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Frontiers in Plant Science 2015Light can penetrate several centimeters below the soil surface. Growth, development and behavior of plant roots are markedly affected by light despite their underground... (Review)
Review
Light can penetrate several centimeters below the soil surface. Growth, development and behavior of plant roots are markedly affected by light despite their underground lifestyle. Early studies provided contrasting information on the spatial and temporal distribution of light-sensing cells in the apical region of root apex and discussed the physiological roles of plant hormones in root responses to light. Recent biological and microscopic advances have improved our understanding of the processes involved in the sensing and transduction of light signals, resulting in subsequent physiological and behavioral responses in growing root apices. Here, we review current knowledge of cellular distributions of photoreceptors and their signal transduction pathways in diverse root tissues and root apex zones. We are discussing also the roles of auxin transporters in roots exposed to light, as well as interactions of light signal perceptions with sensing of other environmental factors relevant to plant roots.
PubMed: 26442084
DOI: 10.3389/fpls.2015.00775 -
Current Biology : CB Sep 2017Light is a vital resource for plants, which compete for it particularly in dense communities. Plants have multiple photosensory receptors to detect the presence of... (Review)
Review
Light is a vital resource for plants, which compete for it particularly in dense communities. Plants have multiple photosensory receptors to detect the presence of competitors and thereby adjust their growth and developmental strategies accordingly. Broadly speaking, plants fall into two categories depending on their response to shading by leaves: shade tolerant or shade avoiding. Here, we describe the photoperception mechanisms and the growth responses elicited by the neighboring vegetation in shade-avoiding plants, focusing on Arabidopsis thaliana, where these responses are best understood. The type of response depends on plant density, ranging from neighbor detection modulating growth in anticipation of future shading to the response to canopy shade where light resources are limiting. These diverse environments are sensed by various photoreceptors, and we will describe our current understanding of signal integration triggered by distinct light cues in diverse light conditions.
Topics: Arabidopsis; Photoreceptors, Plant; Phototropism; Plant Development
PubMed: 28898666
DOI: 10.1016/j.cub.2017.05.085 -
Plants (Basel, Switzerland) Dec 2021Phototropins (phot1 and phot2) are plant-specific blue light receptors that mediate chloroplast movement, stomatal opening, and phototropism. Phototropin is composed of...
Phototropins (phot1 and phot2) are plant-specific blue light receptors that mediate chloroplast movement, stomatal opening, and phototropism. Phototropin is composed of the N-terminus LOV1 and LOV2 domains and the C-terminus Ser/Thr kinase domain. In previous studies, 35-P2CG transgenic plants expressing the phot2 C-terminal fragment-GFP fusion protein (P2CG) under the control of promoter showed constitutive phot2 responses, including chloroplast avoidance response, stomatal opening, and reduced hypocotyl phototropism regardless of blue light, and some detrimental growth phenotypes. In this study, to exclude the detrimental growth phenotypes caused by the ectopic expression of P2C and to improve leaf transpiration, we used the promoter for the endogenous expression of GFP-fused P2C (GP2C) (P2-GP2C) and the promoter for the guard-cell-specific expression of GP2C (B1-GP2C), respectively. In P2-GP2C plants, GP2C expression induced constitutive phototropin responses and a relatively dwarf phenotype as in 35-P2CG plants. In contrast, B1-GP2C plants showed the guard-cell-specific P2C expression that induced constitutive stomatal opening with normal phototropism, chloroplast movement, and growth phenotype. Interestingly, leaf transpiration was significantly improved in B1-GP2C plants compared to that in P2-GP2C plants and WT. Taken together, this transgenic approach could be applied to improve leaf transpiration in indoor plants.
PubMed: 35009069
DOI: 10.3390/plants11010065 -
Current Genomics Oct 2021Changes in environmental conditions like temperature and light critically influence crop production. To deal with these changes, plants possess various photoreceptors... (Review)
Review
Changes in environmental conditions like temperature and light critically influence crop production. To deal with these changes, plants possess various photoreceptors such as Phototropin (PHOT), Phytochrome (PHY), Cryptochrome (CRY), and UVR8 that work synergistically as sensor and stress sensing receptors to different external cues. PHOTs are capable of regulating several functions like growth and development, chloroplast relocation, thermomorphogenesis, metabolite accumulation, stomatal opening, and phototropism in plants. PHOT plays a pivotal role in overcoming the damage caused by excess light and other environmental stresses (heat, cold, and salinity) and biotic stress. The crosstalk between photoreceptors and phytohormones contributes to plant growth, seed germination, photo-protection, flowering, phototropism, and stomatal opening. Molecular genetic studies using gene targeting and synthetic biology approaches have revealed the potential role of different photoreceptor genes in the manipulation of various beneficial agronomic traits. Overexpression of PHOT2 in leads to the increase in anthocyanin content in its leaves and fruits. Artificial illumination with blue light alone and in combination with red light influence the growth, yield, and secondary metabolite production in many plants, while in algal species, it affects growth, chlorophyll content, lipid production and also increases its bioremediation efficiency. Artificial illumination alters the morphological, developmental, and physiological characteristics of agronomic crops and algal species. This review focuses on PHOT modulated signalosome and artificial illumination-based photo-biotechnological approaches for the development of climate-smart crops.
PubMed: 34975290
DOI: 10.2174/1389202922666210412104817 -
Science Advances Dec 2020Almost a century ago, Stiles and Crawford reported that the human eye is more sensitive to light entering through the pupil center than through its periphery...
Almost a century ago, Stiles and Crawford reported that the human eye is more sensitive to light entering through the pupil center than through its periphery (Stiles-Crawford effect). This psychophysical phenomenon, later found to correlate with photoreceptor orientation toward the pupil, was dynamically phototropic, adjustable within days to an eccentrically displaced pupil. For decades, this phototropism has been speculated to involve coordinated movements of the rectilinear photoreceptor outer and inner segments. We report here that, unexpectedly, the murine photoreceptor outer segment has a seemingly light-independent orientation, but the inner segment's orientation undergoes light-dependent movement, giving rise to nonrectilinear outer and inner segments in adult mice born and reared in darkness. Light during an early critical period (~P0 to P8), however, largely sets the correct photoreceptor orientation permanently afterward. Unexpectedly, abolishing rod and cone phototransductions did not mimic darkness in early life, suggesting photosignaling extrinsic to rods and cones is involved.
PubMed: 33328242
DOI: 10.1126/sciadv.abe2782 -
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 -
Journal of Experimental Botany Jul 2016The directional transport of auxin, known as polar auxin transport (PAT), allows asymmetric distribution of this hormone in different cells and tissues. This system... (Review)
Review
The directional transport of auxin, known as polar auxin transport (PAT), allows asymmetric distribution of this hormone in different cells and tissues. This system creates local auxin maxima, minima, and gradients that are instrumental in both organ initiation and shape determination. As such, PAT is crucial for all aspects of plant development but also for environmental interaction, notably in shaping plant architecture to its environment. Cell to cell auxin transport is mediated by a network of auxin carriers that are regulated at the transcriptional and post-translational levels. Here we review our current knowledge on some aspects of the 'non-genomic' regulation of auxin transport, placing an emphasis on how phosphorylation by protein and lipid kinases controls the polarity, intracellular trafficking, stability, and activity of auxin carriers. We describe the role of several AGC kinases, including PINOID, D6PK, and the blue light photoreceptor phot1, in phosphorylating auxin carriers from the PIN and ABCB families. We also highlight the function of some receptor-like kinases (RLKs) and two-component histidine kinase receptors in PAT, noting that there are probably RLKs involved in co-ordinating auxin distribution yet to be discovered. In addition, we describe the emerging role of phospholipid phosphorylation in polarity establishment and intracellular trafficking of PIN proteins. We outline these various phosphorylation mechanisms in the context of primary and lateral root development, leaf cell shape acquisition, as well as root gravitropism and shoot phototropism.
Topics: Biological Transport; Body Patterning; Indoleacetic Acids; Lipids; Phosphorylation; Phosphotransferases; Plant Development; Plant Growth Regulators; Protein Kinases
PubMed: 27242371
DOI: 10.1093/jxb/erw216 -
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 -
Critical Reviews in Microbiology Mar 2017Volatile Organic Sulfur Compounds (VOSCs) are instrumental in global S-cycling and greenhouse gas production. VOSCs occur across a diversity of inland waters, and with... (Review)
Review
Volatile Organic Sulfur Compounds (VOSCs) are instrumental in global S-cycling and greenhouse gas production. VOSCs occur across a diversity of inland waters, and with widespread eutrophication and climate change, are increasingly linked with malodours in organic-rich waterbodies and drinking-water supplies. Compared with marine systems, the role of VOSCs in biogeochemical processes is far less well characterized for inland waters, and often involves different physicochemical and biological processes. This review provides an updated synthesis of VOSCs in inland waters, focusing on compounds known to cause malodours. We examine the major limnological and biochemical processes involved in the formation and degradation of alkylthiols, dialkylsulfides, dialkylpolysulfides, and other organosulfur compounds under different oxygen, salinity and mixing regimes, and key phototropic and heterotrophic microbial producers and degraders (bacteria, cyanobacteria, and algae) in these environs. The data show VOSC levels which vary significantly, sometimes far exceeding human odor thresholds, generated by a diversity of biota, biochemical pathways, enzymes and precursors. We also draw attention to major issues in sampling and analytical artifacts which bias and preclude comparisons among studies, and highlight significant knowledge gaps that need addressing with careful, appropriate methods to provide a more robust understanding of the potential effects of continued global development.
Topics: Bacteria; Biological Phenomena; Chemical Phenomena; Chlorophyta; Sulfur Compounds; Volatile Organic Compounds; Water Microbiology
PubMed: 27822973
DOI: 10.1080/1040841X.2016.1198306