STEMIN transcription factor drives selective chromatin remodeling for gene activation within a relaxed chromatin during reprogramming in the moss Physcomitrium patens.

Land plants exhibit remarkable cellular plasticity, readily reprogramming differentiated cells into stem cells in response to internal and external stimuli. While chromatin remodeling is crucial for cellular reprogramming, its interplay with gene expression during reprogramming into stem cells remains elusive. In the moss Physcomitrium patens, wounding induces reprogramming of leaf cells facing wounded cells to change into chloronema apical stem cells through the activation of the AP2/ERF transcription factor STEMIN.

Physcomitrium LATERAL SUPPRESSOR genes promote formative cell divisions to produce germ cell lineages in both male and female gametangia.

The evolution of green plants from aquatic to terrestrial environments is thought to have been facilitated by the acquisition of gametangia, specialized multicellular organs housing gametes. Antheridia and archegonia, responsible for producing and protecting sperm and egg cells, undergo formative cell divisions to produce a cell to differentiate into germ cell lineages and the other cell to give rise to surrounding structures. However, the genes governing this process remain unidentified.

Infrared laser-induced gene expression in single cells characterized by quantitative imaging in Physcomitrium patens.

A spatiotemporal understanding of gene function requires the precise control of gene expression in each cell. Here, we use an infrared laser-evoked gene operator (IR-LEGO) system to induce gene expression at the single-cell level in the moss Physcomitrium patens by heating a living cell with an IR laser and thereby activating the heat shock response. We identify the laser irradiation conditions that provide higher inducibility with lower invasiveness by changing the laser power and irradiation duration.

An ABCB transporter regulates anisotropic cell expansion via cuticle deposition in the moss Physcomitrium patens.

Anisotropic cell expansion is crucial for the morphogenesis of land plants, as cell migration is restricted by the rigid cell wall. The anisotropy of cell expansion is regulated by mechanisms acting on the deposition or modification of cell wall polysaccharides. Besides the polysaccharide components in the cell wall, a layer of hydrophobic cuticle covers the outer cell wall and is subjected to tensile stress that mechanically restricts cell expansion.

mutation alleviates DNA damage in an mutant sensitive to excess boron.

Excess boron (B) is toxic to plants and thereby causes DNA damage and cell death in root meristems. However, the underlying mechanisms which link boron and DNA damage remain unclear. It has been reported that the mutant of the 26S proteasome is sensitive to excess boron, resulting in more frequent cell death in root meristem and reduced root elongation.

PECT1, a rate-limiting enzyme in phosphatidylethanolamine biosynthesis, is involved in the regulation of stomatal movement in Arabidopsis.

An Arabidopsis mutant displaying impaired stomatal responses to CO , cdi4, was isolated by a leaf thermal imaging screening. The mutated gene PECT1 encodes CTP:phosphorylethanolamine cytidylyltransferase. The cdi4 exhibited a decrease in phosphatidylethanolamine levels and a defect in light-induced stomatal opening as well as low-CO -induced stomatal opening.

Novel inhibitors of microtubule organization and phragmoplast formation in diverse plant species.

Cell division is essential for development and involves spindle assembly, chromosome separation, and cytokinesis. In plants, the genetic tools for controlling the events in cell division at the desired time are limited and ineffective owing to high redundancy and lethality. Therefore, we screened cell division-affecting compounds in zygotes, whose cell division is traceable without time-lapse observations.

GRAS transcription factors regulate cell division planes in moss overriding the default rule.

Plant cells are surrounded by a cell wall and do not migrate, which makes the regulation of cell division orientation crucial for development. Regulatory mechanisms controlling cell division orientation may have contributed to the evolution of body organization in land plants. The GRAS family of transcription factors was transferred horizontally from soil bacteria to an algal common ancestor of land plants.

The genome of Lyophyllum shimeji provides insight into the initial evolution of ectomycorrhizal fungal genomes.

Mycorrhizae are one of the most fundamental symbioses between plants and fungi, with ectomycorrhizae being the most widespread in boreal forest ecosystems. Ectomycorrhizal fungi are hypothesized to have evolved convergently from saprotrophic ancestors in several fungal clades, especially members of the subdivision Agaricomycotina. Studies on fungal genomes have identified several typical characteristics of mycorrhizal fungi, such as genome size expansion and decreases in plant cell-wall degrading enzymes (PCWDEs).

Calcium-mediated rapid movements defend against herbivorous insects in Mimosa pudica.

Animals possess specialized systems, e.g., neuromuscular systems, to sense the environment and then move their bodies quickly in response.

A PSTAIRE-type cyclin-dependent kinase controls light responses in land plants.

Light is a critical signal perceived by plants to adapt their growth rate and direction. Although many signaling components have been studied, how plants respond to constantly fluctuating light remains underexplored. Here, we showed that in the moss () , the PSTAIRE-type cyclin-dependent kinase PpCDKA is dispensable for growth.

Topoisomerase 1α is required for synchronous spermatogenesis in Physcomitrium patens.

DNA topoisomerase 1 (TOP1) plays general roles in DNA replication and transcription by regulating DNA topology in land plants and metazoans. TOP1 is also involved in specific developmental events; however, whether TOP1 plays a conserved developmental role among multicellular organisms is unknown. Here, we investigated the developmental roles of TOP1 in the moss Physcomitrium (Physcomitrella) patens with gene targeting, microscopy, 3D image segmentation and crossing experiments.

Low-invasive 5D visualization of mitotic progression by two-photon excitation spinning-disk confocal microscopy.

Non-linear microscopy, such as multi-photon excitation microscopy, offers spatial localities of excitations, thereby achieving 3D cross-sectional imaging with low phototoxicity even in thick biological specimens. We had developed a multi-point scanning two-photon excitation microscopy system using a spinning-disk confocal scanning unit. However, its severe color cross-talk has precluded multi-color simultaneous imaging.

Molecular mechanisms of reprogramming of differentiated cells into stem cells in the moss Physcomitrium patens.

Plant and animal stem cells can self-renew and give rise to differentiated cells to form tissues or organs. Unlike differentiated cells in animals, those in land plants can be readily reprogrammed into stem cells, reflecting the plasticity of plant cell identity. The moss Physcomitrium patens (synonym: Physcomitrella patens) is highly regenerable, and its leaf cells can be reprogrammed into stem cells in response to wounding or by transient DNA damage without wounding.

Overexpression of enhances wound-induced somatic reprogramming in .

Animal and plant somatic cells have the capacity to switch states or reprogram into stem cells to adapt during stress and injury. This ability to deal with stochastic changes or reprogramming of somatic cells also needs macroautophagy/autophagy. Here, we expand on this notion and provide a primary example of how overexpression of in the moss enhances the ability to reprogram somatic cells into stem cells when subjected to severe wounding.

Chloroplast acquisition without the gene transfer in kleptoplastic sea slugs, .

Some sea slugs sequester chloroplasts from algal food in their intestinal cells and photosynthesize for months. This phenomenon, kleptoplasty, poses a question of how the chloroplast retains its activity without the algal nucleus. There have been debates on the horizontal transfer of algal genes to the animal nucleus.

A discordance of seasonally covarying cues uncovers misregulated phenotypes in the heterophyllous pitcher plant .

Organisms withstand normal ranges of environmental fluctuations by producing a set of phenotypes genetically programmed as a reaction norm; however, extreme conditions can expose a misregulation of phenotypes called a hidden reaction norm. Although an environment consists of multiple factors, how combinations of these factors influence a reaction norm is not well understood. To elucidate the combinatorial effects of environmental factors, we studied the leaf shape plasticity of the carnivorous pitcher plant .

Rapid movements in plants.

Plant movements are generally slow, but some plant species have evolved the ability to move very rapidly at speeds comparable to those of animals. Whereas movement in animals relies on the contraction machinery of muscles, many plant movements use turgor pressure as the primary driving force together with secondarily generated elastic forces. The movement of stomata is the best-characterized model system for studying turgor-driven movement, and many gene products responsible for this movement, especially those related to ion transport, have been identified.

Ethylene signaling mediates host invasion by parasitic plants.

Parasitic plants form a specialized organ, a haustorium, to invade host tissues and acquire water and nutrients. To understand the molecular mechanism of haustorium development, we performed a forward genetics screening to isolate mutants exhibiting haustorial defects in the model parasitic plant We isolated two mutants that show prolonged and sometimes aberrant meristematic activity in the haustorium apex, resulting in severe defects on host invasion. Whole-genome sequencing revealed that the two mutants respectively have point mutations in homologs of () and (), signaling components in response to the gaseous phytohormone ethylene.

Corrigendum: Networking and Specificity-Changing DNA Methyltransferases in .

[This corrects the article DOI: 10.3389/fmicb.2020.

Calcium dynamics during trap closure visualized in transgenic Venus flytrap.

The leaves of the carnivorous plant Venus flytrap, Dionaea muscipula (Dionaea) close rapidly to capture insect prey. The closure response usually requires two successive mechanical stimuli to sensory hairs on the leaf blade within approximately 30 s (refs. ).

DNA damage triggers reprogramming of differentiated cells into stem cells in Physcomitrella.

DNA damage can result from intrinsic cellular processes and from exposure to stressful environments. Such DNA damage generally threatens genome integrity and cell viability. However, here we report that the transient induction of DNA strand breaks (single-strand breaks, double-strand breaks or both) in the moss Physcomitrella patens can trigger the reprogramming of differentiated leaf cells into stem cells without cell death.