Areas of Interest

Hormone physiology, biochemistry, and molecular biology

Research

The emphasis of research in the Muday lab is the understanding of the hormone signaling and action in two different systems.  We are interested in the role of the plant hormone, auxin, in plant growth, development, and response to the environment and the mammalian adipokines, leptin and adiponectin, in control of lipid metabolism. We are interested in the biochemical mechanisms by which these hormones control growth and metabolism and we explore these questions using approaches including genetics, molecular biology, microscopy, and biochemistry. Our interests are not just in the hormonal signaling mechanisms, but also on the physiological consequences of the action of these hormones.  We are interested in the role of auxin in controlling root and shoot branching and gravity response. The impact of leptin on metabolism and weight homeostasis as a function of age and gender are of particular interest.

Auxin transport: Auxins reach plant tissues by a unique cell to cell polar transport system. Auxin transport is carefully regulated to allow growth, development, and responses to light and gravity to be precisely controlled. The biochemical mechanisms of auxin transport and the role of transport in plant growth are one focus of research in the laboratory. We are particularly interested in the regulatory mechanisms that allow changes in auxin transport in response to light and gravity vectors in both the plant genetic model, Arabidopsis thaliana, and the crop model of tomato. The regulatory mechanisms of particular interest include phosphorylation signaling, synthesis of endogenous auxin transport inhibitors of the flavonoid class, and interactions between auxin and ethylene signaling.

Leptin signaling:  Leptin is an adipokine, which is a signaling molecule secreted by adipocytes that regulates lipid metabolism and controls eating behavior.  In most mammals, this hormone is at significantly higher levels in females.  We are exploring the molecular mechanisms that lead to this sexual dimorphism and how aging and changing estrogen levels affect leptin levels.  We are interested in how estrogen affects leptin synthesis and signaling including the abundance and localization of leptin receptors.  

Selected Publications

(bolded names are graduate students and underlined names are undergraduates)

Muday, GK, Brady¹, SR, Argueso, C., Deruère, J, Kieber, JJ, and DeLong, A. (2006) RCN1-regulated phosphatase activity and EIN2 modulate hypocotyl gravitropism by a mechanism that does not require ethylene signaling. Plant Physiology: 141: 1617-1629

Buer, CS, Sukumar, P, and Muday, GK (2006) Ethylene induced flavonoid synthesis modulates root gravitropism. Plant Physiology: 140: 1384-1396

Sibout, R, Sukumar, P, Hettiarachchi, C, Holm, M, Muday, GK and Hardtke, CS (2006) Opposite root growth phenotypes of hy5 vs. hy5 hyh correlate with increased constitutive auxin signaling. Plos Genetics: In press

Sieberth, LE, Muday, GK, King, EJ, Benton, G, Kim, S, Metcalf, KE, Myers, L, and Seamen, E (2006) Scarface encodes an ARF-GAP that is required for normal auxin efflux and vein patterning in Arabidopsis. Plant Cell 18: 1396-1411

Perera, IY, Hung, C-Y, Brady, S, Muday, GK, and Boss, WF (2006) A universal role for inositol 1,4,5-trisphosphate-mediated signaling in plant gravitropism. Plant Physiol. 140: 746-760.

Nadella, V, Shipp, MJ, Muday, GK, and Wyatt, SE (2006) Evidence for altered polar and lateral auxin transport in the gravity persistent signal (gps) mutants of Arabidopsis.  Plant, Cell and Environ. 29: 682-690 

Poupart J , Rashotte AM, Muday GK and Waddell CS. 2005. The rib1 mutant of Arabidopsis has alterations in IBA transport, hypocotyl elongation and root architecture. Plant Physiol. 139: 1460-1471

Buer CS and Muday GK. 2004. The transparent testa4 mutation prevents flavonoid synthesis and alters auxin transport and the response of Arabidopsis roots to gravity and light. Plant Cell, 16:1191-1205

Sun H, Basu S, Brady SR, Luciano RL, and Muday GK. 2004. Interactions between auxin transport and the actin cytoskeleton in developmental polarity of Fucusdistichus embryos in response to light and gravity. Plant Physiol.: 135:266-278

Boa F, Shen J, Brady SR, Muday GK, Asami T, and Yang Z. 2004. Brassinosteroids interact with auxin to promote lateral root development in Arabidopsis. Plant Physiol. 134:1624-1631

Rashotte AM, Poupart J, Waddell CS, and Muday GK. 2003. The natural auxin IBA undergoes tissue specific polar transport in a pathway distinct from IAA transport. Plant Physiology: 133 761-772

Muday GK, Peer WA, Murphy AS. 2003. Vesicular cycling mechanisms that control auxin transport polarity. Trends in Plant Science. 8:301-303

Wyatt SE, Rashotte AM, Roberson D, and Muday GK. 2002. Mutations in the GPS loci in Arabidopsis disrupt the perception and/or signal transduction of gravitropic stimuli. Plant Physiology. 130: 1426-1435

Basu S, Sun H, Brian L, Quatrano RL, and Muday GK. 2002. Early embryo development in Fucus distichus is auxin dependent. Plant Physiology. 130:292-302

Muday GK and Murphy AS. 2002. Insight: An emerging model of auxin transport regulation. Plant Cell 14:293-299

Muday GK and DeLong A. 2001. Polar Auxin Transport: Controlling where and how much. Trends in Plant Science. 6:535-542

Muday GK. 2001. Auxin and tropisms. Journal of Plant Growth Regulation. 20:226-243

Rashotte AM, DeLong A, and Muday GK. 2001. Genetic and chemical reductions in protein phosphatase activity alter auxin transport, gravity response and lateral root elongation. Plant Cell 13:1683-1697

Brown DE, Rashotte AM, Murphy AS, Normanly J, Tague BW, Peer WS, Taiz L , and Muday GK. 2001. Flavonoids act as negative regulators of auxin transport in vivo in Arabidopsis. Plant Physiol 126:524-535

Peer WA, Murphy AS, Brown DE, Tague BW, Muday GK, and Taiz L. 2001. Flavonoid accumulation patterns correlate with developmental phenotypes of transparent testa mutants of Arabidopsis thaliana. Plant Physiol. 126:536-548

Muday GK. 2000. Maintenance of asymmetric cellular localization of an auxin transport protein through interaction with the actin cytoskeleton. J of Plant Growth Reg 19:385-396

Hu S, Brady SR, Kovar D, Staiger C, Clark G, Roux S, and Muday GK. 2000. Identification of plant actin binding proteins by F- actin affinity chromatography. Plant Journal 24:127-137

Rashotte AM, Brady SR, Reed RC, Ante SJ, Muday GK. 2000. Basipetal auxin transport Is required for gravitropism in roots of Arabidopsis thaliana. Plant Physiol. 122:481-490