-
PLoS Biology Oct 2023Sunflowers are famous for their ability to track the sun throughout the day and then reorient at night to face east the following morning. This occurs by differential...
Sunflowers are famous for their ability to track the sun throughout the day and then reorient at night to face east the following morning. This occurs by differential growth patterns, with the east sides of stems growing more during the day and the west sides of stems growing more at night. This process, termed heliotropism, is generally believed to be a specialized form of phototropism; however, the underlying mechanism is unknown. To better understand heliotropism, we compared gene expression patterns in plants undergoing phototropism in a controlled environment and in plants initiating and maintaining heliotropic growth in the field. We found the expected transcriptome signatures of phototropin-mediated phototropism in sunflower stems bending towards monochromatic blue light. Surprisingly, the expression patterns of these phototropism-regulated genes are quite different in heliotropic plants. Most genes rapidly induced during phototropism display only minor differences in expression across solar tracking stems. However, some genes that are both rapidly induced during phototropism and are implicated in growth responses to foliar shade are rapidly induced on the west sides of stems at the onset of heliotropism, suggesting a possible role for red light photoreceptors in solar tracking. To test the involvement of different photoreceptor signaling pathways in heliotropism, we modulated the light environment of plants initiating solar tracking. We found that depletion of either red and far-red light or blue light did not hinder the initiation or maintenance of heliotropism in the field. Together, our results suggest that the transcriptional regulation of heliotropism is distinct from phototropin-mediated phototropism and likely involves inputs from multiple light signaling pathways.
Topics: Helianthus; Phototropins; Sunlight; Light; Phototropism; Signal Transduction; Arabidopsis Proteins
PubMed: 37906610
DOI: 10.1371/journal.pbio.3002344 -
Science (New York, N.Y.) Nov 2023In plants, light direction is perceived by the phototropin photoreceptors, which trigger directional growth responses known as phototropism. The formation of a...
In plants, light direction is perceived by the phototropin photoreceptors, which trigger directional growth responses known as phototropism. The formation of a phototropin activation gradient across a photosensitive organ initiates this response. However, the optical tissue properties that functionally contribute to phototropism remain unclear. In this work, we show that intercellular air channels limit light transmittance through various organs in several species. Air channels enhance light scattering in hypocotyls, thereby steepening the light gradient. This is required for an efficient phototropic response in and Brassica. We identified an embryonically expressed ABC transporter required for the presence of air channels in seedlings and a structure surrounding them. Our work provides insights into intercellular air space development or maintenance and identifies a mechanism of directional light sensing in plants.
Topics: Arabidopsis; Arabidopsis Proteins; ATP Binding Cassette Transporter, Subfamily G, Member 5; Brassica; Hypocotyl; Light; Phototropins; Phototropism; Signal Transduction
PubMed: 37995216
DOI: 10.1126/science.adh9384 -
Communications Biology Jan 2024Plant organs shift their directional growth in response to environmental stimuli through tropisms. Arabidopsis roots exhibit positive hydrotropism (towards water) and...
Plant organs shift their directional growth in response to environmental stimuli through tropisms. Arabidopsis roots exhibit positive hydrotropism (towards water) and negative phototropism (away from light). In a recent study, Pang and colleagues demonstrated that root phototropism is regulated by the activity of two proteins in the elongation zone that also play essential roles in hydrotropism.
PubMed: 38195918
DOI: 10.1038/s42003-023-05707-z -
Scientific Reports Oct 2022Directing plant growth in weightlessness requires understanding the processes that establish plant orientation and how to manipulate them. Both gravi- and phototropism...
Directing plant growth in weightlessness requires understanding the processes that establish plant orientation and how to manipulate them. Both gravi- and phototropism determine directional growth and previous experiments showed that high gradient magnetic fields (HGMF) can induce curvature in roots and shoots. Experiments with Brassica rapa verified that that gravitropism-like induction of curvature is possible in space and that the HGMF-responsive organelles are amyloplasts. We assessed the effect of space and HGMF based on 16 genes and compared their transcription with static growth and clinorotation. Amyloplasts size in root tips increased under weightlessness but decreased under clinorotation but not in response to magnetic fields. Amyloplast size changes were correlated with reduced amylase transcription in space samples and enhanced transcription after clinorotation. Mechanostimulation and weightlessness have opposite effects on the size of amyloplasts. The data show that plants perceive weightlessness, and that their metabolism adjusts to microgravity and mechanostimulation. Thus, clinorotation as surrogate for space research may lead to incorrect interpretations.
Topics: Gravitropism; Weightlessness; Plastids; Plant Roots; Plants; Rotation; Starch; Magnetic Fields; Space Flight
PubMed: 36309570
DOI: 10.1038/s41598-022-22691-2 -
Plant, Cell & Environment Nov 2023Plants 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... (Review)
Review
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. However, given the large overlap between UV-B specific signalling pathways and other photoreceptors, understanding how plants can distinguish UV-B specific signals from other light components deserves more scrutiny. With recent evidence, we propose that UV-B signalling and other light signalling pathways occur within distinct tissues and cell-types and that the contribution of each pathway depends on the type of response and the developmental stage of the plant. Elucidating the precise site(s) of action of each molecular player within these signalling pathways is key to fully understand how plants are able to orchestrate coordinated responses to light within the whole plant body. Focusing our efforts on the molecular study of light signal interactions to understand plant growth in natural environments in a cell-type specific manner will be a next step in the field of photobiology.
Topics: Signal Transduction; Plants; Light Signal Transduction; Ultraviolet Rays
PubMed: 37554043
DOI: 10.1111/pce.14680 -
Plant Physiology and Biochemistry : PPB Jan 2022We performed a series of experiments to study the interaction between phototropism and gravitropism in Arabidopsis thaliana as part of the Seedling Growth Project on the...
We performed a series of experiments to study the interaction between phototropism and gravitropism in Arabidopsis thaliana as part of the Seedling Growth Project on the International Space Station. Red-light-based and blue-light-based phototropism were examined in microgravity and at 1g, a control that was produced by an on-board centrifuge. At the end of the experiments, seedlings were frozen and brought back to Earth for gene profiling studies via RNASeq methods. In this paper, we focus on five genes identified in these space studies by their differential expression in space: one involved in auxin transport and four others encoding genes for: a methyltransferase subunit, a transmembrane protein, a transcription factor for endodermis formation, and a cytoskeletal element (an intermediate filament protein). Time course studies using mutant strains of these five genes were performed for blue-light and red-light phototropism studies as well as for gravitropism assays on ground. Interestingly, all five of the genes had some effects on all the tropisms under the conditions studied. In addition, RT-PCR analyses examined expression of the five genes in wild-type seedlings during blue-light-based phototropism. Previous studies have supported a role of both microfilaments and microtubules in tropism pathways. However, the most interesting finding of the present space studies is that NFL, a gene encoding an intermediate filament protein, plays a role in phototropism and gravitropism, which opens the possibility that this cytoskeletal element modulates signal transduction in plants.
Topics: Gravitropism; Intermediate Filaments; Light; Phototropism; Space Flight; Weightlessness
PubMed: 35007950
DOI: 10.1016/j.plaphy.2021.12.039 -
Physiology and Molecular Biology of... Jun 2023Root systems anchor plants to the substrate in addition to transporting water and nutrients, playing a fundamental role in plant survival. The gene mediates gravity...
UNLABELLED
Root systems anchor plants to the substrate in addition to transporting water and nutrients, playing a fundamental role in plant survival. The gene mediates gravity signal transduction and participates in root and shoot development and auxin flow in many plants. In this study, a regulator, LsLAZY1, was identified from based on previous transcriptome data. The conserved domain and evolutionary relationship were further analyzed comprehensively. The role of in root development was investigated by genetic transformation and associated gravity response and phototropism assay. Subcellular localization showed that LsLAZY1 was localized in the nucleus. overexpression in () increased the length of the primary roots (PRs) and the number of lateral roots (LRs) compared to . Furthermore, : transgenic seedlings affected auxin transport and showed a stronger gravitational and phototropic responses. It also promoted auxin accumulation at the root tips. These results indicated that affects root development and auxin transport.
SUPPLEMENTARY INFORMATION
The online version contains supplementary material available at 10.1007/s12298-023-01326-4.
PubMed: 37520815
DOI: 10.1007/s12298-023-01326-4 -
Frontiers in Plant Science 2019Peanut or groundnut is one of the most important legume crops with high protein and oil content. The high nutritional qualities of peanut and its multiple usage have... (Review)
Review
Peanut or groundnut is one of the most important legume crops with high protein and oil content. The high nutritional qualities of peanut and its multiple usage have made it an indispensable component of our daily life, in both confectionary and therapeutic food industries. Given the socio-economic significance of peanut, understanding its developmental biology is important in providing a molecular framework to support breeding activities. In peanut, the formation and directional growth of a specialized reproductive organ called a peg, or gynophore, is especially relevant in genetic improvement. Several studies have indicated that peanut yield can be improved by improving reproductive traits including peg development. Therefore, we aim to identify unifying principles for the genetic control, underpinning molecular and physiological basis of peg development for devising appropriate strategy for peg improvement. This review discusses the current understanding of the molecular aspects of peanut peg development citing several studies explaining the key mechanisms. Deciphering and integrating recent transcriptomic, proteomic, and miRNA-regulomic studies provide a new perspective for understanding the regulatory events of peg development that participate in pod formation and thus control yield.
PubMed: 31681383
DOI: 10.3389/fpls.2019.01289 -
Frontiers in Neuroscience 2020The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species... (Review)
Review
The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species and their environment. We provide an overview of the tremendous variety of light-detection strategies which have evolved in living organisms - unicellular, plants and animals, covering chloroplasts (plants), and the plethora of ocular and extra-ocular organs (animals). We describe the visual pigments which permit photo-detection, paying attention to their spectral characteristics, which extend from the ultraviolet into infrared. We discuss how organisms use light information in a way crucial for their development, growth and survival: phototropism, phototaxis, photoperiodism, and synchronization of circadian clocks. These aspects are treated in depth, as their perturbation underlies much of the disruptive effects of ALAN. The review goes into detail on circadian networks in living organisms, since these fundamental features are of critical importance in regulating the interface between environment and body. Especially, hormonal synthesis and secretion are often under circadian and circannual control, hence perturbation of the clock will lead to hormonal imbalance. The review addresses how the ubiquitous introduction of light-emitting diode technology may exacerbate, or in some cases reduce, the generalized ever-increasing light pollution. Numerous examples are given of how widespread exposure to ALAN is perturbing many aspects of plant and animal behaviour and survival: foraging, orientation, migration, seasonal reproduction, colonization and more. We examine the potential problems at the level of individual species and populations and extend the debate to the consequences for ecosystems. We stress, through a few examples, the synergistic harmful effects resulting from the impacts of ALAN combined with other anthropogenic pressures, which often impact the neuroendocrine loops in vertebrates. The article concludes by debating how these anthropogenic changes could be mitigated by more reasonable use of available technology - for example by restricting illumination to more essential areas and hours, directing lighting to avoid wasteful radiation and selecting spectral emissions, to reduce impact on circadian clocks. We end by discussing how society should take into account the potentially major consequences that ALAN has on the natural world and the repercussions for ongoing human health and welfare.
PubMed: 33304237
DOI: 10.3389/fnins.2020.602796 -
Frontiers in Bioengineering and... 2022We review fundamental mechanisms and applications of OptoGels: hydrogels with light-programmable properties endowed by photoswitchable proteins ("optoproteins") found in... (Review)
Review
We review fundamental mechanisms and applications of OptoGels: hydrogels with light-programmable properties endowed by photoswitchable proteins ("optoproteins") found in nature. Light, as the primary source of energy on earth, has driven evolution to develop highly-tuned functionalities, such as phototropism and circadian entrainment. These functions are mediated through a growing family of optoproteins that respond to the entire visible spectrum ranging from ultraviolet to infrared by changing their structure to transmit signals inside of cells. In a recent series of articles, engineers and biochemists have incorporated optoproteins into a variety of extracellular systems, endowing them with photocontrollability. While other routes exist for dynamically controlling material properties, light-sensitive proteins have several distinct advantages, including precise spatiotemporal control, reversibility, substrate selectivity, as well as biodegradability and biocompatibility. Available conjugation chemistries endow OptoGels with a combinatorially large design space determined by the set of optoproteins and polymer networks. These combinations result in a variety of tunable material properties. Despite their potential, relatively little of the OptoGel design space has been explored. Here, we aim to summarize innovations in this emerging field and highlight potential future applications of these next generation materials. OptoGels show great promise in applications ranging from mechanobiology, to 3D cell and organoid engineering, and programmable cell eluting materials.
PubMed: 35774061
DOI: 10.3389/fbioe.2022.903982