A morphogenetic trigger: is there an emerging concept in plant developmental biology?

Benková, Eva; Ivanchenko, Maria G.; Friml, Jirÿõ; Shishkova, Svetlana; Dubrovsky, Joseph G.

doi:10.1016/j.tplants.2009.01.006

Cited by 101 publications

(65 citation statements)

References 43 publications

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“…Prior to the establishment of nodules, NFS, and lateral roots induced by such organisms, an accumulation of auxin can be observed. Auxin might have dual roles in guiding the development of these root structures, first as a morphogen specifying the site of organ formation (Benkovà et al, 2009) and second as a regulator of the plant cell cycle (Himanen et al, 2002). Therefore, it is not surprising that auxin is a target for microorganisms that manipulate plant development and consequently that plants have evolved mechanisms to repress auxin signaling during infection as a defense strategy (Wang et al, 2007;Kazan and Manners, 2009).…”

Section: Resultsmentioning

confidence: 99%

Manipulation of Auxin Transport in Plant Roots during Rhizobium Symbiosis and Nematode Parasitism

et al. 2009

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The plant rhizosphere harbors many different microorganisms, ranging from plant growth-promoting bacteria to devastating plant parasites. Some of these microbes are able to induce de novo organ formation in infected roots. Certain soil bacteria, collectively called rhizobia, form a symbiotic interaction with legumes, leading to the formation of nitrogen-fixing root nodules. Sedentary endoparasitic nematodes, on the other hand, induce highly specialized feeding sites in infected plant roots from which they withdraw nutrients. In order to establish these new root structures, it is thought that these organisms use and manipulate the endogenous molecular and physiological pathways of their hosts. Over the years, evidence has accumulated reliably demonstrating the involvement of the plant hormone auxin. Moreover, the auxin responses during microbe-induced de novo organ formation seem to be dynamic, suggesting that plant-associated microbes can actively modify their host's auxin transport. In this review, we focus on recent findings in auxin transport mechanisms during plant development and on how plant symbionts and parasites have evolved to manipulate these mechanisms for their own purposes.

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Section: Resultsmentioning

confidence: 99%

Manipulation of Auxin Transport in Plant Roots during Rhizobium Symbiosis and Nematode Parasitism

et al. 2009

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“…It has been suggested that auxin acts as a morphogen, altering the developmental fate of cells in a concentration-specific manner (Bhalerao and Bennett, 2003). Whether or not auxin fulfills the strict definition of a morphogen or acts as a morphogenetic trigger (Benková et al, 2009), it is clear that setting up auxin concentration gradients requires a strict regulation of many different cellular processes. The concentration of auxin within a plant cell is regulated both by the rate of its metabolism (i.e., biosynthesis, conjugation/deconjugation, and degradation) and the capacity and rate of transport (in and out of cells and between cellular compartments).…”

Section: Introductionmentioning

confidence: 99%

Regulation of Auxin Homeostasis and Gradients in Arabidopsis Roots through the Formation of the Indole-3-Acetic Acid Catabolite 2-Oxindole-3-Acetic Acid

et al. 2013

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“…The localisation of influx and efflux carriers at the plasma membrane directs the transport of IAA in and out of the cell (also called 'polar auxin transport'), providing the plant with a unique way of transporting this important hormone between different cells and tissues. There is plenty of evidence for the importance of polar transport in setting up auxin gradients in specific cell types, and such gradients provide developmental cues during, for example, embryogenesis and root development (Friml et al, 2003;Blilou et al, 2005;Benková et al, 2009).Auxin signalling regulates cell responses to the different auxin levels that are formed by a combination of auxin metabolism and transport. One very important step forward for understanding auxin signalling was the discovery of the TIR1/AFB family of auxin receptors (Dharmasiri et al, 2005; Kepinski and Leyser, 2005).…”

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Auxin metabolism and homeostasis during plant development

2013

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SummaryAuxin plays important roles during the entire life span of a plant. This small organic acid influences cell division, cell elongation and cell differentiation, and has great impact on the final shape and function of cells and tissues in all higher plants. Auxin metabolism is not well understood but recent discoveries, reviewed here, have started to shed light on the processes that regulate the synthesis and degradation of this important plant hormone. Key words: Auxin metabolism, Biosynthesis, Conjugation and degradation, Plant hormone, Arabidopsis thaliana, Root and shoot development IntroductionThe plant hormone auxin or indole-3-acetic acid (IAA) (Fig. 1) was discovered ~70 years ago, although the concept of plant hormones and speculation over their roles in plant development were conceived much earlier (reviewed by Abel and Theologis, 2010). Auxin research took off in the 1980s following the discovery of a battery of genes involved in auxin responses, and more recently with the discovery of the TIR1 auxin receptor family (reviewed by Calderón-Villalobos et al., 2010) and various auxin transporters (reviewed by Zažímalová et al., 2010). These discoveries boosted a wave of research into auxin signalling and the roles of these newly discovered genes during plant development, mostly using the model plant species Arabidopsis thaliana as an experimental system.Although our understanding of auxin signalling has flourished during the last few decades, progress in understanding auxin metabolism (which includes auxin biosynthesis, conjugation and degradation) has been hampered by the lack of suitable tools for the quantification and visualisation of auxin metabolites on a tissue and cellular level. Until recently, key components in these metabolic pathways were missing and the regulation of auxin metabolism was poorly understood, but genetic and biochemical evidence in combination with sensitive methods for auxin metabolite identification and quantification have greatly improved our knowledge in this respect.This Primer describes the recent progress that has been made in our understanding of auxin metabolism, with the aim of putting these discoveries into the context of plant growth and development. I will focus on auxin metabolism in A. thaliana, as these metabolic processes are much better understood in Arabidopsis than in other plant species. Still, it is important to remember that there are differences between plant species, and also that IAA metabolism in some species (including Arabidopsis) is intertwined with, and affected by, the secondary metabolism of plant defence compounds (Normanly, 2010). An overview of auxin transport and signalling pathwaysAuxin is a weak organic acid consisting of a planar indole ring structure coupled to a side chain harbouring a terminal carboxyl group (Fig. 1A,B). The carboxyl group is protonated at low pH, making the molecule less polar (IAA -+ H + ⇔ IAA-H). In this form it can diffuse across cell membranes, whereas the molecule in its unprotonated, negatively charged form ...

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A morphogenetic trigger: is there an emerging concept in plant developmental biology?

Cited by 101 publications

References 43 publications

Manipulation of Auxin Transport in Plant Roots during Rhizobium Symbiosis and Nematode Parasitism

Manipulation of Auxin Transport in Plant Roots during Rhizobium Symbiosis and Nematode Parasitism

Regulation of Auxin Homeostasis and Gradients in Arabidopsis Roots through the Formation of the Indole-3-Acetic Acid Catabolite 2-Oxindole-3-Acetic Acid

Auxin metabolism and homeostasis during plant development

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