids are ubiquitous in the plant kingdom and have many diverse functions including defense, UV protection, auxin transport inhibition, allelopathy, and flower coloring. Interestingly, these compounds also have considerable biological activity in plant, animal and bacterial systems - such broad activity is accomplished by few compounds. Yet, for all the research over the last three decades, many of the cellular targets of these secondary metabolites are unknown. The many mutants available in model plant species such as Arabidopsis thaliana and Medicago truncatula are enabling the intricacies of the physiology of these compounds to be deduced. In the present review, we cover recent advances in flavonoid research, discuss deficiencies in our understanding of the physiological processes, and suggest approaches to identify the cellular targets of flavonoids.
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Affiliation(s)
- Charles S Buer
- Genomic Interactions Group, ARC Centre of Excellence for Integrative Legume Research, Research School of Biology, College of Medicine, Biology, and Environment, The Australian National University, Canberra ACT 2601, Australia
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323
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Thompson EP, Wilkins C, Demidchik V, Davies JM, Glover BJ. An Arabidopsis flavonoid transporter is required for anther dehiscence and pollen development. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:439-51. [PMID: 19995827 PMCID: PMC2803208 DOI: 10.1093/jxb/erp312] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Revised: 10/06/2009] [Accepted: 10/06/2009] [Indexed: 05/17/2023]
Abstract
FLOWER FLAVONOID TRANSPORTER (FFT) encodes a multidrug and toxin efflux family transporter in Arabidopsis thaliana. FFT (AtDTX35) is highly transcribed in floral tissues, the transcript being localized to epidermal guard cells, including those of the anthers, stigma, siliques and nectaries. Mutant analysis demonstrates that the absence of FFT transcript affects flavonoid levels in the plant and that the altered flavonoid metabolism has wide-ranging consequences. Root growth, seed development and germination, and pollen development, release and viability are all affected. Spectrometry of mutant versus wild-type flowers shows altered levels of a glycosylated flavonol whereas anthocyanin seems unlikely to be the substrate as previously speculated. Thus, as well as adding FFT to the incompletely described flavonoid transport network, it is found that correct reproductive development in Arabidopsis is perturbed when this particular transporter is missing.
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324
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Krecek P, Skupa P, Libus J, Naramoto S, Tejos R, Friml J, Zazímalová E. The PIN-FORMED (PIN) protein family of auxin transporters. Genome Biol 2009; 10:249. [PMID: 20053306 PMCID: PMC2812941 DOI: 10.1186/gb-2009-10-12-249] [Citation(s) in RCA: 323] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A review of the PIN auxin-efflux transporters, which have important roles in plant development. Summary The PIN-FORMED (PIN) proteins are secondary transporters acting in the efflux of the plant signal molecule auxin from cells. They are asymmetrically localized within cells and their polarity determines the directionality of intercellular auxin flow. PIN genes are found exclusively in the genomes of multicellular plants and play an important role in regulating asymmetric auxin distribution in multiple developmental processes, including embryogenesis, organogenesis, tissue differentiation and tropic responses. All PIN proteins have a similar structure with amino- and carboxy-terminal hydrophobic, membrane-spanning domains separated by a central hydrophilic domain. The structure of the hydrophobic domains is well conserved. The hydrophilic domain is more divergent and it determines eight groups within the protein family. The activity of PIN proteins is regulated at multiple levels, including transcription, protein stability, subcellular localization and transport activity. Different endogenous and environmental signals can modulate PIN activity and thus modulate auxin-distribution-dependent development. A large group of PIN proteins, including the most ancient members known from mosses, localize to the endoplasmic reticulum and they regulate the subcellular compartmentalization of auxin and thus auxin metabolism. Further work is needed to establish the physiological importance of this unexpected mode of auxin homeostasis regulation. Furthermore, the evolution of PIN-based transport, PIN protein structure and more detailed biochemical characterization of the transport function are important topics for further studies.
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Affiliation(s)
- Pavel Krecek
- Institute of Experimental Botany AS CR, Rozvojová 263, CZ-16502 Prague 6, Czech Republic
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325
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Kant S, Bi YM, Zhu T, Rothstein SJ. SAUR39, a small auxin-up RNA gene, acts as a negative regulator of auxin synthesis and transport in rice. PLANT PHYSIOLOGY 2009; 151:691-701. [PMID: 19700562 PMCID: PMC2754634 DOI: 10.1104/pp.109.143875] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 08/18/2009] [Indexed: 05/18/2023]
Abstract
The phytohormone auxin plays a critical role for plant growth by regulating the expression of a set of genes. One large auxin-responsive gene family of this type is the small auxin-up RNA (SAUR) genes, although their function is largely unknown. The expression of the rice (Oryza sativa) SAUR39 gene showed rapid induction by transient change in different environmental factors, including auxin, nitrogen, salinity, cytokinin, and anoxia. Transgenic rice plants overexpressing the SAUR39 gene resulted in lower shoot and root growth, altered shoot morphology, smaller vascular tissue, and lower yield compared with wild-type plants. The SAUR39 gene was expressed at higher levels in older leaves, unlike auxin biosynthesis, which occurs largely in the meristematic region. The transgenic plants had a lower auxin level and a reduced polar auxin transport as well as the down-regulation of some putative auxin biosynthesis and transporter genes. Biochemical analysis also revealed that transgenic plants had lower chlorophyll content, higher levels of anthocyanin, abscisic acid, sugar, and starch, and faster leaf senescence compared with wild-type plants at the vegetative stage. Most of these phenomena have been shown to be negatively correlated with auxin level and transport. Transcript profiling revealed that metabolic perturbations in overexpresser plants were largely due to transcriptional changes of genes involved in photosynthesis, senescence, chlorophyll production, anthocyanin accumulation, sugar synthesis, and transport. The lower growth and yield of overexpresser plants was largely recovered by exogenous auxin application. Taken together, the results suggest that SAUR39 acts as a negative regulator for auxin synthesis and transport.
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Affiliation(s)
- Surya Kant
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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326
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Moraga ÁR, Mozos AT, Ahrazem O, Gómez-Gómez L. Cloning and characterization of a glucosyltransferase from Crocus sativus stigmas involved in flavonoid glucosylation. BMC PLANT BIOLOGY 2009; 9:109. [PMID: 19695093 PMCID: PMC2736960 DOI: 10.1186/1471-2229-9-109] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Accepted: 08/20/2009] [Indexed: 05/20/2023]
Abstract
BACKGROUND Flavonol glucosides constitute the second group of secondary metabolites that accumulate in Crocus sativus stigmas. To date there are no reports of functionally characterized flavonoid glucosyltransferases in C. sativus, despite the importance of these compounds as antioxidant agents. Moreover, their bitter taste makes them excellent candidates for consideration as potential organoleptic agents of saffron spice, the dry stigmas of C. sativus. RESULTS Using degenerate primers designed to match the plant secondary product glucosyltransferase (PSPG) box we cloned a full length cDNA encoding CsGT45 from C. sativus stigmas. This protein showed homology with flavonoid glucosyltransferases. In vitro reactions showed that CsGT45 catalyses the transfer of glucose from UDP_glucose to kaempferol and quercetin. Kaempferol is the unique flavonol present in C. sativus stigmas and the levels of its glucosides changed during stigma development, and these changes, are correlated with the expression levels of CsGT45 during these developmental stages. CONCLUSION Findings presented here suggest that CsGT45 is an active enzyme that plays a role in the formation of flavonoid glucosides in C. sativus.
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Affiliation(s)
- Ángela Rubio Moraga
- Departamento de Ciencia y Tecnología Agroforestal y Genética, ETSIA, Universidad de Castilla-La Mancha, Campus Universitario s/n, Albacete, 02071, Spain
| | - Almudena Trapero Mozos
- Departamento de Ciencia y Tecnología Agroforestal y Genética, ETSIA, Universidad de Castilla-La Mancha, Campus Universitario s/n, Albacete, 02071, Spain
- Current address: Centro Regional de Investigaciones Biomedicas, C/Almansa 14, Albacete, 02006, Spain
| | - Oussama Ahrazem
- Departamento de Ciencia y Tecnología Agroforestal y Genética, ETSIA, Universidad de Castilla-La Mancha, Campus Universitario s/n, Albacete, 02071, Spain
| | - Lourdes Gómez-Gómez
- Departamento de Ciencia y Tecnología Agroforestal y Genética, ETSIA, Universidad de Castilla-La Mancha, Campus Universitario s/n, Albacete, 02071, Spain
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327
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Dun EA, Brewer PB, Beveridge CA. Strigolactones: discovery of the elusive shoot branching hormone. TRENDS IN PLANT SCIENCE 2009; 14:364-72. [PMID: 19540149 DOI: 10.1016/j.tplants.2009.04.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 04/09/2009] [Accepted: 04/09/2009] [Indexed: 05/21/2023]
Abstract
The control of axillary bud outgrowth involves a network of hormonal signals and feedback regulation. A repressor of bud outgrowth that is central to the story has been missing since it was first postulated more than 70 years ago. This hormone moves upward in plant stems and can act as a long-distance messenger for auxin. Strigolactones, previously known as carotenoid-derived signals exuded from roots, fit the role of this elusive hormone. The discovery of branching inhibition by strigolactones will help solve many confusing aspects of branch control, including interactions with other signals, and is a great step forward toward uncovering the links between environment, genetics and plant form.
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Affiliation(s)
- Elizabeth A Dun
- The University of Queensland, Australian Research Council Centre of Excellence for Integrative Legume Research, St Lucia, QLD 4072, Australia
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328
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Yang H, Murphy AS. Functional expression and characterization of Arabidopsis ABCB, AUX 1 and PIN auxin transporters in Schizosaccharomyces pombe. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 59:179-91. [PMID: 19309458 DOI: 10.1111/j.1365-313x.2009.03856.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Heterologous expression systems based on tobacco BY-2 cells, Arabidopsis cell cultures, Xenopus oocytes, Saccharomyces cerevisiae, and human HeLa cells have been used to express and characterize PIN, ABCB (PGP), and AUX/LAX auxin transporters from Arabidopsis. However, no single system has been identified that can be used for effective comparative analyses of these proteins. We have developed an accessible Schizosaccharomyces pombe system for comparative studies of plant transport proteins. The system includes knockout mutants in all ABC and putative auxin transport genes and Gateway((R))-compatible expression vectors for functional analysis and subcellular localization of recombinant proteins. We expressed Arabidopsis ABCB1 and ABCB19 in mam1pdr1 host lines under the inducible nmt41 promoter. ABCB19 showed a higher (3)H-IAA export activity than ABCB1. Arabidopsis PIN proteins were expressed in a mutant lacking the auxin effluxer like 1 (AEL1) gene. PIN1 showed higher activity than PIN2 with similar protein expression levels. Expression of AUX1 in a permease-deficient vat3 mutant resulted in increased net auxin uptake activity. Finally, ABCB4 expressed in mam1pdr1 displayed a concentration-dependent reversal of (3)H-IAA transport that is consistent with its observed activity in planta. Structural modelling suggests that ABCB4 has three substrate interaction sites rather than the two found in ABCB19, thus providing a rationale for the observed substrate activation. Taken together, these results suggest that the S. pombe system described here can be employed for comparative analyses and subsequent structural characterizations of plant transport proteins.
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Affiliation(s)
- Haibing Yang
- Department of Horticulture, Purdue University, West Lafayette, IN 47907-2010, USA
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329
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Kazan K, Manners JM. Linking development to defense: auxin in plant-pathogen interactions. TRENDS IN PLANT SCIENCE 2009; 14:373-82. [PMID: 19559643 DOI: 10.1016/j.tplants.2009.04.005] [Citation(s) in RCA: 314] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 04/24/2009] [Accepted: 04/27/2009] [Indexed: 05/20/2023]
Abstract
Although the plant growth hormone auxin has long been recognized as a regulator of plant defense, the molecular mechanisms involved are still largely unknown. Recent studies reviewed here reveal new insights into the role of auxin in plant defense. Similar to the signaling pathways of the defense-associated plant hormones salicylic acid (SA) and jasmonic acid (JA), auxin signaling differentially affects resistance to separate pathogen groups. Recent evidence suggests that the auxin and SA pathways act in a mutually antagonistic manner during plant defense, whereas auxin and JA signaling share many commonalities. Auxin also affects disease outcomes indirectly through effects on development. Here, we discuss the multiple ways in which auxin regulation of plant growth and development might be intimately linked to plant defense.
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Affiliation(s)
- Kemal Kazan
- Commonwealth Scientific and Industrial Research Organisation Plant Industry, Queensland Bioscience Precinct, St Lucia, QLD 4067, Australia.
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330
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Abstract
This protocol allows the measurement of auxin transport in roots, hypocotyls and inflorescences of Arabidopsis thaliana plants by examining transport of radiolabeled auxin or movement of an auxin-induced gene expression signal. The protocol contains four stages: seedling growth, auxin application, a transport period of variable length, and quantification of auxin movement or reporter expression. Beyond the time for plant growth, the transport assay can be completed within 4-18 h. Auxin is applied to seedlings in agar cylinders or droplets, which does not require specialized liquid-handling equipment or micromanipulators, in contrast with methods that apply auxin in liquid droplets. Spatial control of auxin application is reduced, but this method has the advantages of being technically more feasible for most laboratories and allowing agar containing radioactive auxin to be removed for pulse chase assays that determine transport rates. These methods allow investigation of genetic and environmental factors that control auxin transport.
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Affiliation(s)
- Daniel R Lewis
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, USA
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331
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Yang H, Liu H, Li G, Feng J, Qin H, Liu X, Xue H, Wang D. Reduction of root flavonoid level and its potential involvement in lateral root emergence in Arabidopsis thaliana grown under low phosphate supply. FUNCTIONAL PLANT BIOLOGY : FPB 2009; 36:564-573. [PMID: 32688670 DOI: 10.1071/fp08283] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 03/25/2009] [Indexed: 06/11/2023]
Abstract
Although it is well known that phosphate (Pi) deficiency affects flavonoid accumulation in higher plants, knowledge on the regulation and potential function of flavonoids in the plants grown with low Pi supply is lacking. In this work, we found that low Pi treatment caused significant reduction of root flavonoid (e.g. quercetin, kaempferol and their derivatives) levels in both Columbia (Col-0) and Landsberg erecta (Ler) ecotypes of Arabidopsis thaliana (L.) Heynh. Further investigations revealed that the dysfunction of PHR1, PHO1, PHO2 and NPC4 did not affect the decrease of root flavonoid level by low Pi treatment. In contrast, pldζ2, a knockout mutant of the Arabidopsis phospholipase Dζ2, exhibited defects in the reduction of root flavonoid level and lateral root (LR) emergence under low Pi conditions. When grown under low Pi supply, the transport of auxin from the shoot apex into the root, expression of the auxin responsive DR5::GUS marker and induction of the auxin responsive genes were all significantly less efficient in pldζ2 than in wild-type (WT) control. This is the first report on the reduction of root flavonoid level and its likely contribution to increased LR emergence in Arabidopsis under Pi deficiency conditions, which may facilitate the adaptation of plants to the growth environments with poor Pi availability.
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Affiliation(s)
- Huixia Yang
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China
| | - Hong Liu
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China
| | - Gang Li
- The State Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China
| | - Juanjuan Feng
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China
| | - Huanju Qin
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China
| | - Xin Liu
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China
| | - Hongwei Xue
- The State Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China
| | - Daowen Wang
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing 100101, China
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332
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Dibley SJ, Zhou Y, Andriunas FA, Talbot MJ, Offler CE, Patrick JW, McCurdy DW. Early gene expression programs accompanying trans-differentiation of epidermal cells of Vicia faba cotyledons into transfer cells. THE NEW PHYTOLOGIST 2009; 182:863-877. [PMID: 19383101 DOI: 10.1111/j.1469-8137.2009.02822.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Transfer cells (TCs) trans-differentiate from differentiated cells by developing extensive wall ingrowths that enhance plasma membrane transport of nutrients. Here, we investigated transcriptional changes accompanying induction of TC development in adaxial epidermal cells of cultured Vicia faba cotyledons. Global changes in gene expression revealed by cDNA-AFLP were compared between adaxial epidermal cells during induction (3 h) and subsequent building (24 h) of wall ingrowths, and in cells of adjoining storage parenchyma tissue, which do not form wall ingrowths. A total of 5795 transcript-derived fragments (TDFs) were detected; of these, 264 TDFs showed epidermal-specific changes in gene expression and a further 207 TDFs were differentially expressed in both epidermal and storage parenchyma cells. Genes involved in signalling (auxin/ethylene), metabolism (mitochondrial; storage product hydrolysis), cell division, vesicle trafficking and cell wall biosynthesis were specifically induced in epidermal TCs. Blockers of auxin action and vesicle trafficking inhibited ingrowth formation and marked increases in cell division accompanied TC development. Auxin and possibly ethylene signalling cascades induce epidermal cells of V. faba cotyledons to trans-differentiate into TCs. Trans-differentiation is initiated by rapid de-differentiation to a mitotic state accompanied by mitochondrial biogenesis driving storage product hydrolysis to fuel wall ingrowth formation orchestrated by a modified vesicle trafficking mechanism.
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Affiliation(s)
- Stephen J Dibley
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Yuchan Zhou
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Felicity A Andriunas
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Mark J Talbot
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - Christina E Offler
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - John W Patrick
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
| | - David W McCurdy
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia
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333
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Peer WA, Hosein FN, Bandyopadhyay A, Makam SN, Otegui MS, Lee GJ, Blakeslee JJ, Cheng Y, Titapiwatanakun B, Yakubov B, Bangari B, Murphy AS. Mutation of the membrane-associated M1 protease APM1 results in distinct embryonic and seedling developmental defects in Arabidopsis. THE PLANT CELL 2009; 21:1693-721. [PMID: 19531600 PMCID: PMC2714933 DOI: 10.1105/tpc.108.059634] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 05/14/2009] [Accepted: 06/01/2009] [Indexed: 05/20/2023]
Abstract
Aminopeptidase M1 (APM1), a single copy gene in Arabidopsis thaliana, encodes a metallopeptidase originally identified via its affinity for, and hydrolysis of, the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). Mutations in this gene result in haploinsufficiency. Loss-of-function mutants show irregular, uncoordinated cell divisions throughout embryogenesis, affecting the shape and number of cotyledons and the hypophysis, and is seedling lethal at 5 d after germination due to root growth arrest. Quiescent center and cell cycle markers show no signals in apm1-1 knockdown mutants, and the ground tissue specifiers SHORTROOT and SCARECROW are misexpressed or mislocalized. apm1 mutants have multiple, fused cotyledons and hypocotyls with enlarged epidermal cells with cell adhesion defects. apm1 alleles show defects in gravitropism and auxin transport. Gravistimulation decreases APM1 expression in auxin-accumulating root epidermal cells, and auxin treatment increases expression in the stele. On sucrose gradients, APM1 occurs in unique light membrane fractions. APM1 localizes at the margins of Golgi cisternae, plasma membrane, select multivesicular bodies, tonoplast, dense intravacuolar bodies, and maturing metaxylem cells. APM1 associates with brefeldin A-sensitive endomembrane structures and the plasma membrane in cortical and epidermal cells. The auxin-related phenotypes and mislocalization of auxin efflux proteins in apm1 are consistent with biochemical interactions between APM1 and NPA.
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Affiliation(s)
- Wendy Ann Peer
- Department of Horticulture, Purdue University, West Lafayette, Indiana 47907, USA
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334
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Wasson AP, Ramsay K, Jones MGK, Mathesius U. Differing requirements for flavonoids during the formation of lateral roots, nodules and root knot nematode galls in Medicago truncatula. THE NEW PHYTOLOGIST 2009; 183:167-179. [PMID: 19402878 DOI: 10.1111/j.1469-8137.2009.02850.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
* In this study, we tested whether the organogenesis of symbiotic root nodules, lateral roots and root galls induced by parasitic root knot nematodes (Meloidogyne javanica) was regulated by the presence of flavonoids in the roots of Medicago truncatula. Flavonoids accumulate in all three types of root organ, and have been hypothesized previously to be required for secondary root organogenesis because of their potential role as auxin transport regulators. * Using RNA interference to silence the flavonoid biosynthetic pathway in M. truncatula, we generated transformed flavonoid-deficient hairy roots which were used to study flavonoid accumulation, cell division and organogenesis of nodules, lateral roots and root galls. * Flavonoid-deficient roots did not form nodules, as demonstrated previously, but showed altered root growth in response to rhizobia. By contrast, flavonoid-deficient roots showed no difference in the number of lateral roots and root galls. Galls on flavonoid-deficient roots formed normal giant cells, but were shorter, and were characterized by reduced numbers of dividing pericycle cells. * We rejected the hypothesis that flavonoids are required as general regulators of the organogenesis of secondary root organs, but flavonoids appear to be necessary for nodulation. Possible reasons for this difference in the requirement for flavonoids are discussed.
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Affiliation(s)
- Anton P Wasson
- Australian Research Council Centre of Excellence for Integrative Legume Research, Department of Biochemistry and Molecular Biology, School of Biology, Australian National University, Canberra ACT 0200, Australia
| | - Kerry Ramsay
- School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
| | - Michael G K Jones
- School of Biological Sciences and Biotechnology, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia
| | - Ulrike Mathesius
- Australian Research Council Centre of Excellence for Integrative Legume Research, Department of Biochemistry and Molecular Biology, School of Biology, Australian National University, Canberra ACT 0200, Australia
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335
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Hur YS, Shin KH, Kim S, Nam KH, Lee MS, Chun JY, Cheon CI. Overexpression of GmAKR1, a stress-induced aldo/keto reductase from soybean, retards nodule development. Mol Cells 2009; 27:217-23. [PMID: 19277505 DOI: 10.1007/s10059-009-0027-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 12/08/2008] [Accepted: 12/10/2008] [Indexed: 02/02/2023] Open
Abstract
Development of symbiotic root nodules in legumes involves the induction and repression of numerous genes in conjunction with changes in the level of phytohormones. We have isolated several genes that exhibit differential expression patterns during the development of soybean nodules. One of such genes, which were repressed in mature nodules, was identified as a putative aldo/keto reductase and thus named Glycine max aldo/keto reductase 1 (GmAKR1). GmAKR1 appears to be a close relative of a yeast aldo/keto reductase YakC whose in vivo substrate has not been identified yet. The expression of GmAKR1 in soybean showed a root-specific expression pattern and inducibility by a synthetic auxin analogue 2,4-D, which appeared to be corroborated by presence of the root-specific element and the stress-response element in the promoter region. In addition, constitutive overexpression of GmAKR1 in transgenic soybean hairy roots inhibited nodule development, which suggests that it plays a negative role in the regulation of nodule development. One of the Arabidopsis orthologues of GmAKR1 is the ARF-GAP domain 2 protein, which is a potential negative regulator of vesicle trafficking; therefore GmAKR1 may have a similar function in the roots and nodules of legume plants.
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MESH Headings
- 2,4-Dichlorophenoxyacetic Acid/pharmacology
- Alcohol Oxidoreductases/genetics
- Alcohol Oxidoreductases/isolation & purification
- Alcohol Oxidoreductases/metabolism
- Aldehyde Reductase
- Aldo-Keto Reductases
- Amino Acid Sequence
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Cloning, Molecular
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Herbicides/pharmacology
- Molecular Sequence Data
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plant Roots/drug effects
- Plant Roots/enzymology
- Plant Roots/microbiology
- Plants, Genetically Modified
- Promoter Regions, Genetic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Rhizobiaceae/pathogenicity
- Root Nodules, Plant/drug effects
- Root Nodules, Plant/enzymology
- Root Nodules, Plant/microbiology
- Seedlings/drug effects
- Seedlings/enzymology
- Seedlings/microbiology
- Sequence Homology, Amino Acid
- Glycine max/enzymology
- Symbiosis
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Affiliation(s)
- Yoon-Sun Hur
- Department of Biological Science, Sookmyung Women's University, Seoul, 140-742, Korea
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336
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Potters G, Pasternak TP, Guisez Y, Jansen MAK. Different stresses, similar morphogenic responses: integrating a plethora of pathways. PLANT, CELL & ENVIRONMENT 2009; 32:158-69. [PMID: 19021890 DOI: 10.1111/j.1365-3040.2008.01908.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Exposure of plants to mild chronic stress can cause induction of specific, stress-induced morphogenic responses (SIMRs). These responses are characterized by a blockage of cell division in the main meristematic tissues, an inhibition of elongation and a redirected outgrowth of lateral organs. Key elements in the ontogenesis of this phenotype appear to be stress-affected gradients of reactive oxygen species (ROS), antioxidants, auxin and ethylene. These gradients are present at the the organismal level, but are integrated on the cellular level, affecting cell division, cell elongation and/or cell differentiation. Our analysis of the literature indicates that stress-induced modulation of plant growth is mediated by a plethora of molecular interactions, whereby different environmental signals can trigger similar morphogenic responses. At least some of the molecular interactions that underlie morphogenic responses appear to be interchangeable. We speculate that this complexity can be viewed in terms of a thermodynamic model, in which not the specific pathway, but the achieved metabolic state is biologically conserved.
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Affiliation(s)
- Geert Potters
- Department of Bioscience Engineering, University of Antwerp, Antwerp, Belgium
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337
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Buer CS, Djordjevic MA. Architectural phenotypes in the transparent testa mutants of Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:751-63. [PMID: 19129166 PMCID: PMC2652062 DOI: 10.1093/jxb/ern323] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 11/17/2008] [Accepted: 11/19/2008] [Indexed: 05/18/2023]
Abstract
Flavonoids are low molecular weight secondary plant metabolites with a myriad of functions. As flavonoids affect auxin transport (an important growth-controlling hormone) and are biologically active in eukaryotes, flavonoid mutants were expected to have undescribed architectural phenotypes. The Arabidopsis thaliana transparent testa (tt) mutants are compromised in the enzymatic steps or transcriptional regulators affecting flavonoid synthesis. tt mutant seedlings were grown on hard-slanted agar (a stress condition), under varying light conditions, and in soil to examine the resulting growth patterns. These tt mutants revealed a wide variety of architectural phenotypes in root and aerial tissues. Mutants with increased inflorescences, siliques, and lateral root density or reduced stature are traits that could affect plant yield or performance under certain environmental conditions. The regulatory genes affected in architectural traits may provide useful molecular targets for examination in other plants.
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Affiliation(s)
- Charles S Buer
- Australian Research Council Centre of Excellence for Integrative Legume Research, School of Science, College of Medicine, Biology, and Environment, The Australian National University, Canberra ACT 2601, Australia.
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338
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Zhang J, Subramanian S, Stacey G, Yu O. Flavones and flavonols play distinct critical roles during nodulation of Medicago truncatula by Sinorhizobium meliloti. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:171-83. [PMID: 18786000 DOI: 10.1111/j.1365-313x.2008.03676.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Flavonoids play critical roles in legume-rhizobium symbiosis. However, the role of individual flavonoid compounds in this process has not yet been clearly established. We silenced different flavonoid-biosynthesis enzymes to generate transgenic Medicago truncatula roots with different flavonoid profiles. Silencing of chalcone synthase, the key entry-point enzyme for flavonoid biosynthesis led to flavonoid-deficient roots. Silencing of isoflavone synthase and flavone synthase led to roots deficient for a subset of flavonoids, isoflavonoids (formononetin and biochanin A) and flavones (7,4'-dihydroxyflavone), respectively. When tested for nodulation by Sinorhizobium meliloti, flavonoid-deficient roots had a near complete loss of nodulation, whereas flavone-deficient roots had reduced nodulation. Isoflavone-deficient roots nodulated normally, suggesting that isoflavones might not play a critical role in M. truncatula nodulation, even though they are the most abundant root flavonoids. Supplementation of flavone-deficient roots with 7, 4'-dihydroxyflavone, a major inducer of S. meliloti nod genes, completely restored nodulation. However, the same treatment did not restore nodulation in flavonoid-deficient roots, suggesting that other non-nod gene-inducing flavonoid compounds are also critical to nodulation. Supplementation of roots with the flavonol kaempferol (an inhibitor of auxin transport), in combination with the use of flavone pre-treated S. meliloti cells, completely restored nodulation in flavonoid-deficient roots. In addition, S. meliloti cells constitutively producing Nod factors were able to nodulate flavone-deficient roots, but not flavonoid-deficient roots. These observations indicated that flavones might act as internal inducers of rhizobial nod genes, and that flavonols might act as auxin transport regulators during nodulation. Both these roles of flavonoids appear critical for symbiosis in M. truncatula.
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Affiliation(s)
- Juan Zhang
- Donald Danforth Plant Science Center, 975 N. Warson Road, Saint Louis, MO 63132, USA
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339
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Titapiwatanakun B, Murphy AS. Post-transcriptional regulation of auxin transport proteins: cellular trafficking, protein phosphorylation, protein maturation, ubiquitination, and membrane composition. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1093-107. [PMID: 18824505 DOI: 10.1093/jxb/ern240] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Auxin concentration gradients, established by polar transport of auxin, are essential for the establishment and maintenance of polar growth and morphological patterning. Three families of cellular transport proteins, PIN-formed (PIN), P-glycoprotein (ABCB/PGP), and AUXIN RESISTANT 1/LIKE AUX1 (AUX1/LAX), can independently and co-ordinately transport auxin in plants. Regulation of these proteins involves intricate and co-ordinated cellular processes, including protein-protein interactions, vesicular trafficking, protein phosphorylation, ubiquitination, and stabilization of the transporter complexes on the plasma membrane.
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340
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Yazaki K, Shitan N, Sugiyama A, Takanashi K. Chapter 6 Cell and Molecular Biology of ATP‐Binding Cassette Proteins in Plants. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:263-99. [DOI: 10.1016/s1937-6448(09)76006-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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341
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Titapiwatanakun B, Blakeslee JJ, Bandyopadhyay A, Yang H, Mravec J, Sauer M, Cheng Y, Adamec J, Nagashima A, Geisler M, Sakai T, Friml J, Peer WA, Murphy AS. ABCB19/PGP19 stabilises PIN1 in membrane microdomains in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 57:27-44. [PMID: 18774968 DOI: 10.1111/j.1365-313x.2008.03668.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Auxin transport is mediated at the cellular level by three independent mechanisms that are characterised by the PIN-formed (PIN), P-glycoprotein (ABCB/PGP) and AUX/LAX transport proteins. The PIN and ABCB transport proteins, best represented by PIN1 and ABCB19 (PGP19), have been shown to coordinately regulate auxin efflux. When PIN1 and ABCB19 coincide on the plasma membrane, their interaction enhances the rate and specificity of auxin efflux and the dynamic cycling of PIN1 is reduced. However, ABCB19 function is not regulated by the dynamic cellular trafficking mechanisms that regulate PIN1 in apical tissues, as localisation of ABCB19 on the plasma membrane was not inhibited by short-term treatments with latrunculin B, oryzalin, brefeldin A (BFA) or wortmannin--all of which have been shown to alter PIN1 and/or PIN2 plasma membrane localisation. When taken up by endocytosis, the styryl dye FM4-64 labels diffuse rather than punctuate intracellular bodies in abcb19 (pgp19), and some aggregations of PIN1 induced by short-term BFA treatment did not disperse after BFA washout in abcb19. Although the subcellular localisations of ABCB19 and PIN1 in the reciprocal mutant backgrounds were like those in wild type, PIN1 plasma membrane localisation in abcb19 roots was more easily perturbed by the detergent Triton X-100, but not other non-ionic detergents. ABCB19 is stably associated with sterol/sphingolipid-enriched membrane fractions containing BIG/TIR3 and partitions into Triton X-100 detergent-resistant membrane (DRM) fractions. In the wild type, PIN1 was also present in DRMs, but was less abundant in abcb19 DRMs. These observations suggested a rationale for the observed lack of auxin transport activity when PIN1 is expressed in a non-plant heterologous system. PIN1 was therefore expressed in Schizosaccharomyces pombe, which has plant-like sterol-enriched microdomains, and catalysed auxin transport in these cells. These data suggest that ABCB19 stabilises PIN1 localisation at the plasma membrane in discrete cellular subdomains where PIN1 and ABCB19 expression overlaps.
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342
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Mathesius U. Auxin: at the root of nodule development? FUNCTIONAL PLANT BIOLOGY : FPB 2008; 35:651-668. [PMID: 32688821 DOI: 10.1071/fp08177] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 08/14/2008] [Indexed: 06/11/2023]
Abstract
Root nodules are formed as a result of an orchestrated exchange of chemical signals between symbiotic nitrogen fixing bacteria and certain plants. In plants that form nodules in symbiosis with actinorhizal bacteria, nodules are derived from lateral roots. In most legumes, nodules are formed de novo from pericycle and cortical cells that are re-stimulated for division and differentiation by rhizobia. The ability of plants to nodulate has only evolved recently and it has, therefore, been suggested that nodule development is likely to have co-opted existing mechanisms for development and differentiation from lateral root formation. Auxin is an important regulator of cell division and differentiation, and changes in auxin accumulation and transport are essential for lateral root development. There is growing evidence that rhizobia alter the root auxin balance as a prerequisite for nodule formation, and that nodule numbers are regulated by shoot-to-root auxin transport. Whereas auxin requirements appear to be similar for lateral root and nodule primordium activation and organ differentiation, the major difference between the two developmental programs lies in the specification of founder cells. It is suggested that differing ratios of auxin and cytokinin are likely to specify the precursors of the different root organs.
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Affiliation(s)
- Ulrike Mathesius
- School of Biochemistry and Molecular Biology, Australian National University and Australian Research Council Centre of Excellence for Integrative Legume Research, Linnaeus Way, Canberra, ACT 0200, Australia. Email
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343
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Dubos C, Le Gourrierec J, Baudry A, Huep G, Lanet E, Debeaujon I, Routaboul JM, Alboresi A, Weisshaar B, Lepiniec L. MYBL2 is a new regulator of flavonoid biosynthesis in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:940-53. [PMID: 18532978 DOI: 10.1111/j.1365-313x.2008.03564.x] [Citation(s) in RCA: 368] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
In Arabidopsis thaliana, several MYB and basic helix-loop-helix (BHLH) proteins form ternary complexes with TTG1 (WD-Repeats) and regulate the transcription of genes involved in anthocyanin and proanthocyanidin (PA) biosynthesis. Similar MYB-BHLH-WDR (MBW) complexes control epidermal patterning and cell fates. A family of small MYB proteins (R3-MYB) has been shown to play an important role in the regulation of epidermal cell fates, acting as inhibitors of the MBW complexes. However, so far none of these small MYB proteins have been demonstrated to regulate flavonoid biosynthesis. The genetic and molecular analyses presented here demonstrated that Arabidopsis MYBL2, which encodes a R3-MYB-related protein, is involved in the regulation of flavonoid biosynthesis. The loss of MYBL2 activity in the seedlings of two independent T-DNA insertion mutants led to a dramatic increase in the accumulation of anthocyanin. In addition, overexpression of MYBL2 in seeds inhibited the biosynthesis of PAs. These changes in flavonoid content correlate well with the increased level of mRNA of several structural and regulatory anthocyanin biosynthesis genes. Interestingly, transient expression analyses in A. thaliana cells suggested that MYBL2 interacts with MBW complexes in planta and directly modulates the expression of flavonoid target genes. These results are fully consistent with the molecular interaction of MYBL2 with BHLH proteins observed in yeast. Finally, MYBL2 expression studies, including its inhibition by light-induced stress, allowed us to hypothesise a physiological role for MYBL2. Taken together, these results bring new insights into the transcriptional regulation of flavonoid biosynthesis and provide new clues and tools for further investigation of its developmental and environmental regulation.
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Affiliation(s)
- Christian Dubos
- INRA and AgroParisTech, UMR204, Seed Biology Laboratory, IJPB, Route de Saint-Cyr 78026 Versailles, France
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344
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Santelia D, Henrichs S, Vincenzetti V, Sauer M, Bigler L, Klein M, Bailly A, Lee Y, Friml J, Geisler M, Martinoia E. Flavonoids redirect PIN-mediated polar auxin fluxes during root gravitropic responses. J Biol Chem 2008; 283:31218-26. [PMID: 18718912 DOI: 10.1074/jbc.m710122200] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The rate, polarity, and symmetry of the flow of the plant hormone auxin are determined by the polar cellular localization of PIN-FORMED (PIN) auxin efflux carriers. Flavonoids, a class of secondary plant metabolites, have been suspected to modulate auxin transport and tropic responses. Nevertheless, the identity of specific flavonoid compounds involved and their molecular function and targets in vivo are essentially unknown. Here we show that the root elongation zone of agravitropic pin2/eir1/wav6/agr1 has an altered pattern and amount of flavonol glycosides. Application of nanomolar concentrations of flavonols to pin2 roots is sufficient to partially restore root gravitropism. By employing a quantitative cell biological approach, we demonstrate that flavonoids partially restore the formation of lateral auxin gradients in the absence of PIN2. Chemical complementation by flavonoids correlates with an asymmetric distribution of the PIN1 protein. pin2 complementation probably does not result from inhibition of auxin efflux, as supply of the auxin transport inhibitor N-1-naphthylphthalamic acid failed to restore pin2 gravitropism. We propose that flavonoids promote asymmetric PIN shifts during gravity stimulation, thus redirecting basipetal auxin streams necessary for root bending.
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Affiliation(s)
- Diana Santelia
- Laboratory of Molecular Plant Physiology, Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland
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345
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Owens DK, Alerding AB, Crosby KC, Bandara AB, Westwood JH, Winkel BSJ. Functional analysis of a predicted flavonol synthase gene family in Arabidopsis. PLANT PHYSIOLOGY 2008; 147:1046-61. [PMID: 18467451 PMCID: PMC2442520 DOI: 10.1104/pp.108.117457] [Citation(s) in RCA: 169] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Accepted: 04/24/2008] [Indexed: 05/18/2023]
Abstract
The genome of Arabidopsis (Arabidopsis thaliana) contains five sequences with high similarity to FLAVONOL SYNTHASE1 (AtFLS1), a previously characterized flavonol synthase gene that plays a central role in flavonoid metabolism. This apparent redundancy suggests the possibility that Arabidopsis uses multiple isoforms of FLS with different substrate specificities to mediate the production of the flavonols, quercetin and kaempferol, in a tissue-specific and inducible manner. However, biochemical and genetic analysis of the six AtFLS sequences indicates that, although several of the members are expressed, only AtFLS1 encodes a catalytically competent protein. AtFLS1 also appears to be the only member of this group that influences flavonoid levels and the root gravitropic response in seedlings under nonstressed conditions. This study showed that the other expressed AtFLS sequences have tissue- and cell type-specific promoter activities that overlap with those of AtFLS1 and encode proteins that interact with other flavonoid enzymes in yeast two-hybrid assays. Thus, it is possible that these "pseudogenes" have alternative, noncatalytic functions that have not yet been uncovered.
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Affiliation(s)
- Daniel K Owens
- Departments of Biological Sciences , Virginia Tech, Blacksburg, Virginia 24061-0390, USA
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346
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Buer CS, Muday GK, Djordjevic MA. Implications of long-distance flavonoid movement in Arabidopsis thaliana. PLANT SIGNALING & BEHAVIOR 2008; 3:415-7. [PMID: 19704584 PMCID: PMC2634320 DOI: 10.4161/psb.3.6.5440] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2007] [Accepted: 12/19/2007] [Indexed: 05/18/2023]
Abstract
Flavonoid synthesis is modulated by developmental and environmental signals that control the amounts and localization of the diverse flavonoids found in plants. Flavonoids are implicated in regulating a number of physiological processes including UV protection, fertilization, auxin transport, plant architecture, gravitropism and pathogenic and symbiotic interactions with other organisms. Recently we showed that flavonoids can move long distances in plants, which may facilitate these molecules reaching positions in the plant where these processes are regulated. The localised application of selective flavonoids to tt4 mutants such as naringenin, dihydrokaempferol and dihydroquercetin showed that they were taken up at the root tip, mid-root or cotyledons and travelled long distances via cell-to-cell movement to distal tissues and converted to quercetin and kaempferol. In contrast, kaempferol and quercetin do not move long distances. They were taken up only at the root tip and did not move from this position. Here we show the movement of endogenous flavonoids by using reciprocal grafting experiments between tt4 and wild-type seedlings. These results demonstrated that to understand the distribution of flavonoids in Arabidopsis, it is necessary to know where the flavonoid biosynthetic enzymes are made and to understand the mechanisms by which certain flavonoids move from their site of synthesis.
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Affiliation(s)
- Charles S Buer
- Genomic Interactions Group; Australian Research Council Centre of Excellence for Integrative Legume Research; Research School of Biological Sciences; The Australian National University; Canberra, Australia
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347
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Bailly A, Sovero V, Vincenzetti V, Santelia D, Bartnik D, Koenig BW, Mancuso S, Martinoia E, Geisler M. Modulation of P-glycoproteins by auxin transport inhibitors is mediated by interaction with immunophilins. J Biol Chem 2008; 283:21817-26. [PMID: 18499676 DOI: 10.1074/jbc.m709655200] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The immunophilin-like FKBP42 TWISTED DWARF1 (TWD1) has been shown to control plant development via the positive modulation of ABCB/P-glycoprotein (PGP)-mediated transport of the plant hormone auxin. TWD1 functionally interacts with two closely related proteins, ABCB1/PGP1 and ABCB19/PGP19/MDR1, both of which exhibit the ability to bind to and be inhibited by the synthetic auxin transport inhibitor N-1-naphylphtalamic acid (NPA). They are also inhibited by flavonoid compounds, which are suspected modulators of auxin transport. The mechanisms by which flavonoids and NPA interfere with auxin efflux components are unclear. We report here the specific disruption of PGP1-TWD1 interaction by NPA and flavonoids using bioluminescence resonance energy transfer with flavonoids functioning as a classical established inhibitor of mammalian and plant PGPs. Accordingly, TWD1 was shown to mediate modulation of PGP1 efflux activity by these auxin transport inhibitors. NPA bound to both PGP1 and TWD1 but was excluded from the PGP1-TWD1 complex expressed in yeast, suggesting a transient mode of action in planta. As a consequence, auxin fluxes and gravitropism in twd1 roots are less affected by NPA treatment, whereas TWD1 gain-of-function promotes root bending. Our data support a novel model for the mode of drug-mediated P-glycoprotein regulation mediated via protein-protein interaction with immunophilin-like TWD1.
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Affiliation(s)
- Aurélien Bailly
- Institute of Plant Biology and Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
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348
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Seeing is believing: engineering anthocyanin and carotenoid biosynthetic pathways. Curr Opin Biotechnol 2008; 19:190-7. [DOI: 10.1016/j.copbio.2008.02.015] [Citation(s) in RCA: 186] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Revised: 02/22/2008] [Accepted: 02/23/2008] [Indexed: 11/20/2022]
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