Barry J Pogson

Australian National University, Canberra, Australian Capital Territory, Australia

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Publications (80)437.84 Total impact

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    ABSTRACT: In addition to acting as photoprotective compounds, carotenoids also serve as precursors in the biosynthesis of several phytohormones and proposed regulatory signals. Here, we report a signaling process derived from carotenoids that regulates early chloroplast and leaf development. Biosynthesis of the signal depends on ζ-carotene desaturase activity encoded by the ζ-CAROTENE DESATURASE (ZDS)/CHLOROPLAST BIOGENESIS5 (CLB5) gene in Arabidopsis thaliana. Unlike other carotenoid-deficient plants, zds/clb5 mutant alleles display profound alterations in leaf morphology and cellular differentiation as well as altered expression of many plastid- and nucleus-encoded genes. The leaf developmental phenotypes and gene expression alterations of zds/clb5/spc1/pde181 plants are rescued by inhibitors or mutations of phytoene desaturase, demonstrating that phytofluene and/or ζ-carotene are substrates for an unidentified signaling molecule. Our work further demonstrates that this signal is an apocarotenoid whose synthesis requires the activity of the carotenoid cleavage dioxygenase CCD4.
    The Plant cell. 06/2014;
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    ABSTRACT: In plants, continuous formation of lateral roots (LRs) facilitates efficient exploration of the soil environment. Roots can maximize developmental capacity in variable environmental conditions through establishment of sites competent to form LRs. This LR prepattern is established by a periodic oscillation in gene expression near the root tip. The spatial distribution of competent (prebranch) sites results from the interplay between this periodic process and primary root growth; yet, much about this oscillatory process and the formation of prebranch sites remains unknown. We find that disruption of carotenoid biosynthesis results in seedlings with very few LRs. Carotenoids are further required for the output of the LR clock because inhibition of carotenoid synthesis also results in fewer sites competent to form LRs. Genetic analyses and a carotenoid cleavage inhibitor indicate that an apocarotenoid, distinct from abscisic acid or strigolactone, is specifically required for LR formation. Expression of a key carotenoid biosynthesis gene occurs in a spatially specific pattern along the root's axis, suggesting spatial regulation of carotenoid synthesis. These results indicate that developmental prepatterning of LRs requires an uncharacterized carotenoid-derived molecule. We propose that this molecule functions non-cell-autonomously in establishment of the LR prepattern.
    Proceedings of the National Academy of Sciences 03/2014; · 9.81 Impact Factor
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    ABSTRACT: Agriculture requires a second green revolution to provide increased food, fodder, fiber, fuel and soil fertility for a growing population while being more resilient to extreme weather on finite land, water, and nutrient resources. Advances in phenomics, genomics and environmental control/sensing can now be used to directly select yield and resilience traits from large collections of germplasm if software can integrate among the technologies. Traits could be Captured throughout development and across environments from multi-dimensional phenotypes, by applying Genome Wide Association Studies (GWAS) to identify causal genes and background variation and functional structural plant models (FSPMs) to predict plant growth and reproduction in target environments. TraitCapture should be applicable to both controlled and field environments and would allow breeders to simulate regional variety trials to pre-select for increased productivity under challenging environments.
    Current Opinion in Plant Biology 03/2014; 18:73-79. · 8.46 Impact Factor
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    ABSTRACT: Cellular auxin homeostasis controls many aspects of plant growth, organogenesis and development. The existence of intracellular auxin transport mediated by endoplasmic reticulum (ER)-localized PIN5, PIN6 and PIN8 proteins is a relatively recent discovery shaping a new era in understanding auxin-mediated growth processes. Here we summarize the importance of PIN6 in mediating intracellular auxin transport during root formation, leaf vein patterning and nectary production. While, it was previously shown that PIN6 was strongly expressed in rosette leaf cell types important in vein formation, here we demonstrate by use a PIN6 promoter-reporter fusion, that PIN6 is also preferentially expressed in the vasculature of the primary root, cotyledons, cauline leaves, floral stem, sepals and the main transmitting tract of the reproductive silique. The strong, vein- specific reporter gene expression patterns enabled by the PIN6 promoter emphasizes that transcriptional control is likely to be a major regulator of PIN6 protein levels, during vasculature formation, and supports the need for ER-localized PIN proteins in selecting specialized cells for vascular function in land plants.
    Plant signaling & behavior 01/2014; 9(1).
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    ABSTRACT: The cytosol is the fluid portion of the cell that is not partitioned by membranes. It contains a highly diverse collection of substances and is central to many essential cellular processes ranging from signal transduction, metabolite production and transport, protein biosynthesis and degradation to stress response and defense. Despite its importance, only a few proteomic studies have been performed on the plant cytosol. This is largely due to difficulties in isolating relatively pure samples from plant material free of disrupted organelle material. In this chapter we outline methods for isolating the cytosolic fraction from Arabidopsis cell cultures and seedlings and provide guidance on assessing purity for analysis by mass spectrometry.
    Methods in molecular biology (Clifton, N.J.) 01/2014; 1072:453-67. · 1.29 Impact Factor
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    ABSTRACT: Thigmomorphogenesis is viewed as being a response process of acclimation to short repetitive bursts of mechanical stimulation or touch. The underlying molecular mechanisms that coordinate changes in how touch signals lead to long-term morphological changes are enigmatic. Touch responsive gene expression is rapid and transient, and no transcription factor or DNA regulatory motif has been reported that could confer a genome wide mechanical stimulus. We report here on a chromatin modifying enzyme, SDG8/ASHH2, which can regulate the expression of many touch responsive genes identified in Arabidopsis. SDG8 is required for the permissive expression of touch induced genes; and the loss of function of sdg8 perturbs the maximum levels of induction on selected touch gene targets. SDG8 is required to maintain permissive H3K4 trimethylation marks surrounding the Arabidopsis touch-inducible gene TOUCH 3 (TCH3), which encodes a calmodulin-like protein (CML12). The gene neighboring was also slightly down regulated, revealing a new target for SDG8 mediated chromatin modification. Finally, sdg8 mutants show perturbed morphological response to wind-agitated mechanical stimuli, implicating an epigenetic memory-forming process in the acclimation response of thigmomorphogenesis.
    Frontiers in Plant Science 01/2014; 5:533. · 3.60 Impact Factor
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    ABSTRACT: Excess light can have a negative impact on photosynthesis, thus plants have evolved many different ways to adapt to different light conditions to both optimize energy use and avoid damage caused by excess light. Analysis of the snowy cotyledon 4 (sco4) mutant revealed a mutation in a chloroplast-targeted protein which shares limited homology with CaaX-type-endopeptidases. The SCO4 protein possesses an important function in photosynthesis and development, with point mutations rendering the seedlings and adult plants susceptible to photo-oxidative stress. The sco4 mutation impairs acclimation of chloroplasts and their photosystems to excess light, evidenced in a reduction in PS I function, decreased linear electron transfer, yet increased non-photochemical quenching. SCO4 is localized to the chloroplasts and suggests the existence of an unreported type of protein modification within this organelle. Phylogenetic and yeast complementation analyses of SCO4-like proteins reveals that SCO4 is a member of a unknown group of higher plant-specific proteinases quite distinct from the well described CaaX-type endopeptidases RCE1 and STE24 and lacks canonical CaaX activity. Therefore, we hypothesize that SCO4 is a novel endopeptidase required for critical protein modifications within chloroplasts, influencing the function of proteins involved in photosynthesis required for tolerance to excess light.
    Plant physiology 08/2013; · 6.56 Impact Factor
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    ABSTRACT: Background / Purpose: Plants have a range of photo-protective mechanisms to prevent damage. Looking for variations in natural populations may identify novel genes and alleles responsible for photoprotection. Main conclusion: Our preliminary results show that high throughput fluorescence imaging methods using TrayScan can be used to study photoprotective mechanisms in large populations. Using this method and analysis pipeline for QTL mapping we can identify novel genes which relate to non-photochemical quenching (NPQ).
    24th International Conference on Arabidopsis Research (ICAR) 2013; 08/2013
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    ABSTRACT: Sunlight provides energy for photosynthesis and is essential for nearly all life on earth. However, too much or too little light or rapidly fluctuating light conditions cause stress to plants. Rapid changes in the amount of light are perceived as a change in the reduced/oxidized (redox) state of photosynthetic electron transport components in chloroplasts. However, how this generates a signal that is relayed to changes in nuclear gene expression is not well understood. We modified redox state in the reference plant, Arabidopsis thaliana, using either excess light or low light plus the herbicide DBMIB (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone), a well-known inhibitor of photosynthetic electron transport. Modification of redox state caused a change in expression of a common set of about 750 genes, many of which are known stress-responsive genes. Among the most highly enriched promoter elements in the induced gene set were heat-shock elements (HSEs), known motifs that change gene expression in response to high temperature in many systems. We show that HSEs from the promoter of the ASCORBATE PEROXIDASE 2 (APX2) gene were necessary and sufficient for APX2 expression in conditions of excess light, or under low light plus the herbicide. We tested APX2 expression phenotypes in overexpression and loss-of-function mutants of 15 Arabidopsis A-type heat-shock transcription factors (HSFs), and identified HSFA1D, HSFA2, and HSFA3 as key factors regulating APX2 expression in diverse stress conditions. Excess light regulates both the subcellular location of HSFA1D and its biochemical properties, making it a key early component of the excess light stress network of plants.
    Proceedings of the National Academy of Sciences 08/2013; · 9.81 Impact Factor
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    ABSTRACT: Plant-specific PIN-formed (PIN) efflux transporters for the plant hormone auxin are required for tissue-specific directional auxin transport and cellular auxin homeostasis. The Arabidopsis PIN protein family has been shown to play important roles in developmental processes such as embryogenesis, organogenesis, vascular tissue differentiation, root meristem patterning and tropic growth. Here we analyzed roles of the less characterised Arabidopsis PIN6 auxin transporter. PIN6 is auxin-inducible and is expressed during multiple auxin-regulated developmental processes. Loss of pin6 function interfered with primary root growth and lateral root development. Misexpression of PIN6 affected auxin transport and interfered with auxin homeostasis in other growth processes such as shoot apical dominance, lateral root primordia development, adventitious root formation, root hair outgrowth and root waving. These changes in auxin-regulated growth correlated with a reduction in total auxin transport as well as with an altered activity of DR5-GUS auxin response reporter. Overall, the data indicate that PIN6 regulates auxin homeostasis during plant development.
    PLoS ONE 01/2013; 8(7):e70069. · 3.53 Impact Factor
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    Melanie E Carmody, Barry J Pogson
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    ABSTRACT: Systemic signalling of photooxidative stress from a high light (HL)-exposed leaf to a shaded leaf results in systemic acquired acclimation (SAA) in the distal tissue. As yet unanswered questions in systemic photooxidative stress signalling are in regard to what type of signal and what form of travel the signal takes from a small area of exposed tissue to as yet unstressed distal tissues. Issues such as the specificity of different stress responses, how different ROS signalling pathways converge, and antagonistically regulated systems are all currently being investigated. The majority of studies in this field, however, focus on the intercellular signalling aspects rather than leaf-to-leaf movement of the signal. Traditional studies of biotic long-distance signalling have not as yet been comprehensively applied to abiotic stress signalling research, particularly in regard to whether an abiotic signal is able to rapidly travel through the vasculature from leaf to leaf. This review covers literature relating to the effects that HL intensity and the production of ROS have on the stress signalling processes of light perception, retrograde and intercellular signalling, as well as leaf-to-leaf systemic signalling in the model organism Arabidopsis thaliana.
    Long-Distance Systemic Signaling and Communication in Plants, Edited by František Baluška, 01/2013: chapter Systemic Photooxidative Stress Signalling: pages 251-274; Springer Berlin Heidelberg., ISBN: 978-3-642-36470-9
  • Melanie E. Carmody, Barry J. Pogson
    Long-Distance Systemic Signaling and Communication in Plants, Edited by F. Baluska, 01/2013: pages 251-274; Springer.
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    ABSTRACT: Half a century of research into the physiology and biochemistry of sun-shade acclimation in diverse plants has provided reality checks for contemporary understanding of thylakoid membrane dynamics. This paper reviews recent insights into photosynthetic efficiency and photoprotection from studies of two xanthophyll cycles in old shade leaves from the inner canopy of the tropical trees Inga sapindoides and Persea americana (avocado). It then presents new physiological data from avocado on the time frames of the slow coordinated photosynthetic development of sink leaves in sunlight and on the slow renovation of photosynthetic properties in old leaves during sun to shade and shade to sun acclimation. In so doing, it grapples with issues in vivo that seem relevant to our increasingly sophisticated understanding of ΔpH-dependent, xanthophyll-pigment-stabilized non-photochemical quenching in the antenna of PSII in thylakoid membranes in vitro.
    Philosophical Transactions of The Royal Society B Biological Sciences 12/2012; 367(1608):3503-14. · 6.23 Impact Factor
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    ABSTRACT: BACKGROUND: Plant grafting techniques have deepened our understanding of the signals facilitating communication between the root and shoot, as well as between shoot and reproductive organs. Transmissible signalling molecules can include hormones, peptides, proteins and metabolites: some of which travel long distances to communicate stress, nutrient status, disease and developmental events. While hypocotyl micrografting techniques have been successfully established for Arabidopsis to explore root to shoot communications, inflorescence grafting in Arabidopsis has not been exploited to the same extent. Two different strategies (horizontal and wedge-style inflorescence grafting) have been developed to explore long distance signalling between the shoot and reproductive organs. We developed a robust wedge-cleft grafting method, with success rates greater than 87%, by developing better tissue contact between the stems from the inflorescence scion and rootstock. We describe how to perform a successful inflorescence stem graft that allows for reproducible translocation experiments into the physiological, developmental and molecular aspects of long distance signalling events that promote reproduction. RESULTS: Wedge grafts of the Arabidopsis inflorescence stem were supported with silicone tubing and further sealed with parafilm to maintain the vascular flow of nutrients to the shoot and reproductive tissues. Nearly all (87%) grafted plants formed a strong union between the scion and rootstock. The success of grafting was scored using an inflorescence growth assay based upon the growth of primary stem. Repeated pruning produced new cauline tissues, healthy flowers and reproductive siliques, which indicates a healthy flow of nutrients from the rootstock. Removal of the silicone tubing showed a tightly fused wedge graft junction with callus proliferation. Histological staining of sections through the graft junction demonstrated the differentiation of newly formed vascular connections, parenchyma tissue and lignin accumulation, supporting the presumed success of the graft union between two sections of the primary inflorescence stem. CONCLUSIONS: We describe a simple and reliable method for grafting sections of an Arabidopsis inflorescence stem. This step-by-step protocol facilitates laboratories without grafting experience to further explore the molecular and chemical signalling which coordinates communications between the shoot and reproductive tissues.
    Plant Methods 12/2012; 8(1):50. · 2.59 Impact Factor
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    ABSTRACT: This study resolved correlations between changes in xanthophyll pigments and photosynthetic properties in attached and detached shade-grown avocado leaves upon sun exposure. Lutein epoxide (Lx) was de-epoxidized to lutein (ΔL) over 5 h, whereas violaxanthin (V) conversion to antheraxanthin (A) and zeaxanthin (Z) ceased after 1 h. During subsequent dark or shade recovery, de novo synthesis of L and Z continued, followed by epoxidation of A and Z, but not of L. Light saturated non-photochemical quenching (NPQ) was strongly and linearly correlated with decreasing [Lx] and increasing [L] but showed a biphasic correlation with declining [V] and increasing [A+Z] separated when V de-epoxidation ceased. When considering [ΔL+Z], the monophasic linear correlation was restored. Photochemical efficiency of PSII (Fv/Fm) and PSII/PSI (deduced from delivery of electrons to PSI in saturating single turnover flashes) showed a strong correlation in their continuous decline in sunlight and the increase in NPQ capacity. This decrease was also reflected in the initial reduction of the slope of photosynthetic electron transport (ETR) vs. PFD. Generally longer, stronger sun exposures enhanced declines in both slope and maximum ETR rates as well as Fv/Fm and PSII/PSI more severely and prevented full recovery. Interestingly, increased NPQ capacity was accompanied by slower relaxation. This was more prominent in detached leaves with closed stomata, indicating photorespiratory recycling of CO2 provided little photoprotection to avocado shade leaves. Sun exposure of these shade leaves initiates a continuum of photoprotection, beyond full engagement of Lx-and V-cycle in the antenna, but ultimately photoinactivated PSII reaction centers.
    Plant physiology 12/2012; · 6.56 Impact Factor
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    ABSTRACT: The Arabidopsis thaliana genome contains two genes with homology to the mitochondrial protein LETM1 (leucine zipper- EF-hand-containing transmembrane protein). Inactivation of both genes, Atletm1 and Atletm2, together is lethal. Plants that are hemizygous for AtLETM2 and homozygous for Atletm1, (letm1(-/-) LETM2(+/-)) displayed a mild retarded growth phenotype during early seedling growth. It was shown that accumulation of mitochondrial proteins was reduced in hemizygous (letm1(-/-) LETM2(+/-)) plants. Examination of respiratory chain proteins by western blotting, BN-PAGE and enzymatic activity assays revealed that the steady state level of ATP synthase was reduced in abundance, while the steady state levels of other respiratory chain proteins remained unchanged. The absence of a functional maternal AtLETM2 allele in an Atletm1 mutant background resulted in early seed abortion. Reciprocal crosses revealed that maternally, but not paternally, derived AtLETM2 was absolutely required for seed development. This requirement for a functional maternal allele of AtLETM2 was confirmed using direct sequencing of reciprocal crosses of Col 0 and Ler accessions. Furthermore, AtLETM2 promoter GUS constructs displayed exclusive maternal expression patterns.
    Journal of Biological Chemistry 10/2012; · 4.65 Impact Factor
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    ABSTRACT: A key plant response to drought is the accumulation of specific sets of metabolites that act as osmoprotectants, osmolytes, antioxidants, and/or stress signals. An emerging question is: how do plants regulate metabolism to balance the 'competing interests' between metabolites during stress? Recent research connects primary sulfur metabolism (e.g., sulfate transport in the vasculature, its assimilation in leaves, and the recycling of sulfur-containing compounds) with the drought stress response. In this review, we highlight key steps in sulfur metabolism that play significant roles in drought stress signaling and responses. We propose that a complex balancing act is required to coordinate primary and secondary sulfur metabolism during the drought stress response in plants.
    Trends in Plant Science 10/2012; · 11.81 Impact Factor
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    ABSTRACT: Functions of α- and β-branch carotenoids in whole-plant acclimation to photo-oxidative stress were studied in Arabidopsis thaliana wild-type (wt) and carotenoid mutants, lutein deficient (lut2, lut5), non-photochemical quenching1 (npq1) and suppressor of zeaxanthin-less1 (szl1) npq1 double mutant. Photo-oxidative stress was applied by exposing plants to sunflecks. The sunflecks caused reduction of chlorophyll content in all plants, but more severely in those having high α- to β-branch carotenoid composition (α/β-ratio) (lut5, szl1npq1). While this did not alter carotenoid composition in wt or lut2, which accumulates only β-branch carotenoids, increased xanthophyll levels were found in the mutants with high α/β-ratios (lut5, szl1npq1) or without xanthophyll-cycle operation (npq1, szl1npq1). The PsbS protein content increased in all sunfleck plants but lut2. These changes were accompanied by no change (npq1, szl1npq1) or enhanced capacity (wt, lut5) of NPQ. Leaf mass per area increased in lut2, but decreased in wt and lut5 that showed increased NPQ. The sunflecks decelerated primary root growth in wt and npq1 having normal α/β-ratios, but suppressed lateral root formation in lut5 and szl1npq1 having high α/β-ratios. The results highlight the importance of proper regulation of the α- and β-branch carotenoid pathways for whole-plant acclimation, not only leaf photoprotection, under photo-oxidative stress.
    Plant Cell and Environment 08/2012; · 5.91 Impact Factor
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    ABSTRACT: The process of chloroplast biogenesis requires a multitude of pathways and processes to establish chloroplast function. In cotyledons of seedlings, chloroplasts develop either directly from proplastids (also named eoplasts) or, if germinated in the dark, via etioplasts, whereas in leaves chloroplasts derive from proplastids in the apical meristem and are then multiplied by division. The snowy cotyledon 2, sco2, mutations specifically disrupt chloroplast biogenesis in cotyledons. SCO2 encodes a chloroplast-localized protein disulphide isomerase, hypothesized to be involved in protein folding. Analysis of co-expressed genes with SCO2 revealed that genes with similar expression patterns encode chloroplast proteins involved in protein translation and in chlorophyll biosynthesis. Indeed, sco2-1 accumulates increased levels of the chlorophyll precursor, protochlorophyllide, in both dark grown cotyledons and leaves. Yeast two-hybrid analyses demonstrated that SCO2 directly interacts with the chlorophyll-binding LHCB1 proteins, being confirmed in planta using bimolecular fluorescence complementation (BIFC). Furthermore, ultrastructural analysis of sco2-1 chloroplasts revealed that formation and movement of transport vesicles from the inner envelope to the thylakoids is perturbed. SCO2 does not interact with the signal recognition particle proteins SRP54 and FtsY, which were shown to be involved in targeting of LHCB1 to the thylakoids. We hypothesize that SCO2 provides an alternative targeting pathway for light-harvesting chlorophyll binding (LHCB) proteins to the thylakoids via transport vesicles predominantly in cotyledons, with the signal recognition particle (SRP) pathway predominant in rosette leaves. Therefore, we propose that SCO2 is involved in the integration of LHCB1 proteins into the thylakoids that feeds back on the regulation of the tetrapyrrole biosynthetic pathway and nuclear gene expression.
    The Plant Journal 03/2012; 69(5):743-54. · 6.58 Impact Factor
  • Barry Pogson
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    ABSTRACT: Carotenoids are essential for all photosynthetic organisms and mammals, ranging from cyanobacteria to alga, plants and humans (1). However, mammals do not produce carotenoids, they rely solely on dietary intake. In addition to the well known roles of carotenoids as antioxidants and as a source of vitamin A, two carotenoids, lutein and zeaxanthin, are believed to provide protection against age-related macular degeneration of the eye (AMD), the leading cause of age-related blindness in developed countries. The talk will provide a brief overview of research into AMD and the similarities and differences between plant and animal systems with respect to carotenoid binding and function. In order to optimise carotenoid content in our diet it is necessary to understand what regulates its accumulation in plants. This seminar will cover the regulation of lutein biosynthesis in Arabidopsis and wheat using QTLs and mutant screening to identify regulatory proteins (2-4). This includes considering the potential to increase lutein content in wheat by non-GM strategies and why an epigenetic regulator of flowering and shoot branching, a histone methyltransferase, would also regulate lutein biosynthesis. (1) Cazzonelli and Pogson (2010) Trends in Plant Science 15(5): 266-274; (2) Cazzonelli et al. (2010) Molecular Plant 3:174-191; (3) Cazzonelli et al. (2009) Plant Cell 21: 39-53; (4) Howitt et al. (2009) Functional and Integrative Genomics 9:363-376
    American Association for the Advancement of Science 2012 Annual Meeting; 02/2012

Publication Stats

3k Citations
437.84 Total Impact Points

Institutions

  • 2000–2013
    • Australian National University
      • • College of Medicine, Biology & Environment
      • • Division of Plant Sciences
      Canberra, Australian Capital Territory, Australia
  • 2009
    • The Commonwealth Scientific and Industrial Research Organisation
      Canberra, Australian Capital Territory, Australia
  • 2008–2009
    • University of Western Australia
      • ARC Centre of Excellence in Plant Energy Biology
      Perth, Western Australia, Australia
  • 2007
    • Northeast Institute of Geography and Agroecology
      • Institute of Botany
      Beijing, Beijing Shi, China
  • 2006
    • Michigan State University
      • Department of Biochemistry and Molecular Biology
      East Lansing, MI, United States
  • 2001
    • Australian Society for Biochemistry and Molecular Biology
      Canberra, Australian Capital Territory, Australia
  • 1998
    • Arizona State University
      Phoenix, Arizona, United States
  • 1996
    • The University of Arizona
      • School of Plant Sciences
      Tucson, AZ, United States