ROS, flavonol, and auxin interactions modulate root gravitropism

Posted by Wake Forest University Department of Biology on Tuesday, May 3, 2016

When primary roots are reoriented relative to the gravity vector, they must have an adaptive growth mechanism to resume downward growth. Central to this growth reorientation is redistribution of auxin to the lower side of the root. This elevated auxin inhibits growth on that side, leading to asymmetric root growth until the root returns to vertical. We previously linked basipetal movement of auxin from the root tip back to gravity response.1 Additionally, the ability of flavonoids, which modulate auxin transport,2 have been implicated in the gravitropic response.3, 4

Current work seeks to understand how reactive oxygen species (ROS) are involved in gravitropic signaling, auxin redistribution, and asymmetric growth regulation. Flavonols scavenge ROS, and ROS are regulators of auxin transport and synthesis.5 We are working to characterize the interactions between ROS, flavonol, and auxin during root gravity response.



1. Rashotte, AM, Brady, SR, Reed, RC, Ante, SJ, Muday, GK (2000) Basipetal auxin transport is required for gravitropism in roots of Arabidopsis. Plant Physiol. 122(2):481-90

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

3. 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.

4. Lewis, DR, Ramirez, MV, Valbuena, P, Miller, ND, Keith, R, Helm, R, Winkel, BSJ, Muday, GK (2011) Auxin and ethylene induce distinct flavonol accumulation patterns through independent transcriptional networks: Plant Physiol. 156: 144-164

5. Fernández-Marcos, M, Sanz, L, Lewis, DR, Muday, GK, Lorenzo, O (2013) Control of Auxin Transport by Reactive Oxygen and Nitrogen Species. In Polar Auxin Transport (Signaling and Communication in Plants), Vol 17, Chen, R, Baluska, F, eds. Springer-Verlag, pp103-117


Additional publications:

**indicates review

Dalal, J, Lewis, DR, Tietz, O., Brown, EM, Brown, CS, Palme, K, Muday, GK, Sederoff, SW (2016) ROSY1, a novel regulator of gravitropic response, is a stigmasterol binding protein. J Plant Physiol 196 (2016) 196: 28-40.

Gerttula, S. Zinkgraf, M., Muday, G, Lewis, D, Ibatulllin, FM, Brumer, H, Hart, F, Mansfield, SD, Filkov, V, and Groover, A. (2015) Transcriptional and hormonal regulation of gravitropism of woody stems in Populus. Plant Cell 27:2800-2813

Cho, M, Henry, EM, Lewis, DR, Wu, G, Muday, GK, Spalding, EP (2014) Block of ABCB19 ion channel activity by 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) impairs polar auxin transport and root gravitropism. Plant Physiol. 166: 2091-2099

Withers, JC, Shipp, MJ, Rupasinghe, SG, Sukumar, P, Clay, SL, Schuler, MA, Muday, GK, and Wyatt, SE (2012) Gravity Persistent Signal 1 (GPS1) reveals novel cytochrome P450s involved in gravitropism. American Journal of Botany:  100:183-193

Sukumar, P, Edwards, KS, Rahman, A, and DeLong, A, and Muday, GK (2009) PINOID kinase regulates root gravitropism through modulation of PIN2-dependent basipetal auxin transport in Arabidopsis thaliana. Plant Physiol: 150: 722-735.

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

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

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

**Muday, GK (2000) Interactions between the actin cytoskeleton and an auxin transport protein. In: Actin: A Dynamic Framework for Multiple Plant Cell Functions. Eds, CJ Staiger, F Baluska, D Volkmann, P Barlow. Kluwer Academic Press: Doldrecht: The Netherlands pp. 541-556

**Lomax, TL, GK Muday, and P Rubery. (1995) Auxin transport.  In Plant Hormones:  Physiology, Biochemistry, and Molecular Biology. PJ Davies, Ed. (Norwell:  Kluwer Academic Press). 509-530.


This work is supported by the National Science Foundation Integrative Organismal Systems: Physiological Mechanisms and Biomechanics.