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FEMS Microbiology Letters Mar 2020Stable, long-term interactions between fungi and algae or cyanobacteria, collectively known as lichens, have repeatedly evolved complex architectures with little... (Review)
Review
Stable, long-term interactions between fungi and algae or cyanobacteria, collectively known as lichens, have repeatedly evolved complex architectures with little resemblance to their component parts. Lacking any central scaffold, the shapes they assume are casts of secreted polymers that cement cells into place, determine the angle of phototropic exposure and regulate water relations. A growing body of evidence suggests that many lichen extracellular polymer matrices harbor unicellular, non-photosynthesizing organisms (UNPOs) not traditionally recognized as lichen symbionts. Understanding organismal input and uptake in this layer is key to interpreting the role UNPOs play in lichen biology. Here, we review both polysaccharide composition determined from whole, pulverized lichens and UNPOs reported from lichens to date. Most reported polysaccharides are thought to be structural cell wall components. The composition of the extracellular matrix is not definitively known. Several lines of evidence suggest some acidic polysaccharides have evaded detection in routine analysis of neutral sugars and may be involved in the extracellular matrix. UNPOs reported from lichens include diverse bacteria and yeasts for which secreted polysaccharides play important biological roles. We conclude by proposing testable hypotheses on the role that symbiont give-and-take in this layer could play in determining or modifying lichen symbiotic outcomes.
Topics: Biofilms; Cyanobacteria; Fungi; Lichens; Phylogeny; Polysaccharides; Symbiosis; Uronic Acids
PubMed: 32037451
DOI: 10.1093/femsle/fnaa023 -
Physiologia Plantarum Mar 2016Auxin is involved in a wide spectrum of physiological processes in plants, including responses controlled by the blue light photoreceptors phototropins: phototropic...
Auxin is involved in a wide spectrum of physiological processes in plants, including responses controlled by the blue light photoreceptors phototropins: phototropic bending and stomatal movement. However, the role of auxin in phototropin-mediated chloroplast movements has never been studied. To address this question we searched for potential interactions between auxin and the chloroplast movement signaling pathway using different experimental approaches and two model plants, Arabidopsis thaliana and Nicotiana tabacum. We observed that the disturbance of auxin homeostasis by shoot decapitation caused a decrease in chloroplast movement parameters, which could be rescued by exogenous auxin application. In several cases, the impairment of polar auxin transport, by chemical inhibitors or in auxin carrier mutants, had a similar negative effect on chloroplast movements. This inhibition was not correlated with changes in auxin levels. Chloroplast relocations were also affected by the antiauxin p-chlorophenoxyisobutyric acid and mutations in genes encoding some of the elements of the SCF(TIR1)-Aux/IAA auxin receptor complex. The observed changes in chloroplast movement parameters are not prominent, which points to a modulatory role of auxin in this process. Taken together, the obtained results suggest that auxin acts indirectly to regulate chloroplast movements, presumably by regulating gene expression via the SCF(TIR1)-Aux/IAA-ARF pathway. Auxin does not seem to be involved in controlling the expression of phototropins.
Topics: Actin Cytoskeleton; Arabidopsis; Biological Transport; Chloroplasts; Gene Expression Regulation, Plant; Indoleacetic Acids; Light; Mesophyll Cells; Movement; Mutation; Phototropins; Plant Growth Regulators; Plant Leaves; Plant Shoots; RNA, Messenger
PubMed: 26467664
DOI: 10.1111/ppl.12396 -
Frontiers in Plant Science 2022Pest management has been a great challenge since the beginning of human agricultural activities. Since the 1930s, chemical pesticide control has been a major control... (Review)
Review
Pest management has been a great challenge since the beginning of human agricultural activities. Since the 1930s, chemical pesticide control has been a major control technology that can solve some of the pest problems in agricultural production. Still, it is harmful to food safety and the ecological environment. Meanwhile, the extensive use of chemical pesticides may lead to the rapid development of pest resistance. Because of the advantages of low cost, eco-friendly advantage, and low side effects, Solar Insecticidal Lamp (SIL) as the main physical control technology has been widely used for pest management in agricultural production in China. Owing to the phototaxis of pests, they have a phototropic rhythm during the nighttime. We can adjust the SIL insecticidal time according to the phototropic rhythm of pests. The purpose of this paper is to provide a comprehensive review of the pest phototactic rhythm in a selection of 24 pest species. It is the first comprehensive survey on the phototactic rhythm of pests and the time segments of this survey are accurate to the hour. The phototactic rhythm of pests are investigated in two different varieties of crops: 1) food crops and 2) economic crops. We also discuss and analyze the various factors (e.g., meteorological conditions, insecticidal devices, physiological states and others) that affect the changing phototactic rhythm of pests. Finally, we highlight some open research challenge issues and future directions.
PubMed: 36743546
DOI: 10.3389/fpls.2022.1018711 -
Methods in Molecular Biology (Clifton,... 2019The distribution patterns of the cytoskeleton, i.e., microtubules and actin filaments, in the apical part of protonemal cells are unique and differ from those of other...
The distribution patterns of the cytoskeleton, i.e., microtubules and actin filaments, in the apical part of protonemal cells are unique and differ from those of other apical growing cells, such as moss and liverwort protonemata, fungal hyphae, and angiosperm pollen tubes. A ring structure composed of microtubules and actin filaments exists at the basal part of the apical dome of protonemal cells. The structure may control the protonemal diameter and growth direction. Herein, the methods of staining of both microtubules and actin filaments are described.
Topics: Actin Cytoskeleton; Adiantum; Cytoskeleton; Light; Microtubules; Phototropism
PubMed: 30694476
DOI: 10.1007/978-1-4939-9015-3_15 -
Plant Physiology Jun 2019Phototropin (phot) receptor kinases play important roles in promoting plant growth by controlling light-capturing processes, such as phototropism. Phototropism is...
Phototropin (phot) receptor kinases play important roles in promoting plant growth by controlling light-capturing processes, such as phototropism. Phototropism is mediated through the action of NON-PHOTOTROPIC HYPOCOTYL3 (NPH3), which is dephosphorylated following phot activation. However, the functional significance of this early signaling event remains unclear. Here, we show that the onset of phototropism in dark-grown (etiolated) seedlings of Arabidopsis () and tomato () is enhanced by greening (deetiolation). Red and blue light were equally effective in promoting phototropism in Arabidopsis, consistent with our observations that deetiolation by phytochrome or cryptochrome was sufficient to enhance phototropism. Increased responsiveness did not result from an enhanced sensitivity to the phytohormone auxin, nor does it involve the phot-interacting protein, ROOT PHOTOTROPISM2. Instead, deetiolated seedlings showed attenuated levels of NPH3 dephosphorylation and diminished relocalization of NPH3 from the plasma membrane during phototropism. Likewise, etiolated seedlings that lack the PHYTOCHROME-INTERACTING FACTORS (PIFs) PIF1, PIF3, PIF4, and PIF5 displayed reduced NPH3 dephosphorylation and enhanced phototropism, consistent with their constitutive photomorphogenic phenotype in darkness. Phototropic enhancement could also be achieved in etiolated seedlings by lowering the light intensity to diminish NPH3 dephosphorylation. Thus, phototropism is enhanced following deetiolation through the modulation of a phosphorylation rheostat, which in turn sustains the activity of NPH3. We propose that this dynamic mode of regulation enables young seedlings to maximize their establishment under changing light conditions, depending on their photoautotrophic capacity.
Topics: Arabidopsis; Arabidopsis Proteins; Cryptochromes; Etiolation; Green Fluorescent Proteins; Hypocotyl; Indoleacetic Acids; Light; Models, Biological; Phosphorylation; Phototropism; Phytochrome; Protein Aggregates; Seedlings
PubMed: 30918082
DOI: 10.1104/pp.19.00206 -
The New Phytologist Jan 2016Phototropins (phots) regulate a range of adaptive processes in plants that serve to optimize photosynthetic efficiency and promote growth. Light sensing by Arabidopsis...
Phototropins (phots) regulate a range of adaptive processes in plants that serve to optimize photosynthetic efficiency and promote growth. Light sensing by Arabidopsis thaliana phots is predominantly mediated by the Light, Oxygen and Voltage sensing 2 (LOV2) flavin-binding motif located within the N-terminus of the photoreceptor. Here we characterize the photochemical and biochemical properties of phot from the marine picoalga Ostreococcus tauri phototropin (Otphot) and examine its ability to replace phot-mediated function in Arabidopsis. Photochemical properties of Otphot rely on both LOV1 and LOV2. Yet, biochemical analysis indicates that light-dependent receptor autophosphorylation is primarily dependent on LOV2. As found for Arabidopsis phots, Otphot associates with the plasma membrane and partially internalizes, albeit to a limited extent, in response to blue-light irradiation. Otphot is able to elicit a number of phot-regulated processes in Arabidopsis, including petiole positioning, leaf expansion, stomatal opening and chloroplast accumulation movement. However, Otphot is unable to restore phototropism and chloroplast avoidance movement. Consistent with its lack of phototropic function in Arabidopsis, Otphot does not associate with or trigger dephosphorylation of the phototropic signalling component Non-Phototropic Hypocotyl 3 (NPH3). Taken together, these findings indicate that the mechanism of action of plant and evolutionarily distant algal phots is less well conserved than previously thought.
Topics: Arabidopsis; Arabidopsis Proteins; Cell Membrane; Chlorophyta; DNA-Binding Proteins; Gene Expression Regulation, Plant; Light; Mutation; Phosphoproteins; Phosphorylation; Phototropins; Phototropism; Plant Leaves; Plant Stomata; Plants, Genetically Modified; Protein Serine-Threonine Kinases
PubMed: 26414490
DOI: 10.1111/nph.13640 -
Frontiers in Plant Science 2015Plant phototropism, the ability to bend toward or away from light, is predominantly controlled by blue-light photoreceptors, the phototropins. Although phototropins have...
Plant phototropism, the ability to bend toward or away from light, is predominantly controlled by blue-light photoreceptors, the phototropins. Although phototropins have been well-characterized in Arabidopsis thaliana, their evolutionary history is largely unknown. In this study, we complete an in-depth survey of phototropin homologs across land plants and algae using newly available transcriptomic and genomic data. We show that phototropins originated in an ancestor of Viridiplantae (land plants + green algae). Phototropins repeatedly underwent independent duplications in most major land-plant lineages (mosses, lycophytes, ferns, and seed plants), but remained single-copy genes in liverworts and hornworts-an evolutionary pattern shared with another family of photoreceptors, the phytochromes. Following each major duplication event, the phototropins differentiated in parallel, resulting in two specialized, yet partially overlapping, functional forms that primarily mediate either low- or high-light responses. Our detailed phylogeny enables us to not only uncover new phototropin lineages, but also link our understanding of phototropin function in Arabidopsis with what is known in Adiantum and Physcomitrella (the major model organisms outside of flowering plants). We propose that the convergent functional divergences of phototropin paralogs likely contributed to the success of plants through time in adapting to habitats with diverse and heterogeneous light conditions.
PubMed: 26322073
DOI: 10.3389/fpls.2015.00637 -
Plant Physiology May 2020Blue-light-induced chloroplast movements play an important role in maximizing light utilization for photosynthesis in plants. Under a weak light condition, chloroplasts...
Blue-light-induced chloroplast movements play an important role in maximizing light utilization for photosynthesis in plants. Under a weak light condition, chloroplasts accumulate to the cell surface to capture light efficiently (chloroplast accumulation response). Conversely, chloroplasts escape from strong light and move to the side wall to reduce photodamage (chloroplast avoidance response). The blue light receptor phototropin (phot) regulates these chloroplast movements and optimizes leaf photosynthesis by controlling other responses in addition to chloroplast movements. Seed plants such as Arabidopsis () have phot1 and phot2. They redundantly mediate phototropism, stomatal opening, leaf flattening, and the chloroplast accumulation response. However, the chloroplast avoidance response is induced by strong blue light and regulated primarily by phot2. Phots are localized mainly on the plasma membrane. However, a substantial amount of phot2 resides on the chloroplast outer envelope. Therefore, differentially localized phot2 might have different functions. To determine the functions of plasma membrane- and chloroplast envelope-localized phot2, we tethered it to these structures with their respective targeting signals. Plasma membrane-localized phot2 regulated phototropism, leaf flattening, stomatal opening, and chloroplast movements. Chloroplast envelope-localized phot2 failed to mediate phototropism, leaf flattening, and the chloroplast accumulation response but partially regulated the chloroplast avoidance response and stomatal opening. Based on the present and previous findings, we propose that phot2 localized at the interface between the plasma membrane and the chloroplasts is required for the chloroplast avoidance response and possibly for stomatal opening as well.
Topics: Arabidopsis; Arabidopsis Proteins; Cell Membrane; Chloroplasts; Photosynthesis; Phototropins; Phototropism; Plant Leaves; Plants, Genetically Modified
PubMed: 32193212
DOI: 10.1104/pp.20.00059 -
Journal of Integrative Plant Biology Oct 2022Plant shoot phototropism is triggered by the formation of a light-driven auxin gradient leading to bending growth. The blue light receptor phototropin 1 (phot1) senses...
Plant shoot phototropism is triggered by the formation of a light-driven auxin gradient leading to bending growth. The blue light receptor phototropin 1 (phot1) senses light direction, but how this leads to auxin gradient formation and growth regulation remains poorly understood. Previous studies have suggested phot1's role for regulated apoplastic acidification, but its relation to phototropin and hypocotyl phototropism is unclear. Herein, we show that blue light can cause phot1 to interact with and phosphorylate FERONIA (FER), a known cell growth regulator, and trigger downstream phototropic bending growth in Arabidopsis hypocotyls. fer mutants showed defects in phototropic growth, similar to phot1/2 mutant. FER also interacts with and phosphorylates phytochrome kinase substrates, the phot1 downstream substrates. The phot1-FER pathway acts upstream of apoplastic acidification and the auxin gradient formation in hypocotyl under lateral blue light, both of which are critical for phototropic bending growth in hypocotyls. Our study highlights a pivotal role of FER in the phot1-mediated phototropic cell growth regulation in plants.
Topics: Arabidopsis; Phototropins; Arabidopsis Proteins; Hypocotyl; Phytochrome; Indoleacetic Acids; Light
PubMed: 35924740
DOI: 10.1111/jipb.13336 -
Frontiers in Plant Science 2015Plants are sessile organisms that are permanently restricted to their site of germination. To compensate for their lack of mobility, plants evolved unique mechanisms... (Review)
Review
Plants are sessile organisms that are permanently restricted to their site of germination. To compensate for their lack of mobility, plants evolved unique mechanisms enabling them to rapidly react to ever changing environmental conditions and flexibly adapt their postembryonic developmental program. A prominent demonstration of this developmental plasticity is their ability to bend organs in order to reach the position most optimal for growth and utilization of light, nutrients, and other resources. Shortly after germination, dicotyledonous seedlings form a bended structure, the so-called apical hook, to protect the delicate shoot meristem and cotyledons from damage when penetrating through the soil. Upon perception of a light stimulus, the apical hook rapidly opens and the photomorphogenic developmental program is activated. After germination, plant organs are able to align their growth with the light source and adopt the most favorable orientation through bending, in a process named phototropism. On the other hand, when roots and shoots are diverted from their upright orientation, they immediately detect a change in the gravity vector and bend to maintain a vertical growth direction. Noteworthy, despite the diversity of external stimuli perceived by different plant organs, all plant tropic movements share a common mechanistic basis: differential cell growth. In our review, we will discuss the molecular principles underlying various tropic responses with the focus on mechanisms mediating the perception of external signals, transduction cascades and downstream responses that regulate differential cell growth and consequently, organ bending. In particular, we highlight common and specific features of regulatory pathways in control of the bending of organs and a role for the plant hormone auxin as a key regulatory component.
PubMed: 25926839
DOI: 10.3389/fpls.2015.00218