Phytochrome A Protects Tomato Plants From Injuries Induced by Continuous Light.

Unlabelled: Plants perceive and transduce information about light quantity, quality, direction and photoperiod via several photoreceptors and use it to adjust their growth and development. A role for photoreceptors has been hypothesized in the injuries that tomato plants develop when exposed to continuous light as the light spectral distribution influences the injury severity. Up to now, however, only indirect clues suggested that phytochromes (PHY), red/far-red photoreceptors, are involved in the continuous-light-induced injuries in tomato.

Sucrose and Starch Content Negatively Correlates with PSII Maximum Quantum Efficiency in Tomato (Solanum lycopersicum) Exposed to Abnormal Light/Dark Cycles and Continuous Light.

Light is most important to plants as it fuels photosynthesis and provides clues about the environment. If provided in unnatural long photoperiods, however, it can be harmful and even lethal. Tomato (Solanum lycopersicum), for example, develops mottled chlorosis and necrosis when exposed to continuous light.

On the induction of injury in tomato under continuous light: circadian asynchrony as the main triggering factor.

Unlike other species, when tomato plants (Solanum lycopersicum L.) are deprived of at least 8h of darkness per day, they develop a potentially lethal injury. In an effort to understand why continuous light (CL) is injurious to tomato, we tested five factors, which potentially could be responsible for triggering the injury in CL-grown tomato: (i) differences in the light spectral distribution between sunlight and artificial light, (ii) continuous light signalling, (iii) continuous supply of light for photosynthesis, (iv) continuous photo-oxidative pressure and (v) circadian asynchrony - a mismatch between the internal circadian clock frequency and the external light/dark cycles.

Ethylene-Mediated Regulation of A2-Type CYCLINs Modulates Hyponastic Growth in Arabidopsis.

Upward leaf movement (hyponastic growth) is frequently observed in response to changing environmental conditions and can be induced by the phytohormone ethylene. Hyponasty results from differential growth (i.e.

Continuous-light tolerance in tomato is graft-transferable.

Continuous light induces a potentially lethal injury in domesticated tomato (Solanum lycopersicum) plants. Recently, continuous-light tolerance was reported in several wild tomato species, yet the molecular mechanisms underpinning tolerance/sensitivity are still elusive. Here, we investigated from which part of the plant continuous-light tolerance originates and whether this trait acts systemically within the plant.

A single locus confers tolerance to continuous light and allows substantial yield increase in tomato.

An important constraint for plant biomass production is the natural day length. Artificial light allows for longer photoperiods, but tomato plants develop a detrimental leaf injury when grown under continuous light--a still poorly understood phenomenon discovered in the 1920s. Here, we report a dominant locus on chromosome 7 of wild tomato species that confers continuous light tolerance.

Modulation of ethylene- and heat-controlled hyponastic leaf movement in Arabidopsis thaliana by the plant defence hormones jasmonate and salicylate.

Upward leaf movement (hyponastic growth) is adopted by several plant species including Arabidopsis thaliana, as a mechanism to escape adverse growth conditions. Among the signals that trigger hyponastic growth are, the gaseous hormone ethylene, low light intensities, and supra-optimal temperatures (heat). Recent studies indicated that the defence-related phytohormones jasmonic acid (JA) and salicylic acid (SA) synthesized by the plant upon biotic infestation repress low light-induced hyponastic growth.

Plants under continuous light.

Continuous light is an essential tool for understanding the plant circadian clock. Additionally, continuous light might increase greenhouse food production. However, using continuous light in research and practice has its challenges.

Kinome profiling reveals an interaction between jasmonate, salicylate and light control of hyponastic petiole growth in Arabidopsis thaliana.

Plants defend themselves against infection by biotic attackers by producing distinct phytohormones. Especially jasmonic acid (JA) and salicylic acid (SA) are well known defense-inducing hormones. Here, the effects of MeJA and SA on the Arabidopsis thaliana kinome were monitored using PepChip arrays containing kinase substrate peptides to analyze posttranslational interactions in MeJA and SA signaling pathways and to test if kinome profiling can provide leads to predict posttranslational events in plant signaling.

Photoreceptors CRYTOCHROME2 and phytochrome B control chromatin compaction in Arabidopsis.

Development and acclimation processes to the environment are associated with large-scale changes in chromatin compaction in Arabidopsis (Arabidopsis thaliana). Here, we studied the effects of light signals on chromatin organization. A decrease in light intensity induces a large-scale reduction in chromatin compaction.

ERECTA controls low light intensity-induced differential petiole growth independent of phytochrome B and cryptochrome 2 action in Arabidopsis thaliana.

Plants can respond quickly and profoundly to changes in their environment. Several species, including Arabidopsis thaliana, are capable of differential petiole growth driven upward leaf movement (hyponastic growth) to escape from detrimental environmental conditions. Recently, we demonstrated that the leucine-rich repeat receptor-like Ser/Thr kinase gene ERECTA, explains a major effect Quantitative Trait Locus (QTL) for ethylene-induced hyponastic growth in Arabidopsis.

Auxin perception and polar auxin transport are not always a prerequisite for differential growth.

Using time-lapse photography, we studied the response kinetics of low light intensity-induced upward leaf-movement, called hyponastic growth, in Arabidopsis thaliana. This response is one of the traits of shade avoidance and directs plant organs to more favorable light conditions. Based on mutant- and pharmacological data we demonstrated that among other factors, functional auxin perception and polar auxin transport (PAT) are required for the amplitude of hyponastic growth and for maintenance of the high leaf angle, upon low light treatment.

Ethylene-induced hyponastic growth in Arabidopsis thaliana is controlled by ERECTA.

Plants can respond quickly and profoundly to detrimental changes in their environment. For example, Arabidopsis thaliana can induce an upward leaf movement response through differential petiole growth (hyponastic growth) to outgrow complete submergence. This response is induced by accumulation of the phytohormone ethylene in the plant.

Hormone- and light-mediated regulation of heat-induced differential petiole growth in Arabidopsis.

Plants react quickly and profoundly to changes in their environment. A sudden increase in temperature, for example, induces differential petiole growth-driven upward leaf movement (hyponastic growth) in Arabidopsis (Arabidopsis thaliana). We show that accessions that face the strongest fluctuations in diurnal temperature in their natural habitat are least sensitive for heat-induced hyponastic growth.

Phytochrome B and histone deacetylase 6 control light-induced chromatin compaction in Arabidopsis thaliana.

Natural genetic variation in Arabidopsis thaliana exists for many traits and often reflects acclimation to local environments. Studying natural variation has proven valuable in the characterization of phenotypic traits and, in particular, in identifying genetic factors controlling these traits. It has been previously shown that chromatin compaction changes during development and biotic stress.

Differential petiole growth in Arabidopsis thaliana: photocontrol and hormonal regulation.

Environmental challenges such as low light intensity induce differential growth-driven upward leaf movement (hyponastic growth) in Arabidopsis thaliana. However, little is known about the physiological regulation of this response. Here, we studied how low light intensity is perceived and translated into a differential growth response in Arabidopsis.

Ethylene modulates the role of NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 in cross talk between salicylate and jasmonate signaling.

The plant hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) play crucial roles in the signaling network that regulates induced defense responses against biotic stresses. Antagonism between SA and JA operates as a mechanism to fine-tune defenses that are activated in response to multiple attackers. In Arabidopsis (Arabidopsis thaliana), NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (NPR1) was demonstrated to be required for SA-mediated suppression of JA-dependent defenses.

Abscisic acid antagonizes ethylene-induced hyponastic growth in Arabidopsis.

Ethylene induces enhanced differential growth in petioles of Arabidopsis (Arabidopsis thaliana), resulting in an upward movement of the leaf blades (hyponastic growth). The amplitude of this effect differs between accessions, with Columbia-0 (Col-0) showing a large response, while in Landsberg erecta (Ler), hyponastic growth is minimal. Abscisic acid (ABA) was found to act as an inhibitory factor of this response in both accessions, but the relationship between ethylene and ABA differed between the two; the ability of ABA to inhibit ethylene-induced hyponasty was significantly more pronounced in Col-0.

How to decide? Different methods of calculating gene expression from short oligonucleotide array data will give different results.

Background: Short oligonucleotide arrays for transcript profiling have been available for several years. Generally, raw data from these arrays are analysed with the aid of the Microarray Analysis Suite or GeneChip Operating Software (MAS or GCOS) from Affymetrix. Recently, more methods to analyse the raw data have become available.

Reaching out of the shade.

Competition for light determines the success of individual plants in dense vegetation. Much depends on the capacity of plants to detect neighbours quickly and on their ability to respond to these signals. Recent findings indicate that although red:far-red ratios, and thus phytochromes, are of major importance in shade-avoidance responses, they do not act alone.

New perspectives in flooding research: the use of shade avoidance and Arabidopsis thaliana.

Background: Complete submergence of Rumex palustris leads to hyponastic (upward) petiole growth followed by enhanced petiole elongation. Previous pharmacological experiments have provided insights into the signal transduction pathway leading to this combined 'escape' response. It will, however, be difficult to gain further knowledge using these methods.

Ethylene-induced differential growth of petioles in Arabidopsis. Analyzing natural variation, response kinetics, and regulation.

Plants can reorient their organs in response to changes in environmental conditions. In some species, ethylene can induce resource-directed growth by stimulating a more vertical orientation of the petioles (hyponasty) and enhanced elongation. In this study on Arabidopsis (Arabidopsis thaliana), we show significant natural variation in ethylene-induced petiole elongation and hyponastic growth.

Plant movement. Submergence-induced petiole elongation in Rumex palustris depends on hyponastic growth.

The submergence-tolerant species Rumex palustris (Sm.) responds to complete submergence by an increase in petiole angle with the horizontal. This hyponastic growth, in combination with stimulated elongation of the petiole, can bring the leaf tips above the water surface, thus restoring gas exchange and enabling survival.

Role of sugars and organic acids in regulating the concentration and activity of the alternative oxidase in Poa annua roots.

Detached roots of Poa annua were used to study alternative oxidase protein expression upon the addition of sucrose, glucose, fructose, inositol, mannitol, citrate or malate, at a concentration of 1 or 10 mM for 24 h. After 24 h the capacity of cytochrome c oxidase was decreased equally in all treatments. Only citrate induced the expression of the alternative oxidase, especially at a concentration of 1 mM (15-fold).