Gloria K Muday

Wake Forest University | WFU · Department of Biology

To identify gene products that participate in auxin-dependent lateral root formation, a high temporal resolution, genome-wide transcript abundance analysis was performed with auxin-treated Arabidopsis thaliana roots. Data analysis identified 1246 transcripts that were consistently regulated by indole-3-acetic acid (IAA), partitioning into 60 cluste...

Adventitious roots emerge from aerial plant tissues and the induction of these roots is essential for clonal propagation of agriculturally important plant species. This process has received extensive study in horticultural species, but much less focus in genetically tractable model species. We have explored the role of auxin transport in this proce...

The individual roles of auxin and ethylene in controlling the growth and development of young seedlings have been well studied. In recent years, these two hormones have been shown to act synergistically to control specific growth and developmental processes, such as root elongation and root hair formation, as well as antagonistically in other proce...

Elevated temperatures impair pollen performance and reproductive success, resulting in lower crop yields. The Solanum lycopersicum anthocyanin reduced ( are ) mutant has a defect in the FLAVANONE 3 HYDROXYLASE ( F3H ) gene and impaired synthesis of flavonol antioxidants. We identified multiple aspects of pollen performance in are that were hypersen...

Transcriptome studies that provide temporal information about transcript abundance facilitate identification of gene regulatory networks (GRNs). Inferring GRNs from time series data using computational modeling remains a central challenge in systems biology. Commonly employed clustering algorithms identify modules of like-responding genes but do no...

Flavonols are plant-specialized metabolites with important functions in plant growth and development. Isolation and characterization of mutants with reduced flavonol levels, especially the transparent testa mutants in Arabidopsis thaliana, have contributed to our understanding of the flavonol biosynthetic pathway. These mutants have also uncovered...

Abscisic acid (ABA) drives stomatal closure to minimize water loss due to transpiration in response to drought. We examined the subcellular location of ABA increased accumulation of reactive oxygen species (ROS) in guard cells, which drive stomatal closure, in Arabidopsis (Arabidopsis thaliana). ABA-dependent increases in fluorescence of the generi...

Reactive oxygen species (ROS) serve as second messengers in plant signaling pathways to remodel plant growth and development. New insights into how enzymatic ROS-producing machinery is regulated by hormones or localized during development have provided a framework for understanding the mechanisms that control ROS accumulation patterns. Signaling-me...

Transcriptome studies which provide temporal information can be valuable for identifying groups of similarly-behaving transcripts and provide insight into overarching gene regulatory networks. Nevertheless, inferring meaningful biological conclusions is challenging, in part because it is difficult to holistically consider both local relationships a...

Root hair initiation is a highly regulated aspect of root development. The plant hormone, ethylene, and its precursor, 1-amino-cyclopropane-1-carboxylic acid (ACC), induce formation and elongation of root hairs. Using confocal microscopy paired with redox biosensors and dyes, we demonstrated that treatments that elevate ethylene levels led to incre...

Abscisic acid (ABA) closes stomata to minimize transpiration and gas exchange in response to drought. ABA signaling increases accumulation of reactive oxygen species (ROS) in guard cells to drive stomatal closure. We used chemical dyes and genetically-encoded biosensors to identify the subcellular localizations where ABA increases hydrogen peroxide...

Root hair initiation is a highly regulated aspect of root development. The plant hormone, ethylene, and its precursor, 1-amino-cyclopropane-1-carboxylic acid (ACC), induce formation and elongation of root hairs. Using confocal microscopy paired with redox biosensors and dyes, we demonstrated that treatments that elevate ethylene levels led to incre...

The construction of gene interaction models must be a fully collaborative and intentional effort. All aspects of the research, such as growing the plants, extracting the mea-surements, refining the measured data, developing the statistical framework, and forming and applying the algorithmic techniques, must lend themselves to repeatable and sound p...

Flavonoids are a class of specialized metabolites with subclasses including flavonols and anthocyanins, which have unique properties as antioxidants. Flavonoids modulate plant development, but whether and how they impact lateral root development is unclear. We examined potential roles for flavonols in this process using Arabidopsis thaliana mutants...

Gene regulatory networks (GRNs) are defined by a cascade of transcriptional events by which signals, such as hormones or environmental cues, change development. To understand these networks, it is necessary to link specific transcription factors (TFs) to the downstream gene targets whose expression they regulate. Although multiple methods provide i...

Auxin is transported in plants with distinct polarity, defined by transport proteins of the PIN-formed (PIN) family. Components of the complex trafficking machinery responsible for polar PIN protein localization have been identified by genetic approaches, but severe developmental phenotypes of trafficking mutants complicate dissection of this pathw...

Flavonoids are plant-specific antioxidant compounds that modulate plant development, which include flavonols and anthocyanins subclasses. In Arabidopsis thaliana, mutants in genes encoding each step in the flavonoid biosynthetic pathway have been isolated. We used these mutants to examine the role of flavonols in initiation and emergence of lateral...

The hormonal and environmental regulation of stomatal aperture is mediated by a complex signaling pathway found within the guard cells that surround stomata. Abscisic acid (ABA) induces stomatal closure in response to drought stress by binding to its guard cell localized receptor, initiating a signaling cascade that includes synthesis of reactive o...

Network models of gene interactions, using time course gene transcript abundance data, are computationally created using a genetic algorithm designed to incorporate hierarchical Bayesian methods with time series adjustments. The posterior probabilities of interaction between pairs of genes are based on likelihoods of directed acyclic graphs. This a...

Reactive oxygen species (ROS) are signaling molecules produced by tissue-specific respiratory burst oxidase homolog (RBOH) enzymes to drive development. In Arabidopsis thaliana, ROS produced by RBOHC was previously reported to drive root hair elongation. We identified a specific role of one ROS, H2O2, in driving root hair initiation and demonstrate...

While the effects of phytohormones on plant gene expression have been well characterized, comparatively little is known about how hormones influence metabolite profiles. This study examined the effects of elevated auxin and ethylene on the metabolome of Arabidopsis roots using a high-resolution 24 h time course, conducted in parallel to time-matche...

The inhibition of hypocotyl elongation by ethylene in dark-grown seedlings was the basis of elegant screens that identified ethylene-insensitive Arabidopsis mutants, which remained tall even when treated with high concentrations of ethylene. This simple approach proved invaluable for identification and molecular characterization of major players in...

We analyzed effects of peer teaching on non-science major undergraduates' knowledge, perceptions, and opinions about genetically modified (GM) crops and their use in agriculture. Undergraduates enrolled in an introductory nonmajors biology course participated in a service-learning program (SLP) in which they acted as cross-age peer teachers to high...

Reactive Oxygen Species (ROS) have recently been shown to regulate plant growth and development. ROS are kept at low levels in cells to prevent oxidative damage, allowing them to be effective signaling molecules upon increased synthesis. In plants and animals, NADPH Oxidase/Respiratory Burst Oxidase proteins provide localized ROS bursts to regulate...

Significance Plant sexual reproduction is required for seed and fruit production and is highly sensitive to elevated temperatures, suggesting that climate change may have profound agricultural impacts through inhibition of this process. During reproduction, pollen tubes must navigate long distances through floral tissues to fertilize ovules. We dem...

Herbivory induces rapid long-distance calcium signals through glutamate-like receptors

Transcriptomic analyses with high temporal resolution provide substantial new insight into hormonal response networks. This study identified the kinetics of genome-wide transcript abundance changes in response to elevated levels of the plant hormone ethylene in roots from light grown Arabidopsis seedlings, which were overlaid on time matched develo...

Leptin is an adipokine produced by fat cells that regulates food consumption and metabolic activity. Sexual dimorphism in leptin and fat stores have been observed in humans and rodents with females having more leptin and greater levels of subcutaneous fat than males. One potential mechanism leading to this dimorphism is steroid hormone regulated sy...

Abscisic acid (ABA) increases reactive oxygen species (ROS) in guard cells to close Arabidopsis stomata. In Solanum lycopersicum we find that ABA increased ROS is followed by stomatal closure and both responses are blocked by inhibitors of ROS-producing respiratory burst oxidase enzymes. ABA-induced ROS sensor fluorescence accumulates in the nucleu...

Interest in the roles of flavonoids in fundamental biological processes has spurred an extensive characterization of their biosynthesis and demonstrated that specific metabolites in this pathway modulate a diversity of plant developmental and stress responses. Arabidopsis thaliana mutants with defects in flavonol biosynthesis have been used to demo...

The gravitropic bending in plant roots is caused by asymmetric cell elongation. This requires an asymmetric increase in cell surface and therefore plasma membrane components such as lipids, sterols, and membrane proteins. We have identified an early gravity-regulated protein in Arabidopsis thaliana root apices that binds stigmasterol and phosphoeth...

Significance The exocyst complex is a conserved protein complex that tethers the secretory vesicles to the site of membrane fusion during exocytosis, an essential cellular process that transports molecules, such as protein, to the cell surface or extracellular space. We identified a small molecule that targets the EXO70 (exocyst component of 70 kDa...

Ethylene and auxin have overlapping effects on growth and development of young seedlings, with either synergistic or antagonistic actions depending on the developmental process. This chapter introduces the growth and developmental processes that are regulated by these two hormones and explores recent studies that provide insight into the mechanisti...

Angiosperm trees reorient their woody stems by asymmetrically producing a specialized xylem tissue, tension wood, which exerts a strong contractile force resulting in negative gravitropism of the stem. Here, we show, in Populus trees, that initial gravity perception and response occurs in specialized cells through sedimentation of starch-filled amy...

Development of models that explain relationships between changes in gene products often involve multiple replications of transcript abundance measurements across time courses. This paper develops a composite probabilistic analysis using a next-state paradigm. We not only consider the usual first-order Markov (next time step) setting but we also int...

This study tests the hypothesis that undergraduates who peer teach genetics will have greater understanding of genetic and molecular biology concepts as a result of their teaching experiences. Undergraduates enrolled in a non-majors biology course participated in a service-learning program in which they led middle school (MS) or high school (HS) st...

Polar transport of the hormone auxin through tissues and organs depends on membrane proteins including some B-subgroup members of the ATP-binding cassette (ABC) transporter family. The mRNA level of at least one B-subgroup ABCB gene in Arabidopsis thaliana, ABCB19, increases upon treatment with the anion channel blocker 5-nitro-2-(3-phenylpropylami...

Nitric oxide (NO) is a unique reactive nitrogen molecule with an array of signalling functions that modulates plant developmental processes and stress responses. To explore the mechanisms by which NO modulates root development, we used a pharmacological approach and NO deficient mutants to unravel the role of NO in establishing auxin distribution p...

This study utilized Solanum lycopersicum (tomato) mutants with altered flavonoid biosynthesis to understand the impact of these metabolites on root development. The mutant anthocyanin reduced (are) has a mutation in the gene encoding flavonoid 3-hydroxylase (F3H), the first step in flavonol synthesis, and accumulates higher concentrations of the F3...

Guard cell swelling controls the aperture of stomata, pores that facilitate gas exchange and water loss from leaves. The hormone abscisic acid (ABA) has a central role in regulation of stomatal closure through synthesis of second messengers, which include reactive oxygen species (ROS). ROS accumulation must be minimized by antioxidants to keep conc...

Microarray technology allows for the collection of multiple replicates of gene expression time course data for hundreds of genes at a handful of time points. Developing hypotheses about a gene transcriptional network, based on time course gene expression data is an important and very challenging problem. In many situations there are similarities wh...

Like the figurative apple for the teacher, the tomato is a well-known food symbol representing a variety of cuisines. We drew on current scientific research and partnerships with classroom teachers to develop a case study activity consisting of four layers to teach concepts of plant biology and genetics to middle and high school students. The goal...

Ethylene is a gaseous plant hormone that has profound effects on many aspects of plant growth and development. The role of changing levels of ethylene in modulating fruit ripening, seed germination, hypocotyl and root elongation, abscission, and responses to biotic and abiotic stresses has been well described (Abeles et al. 1992; Kendrick and Chang...

Auxin transport is a central process in plant growth and development and as a result is highly regulated. The amount and direction of auxin transport is defined by a set of auxin influx and efflux carriers with precise localization that lead to long-distance polar auxin transport. These auxin transport proteins are regulated by transcriptional and...

Premise: Gravity is an important environmental factor that affects growth and development of plants. In response to changes in gravity, directional growth occurs along the major axes and lateral branches of both shoots and roots. The gravity persistent signal (gps) mutants of Arabidopsis thaliana were previously identified as having an altered res...

Objective: To investigate effects of weight loss on adipokines and health measures in obese older adults with symptomatic knee osteoarthritis. Methods: Participants were randomly assigned to either weight loss (WL) (men: 12, women: 14) or weight stable (WS) group (men: 12, women: 13). WL intervention included meal replacements and structured exe...

Recent evidence indicates that extracellular nucleotides regulate plant growth. Exogenous ATP has been shown to block auxin transport and gravitropic growth in primary roots of Arabidopsis. Cells limit the concentration of extracellular ATP in part through the activity of ectoapyrases (ecto-nucleoside triphosphate diphosphohydrolases), and two near...

Auxin regulates plant growth and development in part by activating gene expression. Arabidopsis thaliana SMALL AUXIN UP RNAs (SAURs) are a family of early auxin-responsive genes with unknown functionality. Here, we show that transgenic plant lines expressing artificial microRNA constructs (aMIR-SAUR-A or -B) that target a SAUR subfamily (SAUR61-SAU...

Gradients of the plant hormone auxin, which depend on its active intercellular transport, are crucial for the maintenance of root meristematic activity. This directional transport is largely orchestrated by a complex interaction of specific influx and efflux carriers that mediate the auxin flow into and out of cells, respectively. Besides these tra...

Nitric oxide (NO) is considered a key regulator of plant developmental processes and defense, although the mechanism and direct targets of NO action remain largely unknown. We used phenotypic, cellular, and genetic analyses in Arabidopsis thaliana to explore the role of NO in regulating primary root growth and auxin transport. Treatment with the NO...

We used genetic and molecular approaches to identify mechanisms by which the gaseous plant hormone ethylene reduces lateral root formation and enhances polar transport of the hormone auxin. Arabidopsis thaliana mutants, aux1, lax3, pin3 and pin7, which are defective in auxin influx and efflux proteins, were less sensitive to the inhibition of later...

Plant root development is mediated by the concerted action of the auxin and cytokinin phytohormones, with cytokinin serving as an antagonist of auxin transport. Here, we identify the AUXIN UP-REGULATED F-BOX PROTEIN1 (AUF1) and its potential paralog AUF2 as important positive modifiers of root elongation that tether auxin movements to cytokinin sig...

Auxin and ethylene are key regulators of plant growth and development, and thus the transcriptional networks that mediate responses to these hormones have been the subject of intense research. This study dissected the hormonal cross talk regulating the synthesis of flavonols and examined their impact on root growth and development. We analyzed the...

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In this study we investigated the role of ethylene in the formation of lateral and adventitious roots in tomato (Solanum lycopersicum) using mutants isolated for altered ethylene signaling and fruit ripening. Mutations that block ethylene responses and delay ripening -Nr (Never ripe), gr (green ripe), nor (non ripening), and rin (ripening inhibitor...

Directional root expansion is governed by nutrient gradients, positive gravitropism and hydrotropism, negative phototropism and thigmotropism, as well as endogenous oscillations in the growth trajectory (circumnutation). Null mutations in phylogenetically related Arabidopsis thaliana genes MILDEW RESISTANCE LOCUS O 4 (MLO4) and MLO11, encoding hept...

Reversible protein phosphorylation is a key regulatory mechanism governing polar auxin transport. We characterized the auxin transport and gravitropic phenotypes of the pinoid-9 (pid-9) mutant of Arabidopsis (Arabidopsis thaliana) and tested the hypothesis that phosphorylation mediated by PID kinase and dephosphorylation regulated by the ROOTS CURL...

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 quantifi...

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 symb...

Plant root systems display considerable plasticity in response to endogenous and environmental signals. Auxin stimulates pericycle cells within elongating primary roots to enter de novo organogenesis, leading to the establishment of new lateral root meristems. Crosstalk between auxin and ethylene in root elongation has been demonstrated, but intera...

Lateral root branching is a genetically defined and environmentally regulated process. Auxin is required for lateral root formation, and mutants that are altered in auxin synthesis, transport or signaling often have lateral root defects. Crosstalk between auxin and ethylene in root elongation has been demonstrated, but interactions between these ho...

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Flavonoids are synthesized in response to developmental and environmental signals and perform many functions in plants. Arabidopsis (Arabidopsis thaliana) roots grown in complete darkness do not accumulate flavonoids since the expression of genes encoding enzymes of flavonoid biosynthesis is light dependent. Yet, flavonoids accumulate in root tips...

The Arabidopsis transcription factor HY5 controls light-induced gene expression downstream of photoreceptors and plays an important role in the switch of seedling shoots from dark-adapted to light-adapted development. In addition, HY5 has been implicated in plant hormone signaling, accounting for the accelerated root system growth phenotype of hy5...

List of All Genes that Were Auxin Responsive in the Wild-Type and Their Response in the Mutant Genotypes The columns indicate the Affymetrix probe identifier, the Arabidopsis gene identifier, the gene description, and the expression ratios as indicated. dbl. indicates hy5 hyh double mutant. (88 KB XLS)

List of All Genes Consistently Misregulated in hy5 hyh Double Mutants The columns indicate the Affymetrix probe identifier, the Arabidopsis gene identifier, the gene description, and the expression ratios as indicated. dbl. indicates hy5 hyh double mutant. (195 KB XLS)

The roots curl in naphthylphthalamic acid1 (rcn1) mutant of Arabidopsis (Arabidopsis thaliana) has altered auxin transport, gravitropism, and ethylene response, providing an opportunity to analyze the interplay between ethylene and auxin in control of seedling growth. Roots of rcn1 seedlings were previously shown to have altered auxin transport, gr...

To identify molecular mechanisms controlling vein patterns, we analyzed scarface (sfc) mutants. sfc cotyledon and leaf veins are largely fragmented, unlike the interconnected networks in wild-type plants. SFC encodes an ADP ribosylation factor GTPase activating protein (ARF-GAP), a class with well-established roles in vesicle trafficking regulation...

Plant shoots do not respond when they are reoriented relative to gravity at 4 degrees C. However, when returned to vertical at room temperature, these organs bend in response to the previous cold gravistimulation. The inflorescence stem of the Arabidopsis thaliana gravity persistent signal (gps) mutants respond abnormally after the cold gravistimul...

Plant organs change their growth direction in response to reorientation relative to the gravity vector. We explored the role of ethylene in Arabidopsis (Arabidopsis thaliana) root gravitropism. Treatment of wild-type Columbia seedlings with the ethylene precursor 1-aminocyclopropane carboxylic acid (ACC) reduced root elongation and gravitropic curv...

Inositol 1,4,5-trisphosphate (InsP3) has been implicated in the early signaling events of plants linking gravity sensing to the initiation of the gravitropic response. However, at present, the contribution of the phosphoinositide signaling pathway in plant gravitropism is not well understood. To delineate the role of InsP3 in plant gravitropism, we...

Polar transport of the auxin indole-3-butyric acid (IBA) has recently been shown to occur in Arabidopsis (Arabidopis thaliana) seedlings, yet the physiological importance of this process has yet to be fully resolved. Here we describe the first demonstration of altered IBA transport in an Arabidopsis mutant, and show that the resistant to IBA (rib1)...

Land plants orient their growth relative to light and gravity through complex mechanisms that require auxin redistribution. Embryos of brown algae use similar environmental stimuli to orient their developmental polarity. These studies of the brown algae Fucus distichus examined whether auxin and auxin transport are also required during polarization...

We examined whether flavonoids act as endogenous auxin transport regulators during gravity vector and light intensity changes in Arabidopsis thaliana roots. Flavonoid deficient transparent testa4 [tt4(2YY6)] seedlings had elevated root basipetal auxin transport compared with the wild type, consistent with the absence of a negative auxin transport r...

Plant hormone brassinosteroids (BRs) and auxin exert some similar physiological effects likely through their functional interaction, but the mechanism for this interaction is unknown. In this study, we show that BRs are required for lateral root development in Arabidopsis and that BRs act synergistically with auxin to promte lateral root formation....

Polar transport of the natural auxin indole-3-acetic acid (IAA) is important in a number of plant developmental processes. However, few studies have investigated the polar transport of other endogenous auxins, such as indole-3-butyric acid (IBA), in Arabidopsis. This study details the similarities and differences between IBA and IAA transport in se...

The polar transport of auxin controls many important plant growth and developmental processes. The polarity of auxin movement has long been suggested to be mediated by asymmetric distribution of auxin transport proteins, yet, until recently, little was known about the mechanisms that establish protein asymmetry in auxin-transporting cells. Now, a r...

Raising the level of extracellular ATP to mM concentrations similar to those found inside cells can block gravitropism of Arabidopsis roots. When plants are grown in Murashige and Skoog medium supplied with 1 mM ATP, their roots grow horizontally instead of growing straight down. Medium with 2 mM ATP induces root curling, and 3 mM ATP stimulates la...

The overarching goal of this proposal was to examine the mechanisms for the cellular asymmetry in auxin transport proteins. As auxin transport polarity changes in response to reorientation of algal and plant cells relative to the gravity vector, it was critical to ask how auxin transport polarity is established and how this transport polarity may c...

Gravity plays a fundamental role in plant growth and development, yet little is understood about the early events of gravitropism. To identify genes affected in the signal perception and/or transduction phase of the gravity response, a mutant screen was devised using cold treatment to delay the gravity response of inflorescence stems of Arabidopsis...