Mechanosensory trichome cells evoke a mechanical stimuli-induced immune response in Arabidopsis thaliana

Overexpression of the tomato nuclear-cytoplasmic shuttling bZIP transcription factor VSF-1 in Arabidopsis retards plant development under mannitol-stressed conditions

VASCULAR SPECIFICITY FACTOR 1 (VSF-1) is a basic leucine zipper transcription factor identified in tomato (Solanum lycopersicum L.). VSF-1 regulates vascular-specific gene expression and is homologous to an Arabidopsis thaliana mechanical stress regulator, VIP1, but physiological roles for VSF-1 remain unclear. Here, we demonstrate that VSF-1 shuttles between the nucleus and the cytoplasm in response to hypo-osmotic stress. In Arabidopsis plants overexpressing the VSF-1-GFP fusion protein, VSF-1-GFP was mainly detected in the cytoplasm under unstressed conditions but in the nucleus under hypo-osmotically stressed conditions. VSF-1 contains three serine residues within HXRXXS motifs, which can serve as its phosphorylation and 14-3-3 protein-binding sites. In a transient gene expression system in Nicotiana benthamiana leaves, GFP-fused VSF-1 variants where those serine residues were replaced with alanine exhibited nuclear accumulation even under unstressed conditions. GFP-fused VSF-1 variants lacking those HXRXXS motifs also exhibited such nuclear accumulation. The VSF-1 variants lacking those HXRXXS motifs failed to interact with 14-3-3 proteins in a yeast two-hybrid system. These findings suggest that the nuclear accumulation of VSF-1 is triggered by hypo-osmotic stress through its dissociation from 14-3-3 proteins, similar to that of VIP1. The Arabidopsis VSF-1-GFP-overexpressing lines exhibited retarded germination and growth in the presence of mannitol, which can induce hyper-osmotic stress and repress nuclear accumulation of VSF-1. These results are consistent with phenotypes from VIP1-GFP-overexpressing lines in a previous study, indicating a conserved role for VIP1 and VSF-1 in regulating osmotic stress responses.

Spatial ploidy inference using quantitative imaging

Polyploidy (whole-genome multiplication) is a common yet under-surveyed property of tissues across multicellular organisms. Polyploidy plays a critical role during tissue development, following acute stress, and during disease progression. Common methods to reveal polyploidy involve either destroying tissue architecture by cell isolation or by tedious identification of individual nuclei in intact tissue. Therefore, there is a critical need for rapid and high-throughput ploidy quantification using images of nuclei in intact tissues. Here, we present iSPy (Inferring Spatial Ploidy), a new unsupervised learning pipeline that is designed to create a spatial map of nuclear ploidy across a tissue of interest. We demonstrate the use of iSPy in Arabidopsis, Drosophila, and human tissue. iSPy can be adapted for a variety of tissue preparations, including whole mount and sectioned. This high-throughput pipeline will facilitate rapid and sensitive identification of nuclear ploidy in diverse biological contexts and organisms.

Plasma membrane H+-ATPase activation increases global transcript levels and promotes the shoot growth of light-grown Arabidopsis seedlings

Plant cell growth requires the elongation of cells mediated by cell wall remodelling and turgor pressure changes. The plasma membrane (PM) H+-ATPase facilitates both cell wall loosening and turgor pressure changes by acidifying the apoplast of cells, referred to as acid growth. The acid growth theory is mostly established on the auxin-induced activation of PM H+-ATPase in non-photosynthetic tissues. However, how PM H+-ATPase affects the growth in photosynthetic tissues of Arabidopsis remains unclear. Here, a combination of transcriptomics and cis-regulatory element analysis was conducted to identify the impact of PM H+-ATPase on global transcript levels and the molecular mechanism downstream of the PM H+-ATPase. The PM H+-ATPase activation increased transcript levels globally, especially cell wall modification-related genes. The transcript level changes were in PM H+-ATPase-dependent manner. Involvement of Ca2+ was suggested as CAMTA motif was enriched in the promoter of PM H+-ATPase-induced genes and cytosolic Ca2+ elevated upon PM H+-ATPase activation. PM H+-ATPase activation in photosynthetic tissues promotes the expression of cell wall modification enzymes and shoot growth, adding a novel perspective of photosynthesis-dependent PM H+-ATPase activation in photosynthetic tissues to the acid growth theory that has primarily based on findings from non-photosynthetic tissues.

Plant memory and communication of encounters

Plants can communicate with each other and other living organisms in a very sophisticated manner. They use biological molecules and even physical cues to establish a molecular dialogue with beneficial organisms as well as with their predators and pathogens. Several studies were recently published that explore how plants communicate with each other about their previous encounters or stressful experiences. However, there is an almost complete lack of knowledge about how these intra- and interspecies communications are directly regulated at the epigenetic level. In this perspective article we provide new hypotheses for the possible epigenetic modifications that regulate plant responses at the communication level.

Calcium signaling triggers early high humidity responses in Arabidopsis thaliana

Plants need to adapt to fluctuating atmospheric humidity and respond to both high and low humidity. Despite our substantial understanding of plant responses to low humidity, molecular mechanisms underlying the high humidity (HH) response are much less well understood. In this study, we investigated early responses to HH in Arabidopsis. Expression of CYP707A3, encoding an abscisic acid (ABA) 8'-hydroxylase, is induced by HH within 10 min, which leads to a decrease in foliar ABA level. We identified that the combined action of CAMTA3 and CAMTA2 transcription factors regulate this response. This regulation requires a calmodulin (CaM)-binding domain of CAMTA3. Transcriptomes of HH-regulated genes are enriched in those related to calcium signaling, including cyclic nucleotide-gated ion channels (CNGCs). Moreover, HH induces CNGC2- and CNGC4-mediated increases in cytosolic Ca2+ concentrations in leaves within a few minutes. We also found that CNGC2, CNGC4, and CAMTAs participate in HH-induced hyponastic movement of petioles. Taken together, our results indicate that CNGC2/CNGC4-Ca2+-CaM-CAMTA3/CAMTA2 acts as a primary regulatory module to trigger downstream HH responses.

The trichome pattern diversity of Cardamine shares genetic mechanisms with Arabidopsis but differs in environmental drivers

Natural variation in trichome pattern (amount and distribution) is prominent among populations of many angiosperms. However, the degree of parallelism in the genetic mechanisms underlying this diversity and its environmental drivers in different species remain unclear. To address these questions, we analyzed the genomic and environmental bases of leaf trichome pattern diversity in Cardamine hirsuta, a relative of Arabidopsis (Arabidopsis thaliana). We characterized 123 wild accessions for their genomic diversity, leaf trichome patterns at different temperatures, and environmental adjustments. Nucleotide diversities and biogeographical distribution models identified two major genetic lineages with distinct demographic and adaptive histories. Additionally, C. hirsuta showed substantial variation in trichome pattern and plasticity to temperature. Trichome amount in C. hirsuta correlated positively with spring precipitation but negatively with temperature, which is opposite to climatic patterns in A. thaliana. Contrastingly, genetic analysis of C. hirsuta glabrous accessions indicated that, like for A. thaliana, glabrousness is caused by null mutations in ChGLABRA1 (ChGL1). Phenotypic genome-wide association studies (GWAS) further identified a ChGL1 haplogroup associated with low trichome density and ChGL1 expression. Therefore, a ChGL1 series of null and partial loss-of-function alleles accounts for the parallel evolution of leaf trichome pattern in C. hirsuta and A. thaliana. Finally, GWAS also detected other candidate genes (e.g. ChETC3, ChCLE17) that might affect trichome pattern. Accordingly, the evolution of this trait in C. hirsuta and A. thaliana shows partially conserved genetic mechanisms but is likely involved in adaptation to different environments.

Touch, light, wounding: how anaesthetics affect plant sensing abilities

KEY MESSAGE

Anaesthetics affect not only humans and animals but also plants. Plants exposed to certain anaesthetics lose their ability to respond adequately to various stimuli such as touch, injury or light. Available results indicate that anaesthetics modulate ion channel activities in plants, e.g. Ca2+ influx. The word anaesthesia means loss of sensation. Plants, as all living creatures, can also sense their environment and they are susceptible to anaesthesia. Although some anaesthetics are often known as drugs with well-defined target to their animal/human receptors, some other are promiscuous in their binding. Both have effects on plants. Application of general volatile anaesthetics (GVAs) inhibits plant responses to different stimuli but also induces strong cellular response. Of particular interest is the ability of GVAs inhibit long-distance electrical and Ca2+ signalling probably through inhibition of GLUTAMATE RECEPTOR-LIKE proteins (GLRs), the effect which is surprisingly very similar to inhibition of nerve impulse transmission in animals or human. However, GVAs act also as a stressor for plants and can induce their own Ca2+ signature, which strongly reprograms gene expression . Down-regulation of genes encoding enzymes of chlorophyll biosynthesis and pigment-protein complexes are responsible for inhibited de-etiolation and photomorphogenesis. Vesicle trafficking, germination, and circumnutation movement of climbing plants are also strongly inhibited. On the other hand, other cellular processes can be upregulated, for example, heat shock response and generation of reactive oxygen species (ROS). Upregulation of stress response by GVAs results in preconditioning/priming and can be helpful to withstand abiotic stresses in plants. Thus, anaesthetic drugs may become a useful tool for scientists studying plant responses to environmental stimuli.

Characterizing the role of PP2A B'' family subunits in mechanical stress response and plant development through calcium and ABA signaling in Arabidopsis thaliana

Protein phosphatase 2AB'' (PP2A B'') family subunits have calcium-binding EF-hand motifs, facilitating interaction with PP2A substrates. In Arabidopsis thaliana, the PP2A B'' family subunits consist of six members, AtB''α-ε and FASS. These subunits can interact with a basic leucine zipper transcription factor, VIP1, and its close homologs. Mechanical stress triggers PP2A-mediated dephosphorylation of VIP1 and its close homologs, leading to nuclear localization and gene upregulation to alleviate touch-induced root bending and leaf damage. However, the physiological roles of PP2A B'' family subunits in the mechanical stress response in Arabidopsis remain unclear. This study aims to characterize such roles. A quadruple knockout mutant with T-DNA insertions in AtB''α, AtB''β, AtB''γ, and AtB''δ was generated. atb''αβγδ mutants exhibited no significant damage upon brushing or touch-induced root bending compared to the wild type. Transcriptome analysis showed a significant decrease in the expression of CYP707A3, a gene potentially targeted by VIP1 that regulates abscisic acid (ABA) catabolism, in the atb''αβγδ mutant compared to wild type leaves. However, other genes, including XTH23, EXLA1, and CYP707A1, also VIP1 targets, exhibited similar induction in both brushed atb''αβγδ mutants and wild type leaves. We observed an enrichment of the CAMTA motif, CGCG(C/T) in the promoters of genes showing downregulated expression levels in brushed atb''αβγδ leaves compared to brushed wild type leaves. These findings suggest that PP2A B'' family subunits exhibit functional redundancy in the VIP1-dependent pathway but influence CAMTA-dependent gene expression under mechanical stress. Under calcium-deficient and ABA-supplemented conditions, growth of atb''αβγδ seedlings was retarded when compared to wild type and single knockout mutants, atb''γ and atb''δ, indicating a crucial role in plant development by modulating calcium or ABA signaling.

Understanding the mechanobiology of phytoacoustics through molecular Lens: Mechanisms and future perspectives

BACKGROUND

How plants emit, perceive, and respond to sound vibrations (SVs) is a long-standing question in the field of plant sensory biology. In recent years, there have been numerous studies on how SVs affect plant morphological, physiological, and biochemical traits related to growth and adaptive responses. For instance, under drought SVs navigate plant roots towards water, activate their defence responses against stressors, and increase nectar sugar in response to pollinator SVs. Also, plants emit SVs during stresses which are informative in terms of ecological and adaptive perspective. However, the molecular mechanisms underlying the SV perception and emission in plants remain largely unknown. Therefore, deciphering the complexity of plant-SV interactions and identifying bonafide receptors and signaling players will be game changers overcoming the roadblocks in phytoacoustics.

AIM OF REVIEW

The aim of this review is to provide an overview of recent developments in phytoacoustics. We primarily focuss on SV signal perception and transduction with current challenges and future perspectives.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Timeline breakthroughs in phytoacoustics have constantly shaped our understanding and belief that plants may emit and respond to SVs like other species. However, unlike other plant mechanostimuli, little is known about SV perception and signal transduction. Here, we provide an update on phytoacoustics and its ecological importance. Next, we discuss the role of cell wall receptor-like kinases, mechanosensitive channels, intracellular organelle signaling, and other key players involved in plant-SV receptive pathways that connect them. We also highlight the role of calcium (Ca2+), reactive oxygen species (ROS), hormones, and other emerging signaling molecules in SV signal transduction. Further, we discuss the importance of molecular, biophysical, computational, and live cell imaging tools for decoding the molecular complexity of acoustic signaling in plants. Finally, we summarised the role of SV priming in plants and discuss how SVs could modulate plant defense and growth trade-offs during other stresses.

Different multicellular trichome types coordinate herbivore mechanosensing and defense in tomato

Herbivore-induced wounding can elicit a defense response in plants. However, whether plants possess a surveillance system capable of detecting herbivore threats and initiating preparatory defenses before wounding occurs remains unclear. In this study, we reveal that tomato (Solanum lycopersicum) trichomes can detect and respond to the mechanical stimuli generated by herbivores. Mechanical stimuli are preferentially perceived by long trichomes, and this mechanosensation is transduced via intra-trichome communication. This communication presumably involves calcium waves, and the transduced signals activate the jasmonic acid (JA) signaling pathway in short glandular trichomes, resulting in the upregulation of the Woolly (Wo)-SlMYC1 regulatory module for terpene biosynthesis. This induced defense mechanism provides plants with an early warning system against the threat of herbivore invasion. Our findings represent a perspective on the role of multicellular trichomes in plant defense and the underlying intra-trichome communication.

VIP1 and its close homologs confer mechanical stress tolerance in Arabidopsis leaves

VIP1, an Arabidopsis thaliana basic leucine zipper transcription factor, and its close homologs are imported from the cytoplasm to the nucleus when cells are exposed to mechanical stress. They bind to AGCTG (G/T) and regulate mechanical stress responses in roots. However, their role in leaves is unclear. To clarify this, mutant lines (QM1 and QM2) that lack the functions of VIP1 and its close homologs (bZIP29, bZIP30 and PosF21) were generated. Brushing more severely damaged QM1 and QM2 leaves than wild-type leaves. Genes regulating stress responses and cell wall properties were downregulated in brushed QM2 leaves and upregulated in brushed VIP1-GFP-overexpressing (VIP1-GFPox) leaves compared to wild-type leaves in a transcriptome analysis. The VIP1-binding sequence AGCTG (G/T) was enriched in the promoters of genes downregulated in brushed QM2 leaves compared to wild-type leaves and in those upregulated in brushed VIP1-GFPox leaves. Calmodulin-binding transcription activators (CAMTAs) are known regulators of mechanical stress responses, and the CAMTA-binding sequence CGCGT was enriched in the promoters of genes upregulated in the brushed QM2 leaves and in those downregulated in the brushed VIP1-GFPox leaves. These findings suggest that VIP1 and its homologs upregulate genes via AGCTG (G/T) and influence CAMTA-dependent gene expression to enhance mechanical stress tolerance in leaves.

The genetic basis of leaf hair development in upland cotton (Gossypium hirsutum)

Trichomes, which originate from the epidermal cell of aerial organs, provide plants with defense and secretion functions. Although numerous genes have been implicated in trichome development, the molecular mechanisms underlying trichome cell formation in plants remain incompletely understood. Here, we using genome-wide association study (GWAS) across 1037 diverse accessions in upland cotton (Gossypium hirsutum) to identify three loci associated with leaf pubescence (hair) amount, located on chromosome A06 (LPA1), A08 (LPA2) and A11 (LPA3), respectively. GhHD1, a previously characterized candidate gene, was identified on LPA1 and encodes an HD-Zip transcription factor. For LPA2 and LPA3, we identified two candidate genes, GhGIR1 and GhGIR2, both encoding proteins with WD40 and RING domains that act as inhibitors of leaf hair formation. Expression analysis revealed that GhHD1 was predominantly expressed in hairy accessions, whereas GhGIR1 and GhGIR2 were expressed in hairless accessions. Silencing GhHD1 or overexpressing GhGIR1 in hairy accessions induced in a hairless phenotype, whereas silencing GhGIR2 in hairless accessions resulted in a hairy phenotype. We also demonstrated that GhHD1 interact with both GhGIR1 and GhGIR2, and GhGIR1 can interact with GhGIR2. Further investigation indicated that GhHD1 functions as a transcriptional activator, binding to the promoters of the GhGIR1 and GhGIR2 to active their expression, whereas GhGIR1 and GhGIR2 can suppress the transcriptional activation of GhHD1. Our findings shed light on the intricate regulatory network involving GhHD1, GhGIR1 and GhGIR2 in the initiation and development of plant epidermal hairs in cotton.

Diethyl ether anaesthesia does not block local touch response in Arabidopsis thaliana

Plants can sense and respond to non-damaging mechanical stimulation such as touch, rain, or wind. Mechanical stimulation induces an increase of cytosolic calcium ([Ca2+]cyt), accumulation of phytohormones from the group of jasmonates (JAs) and activation of gene expression, which can be JAs-dependent or JAs-independent. Response to touch shares similar properties with reactions to stresses such as wounding or pathogen attack, and regular mechanical stimulation leads to changes in growth and development called thigmomorphogenesis. Previous studies showed that well-known seismonastic plants such as Venus flytrap (Dionaea muscipula) or sensitive plant (Mimosa pudica) lost their touch-induced motive responses during exposure to general volatile anaesthetic (GVA) diethyl ether. Here, we investigated the effect of diethyl ether anaesthesia on touch response in Arabidopsis thaliana. We monitored [Ca2+]cyt level, accumulation of JAs and expression of touch-responsive genes. Our results showed that none of the investigated responses was affected by diethyl ether. However, diethyl ether alone increased [Ca2+]cyt and modulated JAs-independent touch-responsive genes, thus partially activating touch response non-specifically. Together with our previous studies, we concluded that GVA diethyl ether cannot block the local rise of [Ca2+]cyt but only its systemic propagation dependent on GLUTAMATE LIKE RECEPTOR 3s (GLR3s) channels.

Suprathreshold Water Spray Stimulus Enhances Plant Defenses against Biotic Stresses in Tomato

Mechanical stimuli can affect plant growth, development, and defenses. The role of water spray stimulation, as a prevalent mechanical stimulus in the environment, in crop growth and defense cannot be overlooked. In this study, the effects of water spray on tomato plant growth and defense against the chewing herbivore Helicoverpa armigera and necrotrophic fungus Botrytis cinerea were investigated. Suprathreshold water spray stimulus (LS) was found to enhance tomato plant defenses against pests and pathogens while concurrently modifying plant architecture. The results of the phytohormone and chemical metabolite analysis revealed that LS improved the plant defense response via jasmonic acid (JA) signaling. LS significantly elevated the level of a pivotal defensive metabolite, chlorogenic acid, and reduced the emissions of volatile organic compounds (VOCs) from tomato plants, thereby defending against pest and pathogen attacks. The most obvious finding to emerge from this study is that LS enhances tomato plant defenses against biotic stresses, which will pave the way for further work on the application of mechanical stimuli for pest management.

Physiological roles of Arabidopsis MCA1 and MCA2 based on their dynamic expression patterns

Determining the mechanisms by which plants sense and respond to mechanical stimuli is crucial for unraveling the detailed processes by which plants grow and develop. Mechanosensitive (MS) channels, including MCA1 and its paralog MCA2 in Arabidopsis thaliana, may be essential for these processes. Although significant progress has been made in elucidating the physiological roles of MS channels, comprehensive insights into their expression dynamics remain elusive. Here, we summarize recent advancements and new data on the spatiotemporal expression patterns of the MCA1 and MCA2 genes, revealing their involvement in various developmental processes. Then, we describe findings from our study, in which the expression profiles of MCA1 and MCA2 were characterized in different plant organs at various developmental stages through histochemical analyses and semiquantitative RT‒PCR. Our findings revealed that MCA1 and MCA2 are preferentially expressed in young tissues, suggesting their pivotal roles in processes such as cell division, expansion, and mechanosensing. Lastly, we discuss the differential expression patterns observed in reproductive organs and trichomes, hinting at their specialized functions in response to mechanical cues. Overall, this review provides valuable insights into the dynamic expression patterns of MCA1 and MCA2, paving the way for future research on the precise roles of these genes in planta.

Genome sequence and cell biological toolbox of the highly regenerative, coenocytic green feather alga Bryopsis

Green feather algae (Bryopsidales) undergo a unique life cycle in which a single cell repeatedly executes nuclear division without cytokinesis, resulting in the development of a thallus (>100 mm) with characteristic morphology called coenocyte. Bryopsis is a representative coenocytic alga that has exceptionally high regeneration ability: extruded cytoplasm aggregates rapidly in seawater, leading to the formation of protoplasts. However, the genetic basis of the unique cell biology of Bryopsis remains poorly understood. Here, we present a high-quality assembly and annotation of the nuclear genome of Bryopsis sp. (90.7 Mbp, 27 contigs, N50 = 6.7 Mbp, 14 034 protein-coding genes). Comparative genomic analyses indicate that the genes encoding BPL-1/Bryohealin, the aggregation-promoting lectin, are heavily duplicated in Bryopsis, whereas homologous genes are absent in other ulvophyceans, suggesting the basis of regeneration capability of Bryopsis. Bryopsis sp. possesses >30 kinesins but only a single myosin, which differs from other green algae that have multiple types of myosin genes. Consistent with this biased motor toolkit, we observed that the bidirectional motility of chloroplasts in the cytoplasm was dependent on microtubules but not actin in Bryopsis sp. Most genes required for cytokinesis in plants are present in Bryopsis, including those in the SNARE or kinesin superfamily. Nevertheless, a kinesin crucial for cytokinesis initiation in plants (NACK/Kinesin-7II) is hardly expressed in the coenocytic part of the thallus, possibly underlying the lack of cytokinesis in this portion. The present genome sequence lays the foundation for experimental biology in coenocytic macroalgae.

CDC48 regulates immunity pathway in tobacco plants

The CDC48 protein, highly conserved in the living kingdom, is a player of the ubiquitin proteasome system and contributes to various cellular processes. In plants, CDC48 is involved in cell division, plant growth and, as recently highlighted in several reports, in plant immunity. In the present study, to further extend our knowledge about CDC48 functions in plants, we analysed the incidence of its overexpression on tobacco development and immune responses. CDC48 overexpression disrupted plant development and morphology, induced changes in plastoglobule appearance and exacerbated ROS production. In addition, levels of salicylic acid (SA) and glycosylated SA were higher in transgenic plants, both in the basal state and in response to cryptogein, a protein produced by the oomycete Phytophthora cryptogea triggering defence responses. The expression of defence genes, notably those coding for some pathogenesis-related (PR) proteins, was also exacerbated in the basal state in transgenic plant lines. Finally, tobacco plants overexpressing CDC48 did not develop necrosis in response to tobacco mosaic virus (TMV) infection, suggesting a role for CDC48 in virus resistance.

Is plant acoustic communication fact or fiction?

In recent years, the idea has flourished that plants emit and perceive sound and could even be capable of exchanging information through the acoustic channel. While research into plant bioacoustics is still in its infancy, with potentially fascinating discoveries awaiting ahead, here we show that the current knowledge is not conclusive. While plants do emit sounds under biotic and abiotic stresses such as drought, these sounds are high-pitched, of low intensity, and propagate only to a short distance. Most studies suggesting plant sensitivity to airborne sound actually concern the perception of substrate vibrations from the soil or plant part. In short, while low-frequency, high-intensity sounds emitted by a loudspeaker close to the plant seem to have tangible effects on various plant processes such as growth - a finding with possible applications in agriculture - it is unlikely that plants can perceive the sounds they produce, at least over long distances. So far, there is no evidence of plants communicating with each other via the acoustic channel.

Arabidopsis Transcriptomics Reveals the Role of Lipoxygenase2 (AtLOX2) in Wound-Induced Responses

In wounded Arabidopsis thaliana leaves, four 13S-lipoxygenases (AtLOX2, AtLOX3, AtLOX4, AtLOX6) act in a hierarchical manner to contribute to the jasmonate burst. This leads to defense responses with LOX2 playing an important role in plant resistance against caterpillar herb-ivory. In this study, we sought to characterize the impact of AtLOX2 on wound-induced phytohormonal and transcriptional responses to foliar mechanical damage using wildtype (WT) and lox2 mutant plants. Compared with WT, the lox2 mutant had higher constitutive levels of the phytohormone salicylic acid (SA) and enhanced expression of SA-responsive genes. This suggests that AtLOX2 may be involved in the biosynthesis of jasmonates that are involved in the antagonism of SA biosynthesis. As expected, the jasmonate burst in response to wounding was dampened in lox2 plants. Generally, 1 h after wounding, genes linked to jasmonate biosynthesis, jasmonate signaling attenuation and abscisic acid-responsive genes, which are primarily involved in wound sealing and healing, were differentially regulated between WT and lox2 mutants. Twelve h after wounding, WT plants showed stronger expression of genes associated with plant protection against insect herbivory. This study highlights the dynamic nature of jasmonate-responsive gene expression and the contribution of AtLOX2 to this pathway and plant resistance against insects.

Regulatory networks in plant responses to drought and cold stress

Drought and cold represent distinct types of abiotic stress, each initiating unique primary signaling pathways in response to dehydration and temperature changes, respectively. However, a convergence at the gene regulatory level is observed where a common set of stress-responsive genes is activated to mitigate the impacts of both stresses. In this review, we explore these intricate regulatory networks, illustrating how plants coordinate distinct stress signals into a collective transcriptional strategy. We delve into the molecular mechanisms of stress perception, stress signaling, and the activation of gene regulatory pathways, with a focus on insights gained from model species. By elucidating both the shared and distinct aspects of plant responses to drought and cold, we provide insight into the adaptive strategies of plants, paving the way for the engineering of stress-resilient crop varieties that can withstand a changing climate.

Carbon Nanomaterials for Plant Priming through Mechanostimulation: Emphasizing the Role of Shape

The use of nanomaterials to improve plant immunity for sustainable agriculture is gaining increasing attention; yet, the mechanisms involved remain unclear. In contrast to metal-based counterparts, carbon-based nanomaterials do not release components. Determining how these carbon-based nanomaterials strengthen the resistance of plants to diseases is essential as well as whether shape influences this process. Our study compared single-walled carbon nanotubes (SWNTs) and graphene oxide (GO) infiltration against the phytopathogen Pseudomonas syringae pv tomato DC3000. Compared with plants treated with GO, plants primed with SWNTs showed a 29% improvement in the pathogen resistance. Upon nanopriming, the plant displayed wound signaling with transcriptional regulation similar to that observed under brushing-induced mechanostimulation. Compared with GO, SWNTs penetrated more greatly into the leaf and improved transport, resulting in a heightened wound response; this effect resulted from the tubular structure of SWNTs, which differed from the planar form of GO. The shape effect was further demonstrated by wrapping SWNTs with bovine serum albumin, which masked the sharp edges of SWNTs and resulted in a significant decrease in the overall plant wound response. Finally, we clarified how the local wound response led to systemic immunity through increased calcium ion signaling in distant plant areas, which increased the antimicrobial efficacy. In summary, our systematic investigation established connections among carbon nanomaterial priming, mechanostimulation, and wound response, revealing recognition patterns in plant immunity. These findings promise to advance nanotechnology in sustainable agriculture by strengthening plant defenses, enhancing resilience, and reducing reliance on traditional chemicals.

The plant is neither dumb nor deaf; it talks and hears

Animals and insects communicate using vibrations that are frequently too low or too high for human ears to detect. Plants and trees can communicate and sense sound. Khait et al. used a dependable recording system to capture airborne sounds produced by stressed plants. In addition to allowing plants to communicate their stress, sound aids in plant defense, development, and resilience. It also serves as a warning that danger is approaching. Demey et al. and others discussed the audit examinations that were conducted to investigate sound discernment in plants at the atomic and biological levels. The biological significance of sound in plants, the morphophysiological response of plants to sound, and the airborne noises that plants make and can hear from a few meters away were all discussed.

Is the co-option of jasmonate signalling for botanical carnivory a universal trait for all carnivorous plants?

The carnivorous plants in the order Caryophyllales co-opted jasmonate signalling from plant defence to botanical carnivory. However, carnivorous plants have at least 11 independent origins, and here we ask whether jasmonate signalling has been co-opted repeatedly in different evolutionary lineages. We experimentally wounded and fed the carnivorous plants Sarracenia purpurea (order Ericales), Cephalotus follicularis (order Oxalidales), Drosophyllum lusitanicum (order Caryophyllales), and measured electrical signals, phytohormone tissue level, and digestive enzymes activity. Coronatine was added exogenously to confirm the role of jasmonates in the induction of digestive process. Immunodetection of aspartic protease and proteomic analysis of digestive fluid was also performed. We found that prey capture induced accumulation of endogenous jasmonates only in D. lusitanicum, in accordance with increased enzyme activity after insect prey or coronatine application. In C. follicularis, the enzyme activity was constitutive while in S. purpurea was regulated by multiple factors. Several classes of digestive enzymes were identified in the digestive fluid of D. lusitanicum. Although carnivorous plants from different evolutionary lineages use the same digestive enzymes, the mechanism of their regulation differs. All investigated genera use jasmonates for their ancient role, defence, but jasmonate signalling has been co-opted for botanical carnivory only in some of them.

The power of patterns: new insights into pattern-triggered immunity

The plant immune system features numerous immune receptors localized on the cell surface to monitor the apoplastic space for danger signals from a broad range of plant colonizers. Recent discoveries shed light on the enormous complexity of molecular signals sensed by these receptors, how they are generated and removed to maintain cellular homeostasis and immunocompetence, and how they are shaped by host-imposed evolutionary constraints. Fine-tuning receptor sensing mechanisms at the molecular, cellular and physiological level is critical for maintaining a robust but adaptive host barrier to commensal, pathogenic, and symbiotic colonizers alike. These receptors are at the core of any plant-colonizer interaction and hold great potential for engineering disease resistance and harnessing beneficial microbiota to keep crops healthy.

The dynamics of touch-responsive gene expression in cereals

Wind, rain, herbivores, obstacles, neighbouring plants, etc. provide important mechanical cues to steer plant growth and survival. Mechanostimulation to stimulate yield and stress resistance of crops is of significant research interest, yet a molecular understanding of transcriptional responses to touch is largely absent in cereals. To address this, we performed whole-genome transcriptomics following mechanostimulation of wheat, barley, and the recent genome-sequenced oat. The largest transcriptome changes occurred ±25 min after touching, with most of the genes being upregulated. While most genes returned to basal expression level by 1-2 h in oat, many genes retained high expression even 4 h post-treatment in barley and wheat. Functional categories such as transcription factors, kinases, phytohormones, and Ca2+ regulation were affected. In addition, cell wall-related genes involved in (hemi)cellulose, lignin, suberin, and callose biosynthesis were touch-responsive, providing molecular insight into mechanically induced changes in cell wall composition. Furthermore, several cereal-specific transcriptomic footprints were identified that were not observed in Arabidopsis. In oat and barley, we found evidence for systemic spreading of touch-induced signalling. Finally, we provide evidence that both the jasmonic acid-dependent and the jasmonic acid-independent pathways underlie touch-signalling in cereals, providing a detailed framework and marker genes for further study of (a)biotic stress responses in cereals.

Mechanosensation in leaf veins

Whether the plant vasculature has the capacity to sense touch is unknown. We developed a quantitative assay to investigate touch-response electrical signals in the leaves and veins of Arabidopsis thaliana. Mechanostimulated electrical signaling in leaves displayed strong diel regulation. Signals of full amplitude could be generated by repeated stimulation at the same site after approximately 90 minutes. However, the signals showed intermediate amplitudes when repeatedly stimulated in shorter timeframes. Using intracellular electrodes, we detected touch-response membrane depolarizations in the phloem. On the basis of this, we mutated multiple Arabidopsis H+-ATPase (AHA) genes expressed in companion cells. We found that aha1 aha3 double mutants attenuated touch-responses, and this was coupled to growth rate reduction. Moreover, propagating membrane depolarizations could be triggered by mechanostimulating the exposed primary vasculature of wild-type plants but not of aha1 aha3 mutants. Primary veins have autonomous mechanosensory properties which depend on P-type proton pumps.

Mechanodetection of neighbor plants elicits adaptive leaf movements through calcium dynamics

Plants detect their neighbors via various cues, including reflected light and touching of leaf tips, which elicit upward leaf movement (hyponasty). It is currently unknown how touch is sensed and how the signal is transferred from the leaf tip to the petiole base that drives hyponasty. Here, we show that touch-induced hyponasty involves a signal transduction pathway that is distinct from light-mediated hyponasty. We found that mechanostimulation of the leaf tip upon touching causes cytosolic calcium ([Ca2+]cyt induction in leaf tip trichomes that spreads towards the petiole. Both perturbation of the calcium response and the absence of trichomes reduce touch-induced hyponasty. Finally, using plant competition assays, we show that touch-induced hyponasty is adaptive in dense stands of Arabidopsis. We thus establish a novel, adaptive mechanism regulating hyponastic leaf movement in response to mechanostimulation by neighbors in dense vegetation.

Promoter characterization of a citrus linalool synthase gene mediating interspecific variation in resistance to a bacterial pathogen

BACKGROUND

Terpenoids play essential roles in plant defense against biotic stresses. In Citrus species, the monoterpene linalool mediates resistance against citrus canker disease caused by the gram-negative bacteria Xanthomonas citri subsp. citri (Xcc). Previous work had associated linalool contents with resistance; here we characterize transcriptional responses of linalool synthase genes.

RESULTS

Leaf linalool contents are highly variable among different Citrus species. "Dongfang" tangerine (Citrus reticulata), a species with high linalool levels was more resistant to Xcc than "Shatian" pummelo (C. grandis) which accumulates only small amounts of linalool. The coding sequences of the major leaf-expressed linalool synthase gene (STS4) are highly conserved, while transcript levels differ between the two Citrus species. To understand this apparent differential transcription, we isolated the promoters of STS4 from the two species, fused them to a GUS reporter and expressed them in Arabidopsis. This reporter system revealed that the two promoters have different constitutive activities, mainly in trichomes. Interestingly, both linalool contents and STS4 transcript levels are insensitive to Xcc infestation in citrus plants, but in these transgenic Arabidopsis plants, the promoters are activated by challenge of a bacterial pathogen Pseudomonas syringae, as well as wounding and external jasmonic acid treatment.

CONCLUSIONS

Our study reveals variation in linalool and resistance to Xcc in citrus plants, which may be mediated by different promoter activities of a terpene synthase gene in different Citrus species.

Genome-Wide Identification of the MPK Gene Family and Expression Analysis under Low-Temperature Stress in the Banana

Mitogen-activated protein kinases (MAPKs and MPKs) are important in the process of resisting plant stress. In this study, 21, 12, 18, 16, and 10 MPKs were identified from Musa acuminata, Musa balbisiana, Musa itinerans, Musa schizocarpa, and Musa textilis, respectively. These MPKs were divided into Group A, B, C, and D. Phylogenetic analysis revealed that this difference in number was due to the gene shrinkage of the Group B subfamily of Musa balbisiana and Musa textilis. KEGG annotations revealed that K14512, which is involved in plant hormone signal transduction and the plant-pathogen interaction, was the most conserved pathway of the MPKs. The results of promoter cis-acting element prediction and focTR4 (Fusarium oxysporum f. sp. cubense tropical race 4) transcriptome expression analysis preliminarily confirmed that MPKs were relevant to plant hormone and biotic stress, respectively. The expression of MPKs in Group A was significantly upregulated at 4 °C, and dramatically, the MPKs in the root were affected by low temperature. miR172, miR319, miR395, miR398, and miR399 may be the miRNAs that regulate MPKs during low-temperature stress, with miR172 being the most critical. miRNA prediction and qRT-PCR results indicated that miR172 may negatively regulate MPKs. Therefore, we deduced that MPKs might coordinate with miR172 to participate in the process of the resistance to low-temperature stress in the roots of the banana. This study will provide a theoretical basis for further analysis of the mechanism of MPKs under low-temperature stress of bananas, and this study could be applied to molecular breeding of bananas in the future.

Sound perception in plants: from ecological significance to molecular understanding

In addition to positive effects on plant growth and resilience, sound alerts plants of potential danger and aids in defense. Sound guides plants towards essential resources, like water, through phonotropic root growth. Sound also facilitates mutualistic interactions such as buzz pollination. Molecularly, sound induces Ca2+ signatures, K+ fluxes, and an increase in reactive oxygen species (ROS) levels in a mechanosensitive ion channel-dependent fashion. We review the two major open questions in the field of plant acoustics: (i) what is the ecological relevance of sound in plant life, and (ii) how is sound sensed and transduced to evoke a morphophysiological response? We highlight the clear need to combine the ecological and molecular perspectives for a more holistic approach to better understand plant behavior.

ABA spray on Arabidopsis seedlings increases mature plants vigor under optimal and water-deficit conditions partly by enhancing nitrogen assimilation

Here, we report the effects of a single abscisic acid (ABA) spray on Arabidopsis seedlings on growth, development, primary metabolism, and response to water-deficit stress in adult and next-generation plants. The experiments were performed over 2 years in two different laboratories in Iran and South Africa. In each experiment, fifty 7-day-old Arabidopsis seedlings were sprayed with 10 μM ABA, 1 mM H2 O2 , distilled water, or left without spraying as priming treatments. Water-deficit stress was applied on half of the plants in each treatment by withholding water 2 days after spraying. Results showed that a single ABA spray at the cotyledonary stage significantly increased plant biomass and delayed flowering. The ABA spray significantly enhanced drought tolerance so that the survival rate after rehydration was 100 and 33% in the first and the second experiments, respectively, for ABA-treated plants compared to 35 and 0% for water-sprayed plants. This enhanced drought tolerance was not inheritable. Metabolomics analyses suggested that ABA probably increases the antioxidant capacity of the plant cells and modulates tricarboxylic acid cycle toward enhanced nitrogen assimilation. Strikingly, we also observed that the early water spray decreases mature plant resilience under water-deficit conditions and cause substantial transient metabolomics perturbations.

Pavement cells distinguish touch from letting go

A micro-cantilever technique applied to individual leaf epidermis cells of intact Arabidopsis thaliana and Nicotiana tabacum synthesizing genetically encoded calcium indicators (R-GECO1 and GCaMP3) revealed that compressive forces induced local calcium peaks that preceded delayed, slowly moving calcium waves. Releasing the force evoked significantly faster calcium waves. Slow waves were also triggered by increased turgor and fast waves by turgor drops in pressure probe tests. The distinct characteristics of the wave types suggest different underlying mechanisms and an ability of plants to distinguish touch from letting go.

Engineering Climate-Resilient Rice Using a Nanobiostimulant-Based "Stress Training" Strategy

Under a changing climate, cultivating climate-resilient crops will be critical to maintaining food security. Here, we propose the application of reactive oxygen species (ROS)-generating nanoparticles as nanobiostimulants to trigger stress/immune responses and subsequently increase the stress resilience of plants. We established three regimens of silver nanoparticles (AgNPs)-based "stress training": seed training (ST), leaf training (LT), and combined seed and leaf training (SLT). Trained rice seedlings were then exposed to either rice blast fungus (Magnaporthe oryzae) or chilling stress (10 °C). The results show that all "stress training" regimes, particularly SLT, significantly enhanced the resistance of rice against the fungal pathogen (lesion size reduced by 82% relative to untrained control). SLT also significantly enhanced rice tolerance to cold stress. The mechanisms for the enhanced resilience were investigated with metabolomics and transcriptomics, which show that "stress training" induced considerable metabolic and transcriptional reprogramming in rice leaves. AgNPs boosted ROS-activated stress signaling pathways by oxidative post-translational modifications of stress-related kinases, hormones, and transcriptional factors (TFs). These signaling pathways subsequently modulated the expression of defense genes, including specialized metabolites (SMs) biosynthesis genes, cell membrane lipid metabolism genes, and pathogen-plant interaction genes. Importantly, results showed that the "stress memory" can be transferred transgenerationally, conferring offspring seeds with improved seed germination and seedling vigor. This may provide an epigenetic breeding strategy to fortify stress resilience of crops. This nanobiostimulant-based stress training strategy will increase yield vigor against a changing climate and will contribute to sustainable agriculture by reducing agrochemical use.

Engineering Themes in Plant Forms and Functions

Living structures constantly interact with the biotic and abiotic environment by sensing and responding via specialized functional parts. In other words, biological bodies embody highly functional machines and actuators. What are the signatures of engineering mechanisms in biology? In this review, we connect the dots in the literature to seek engineering principles in plant structures. We identify three thematic motifs-bilayer actuator, slender-bodied functional surface, and self-similarity-and provide an overview of their structure-function relationships. Unlike human-engineered machines and actuators, biological counterparts may appear suboptimal in design, loosely complying with physical theories or engineering principles. We postulate what factors may influence the evolution of functional morphology and anatomy to dissect and comprehend better the why behind the biological forms.

Water Cannot Activate Traps of the Carnivorous Sundew Plant Drosera capensis: On the Trail of Darwin's 150-Years-Old Mystery

In his famous book Insectivorous plants, Charles Darwin observed that the bending response of tentacles in the carnivorous sundew plant Drosera rotundifolia was not triggered by a drop of water, but rather the application of many dissolved chemicals or mechanical stimulation. In this study, we tried to reveal this 150-years-old mystery using methods not available in his time. We measured electrical signals, phytohormone tissue level, enzyme activities and an abundance of digestive enzyme aspartic protease droserasin in response to different stimuli (water drop, ammonia, mechanostimulation, chitin, insect prey) in Cape sundew (Drosera capensis). Drops of water induced the lowest number of action potentials (APs) in the tentacle head, and accumulation of jasmonates in the trap was not significantly different from control plants. On the other hand, all other stimuli significantly increased jasmonate accumulation; the highest was found after the application of insect prey. Drops of water also did not induce proteolytic activity and an abundance of aspartic protease droserasin in contrast to other stimuli. We found that the tentacles of sundew plants are not responsive to water drops due to an inactive jasmonic acid signalling pathway, important for the induction of significant digestive enzyme activities.

Mechanical wounding impacts the growth versus defense balance in tomato (Solanum lycopersicum)

Plants have evolved elaborate surveillance systems that allow them to perceive the attack by pests and pathogens and activate the appropriate defenses. Mechanical stimulation, such as mechanical wounding, represents one of the most reliable cues for the perception of potential herbivore aggressors. Here we demonstrate that mechanical wounding disturbs the growth versus defense balance in tomato, a physiological condition where growth reduction arises as a pleiotropic consequence of the activation of defense responses (or vice-versa). We observed that multiple lesions on tomato leaves impairs the formation of several growth-related traits, including shoot elongation, leaf expansion and time for flowering, while concomitantly activating the production of defense responses such as trichome formation and the upregulation of defense-related genes. We also provide genetic evidence that this wound-induced growth repression is possibly a consequence of tomato plants sensing the injuries via jasmonates (JAs), a class of plant hormones known to be master regulators of the plant growth versus defense balance. Besides providing a mechanistic explanation on how the growth and defense balance is shifted when plants are subjected to a specific type of mechanical stimulus, our results may offer a practical explanation for why tomato productivity is so negatively impacted by herbivore attack.

Plant ecoacoustics: a sensory ecology approach

Many interactions of plants with the environment have an acoustic component, including the actions of herbivores and pollinators, wind and rain. Although plants have long been tested for their response to single tones or music, their response to naturally occurring sources of sound and vibration is barely explored. We argue that progress in understanding the ecology and evolution of plant acoustic sensing requires testing how plants respond to acoustic features of their natural environments, using methods that precisely measure and reproduce the stimulus experienced by the plant.

The Course of Mechanical Stress: Types, Perception, and Plant Response

Mechanical stimuli, together with the corresponding plant perception mechanisms and the finely tuned thigmomorphogenetic response, has been of scientific and practical interest since the mid-17th century. As an emerging field, there are many challenges in the research of mechanical stress. Indeed, studies on different plant species (annual/perennial) and plant organs (stem/root) using different approaches (field, wet lab, and in silico/computational) have delivered insufficient findings that frequently impede the practical application of the acquired knowledge. Accordingly, the current work distils existing mechanical stress knowledge by bringing in side-by-side the research conducted on both stem and roots. First, the various types of mechanical stress encountered by plants are defined. Second, plant perception mechanisms are outlined. Finally, the different strategies employed by the plant stem and roots to counteract the perceived mechanical stresses are summarized, depicting the corresponding morphological, phytohormonal, and molecular characteristics. The comprehensive literature on both perennial (woody) and annual plants was reviewed, considering the potential benefits and drawbacks of the two plant types, which allowed us to highlight current gaps in knowledge as areas of interest for future research.

Cryptochromes and UBP12/13 deubiquitinases antagonistically regulate DNA damage response in Arabidopsis

Cryptochromes (CRYs) are evolutionarily conserved blue-light receptors that evolved from bacterial photolyases that repair damaged DNA. Today, CRYs have lost their ability to repair damaged DNA; however, prior reports suggest that human CRYs can respond to DNA damage. Currently, the role of CRYs in the DNA damage response (DDR) is lacking, especially in plants. Therefore, we evaluated the role of plant CRYs in DDR along with UBP12/13 deubiquitinases, which interact with and regulate the CRY2 protein. We found that cry1cry2 was hypersensitive, while ubp12ubp13 was hyposensitive to UVC-induced DNA damage. Elevated UV-induced cyclobutane pyrimidine dimers (CPDs) and the lack of DNA repair protein RAD51 accumulation in cry1cry2 plants indicate that CRYs are required for DNA repair. On the contrary, CPD levels diminished and RAD51 protein levels elevated in plants lacking UBP12 and UBP13, indicating their role in DDR repression. Temporal transcriptomic analysis revealed that DDR-induced transcriptional responses were subdued in cry1cry2, but elevated in ubp12ubp13 compared to WT. Through transcriptional modeling of the time-course transcriptome, we found that genes quickly induced by UVC (15 min) are targets of CAMTA 1-3 transcription factors, which we found are required for DDR. This transcriptional regulation seems, however, diminished in the cry1cry2 mutant, indicating that CAMTAs are required for CRY2-mediated DDR. Furthermore, we observed enhanced CRY2-UBP13 interaction and formation of CRY2 nuclear speckles under UVC, suggesting that UVC activates CRY2 similarly to blue light. Together, our data reveal the temporal dynamics of the transcriptional events underlying UVC-induced genotoxicity and expand our knowledge of the role of CRY and UBP12/13 in DDR.

Pathogen-derived mechanical cues potentiate the spatio-temporal implementation of plant defense

BACKGROUND

The ongoing adaptation of plants to their environment is the basis for their survival. In this adaptation, mechanoperception of gravity and local curvature plays a role of prime importance in finely regulating growth and ensuring a dynamic balance preventing buckling. However, the abiotic environment is not the exclusive cause of mechanical stimuli. Biotic interactions between plants and microorganisms also involve physical forces and potentially mechanoperception. Whether pathogens trigger mechanoperception in plants and the impact of mechanotransduction on the regulation of plant defense remains however elusive.

RESULTS

Here, we found that the perception of pathogen-derived mechanical cues by microtubules potentiates the spatio-temporal implementation of plant immunity to fungus. By combining biomechanics modeling and image analysis of the post-invasion stage, we reveal that fungal colonization releases plant cell wall-born tension locally, causing fluctuations of tensile stress in walls of healthy cells distant from the infection site. In healthy cells, the pathogen-derived mechanical cues guide the reorganization of mechanosensing cortical microtubules (CMT). The anisotropic patterning of CMTs is required for the regulation of immunity-related genes in distal cells. The CMT-mediated mechanotransduction of pathogen-derived cues increases Arabidopsis disease resistance by 40% when challenged with the fungus Sclerotinia sclerotiorum.

CONCLUSIONS

CMT anisotropic patterning triggered by pathogen-derived mechanical cues activates the implementation of early plant defense in cells distant from the infection site. We propose that the mechano-signaling triggered immunity (MTI) complements the molecular signals involved in pattern and effector-triggered immunity.

Mechanosensing, from forces to structures

Sessile plants evolve diverse structures in response to complex environmental cues. These factors, in essence, involve mechanical stimuli, which must be sensed and coordinated properly by the plants to ensure effective growth and development. While we have accumulated substantial knowledge on plant mechanobiology, how plants translate mechanical information into three-dimensional structures is still an open question. In this review, we summarize our current understanding of plant mechanosensing at different levels, particularly using Arabidopsis as a model plant system. We also attempt to abstract the mechanosensing process and link the gaps from mechanical cues to the generation of complex plant structures. Here we review the recent advancements on mechanical response and transduction in plant morphogenesis, and we also raise several questions that interest us in different sections.

In vivo Imaging Enables Understanding of Seamless Plant Defense Responses to Wounding and Pathogen Attack

Plants are exposed to varied biotic stresses, including sequential or simultaneous attack by insects and pathogens. To overcome these complex stresses, plants must perceive each of the stresses, then integrate and relay the information throughout the plant body and eventually activate local and systemic resistance responses. Previous molecular genetic studies identified jasmonic acid and salicylic acid as key plant hormones of wound and immune responses. These hormones, combined with their antagonistic interaction, play critical roles in the initiation and regulation of defense responses against insects and pathogens. Aside from molecular and genetic information, the latest in vivo imaging technology has revealed that plant defense responses are regulated spatially and temporally. In this review, we summarize the current knowledge of local and systemic defense responses against wounding and diseases with a focus on past and recent advances in imaging technologies. We discuss how imaging-based multiparametric analysis has improved our understanding of the spatiotemporal regulation of dynamic plant stress responses. We also emphasize the importance of compiling the knowledge generated from individual studies on plant wounding and immune responses for a more seamless understanding of plant defense responses in the natural environment.