Lateral/Secondary Roots

Soazig Guyomarc'h, Université Montpellier II, Montpellier, France
Mikaël Lucas, University of Nottingham, Loughborough, UK
Laurent Laplaze, Institut de Recherche pour le Développement, Montpellier, France

Published online: April 2010

DOI: 10.1002/9780470015902.a0002060.pub2

The plant root system is made of an elongating primary root of embryonic origin as well as multiple lateral or secondary roots initiated post-embryonically. Initiation, organisation and emergence/elongation of lateral roots are tightly regulated by local and global, as well as endogenous and environmental factors, resulting in the adaptation of the whole root system to its functions. The plant hormone auxin is a key player in lateral root initiation, development and elongation. Yet, complex interactions with other hormones such as cytokinins, ethylene, brassinosteroids or abscisic acid (ABA) are also involved. Transcription factors and other proteins of unknown function have been identified in the signalling cascades regulating lateral root formation in response to endogenous or environmental cues. Progresses in understanding the multiple regulations of lateral root formation open new possibilities to use these strategies for plant adaptation to abiotic stresses such as drought or nutrient deprivation.

Key Concepts:

  • The regulation of lateral root formation influences the overall architecture of the root system and its adaptation to various constraints.
  • The commitment of pericycle cells to become lateral root founder cells is the first step of formation of secondary roots and determines their positioning.

Keywords: lateral root formation; pericycle; founder cell; auxin; secondary root; root architecture

Figure 1. Formation of a new lateral root from the pericycle of a pre-existing primary root. Initiation starts with anticlinal divisions of contiguous pericycle cells in the primary root (stage I). Then anticlinal and periclinal cell divisions progressively generate an organised lateral root primordium (stages II–VI). Eventually expansion of the basal cells leads to the emergence of the lateral root (stage VIII).
Figure 2. Multiple hormonal crosstalks regulate the initiation, organisation and emergence of the lateral root primordium. Central is the hormone auxin that positively influences each of these successive steps in lateral root formation.
close
 References
    Bao F, Shen J, Brady SR et al. (2004) Brassinosteroids interact with auxin to promote lateral root development in Arabidopsis. Plant Physiology 134: 1624–1631.
    Benková E and Hejátko J (2009) Hormone interactions at the root apical meristem. Plant Molecular Biology 69: 383–396.
    Benková E, Ivanchenko MG, Friml J, Shishkova S and Dubrovsky JG (2009) A morphogenetic trigger: is there an emerging concept in plant developmental biology? Trends in Plant Science 14: 189–193.
    Benková E, Michniewicz M, Sauer M et al. (2003) Local, efflux-dependent auxin gradients as a common module for plant organ formation. Cell 115: 591–602.
    Brady SM, Sarkar SF, Bonetta D and McCourt P (2003) The ABSCISIC ACID INSENSITIVE 3 (ABI3) gene is modulated by farnesylation and is involved in auxin signaling and lateral root development in Arabidopsis. Plant Journal 34: 67–75.
    Casimiro I, Beeckman T, Graham N et al. (2003) Dissecting Arabidopsis lateral root development. Trends in Plant Science 8: 165–171.
    book Charlton WA (1996) "Lateral root initiation". In: Waisel Y, Eshel A and Kafkafi U (eds) Plant Roots: The Hidden Half, pp. 149–173. New York: Marcel Dekker.
    De Smet I, Signora L, Beeckman T et al. (2003) An abscisic acid-sensitive checkpoint in lateral root development of Arabidopsis. Plant Journal 33: 543–555.
    De Smet I, Tetsumura T, De Rybel B et al. (2007) Auxin-dependent regulation of lateral root positioning in the basal meristem of Arabidopsis. Development 134: 681–690.
    Ditengou FA, Teale WD, Kochersperger P et al. (2008) Mechanical induction of lateral root initiation in Arabidopsis thaliana. Proceedings of the National Academy of Sciences of the USA 105: 18818–18823.
    Dubrovsky JG, Sauer M, Napsucialy Mendivil S et al. (2008) Auxin acts as a local morphogenetic trigger to specify lateral root founder cells. Proceedings of the National Academy of Sciences of the USA 105: 8790–8794.
    Fukaki H, Okushima Y and Tasaka M (2007) Auxin-mediated lateral root formation in higher plants. International Review of Cytology 256: 111–137.
    Fukaki H and Tasaka M (2009) Hormone interactions during lateral root formation. Plant Molecular Biology 69: 437–449.
    Hardtke CS (2007) Transcriptional auxin-brassinosteroid crosstalk: who's talking? BioEssays 29: 1115–1123.
    Himanen IK, Boucheron E, Vanneste S et al. (2002) Auxin-mediated cell cycle activation during early lateral root initiation. Plant Cell 14: 2339–2351.
    Himanen K, Vuylsteke M, Vanneste S et al. (2004) Transcript profiling of early lateral root initiation. Proceedings of the National Academy of Sciences of the USA 101: 5146–5151.
    Ivanchenko MG, Muday GK and Dubrovsky JG (2008) Ethylene-auxin interactions regulate lateral root initiation and emergence in Arabidopsis thaliana. Plant Journal 55: 335–347.
    Laplaze L, Benkova E, Casimiro I et al. (2007) Cytokinins act directly on lateral root founder cells to inhibit root initiation. Plant Cell 19: 3889–3900.
    Li X, Mo X, Shou H and Wu P (2006) Cytokinin-mediated cell cycling arrest of pericycle founder cells in lateral root initiation of Arabidopsis. Plant and Cell Physiology 47: 1112–1123.
    Lucas M, Godin C, Jay-Allemand C and Laplaze L (2008) Auxin fluxes in the root apex co-regulate gravitropism and lateral root initiation. Journal of Experimental Botany 59: 55–66.
    Malamy JE and Benfey PN (1997) Organization and cell differentiation in lateral roots of Arabidopsis thaliana. Development 124: 33–44.
    Negi S, Ivanchenko MG and Muday GK (2008) Ethylene regulates lateral root formation and auxin transport in Arabidopsis thaliana. Plant Journal 55: 175–187.
    Neumann G and Martinoia E (2002) Cluster roots: an underground adaptation for survival in extreme environments. Trends in Plant Sciences 7: 162–167.
    Péret B, De Rybel B, Casimiro I et al. (2009) Arabidopsis lateral root development: an emerging story. Trends in Plant Sciences 14: 399–408.
    Pérez-Torres CA, López-Bucio J, Cruz-Ramírez A et al. (2008) Phosphate availability alters lateral root development in Arabidopsis by modulating auxin sensitivity via a mechanism involving the TIR1 auxin receptor. Plant Cell 20: 3258–3272.
    Reed RC, Brady SR and Muday GK (1998) Inhibition of auxin movement from the shoot into the root inhibits lateral root development in Arabidopsis. Plant Physiology 118: 1369–1378.
    Riefler M, Novak O, Strnad M and Schmülling T (2006) Arabidopsis cytokinin receptor mutants reveal functions in shoot growth, leaf senescence, seed size, germination, root development, and cytokinin metabolism. Plant Cell 18: 40–54.
    Robert HS and Friml J (2009) Auxin and other signals on the move in plants. Nature Chemical Biology 5: 325–332.
    Sanchez-Calderon L, Lopez-Bucio J, Chacon-Lopez A et al. (2005) Phosphate starvation induces a determinate developmental program in the roots of Arabidopsis thaliana. Plant and Cell Physiology 46: 174–184.
    Signora L, De Smet I, Foyer CH and Zhang H (2001) ABA plays a central role in mediating the regulatory effects of nitrate on root branching in Arabidopsis. Plant Journal 28: 655–662.
    Svistoonoff S, Creff A, Reymond M et al. (2007) Root tip contact with low-phosphate media reprograms plant root architecture. Nature Genetics 39: 792–796.
    Swarup K, Benková E, Swarup R et al. (2008) The auxin influx carrier LAX3 promotes lateral root emergence. Nature Cell Biology 10: 946–954.
    Vanneste S, De Rybel B, Beemster GT et al. (2005) Cell cycle progression in the pericycle is not sufficient for SOLITARY ROOT/IAA14-mediated lateral root initiation in Arabidopsis thaliana. Plant Cell 17: 3035–3050.
    Werner T, Motyka V, Laucou V et al. (2003) Cytokinin-deficient transgenic Arabidopsis plants show multiple developmental alterations indicating opposite functions of cytokinins in the regulation of shoot and root meristem activity. Plant Cell 15: 2532–2550.
    Williamson LC, Ribrioux SP, Fitter AH and Leyser HM (2001) Phosphate availability regulates root system architecture in Arabidopsis. Plant Physiology 126: 875–882.
    Zhang H and Forde BG (2000) Regulation of Arabidopsis root development by nitrate availability. Journal of Experimental Botany 51: 51–59.
 Further Reading
    Desnos T (2008) Root branching responses to phosphate and nitrate. Current Opinion in Plant Biology 11: 82–87.
    Malamy JE (2005) Intrinsic and environmental response pathways that regulate root system architecture. Plant Cell and Environment 28: 67–77.

Related Sub-Topics:

Meristems | Roots and Root Systems
Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

Article Title: Lateral/Secondary Roots
 
How to Cite close
Guyomarc'h, Soazig, Lucas, Mikaël, and Laplaze, Laurent(Apr 2010) Lateral/Secondary Roots. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002060.pub2]