Lateral/Secondary Roots

Abstract

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.

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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.

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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]