Trends in Plant Science
Volume 25, Issue 2, February 2020, Pages 121-123
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Spotlight
Adaptive Growth: Shaping Auxin-Mediated Root System Architecture

https://doi.org/10.1016/j.tplants.2019.12.001Get rights and content

Root system architecture (RSA), governed by the phytohormone auxin, endows plants with an adaptive advantage in particular environments. Using geographically representative arabidopsis (Arabidopsis thaliana) accessions as a resource for GWA mapping, Waidmann et al. and Ogura et al. recently identified two novel components involved in modulating auxin-mediated RSA and conferring plant fitness in particular habitats.

Section snippets

Auxin-Dependent Root System Patterning

Roots, which evolved during the rise of vascular plants, enable plants to anchor themselves in soil and forage for nutrients and water from their surroundings. During plant evolution, the root evolved into an organ with a complex architecture, expediting plant colonization of the terrestrial environment and transforming the landscape of our planet [1].

RSA, which is defined as the spatial distribution of roots in soil and confers plant fitness in particular environments, largely depends on two

Cytokinin Signaling Antagonizes Auxin-Mediated Root Gravitropism to Shape RSA

Cytokinin turnover in arabidopsis depends on the ATP/ADP-isopentenyltransferase (IPT) genes that activate the biosynthesis of cytokinins, and cytokinin oxidase/dehydrogenase (CKX) genes, which inactive the cytokinin accumulation [8]. Waidmann et al. identified the cytokinin metabolism-related gene CKX2, acting as an LR-specific antigravitropic component in defining the angular growth of LRs and spatial architecture of the root system [6]. In vivo and in vitro experiments confirmed that a SNP

An Exocytosis Pathway Modulates Auxin Transport to Shape RSA

The auxin transporter PIN proteins have a pivotal role in root gravitropism, as evidenced by the fact that application of the auxin transporter inhibitor N-1-naphtylphthalamic acid (NPA) interferes with root gravitropism. By comparing NPA sensitivity among 215 natural arabidopsis accessions and then performing GWA mapping, Ogura et al. identified a specific SNP located in the gene EXOCYST70A3 (EXO70A3), a homolog of yeast and human EXO70, which is involved in an endocytosis pathway that

Concluding Remarks and Future Perspectives

Combining the natural variation of geographically representative arabidopsis accessions and GWA mapping, two recent studies identified two key factors, CKX2 and EXO70A3, that explicitly modulate auxin-dependent root gravitropic growth, resulting in a shift between shallow versus deep RSA and, therefore, allowing the ecological adaptation of plants to hypoxia and drought stresses [6,7]. Additionally, RSA is also linked to other root traits, including nutrient uptake, root anchorage, and

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