Old Town Roads: routes of auxin biosynthesis across kingdoms

Morffy, Nicholas; Strader, Lucia

doi:10.1016/j.pbi.2020.02.002

Cited by 59 publications

(40 citation statements)

References 59 publications

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“…When energy levels rise again, as is the case of elevated photosynthetic activity, rising sugar levels are followed by an enhanced auxin biosynthesis, whereas elevated auxin levels are connected with the activation of TOR by phosphorylation [ 2 , 11 , 46 , 56 ] ( Figure 1 ). Besides sugar levels, the availability of amino acids underpins TOR activity, like tryptophan, which is an important precursor for the biosynthesis of auxins [ 57 , 58 , 59 , 60 , 61 ]. TOR signaling and auxin abundance and distribution are tightly interconnected, as auxin levels decrease upon treatment with TOR inhibitors in the root [ 62 ].…”

Section: Plant Growth Is Dynamic and Orchestrated By Interwoven Simentioning

confidence: 99%

The TOR–Auxin Connection Upstream of Root Hair Growth

Retzer

Weckwerth

2021

Plants

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Plant growth and productivity are orchestrated by a network of signaling cascades involved in balancing responses to perceived environmental changes with resource availability. Vascular plants are divided into the shoot, an aboveground organ where sugar is synthesized, and the underground located root. Continuous growth requires the generation of energy in the form of carbohydrates in the leaves upon photosynthesis and uptake of nutrients and water through root hairs. Root hair outgrowth depends on the overall condition of the plant and its energy level must be high enough to maintain root growth. TARGET OF RAPAMYCIN (TOR)-mediated signaling cascades serve as a hub to evaluate which resources are needed to respond to external stimuli and which are available to maintain proper plant adaptation. Root hair growth further requires appropriate distribution of the phytohormone auxin, which primes root hair cell fate and triggers root hair elongation. Auxin is transported in an active, directed manner by a plasma membrane located carrier. The auxin efflux carrier PIN-FORMED 2 is necessary to transport auxin to root hair cells, followed by subcellular rearrangements involved in root hair outgrowth. This review presents an overview of events upstream and downstream of PIN2 action, which are involved in root hair growth control.

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Section: Plant Growth Is Dynamic and Orchestrated By Interwoven Simentioning

confidence: 99%

The TOR–Auxin Connection Upstream of Root Hair Growth

Retzer

Weckwerth

2021

Plants

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“…Although phylogenetic analyses indicate that the Trp-dependent pathways of IAA biosynthesis have evolved separately in plants and bacteria [3,18,19], most of these pathways appear to be quite similar in these organisms. Accordingly, the major proposed Trp-dependent IAA biosynthesis pathways in plants and/or bacteria include the indole-3-pyruvic acid (IPA), the indole-3-acetamide (IAM), the indole-3-acetonitrile (IAN), the tryptamine (TAM), and the indole-3-acetaldoxime (IAOx) pathways [2,[20][21][22]. Notably, these major pathways are to some extent also interlinked and not all enzymatic reactions are yet fully understood.…”

Section: Introductionmentioning

confidence: 99%

Indole-3-acetic acid is a physiological inhibitor of TORC1 in yeast

et al. 2021

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Indole-3-acetic acid (IAA) is the most common, naturally occurring phytohormone that regulates cell division, differentiation, and senescence in plants. The capacity to synthesize IAA is also widespread among plant-associated bacterial and fungal species, which may use IAA as an effector molecule to define their relationships with plants or to coordinate their physiological behavior through cell-cell communication. Fungi, including many species that do not entertain a plant-associated life style, are also able to synthesize IAA, but the physiological role of IAA in these fungi has largely remained enigmatic. Interestingly, in this context, growth of the budding yeast Saccharomyces cerevisiae is sensitive to extracellular IAA. Here, we use a combination of various genetic approaches including chemical-genetic profiling, SAturated Transposon Analysis in Yeast (SATAY), and genetic epistasis analyses to identify the mode-of-action by which IAA inhibits growth in yeast. Surprisingly, these analyses pinpointed the target of rapamycin complex 1 (TORC1), a central regulator of eukaryotic cell growth, as the major growth-limiting target of IAA. Our biochemical analyses further demonstrate that IAA inhibits TORC1 both in vivo and in vitro. Intriguingly, we also show that yeast cells are able to synthesize IAA and specifically accumulate IAA upon entry into stationary phase. Our data therefore suggest that IAA contributes to proper entry of yeast cells into a quiescent state by acting as a metabolic inhibitor of TORC1.

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“…In Phalaris canariensis, Charles and Francis Darwin observed that light and gravity are perceived by the shoots and roots and that these stimuli are transmitted to other plant parts during growth (Darwin, 1880;Morffy & Strader, 2020). Subsequently, Fritz Went and Nicolai Cholodny performed an in vitro bioassay of Avena sativa coleoptile segments and observed the formation of a curvature in the absence of a unilateral light source (Cholodny, 1928;Went, 1928;Du et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Interestingly, when the stem segments were moved into the shade, faster growth was noted (Shu et al, 2019;Du et al, 2020). This A. sativa bioassay is used for the quantitative analysis of auxins even today (Enders & Strader, 2015;Morffy & Strader, 2020).…”

Section: Introductionmentioning

confidence: 99%

Auxin and its role in plant development: structure, signalling, regulation and response mechanisms

Gomes

Scortecci

2021

Plant Biol J

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Auxins are plant hormones that play a central role in controlling plant growth and development across different environmental conditions. Even at low concentrations, auxins can regulate gene expression through specific transcription factors and proteins that are modulated to environmental responses in the signalling cascade. Auxins are synthesized in tissues with high cell division activity and distributed by specific transmembrane proteins that regulate efflux and influx. This review presents recent advances in understanding the biosynthetic pathways, both dependent and independent of tryptophan, highlighting the intermediate indole compounds (indole-3-acetamide, indole-3-acetaldoxime, indole-3-pyruvic acid and tryptamine) and the key enzymes for auxin biosynthesis, such as YUCs and TAAs. In relation to the signalling cascade, it has been shown that auxins influence gene expression regulation by the connection between synthesis and distribution. Moreover, the molecular action of the auxin response factors and auxin/indole-3-acetic acid transcription factors with the F-box TIR1/AFB auxin receptors regulates gene expression. In addition, the importance of microRNAs in the auxin signalling pathway and their influence on plant plasticity to environmental fluctuations is also demonstrated. Finally, this review describes the chemical and biological processes involving auxins in plants.

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Old Town Roads: routes of auxin biosynthesis across kingdoms

Cited by 59 publications

References 59 publications

The TOR–Auxin Connection Upstream of Root Hair Growth

The TOR–Auxin Connection Upstream of Root Hair Growth

Indole-3-acetic acid is a physiological inhibitor of TORC1 in yeast

Auxin and its role in plant development: structure, signalling, regulation and response mechanisms

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