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AoB PLANTS Feb 2022Phototropism is an essential response in some plant organs and features several signalling molecules involved in either photo-sensing or post-sensing responses. Annexins...
Phototropism is an essential response in some plant organs and features several signalling molecules involved in either photo-sensing or post-sensing responses. Annexins are involved in regulating plant growth and its responses to various stimuli. Here, we provide novel data showing that two members of the Annexin family in , AtANN1 and AtANN2, may be involved in the phototropism of etiolated hypocotyls. In wild type, unilateral blue light (BL) induced a strong phototropic response, while red light (RL) only induced a weak response. The responses of single- or double-null mutants of the two annexins, including , and , were significantly weaker than those observed in wild type, indicating the involvement of AtANN1 and AtANN2 in BL-induced phototropism. Unilateral BL induced asymmetric distribution of DR5-GFP and PIN3-GFP fluorescence in hypocotyls; notably, fluorescent intensity on the shaded side was markedly stronger than that on the illuminated side. In etiolated , or / hypocotyls, unilateral BL-induced asymmetric distributions of DR5-GFP and PIN3-GFP were weakened or impaired. Herein, we suggest that during hypocotyls phototropic response, AtANN1 and AtANN2 may be involved in BL-stimulated signalling by regulating PIN3-charged auxin transport.
PubMed: 35079328
DOI: 10.1093/aobpla/plab075 -
The New Phytologist Sep 2021Shade and warmth promote the growth of the stem, but the degree of mechanistic convergence and functional association between these responses is not clear. We analysed...
Shade and warmth promote the growth of the stem, but the degree of mechanistic convergence and functional association between these responses is not clear. We analysed the quantitative impact of mutations and natural genetic variation on the hypocotyl growth responses of Arabidopsis thaliana to shade and warmth, the relationship between the abundance of PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and growth stimulation by shade or warmth, the effects of both cues on the transcriptome and the consequences of warm temperature on carbon balance. Growth responses to shade and warmth showed strong genetic linkage and similar dependence on PIF4 levels. Temperature increased growth and phototropism even within a range where damage by extreme high temperatures is unlikely to occur in nature. Both cues enhanced the expression of growth-related genes and reduced the expression of photosynthetic genes. However, only warmth enhanced the expression of genes involved in responses to heat. Warm temperatures substantially increased the amount of light required to compensate for the daily carbon dioxide balance. We propose that the main ecological function of hypocotyl growth responses to warmth is to increase the access of shaded photosynthetic organs to light, which implies functional convergence with shade avoidance.
Topics: Arabidopsis; Arabidopsis Proteins; Gene Expression Regulation, Plant; Hypocotyl; Phototropism
PubMed: 33909310
DOI: 10.1111/nph.17430 -
Plant Biotechnology (Tokyo, Japan) Dec 2020Environmental stimuli such as gravity and light modify the plant development to optimize overall architecture. Many physiological and molecular biological studies of...
Environmental stimuli such as gravity and light modify the plant development to optimize overall architecture. Many physiological and molecular biological studies of gravitropism and phototropism have been carried out. However, sufficient analysis has not been performed from a mechanical point of view. If the biological and mechanical characteristics of gravitropism and phototropism can be accurately grasped, then controlling the environmental conditions would be helpful to control the growth of plants into a specific shape. In this study, to clarify the mechanical characteristics of gravitropism, we examined the transverse bending moment occurring in cantilevered pea () sprouts in response to gravistimulation. The force of the pea sprouts lifting themselves during gravitropism was measured using an electronic balance. The gravitropic bending force of the pea sprouts was in the order of 10 Nmm in the conditions set for this study, although there were wide variations due to individual differences.
PubMed: 33850437
DOI: 10.5511/plantbiotechnology.20.1201b -
Plant Signaling & Behavior Dec 2022The blue light photoreceptors, phototropin 1 (phot1) and phot2, and their signal transducer, NONPHOTOTROPIC HYPOCOTYL3 (NPH3), are activators of the phototropic...
The blue light photoreceptors, phototropin 1 (phot1) and phot2, and their signal transducer, NONPHOTOTROPIC HYPOCOTYL3 (NPH3), are activators of the phototropic responses of hypocotyls. In a recent study, we reported that the control of NPH3 phosphorylation at serine 7 (S7: or S5), S213, S223, S237, S467, S474 (or S476), and S722 (or S723) contributes to the photosensory adaptation of phot1 signaling during the phototropic response. Phosphomimetic NPH3 mutant and unphosphorylatable NPH3 mutant on those serine residues function efficiently under blue light conditions at fluence rates of 10 µmol m s and 10 µmol m s or more, respectively. We here demonstrate that phosphomimetic NPH3, but not unphosphorylatable NPH3, promotes phot2-dependent phototropism under blue light condition at 100 µmol m s. This result suggests that phot1 negatively controls phot2 signaling through the dephosphorylation of NPH3 at those residues and that the hyperactivation of phot1- and phot2-NPH3 complexes does not occur at the same time under high intensity blue light. We hypothesize that the dephosphorylation of NPH3 on those serine residues suppresses both phot1 and phot2 signaling, which results in different impacts on phot1- and phot2-dependent hypocotyl phototropism due to the differences in the photosensitivity and activation levels of phot1 and phot2.
Topics: Arabidopsis; Arabidopsis Proteins; Hypocotyl; Light; Phosphoproteins; Phosphorylation; Phototropins; Phototropism; Serine
PubMed: 35068333
DOI: 10.1080/15592324.2022.2027138 -
Plant Physiology Feb 2018NRL proteins coordinate different aspects of phototropin signaling through signaling processes that are conserved in land plants and algae. (Review)
Review
NRL proteins coordinate different aspects of phototropin signaling through signaling processes that are conserved in land plants and algae.
Topics: Arabidopsis; Arabidopsis Proteins; Gene Expression Regulation, Plant; Light; Phosphoproteins; Phototropism; Phylogeny; Phytochrome; Protein Serine-Threonine Kinases; Signal Transduction
PubMed: 28720608
DOI: 10.1104/pp.17.00835 -
PloS One 2016Auxins are the key players in plant growth development involving leaf formation, phototropism, root, fruit and embryo development. Auxin/Indole-3-Acetic Acid (Aux/IAA)...
Auxins are the key players in plant growth development involving leaf formation, phototropism, root, fruit and embryo development. Auxin/Indole-3-Acetic Acid (Aux/IAA) are early auxin response genes noted as transcriptional repressors in plant auxin signaling. However, many studies focus on Aux/ARF gene families and much less is known about the Aux/IAA gene family in Brassica rapa (B. rapa). Here we performed a comprehensive genome-wide analysis and identified 55 Aux/IAA genes in B. rapa using four conserved motifs of Aux/IAA family (PF02309). Chromosomal mapping of the B. rapa Aux/IAA (BrIAA) genes facilitated understanding cluster rearrangement of the crucifer building blocks in the genome. Phylogenetic analysis of BrIAA with Arabidopsis thaliana, Oryza sativa and Zea mays identified 51 sister pairs including 15 same species (BrIAA-BrIAA) and 36 cross species (BrIAA-AtIAA) IAA genes. Among the 55 BrIAA genes, expression of 43 and 45 genes were verified using Genebank B. rapa ESTs and in home developed microarray data from mature leaves of Chiifu and RcBr lines. Despite their huge morphological difference, tissue specific expression analysis of BrIAA genes between the parental lines Chiifu and RcBr showed that the genes followed a similar pattern of expression during leaf development and a different pattern during bud, flower and siliqua development stages. The response of the BrIAA genes to abiotic and auxin stress at different time intervals revealed their involvement in stress response. Single Nucleotide Polymorphisms between IAA genes of reference genome Chiifu and RcBr were focused and identified. Our study examines the scope of conservation and divergence of Aux/IAA genes and their structures in B. rapa. Analyzing the expression and structural variation between two parental lines will significantly contribute to functional genomics of Brassica crops and we belive our study would provide a foundation in understanding the Aux/IAA genes in B. rapa.
Topics: Brassica rapa; Chromosome Mapping; Chromosomes, Plant; Gene Expression Profiling; Gene Expression Regulation, Plant; Genome, Plant; Indoleacetic Acids; Phylogeny; Plant Growth Regulators; Plant Proteins; RNA, Plant; Reverse Transcriptase Polymerase Chain Reaction
PubMed: 27049520
DOI: 10.1371/journal.pone.0151522 -
Life Sciences in Space Research Feb 2022Long-duration space missions will need to rely on the use of plants in bio-regenerative life support systems (BLSSs) because these systems can produce fresh food and...
Long-duration space missions will need to rely on the use of plants in bio-regenerative life support systems (BLSSs) because these systems can produce fresh food and oxygen, reduce carbon dioxide levels, recycle metabolic waste, and purify water. In this scenario, the need for new experiments on the effects of altered gravity conditions on plant biological processes is increasing, and significant efforts should be devoted to new ideas aimed at increasing the scientific output and lowering the experimental costs. Here, we report the design of an easy-to-produce and inexpensive device conceived to analyze the effect of interaction between gravity and light on root tropisms. Each unit consisted of a polystyrene multi-slot rack with light-emitting diodes (LEDs), capable of holding Petri dishes and assembled with a particular filter-paper folding. The device was successfully used for the ROOTROPS (for root tropisms) experiment performed in the Large Diameter Centrifuge (LDC) and Random Positioning Machine (RPM) at ESA's European Space Research and Technology centre (ESTEC). During the experiments, four light treatments and six gravity conditions were factorially combined to study their effects on root orientation of Brassica oleracea seedlings. Light treatments (red, blue, and white) and a dark condition were tested under four hypergravity levels (20 g, 15 g, 10 g, 5 g), a 1 g control, and a simulated microgravity (RPM) condition. Results of validation tests showed that after 24 h, the assembled system remained unaltered, no slipping or displacement of seedlings occurred at any hypergravity treatment or on the RPM, and seedlings exhibited robust growth. Overall, the device was effective and reliable in achieving scientific goals, suggesting that it can be used for ground-based research on phototropism-gravitropism interactions. Moreover, the concepts developed can be further expanded for use in future spaceflight experiments with plants.
Topics: Gravitropism; Phototropism; Seedlings; Space Flight; Tropism; Weightlessness
PubMed: 35065766
DOI: 10.1016/j.lssr.2021.09.005 -
Plant Physiology Nov 2018Under high light intensity, chloroplasts avoid absorbing excess light by moving to anticlinal cell walls (avoidance response), but under low light intensity,...
Under high light intensity, chloroplasts avoid absorbing excess light by moving to anticlinal cell walls (avoidance response), but under low light intensity, chloroplasts accumulate along periclinal cell walls (accumulation response). In most plant species, these responses are induced by blue light and are mediated by the blue light photoreceptor, phototropin, which also regulates phototropism, leaf flattening, and stomatal opening. These phototropin-mediated responses could enhance photosynthesis and biomass production. Here, using various Arabidopsis () mutants deficient in chloroplast movement, we demonstrated that the accumulation response enhances leaf photosynthesis and plant biomass production. Conspicuously, mutant plants specifically defective in the avoidance response but not in other phototropin-mediated responses displayed a constitutive accumulation response irrespective of light intensities, enhanced leaf photosynthesis, and increased plant biomass production. Therefore, our findings provide clear experimental evidence of the importance of the chloroplast accumulation response in leaf photosynthesis and biomass production.
Topics: Arabidopsis; Arabidopsis Proteins; Biomass; Chloroplasts; Photosynthesis; Phototropins; Phototropism; Plant Leaves; Plant Stomata
PubMed: 30266749
DOI: 10.1104/pp.18.00484 -
BMC Genomics Nov 2022Continuous tilling and the lateral growth of rhizomes confer rhizomatous grasses with the unique ability to laterally expand, migrate and resist disturbances. They play...
BACKGROUND
Continuous tilling and the lateral growth of rhizomes confer rhizomatous grasses with the unique ability to laterally expand, migrate and resist disturbances. They play key roles especially in degraded grasslands, deserts, sand dunes, and other fragile ecological system. The rhizomatous plant Leymus secalinus has both rhizome buds and tiller buds that grow horizontally and upward at the ends of rhizome differentiation and elongation, respectively. The mechanisms of rhizome formation and differentiation in L. secalinus have not yet been clarified.
RESULTS
In this study, we found that the content of gibberellin A3 (GA) and indole-3-acetic acid (IAA) were significantly higher in upward rhizome tips than in horizontal rhizome tips; by contrast, the content of methyl jasmonate and brassinolide were significantly higher in horizontal rhizome tips than in upward rhizome tips. GA and IAA could stimulate the formation and turning of rhizomes. An auxin efflux carrier gene, LsPIN1, was identified from L. secalinus based on previous transcriptome data. The conserved domains of LsPIN1 and the relationship of LsPIN1 with PIN1 genes from other plants were analyzed. Subcellular localization analysis revealed that LsPIN1 was localized to the plasma membrane. The length of the primary roots (PRs) and the number of lateral roots (LRs) were higher in Arabidopsis thaliana plants overexpressing LsPIN1 than in wild-type (Col-0) plants. Auxin transport was altered and the gravitropic response and phototropic response were stronger in 35S:LsPIN1 transgenic plants compared with Col-0 plants. It also promoted auxin accumulation in root tips.
CONCLUSION
Our findings indicated that LsPIN1 plays key roles in auxin transport and root development. Generally, our results provide new insights into the regulatory mechanisms underlying rhizome development in L. secalinus.
Topics: Rhizome; Indoleacetic Acids; Poaceae; Plant Roots; Arabidopsis
PubMed: 36384450
DOI: 10.1186/s12864-022-08979-7 -
Plant Communications Sep 2020Small ubiquitin-like modifier (SUMO) post-translational modification (SUMOylation) plays essential roles in regulating various biological processes; however, its...
Small ubiquitin-like modifier (SUMO) post-translational modification (SUMOylation) plays essential roles in regulating various biological processes; however, its function and regulation in the plant light signaling pathway are largely unknown. SEUSS (SEU) is a transcriptional co-regulator that integrates light and temperature signaling pathways, thereby regulating plant growth and development in . Here, we show that SEU is a substrate of SUMO1, and that substitution of four conserved lysine residues disrupts the SUMOylation of SEU, impairs its function in photo- and thermomorphogenesis, and enhances its interaction with PHYTOCHROME-INTERACTING FACTOR 4 transcription factors. Furthermore, the SUMO E3 ligase SIZ1 interacts with SEU and regulates its SUMOylation. Moreover, SEU directly interacts with phytochrome B photoreceptors, and the SUMOylation and stability of SEU are activated by light. Our study reveals a novel post-translational modification mechanism of SEU in which light regulates plant growth and development through SUMOylation-mediated protein stability.
Topics: Arabidopsis; Arabidopsis Proteins; Basic Helix-Loop-Helix Transcription Factors; Ligases; Phototropism; Reverse Transcriptase Polymerase Chain Reaction; Sumoylation; Two-Hybrid System Techniques
PubMed: 33367258
DOI: 10.1016/j.xplc.2020.100080