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Apoplast
The ''apoplast '' is the extracellular space outside of plant cell membranes, especially the fluid-filled cell walls of adjacent cells where water and dissolved material can flow and diffuse freely. Fluid and material flows occurring in any extracellular space are called ''apoplastic'' flow or apoplastic transport. The apoplastic pathway is one route by which water and solutes are transported and distributed to different places through tissues and organs, contrasting with the symplastic pathway. To prevent uncontrolled leakage to unwanted places, in certain areas there are barriers to the apoplastic flow: in roots the Casparian strip has this function Outside the plant epidermis of aerial plant parts is a protective waxy film called plant cuticle that protects against drying out, but also waterproofs the plant against external water. The apoplast is important for all the plant's interaction with its environment: The main carbon source (carbon dioxide) needs to be solubil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Casparian Strip
The Casparian strip is a band-like thickening in the center of the root endodermis (radial and tangential walls of endodermal cells) of vascular plants (Pteridophytes and Spermatophytes). The composition of the region is mainly suberin, lignin and some structural proteins, which are capable of reducing the diffusive apoplastic flow of water and solutes into the stele, its width varies between species. In the root, the Casparian strip is embedded within the cell wall of endodermal cells in the non-growing region of the root behind the root tip.Taiz, L., Zeiger, Eduardo, Møller, Ian Max, & Murphy, Angus. (2015). Plant physiology and development (Sixth ed.). Here, the Casparian strip serves as a boundary layer separating the apoplast of the cortex from the apoplast of the vascular tissue thereby blocking diffusion of material between the two. This separation forces water and solutes to pass through the plasma membrane via a symplastic route in order to cross the endodermis layer. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symplast
The symplast of a plant is the region enclosed by the cell membranes, within which water and solutes can diffuse freely. By contrast the apoplast is any fluid-filled space within the cell wall and extracellular space. Neighbouring cells are interconnected by microscopic channels known as plasmodesmata that traverse the cell walls. These channels, allow the flow of small molecules such as sugars, amino acids, and ions between cells (from the inner part of one cell to the inner part of the next cell). Larger molecules, including transcription factors and plant viruses, can also be transported through with the help of actin structures. The symplast allows direct cytoplasm-to-cytoplasm flow of water and other nutrients along concentration gradients. In particular, symplastic flow is used in the root systems to bring in nutrients from soil. Nutrient solutes move in this way through three skin layers of the roots: from cells of the ''epidermis'', the outermost layer, through the ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuolar Pathway
The symplast of a plant is the region enclosed by the cell membranes, within which water and solutes can diffuse freely. By contrast the apoplast is any fluid-filled space within the cell wall and extracellular space. Neighbouring cells are interconnected by microscopic channels known as plasmodesmata that traverse the cell walls. These channels, allow the flow of small molecules such as sugars, amino acids, and ions between cells (from the inner part of one cell to the inner part of the next cell). Larger molecules, including transcription factors and plant viruses, can also be transported through with the help of actin structures. The symplast allows direct cytoplasm-to-cytoplasm flow of water and other nutrients along concentration gradients. In particular, symplastic flow is used in the root systems to bring in nutrients from soil. Nutrient solutes move in this way through three skin layers of the roots: from cells of the ''epidermis'', the outermost layer, through the ''c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symplast
The symplast of a plant is the region enclosed by the cell membranes, within which water and solutes can diffuse freely. By contrast the apoplast is any fluid-filled space within the cell wall and extracellular space. Neighbouring cells are interconnected by microscopic channels known as plasmodesmata that traverse the cell walls. These channels, allow the flow of small molecules such as sugars, amino acids, and ions between cells (from the inner part of one cell to the inner part of the next cell). Larger molecules, including transcription factors and plant viruses, can also be transported through with the help of actin structures. The symplast allows direct cytoplasm-to-cytoplasm flow of water and other nutrients along concentration gradients. In particular, symplastic flow is used in the root systems to bring in nutrients from soil. Nutrient solutes move in this way through three skin layers of the roots: from cells of the ''epidermis'', the outermost layer, through the ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transpiration Stream
In plants, the transpiration stream is the uninterrupted stream of water and solutes which is taken up by the roots and transported via the xylem to the leaves where it evaporates into the air/ apoplast-interface of the substomatal cavity. It is driven by capillary action and in some plants by root pressure. The main driving factor is the difference in water potential between the soil and the substomatal cavity caused by transpiration. Transpiration Transpiration can be regulated through stomatal closure or opening. It allows for plants to efficiently transport water up to their highest body organs, regulate the temperature of stem and leaves and it allows for upstream signaling such as the dispersal of an apoplastic alkalinization during local oxidative stress. Summary of water movement: #Soil #Roots and Root Hair #Xylem #Leaves #Stomata #Air Osmosis The water passes from the soil to the root by osmosis. The long and thin shape of root hairs maximizes surface area so tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Wall
A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, and functions as a selective barrier. Another vital role of the cell wall is to help the cell withstand osmotic pressure and mechanical stress. While absent in many eukaryotes, including animals, cell walls are prevalent in other organisms such as fungi, algae and plants, and are commonly found in most Prokaryote, prokaryotes, with the exception of Mollicutes, mollicute bacteria. The composition of cell walls varies across taxonomic groups, species, cell type, and the cell cycle. In Embryophyte, land plants, the primary cell wall comprises Polysaccharide, polysaccharides like cellulose, hemicelluloses, and pectin. Often, other Polymer, polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae exhibit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endophytes
An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; however, most of the endophyte/plant relationships are not well understood. Some endophytes may enhance host growth and nutrient acquisition and improve the plant's ability to tolerate abiotic stresses, such as drought, and decrease biotic stresses by enhancing plant resistance to insects, pathogens and herbivores. Although endophytic bacteria and fungi are frequently studied, endophytic archaea are increasingly being considered for their role in plant growth promotion as part of the core microbiome of a plant. History Endophytes were first described by the German botanist Johann Heinrich Friedrich Link in 1809. They were thought to be plant parasitic fungi and they were later termed as "microzymas" by the French scientist Béchamp. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xylem
Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts of the plants such as stems and leaves, but it also transports plant nutrition, nutrients. The word ''xylem'' is derived from the Ancient Greek word (), meaning "wood"; the best-known wood organism is plants, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858. Structure The most distinctive xylem cell (biology), cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called ''vessels''. Wood also contains two other type of cells: Ground tissue#Parenchyma, parenchyma and ground tissue#Fibres, fibers. Xylem can be found: * in vascular bundles, present in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Systemic Acquired Resistance
Systemic acquired resistance (SAR) is a "whole-plant" resistance response that occurs following an earlier localized exposure to a pathogen. SAR is analogous to the innate immune system found in animals, and although there are many shared aspects between the two systems, it is thought to be a result of convergent evolution. The systemic acquired resistance response is dependent on the plant hormone, salicylic acid. Discovery While, it has been recognized since at least the 1930s that plants have some kind of induced immunity to pathogens, the modern study of systemic acquired resistance began in the 1980s when the invention of new tools allowed scientists to probe the molecular mechanisms of SAR. A number of 'marker genes' were characterized in the 1980s and 1990s which are strongly induced as part of the SAR response. These pathogenesis-related proteins (PR) belong to a number of different protein families. While there is substantial overlap, the spectrum of PR proteins expresse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonoplast
A vacuole () is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain cases they may contain solids which have been engulfed. Vacuoles are formed by the fusion of multiple membrane vesicles and are effectively just larger forms of these. The organelle has no basic shape or size; its structure varies according to the requirements of the cell. Discovery Antonie van Leeuwenhoek described the plant vacuole in 1676. Contractile vacuoles ("stars") were first observed by Spallanzani (1776) in protozoa, although mistaken for respiratory organs. Dujardin (1841) named these "stars" as ''vacuoles''. In 1842, Schleiden applied the term for plant cells, to distinguish the structure with cell sap from the rest of the protoplasm. In 1885, de Vries named the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernst Münch
Ernst Münch (26 November 1876 – 9 October 1946) was a German plant physiologist who proposed the pressure flow hypothesis in 1930. He studied in Aschaffenburg, and then in Munich Munich is the capital and most populous city of Bavaria, Germany. As of 30 November 2024, its population was 1,604,384, making it the third-largest city in Germany after Berlin and Hamburg. Munich is the largest city in Germany that is no ... with Robert Hartig. He worked in a number of fields including forest pathology, resin production, and fungi. He is best known for the phloem pressure flow hypothesis. Works * ''Untersuchungen über Immunität und Krankheitsempfänglichkeit der Holzpflanzen'', Dissertation, Ludwigsburg 1909 (doctorate thesis) * ''Die Stoffbewegungen in der Pflanze'', Jena 1930 * ''Beiträge zur Forstpflanzenzüchtung. Versuche einer Auslesezüchtung durch Einzelstamm-Absaaten bei Fichte. Weitere Beiträge zur Forstpflanzenzüchtung'' us dem wissenschaftlichen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
