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)

Negi, S, Ivanchenko, MG, and Muday, GK (2008) Ethylene regulates lateral root formation and auxin transport in Arabidopsis thaliana. Plant J. 55: 175-187

Ivanchenko, MG, Muday, GK, and Dubrovsky, JG. (2008) Ethylene-auxin interactions regulate lateral root initiation and emergence in Arabidopsis thaliana. Plant J. 55: 335-347

Buer, CS, Muday, GK, Djordjevic, MA (2008) Implications of long-distance flavonoid movement in Arabidopsis thaliana. Plant Signaling and Behavior: 3: 415-417

Muday, GK and Rahman, A (2007) Auxin transport and the integration of gravitropic growth.  In Plant Tropisms: eds Gilroy, S and Masson, P, Blackwell Publishing pp 47-78.

Buer, CS, Muday, GK, Djordjevic, MA (2007) Flavonoids are transported long distances in Arabidopsis. Plant Physiol.  145: 478-490.

Muday, GK, Brady, 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