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Kofuji R.,Kanazawa University | Hasebe M.,Japan National Institute for Basic Biology
Current Opinion in Plant Biology | Year: 2014

Stem cells self-renew and produce cells that differentiate to become the source of the plant body. The moss Physcomitrella patens forms eight types of stem cells during its life cycle and serves as a useful model in which to explore the evolution of such cells. The common ancestor of land plants is inferred to have been haplontic and to have formed stem cells only in the gametophyte generation. A single stem cell would have been maintained in the ancestral gametophyte meristem, as occurs in extant basal land plants. During land plant evolution, stem cells diverged in the gametophyte generation to form different types of body parts, including the protonema and rhizoid filaments, leafy-shoot and thalloid gametophores, and gametangia formed in moss. A simplex meristem with a single stem cell was acquired in the sporophyte generation early in land plant evolution. Subsequently, sporophyte stem cells became multiple in the meristem and were elaborated further in seed plant lineages, although the evolutionary origin of niche cells, which maintain stem cells is unknown. Comparisons of gene regulatory networks are expected to give insights into the general mechanisms of stem cell formation and maintenance in land plants and provide information about their evolution. P. patens develops at least seven types of simplex meristem in the gametophyte and at least one type in the sporophyte generation and is a good material for regulatory network comparisons. In this review, we summarize recently revealed molecular mechanisms of stem cell initiation and maintenance in the moss. © 2013 Elsevier Ltd. Source

Matsubayashi Y.,Japan National Institute for Basic Biology
Annual Review of Plant Biology | Year: 2014

Cell-to-cell signaling is essential for many processes in plant growth and development, including coordination of cellular responses to developmental and environmental cues. Cumulative studies have demonstrated that peptide signaling plays a greater-than-anticipated role in such intercellular communication. Some peptides act as signals during plant growth and development, whereas others are involved in defense responses or symbiosis. Peptides secreted as signals often undergo posttranslational modification and proteolytic processing to generate smaller peptides composed of approximately 10 amino acid residues. Such posttranslationally modified small-peptide signals constitute one of the largest groups of secreted peptide signals in plants. The location of the modification group incorporated into the peptides by specific modification enzymes and the peptide chain length defined by the processing enzymes are critical for biological function and receptor interaction. This review covers 20 years of research into posttranslationally modified small-peptide signals in plants. Copyright © 2014 by Annual Reviews. Source

Minagawa J.,Japan National Institute for Basic Biology
Frontiers in Plant Science | Year: 2013

Plants and algae have acquired the ability to acclimate to ever-changing environments in order to survive. During photosynthesis, light energy is converted by several membrane protein supercomplexes into electrochemical energy, which is eventually used to assimilate CO2. The efficiency of photosynthesis is modulated by many environmental factors such as quality and quantity of light, temperature, drought, and CO2 concentration, among others. Accumulating evidence indicates that photosynthetic supercomplexes undergo supramolecular reorganization within a short time frame during acclimation to an environmental change. This reorganization includes state transitions that balance the excitation of photosystem I and II by shuttling peripheral antenna proteins between the two, thermal energy dissipation that occurs at energy-quenching sites within the light-harvesting antenna generated for negative feedback when excess light is absorbed, and cyclic electron flow that is facilitated between photosystem I and the cytochrome bf complex when cells demand more ATP and/or need to activate energy dissipation. This review will highlight the recent findings regarding these environmental acclimation events in model organisms with particular attention to the unicellular green alga C. reinhardtii and with reference to the vascular plant A. thaliana, which offers a glimpse into the dynamic behavior of photosynthetic machineries in nature. © 2013 Minagawa. Source

Guillette Jr. L.J.,Medical University of South Carolina | Iguchi T.,Japan National Institute for Basic Biology
Science | Year: 2012

Exposure to pesticides and other chemicals can have complex long-term health effects. Source

Minagawa J.,Japan National Institute for Basic Biology
Biochimica et Biophysica Acta - Bioenergetics | Year: 2011

In oxygen-evolving photosynthesis, the two photosystems-photosystem I and photosystem II-function in parallel, and their excitation levels must be balanced to maintain an optimal photosynthetic rate under natural light conditions. State transitions in photosynthetic organisms balance the absorbed light energy between the two photosystems in a short time by relocating light-harvesting complex II proteins. For over a decade, the understanding of the physiological consequences, the molecular mechanism, and its regulation has increased considerably. After providing an overview of the general understanding of state transitions, this review focuses on the recent advances of the molecular aspects of state transitions with a particular emphasis on the studies using the green alga Chlamydomonas reinhardtii. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts. © 2010 Elsevier B.V. All rights reserved. Source

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