Roadmap for the next decade of plant programmed cell death research.

Programmed cell death (PCD) is fundamentally important for plant development, abiotic stress responses and immunity, but our understanding of its regulation remains fragmented. Building a stronger research community is required to accelerate progress in this area through knowledge exchange and constructive debate. In this Viewpoint, we aim to initiate a collective effort to integrate data across a diverse set of experimental models to facilitate characterisation of the fundamental mechanisms underlying plant PCD and ultimately aid the development of a new plant cell death classification system in the future.

Growth control of Marchantia polymorpha gemmae using nonthermal plasma irradiation.

Several studies have documented that treatment by cold atmospheric pressure plasma (CAPP) on plants foster seed germination and growth in recent years. However, the molecular processes that underlie the action of CAPP on the seeds and plants remain mostly enigmatic. We here introduce gemmae of Marchantia polymorpha, a basal liverwort, as a novel model plant material suitable for CAPP research.

Rapid Propagation of Ca2+ Waves and Electrical Signals in the Liverwort Marchantia polymorpha.

In response to both biotic and abiotic stresses, vascular plants transmit long-distance Ca2+ and electrical signals from localized stress sites to distant tissues through their vasculature. Various models have been proposed for the mechanisms underlying the long-distance signaling, primarily centered around the presence of vascular bundles. We here demonstrate that the non-vascular liverwort Marchantia polymorpha possesses a mechanism for propagating Ca2+ waves and electrical signals in response to wounding.

Enhanced Ca binding to EF-hands through phosphorylation of conserved serine residues activates MpRBOHB and chitin-triggered ROS production.

NADPH oxidases/RBOHs catalyze apoplastic ROS production and act as key signaling nodes, integrating multiple signal transduction pathways regulating plant development and stress responses. Although RBOHs have been suggested to be activated by Ca binding and phosphorylation by various protein kinases, a mechanism linking Ca binding and phosphorylation in the activity regulation remained elusive. Chitin-triggered ROS production required cytosolic Ca elevation and Ca binding to MpRBOHB in a liverwort Marchantia polymorpha.

Diversity and characteristics of plant immunity-activating bacteria from Brassicaceae plants.

Background: Microorganisms that activate plant immune responses are useful for application as biocontrol agents in agriculture to minimize crop losses. The present study was conducted to identify and characterize plant immunity-activating microorganisms in Brassicaceae plants.

Results: A total of 25 bacterial strains were isolated from the interior of a Brassicaceae plant, Raphanus sativus var.

Regulation of PaRBOH1-mediated ROS production in Norway spruce by Ca binding and phosphorylation.

Plant respiratory burst oxidase homologs (RBOHs) are plasma membrane-localized NADPH oxidases that generate superoxide anion radicals, which then dismutate to HO, into the apoplast using cytoplasmic NADPH as an electron donor. is the most highly expressed gene in developing xylem as well as in a lignin-forming cell culture of Norway spruce ( L. Karst.

Detection of NO introduced in plasma-irradiated dry lettuce seeds using liquid chromatography-electrospray ionization quantum mass spectrometry (LC-ESI QMS).

Discharge plasma irradiates seeds with reactive oxygen and nitrogen species (RONS). However, RONS introduced in seeds by plasma irradiation have not been successfully detected thus far. This study provides experimental evidence that nitrate ion NO is introduced in lettuce seeds as RONS upon irradiation with atmospheric-pressure air dielectric barrier discharge plasma.

Quantitative Analysis for ROS-Producing Activity and Regulation of Plant NADPH Oxidases in HEK293T Cells.

Reactive oxygen species (ROS) produced by plant NADPH oxidases, respiratory burst oxidase homologs (RBOHs), play key roles in biotic and abiotic stress responses and development in plants. While properly controlled amounts of ROS function as signaling molecules, excessive accumulation of ROS can cause undesirable side effects due to their ability to oxidize DNA, lipids, and proteins. To limit the damaging consequences of unrestricted ROS accumulation, RBOH activity is tightly controlled by post-translational modifications (PTMs) and protein-protein interactions.

Interactions between pH, reactive species, and cells in plasma-activated water can remove algae.

Lightning strikes cause nitrogen to dissolve in water and form reactive nitrogen and oxygen species, which form natural fertilizers that can be absorbed through plant roots. Such processes during rainstorm events can be simulated by applying plasma to a solution. Plasma-activated water (PAW) has great potential as a source of various dissolved reactive chemical species.

Ultrafine bubble water mitigates plant growth in damaged soil.

Water containing ultrafine/nano bubbles (UFBs) promoted the growth of tomato (Solanum lycopersicum) in soil damaged by cultivation of tomato in the previous year or bacterial wilt-like disease and also promoted the growth of lettuce (Lactuca sativa) when lettuce was grown in the soil damaged by repeated cultivation of lettuce. On the other hand, UFB supply did not affect plant growth in rock wool or healthy soil. Furthermore, the growth of lettuce was not affected by UFB water treatment in the soil damaged by the cultivation of tomato.

Impact of Mammalian Two-Pore Channel Inhibitors on Long-Distance Electrical Signals in the Characean Macroalga and the Early Terrestrial Liverwort .

Inhibitors of human two-pore channels (TPC1 and TPC2), i.e., verapamil, tetrandrine, and NED-19, are promising medicines used in treatment of serious diseases.

An efficient direct screening system for microorganisms that activate plant immune responses based on plant-microbe interactions using cultured plant cells.

Microorganisms that activate plant immune responses have attracted considerable attention as potential biocontrol agents in agriculture because they could reduce agrochemical use. However, conventional methods to screen for such microorganisms using whole plants and pathogens are generally laborious and time consuming. Here, we describe a general strategy using cultured plant cells to identify microorganisms that activate plant defense responses based on plant-microbe interactions.

Multicolour chemical imaging of plant tissues with hyperspectral stimulated Raman scattering microscopy.

Recent development of stimulated Raman scattering (SRS) microscopy allows for label-free biological imaging with chemical specificity based on molecular-vibrational signatures. In particular, hyperspectral SRS imaging can acquire a molecular-vibrational spectrum at each pixel, allowing us not only to investigate the spectral difference of various biological molecules but also to discriminate different constituents based on their spectral difference. However, the number of constituents discriminated in previous label-free SRS imaging was limited to four because of the subtleness of spectral difference.

Cell Cycle-Dependence of Autophagic Activity and Inhibition of Autophagosome Formation at M Phase in Tobacco BY-2 Cells.

Autophagy is ubiquitous in eukaryotic cells and plays an essential role in stress adaptation and development by recycling nutrients and maintaining cellular homeostasis. However, the dynamics and regulatory mechanisms of autophagosome formation during the cell cycle in plant cells remain poorly elucidated. We here analyzed the number of autophagosomes during cell cycle progression in synchronized tobacco BY-2 cells expressing YFP-NtATG8a as a marker for the autophagosomes.

Ultrastructural characterization of microlipophagy induced by the interaction of vacuoles and lipid bodies around generative and sperm cells in Arabidopsis pollen.

During pollen maturation, various organelles change their distribution and function during development as male gametophytes. We analyzed the behavior of lipid bodies and vacuoles involved in lipophagy in Arabidopsis pollen using serial section SEM and conventional TEM. At the bicellular pollen stage, lipid bodies in the vegetative cells lined up at the surface of the generative cell.

Impact of Autophagy on Gene Expression and Tapetal Programmed Cell Death During Pollen Development in Rice.

Autophagy has recently been shown to be required for tapetal programmed cell death (PCD) and pollen maturation in rice. A transcriptional regulatory network is also known to play a key role in the progression of tapetal PCD. However, the relationship between the gene regulatory network and autophagy in rice anther development is mostly unknown.

Essential roles of autophagy in metabolic regulation in endosperm development during rice seed maturation.

Autophagy plays crucial roles in the recycling of metabolites, and is involved in many developmental processes. Rice mutants defective in autophagy are male sterile due to immature pollens, indicating its critical role in pollen development. However, physiological roles of autophagy during seed maturation had remained unknown.

Monitoring autophagy in rice tapetal cells during pollen maturation.

We have previously shown that autophagy is required for post meiotic anther development including programmed cell death-mediated degradation of the tapetum and pollen maturation in rice. However, the spatiotemporal dynamics of autophagy in the tapetum remain poorly understood. We here established an in vivo imaging technique to analyze the dynamics of autophagy in rice tapetum cells by expressing green fluorescent protein-tagged AtATG8, a marker for autophagosomes.

Differential tetraspanin genes expression and subcellular localization during mutualistic interactions in Phaseolus vulgaris.

Arbuscular mycorrhizal fungi and rhizobia association with plants are two of the most successful plant-microbe associations that allow the assimilation of P and N by plants, respectively. These mutualistic interactions require a molecular dialogue, i.e.

Development of a Near-infrared Laser-induced Surface Deformation Microscope and Its Application to the Dynamic Viscoelastic Measurements of Single Living Plant Cell Surfaces.

A near-infrared laser-induced surface deformation (NIR-LISD) microscope is developed and is applied to the dynamic viscoelastic measurements of the surface of a living plant cell. In the microscope, the deformation of the surface is induced by an NIR laser beam, and then the change in intensity of the probe beam reflected from the surface reflects its viscoelasticity. The application of the NIR laser beam has a great advantage for the prevention of damage to the plant cell compared to the irradiation of a visible laser beam in LISD measurements.