Machine-learning meta-analysis reveals ethylene as a central component of the molecular core in abiotic stress responses in Arabidopsis.

Understanding how plants adapt their physiology to overcome severe and often multifactorial stress conditions in nature is vital in light of the climate crisis. This remains a challenge given the complex nature of the underlying molecular mechanisms. To provide a comprehensive picture of stress-mitigation mechanisms, an exhaustive analysis of publicly available stress-related transcriptomic data has been conducted.

Cytokinins regulate spatially specific ethylene production to control root growth in Arabidopsis.

Two principal growth regulators, cytokinins and ethylene, are known to interact in the regulation of plant growth. However, information about the underlying molecular mechanism and positional specificity of cytokinin/ethylene crosstalk in the control of root growth is scarce. We have identified the spatial specificity of cytokinin-regulated root elongation and root apical meristem (RAM) size, both of which we demonstrate to be dependent on ethylene biosynthesis.

Arinole, a novel auxin-stimulating benzoxazole, affects root growth and promotes adventitious root formation.

The triple response phenotype is characteristic for seedlings treated with the phytohormone ethylene or its direct precursor 1-aminocyclopropane-carboxylic acid, and is often employed to find novel chemical tools to probe ethylene responses. We identified a benzoxazole-urea derivative (B2) partially mimicking ethylene effects in a triple response bioassay. A phenotypic analysis demonstrated that B2 and its closest analogue arinole (ARI) induced phenotypic responses reminiscent of seedlings with elevated levels of auxin, including impaired hook development and inhibition of seedling growth.

A UPLC-MS/MS method for quantification of metabolites in the ethylene biosynthesis pathway and its biological validation in Arabidopsis.

The plant hormone ethylene is of vital importance in the regulation of plant development and stress responses. Recent studies revealed that 1-aminocyclopropane-1-carboxylic acid (ACC) plays a role beyond its function as an ethylene precursor. However, the absence of reliable methods to quantify ACC and its conjugates malonyl-ACC (MACC), glutamyl-ACC (GACC), and jasmonyl-ACC (JA-ACC) hinders related research.

Phytohormone profiling in an evolutionary framework.

The genomes of charophyte green algae, close relatives of land plants, typically do not show signs of developmental regulation by phytohormones. However, scattered reports of endogenous phytohormone production in these organisms exist. We performed a comprehensive analysis of multiple phytohormones in Viridiplantae, focusing mainly on charophytes.

UV-B responses in the spotlight: Dynamic photoreceptor interplay and cell-type specificity.

Plants are constantly exposed to a multitude of external signals, including light. The information contained within the full spectrum of light is perceived by a battery of photoreceptors, each with specific and shared signalling outputs. Recently, it has become clear that UV-B radiation is a vital component of the electromagnetic spectrum, guiding growth and being crucial for plant fitness.

Ethylene signaling in salt-stressed Arabidopsis thaliana ein2-1 and ctr1-1 mutants - A dissection of molecular mechanisms involved in acclimation.

To pinpoint ethylene-mediated molecular mechanisms involved in the adaptive response to salt stress we conducted a comparative study of Arabidopsis thaliana wild type (Col-0), ethylene insensitive (ein2-1), and constitutive signaling (ctr1-1) mutant plants. Reduced germination and survival rates were observed in ein2-1 plants at increasing NaCl concentrations. By contrast, ctr1-1 mutation conferred salt stress tolerance during early vegetative development, corroborating earlier studies.

The Diverse Salt-Stress Response of Arabidopsis and Ethylene Signaling Mutants Is Linked to Altered Root Auxin Homeostasis.

We explored the interplay between ethylene signals and the auxin pool in roots exposed to high salinity using wild-type plants (Col-0), and the ethylene-signaling mutants (constitutive) and (insensitive). The negative effect of salt stress was less pronounced in individuals, which was concomitant with augmented auxin signaling both in the controls and after 100 mM NaCl treatment. The R2D2 auxin sensorallowed mapping this active auxin increase to the root epidermal cells in the late Cell Division (CDZ) and Transition Zone (TZ).

At the Crossroads of Survival and Death: The Reactive Oxygen Species-Ethylene-Sugar Triad and the Unfolded Protein Response.

Upon stress, a trade-off between plant growth and defense responses defines the capacity for survival. Stress can result in accumulation of misfolded proteins in the endoplasmic reticulum (ER) and other organelles. To cope with these proteotoxic effects, plants rely on the unfolded protein response (UPR).

Comparable canopy and soil free-living nitrogen fixation rates in a lowland tropical forest.

Biological nitrogen fixation (BNF) is a fundamental part of nitrogen cycling in tropical forests, yet little is known about the contribution made by free-living nitrogen fixers inhabiting the often-extensive forest canopy. We used the acetylene reduction assay, calibrated with N, to measure free-living BNF on forest canopy leaves, vascular epiphytes, bryophytes and canopy soil, as well as on the forest floor in leaf litter and soil. We used a combination of calculated and published component densities to upscale free-living BNF rates to the forest level.

Regulation of nitrogen fixation from free-living organisms in soil and leaf litter of two tropical forests of the Guiana shield.

Background And Aims: Biological fixation of atmospheric nitrogen (N) is the main pathway for introducing N into unmanaged ecosystems. While recent estimates suggest that free-living N fixation (FLNF) accounts for the majority of N fixed in mature tropical forests, the controls governing this process are not completely understood. The aim of this study was to quantify FLNF rates and determine its drivers in two tropical pristine forests of French Guiana.

The Ethylene Precursor ACC Affects Early Vegetative Development Independently of Ethylene Signaling.

The plant hormone ethylene plays a pivotal role in virtually every aspect of plant development, including vegetative growth, fruit ripening, senescence, and abscission. Moreover, it acts as a primary defense signal during plant stress. Being a volatile, its immediate biosynthetic precursor, 1-aminocyclopropane-1-carboxylic acid, ACC, is generally employed as a tool to provoke ethylene responses.

Ethylene induced plant stress tolerance by Enterobacter sp. SA187 is mediated by 2-keto-4-methylthiobutyric acid production.

Several plant species require microbial associations for survival under different biotic and abiotic stresses. In this study, we show that Enterobacter sp. SA187, a desert plant endophytic bacterium, enhances yield of the crop plant alfalfa under field conditions as well as growth of the model plant Arabidopsis thaliana in vitro, revealing a high potential of SA187 as a biological solution for improving crop production.

ACCERBATIN, a small molecule at the intersection of auxin and reactive oxygen species homeostasis with herbicidal properties.

The volatile two-carbon hormone ethylene acts in concert with an array of signals to affect etiolated seedling development. From a chemical screen, we isolated a quinoline carboxamide designated ACCERBATIN (AEX) that exacerbates the 1-aminocyclopropane-1-carboxylic acid-induced triple response, typical for ethylene-treated seedlings in darkness. Phenotypic analyses revealed distinct AEX effects including inhibition of root hair development and shortening of the root meristem.