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Root primordia (brown spots) as seen on the butt of a freshly cut pineapple crown intended for vegetative reproduction. Root primordia.JPG
Root primordia (brown spots) as seen on the butt of a freshly cut pineapple crown intended for vegetative reproduction.

A primordium ( /prˈmɔːrdiəm/ ; plural: primordia; synonym: anlage) in embryology, is an organ or tissue in its earliest recognizable stage of development. [1] Cells of the primordium are called primordial cells. A primordium is the simplest set of cells capable of triggering growth of the would-be organ and the initial foundation from which an organ is able to grow. In flowering plants, a floral primordium gives rise to a flower.

Embryology branch of biology studying prenatal biology

Embryology is the branch of biology that studies the prenatal development of gametes, fertilization, and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology.

Organ (anatomy) Collection go tissues

Organs are groups of tissues with similar functions. Plant and animal life relies on many organs that coexist in organ systems.

Cell (biology) The basic structural and functional unit of all organisms; the smallest unit of life.

The cell is the basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life. Cells are often called the "building blocks of life". The study of cells is called cell biology or cellular biology.


Although it is a frequently used term in plant biology, the word is used in describing the biology of all multicellular organisms (for example: a tooth primordium in animals, a leaf primordium in plants or a sporophore primordium in fungi. [2] )

Sporocarp (fungi) multicellular structure on which spore-producing structures (basidia or asci) are borne; part of the sexual phase of a fungal life cycle, with the rest of the life cycle being characterized by vegetative mycelial growth and asexual spore production

In fungi, the sporocarp is a multicellular structure on which spore-producing structures, such as basidia or asci, are born. The fruitbody is part of the sexual phase of a fungal life cycle, while the rest of the life cycle is characterized by vegetative mycelial growth and asexual spore production.

Primordium development in plants

Two primordia
New primordium forming
Generative spiral.png
Generative spiral
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Leaf migration

Plants produce both leaf and flower primordia cells at the shoot apical meristem (SAM). Primordium development in plants is critical to the proper positioning and development of plant organs and cells. The process of primordium development is intricately regulated by a set of genes that affect the positioning, growth and differentiation of the primordium. Genes including STM (SHOOT MERISTEMLESS) and CUC (CUP-SHAPED COTYLEDON) are involved in defining the borders of the newly formed primordium. [3]

The plant hormone auxin has also been implicated in this process, with the new primordium being initiated at the placenta, where the auxin concentration is highest. [3] There is still much to understand about the genes involved in primordium development.

Auxin class of plant hormones

Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by the Dutch biologist Frits Warmolt Went. Kenneth V. Thimann was the first to isolate one of these phytohormones and determine its chemical structure as indole-3-acetic acid (IAA). Went and Thimann co-authored a book on plant hormones, Phytohormones, in 1937.

Leaf primordia are groups of cells that will form into new leaves. These new leaves form near the top of the shoot and resemble knobby outgrowths or inverted cones. [4] Flower primordia are the little buds we see at the end of stems, from which flowers will develop. Flower primordia start off as a crease or indentation and later form into a bulge. This bulging is caused by slower and less anisotropic, or directionally dependent, growth.

Anisotropy property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy

Anisotropy, is the property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physical or mechanical properties

See also

Morphogenesis is the biological process that causes an organism to develop its shape. It is one of three fundamental aspects of developmental biology along with the control of cell growth and cellular differentiation, unified in evolutionary developmental biology (evo-devo).

Primordial phallus the clitoris of a female or the penis in the male, particularly during fetal development of the urinary and reproductive organs, before sexual differentiation is evident

In embryology, the primordial phallus refers to the clitoris of a female or the penis in the male, particularly during fetal development of the urinary and reproductive organs, before sexual differentiation is evident. This is also the case for the immature male analog, the immature glans penis.

Related Research Articles

Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism.

Root part of plant

In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. Roots can also be aerial or aerating, that is, growing up above the ground or especially above water. Furthermore, a stem normally occurring below ground is not exceptional either. Therefore, the root is best defined as the non-leaf, non-nodes bearing parts of the plant's body. However, important internal structural differences between stems and roots exist.

Inflorescence Term used in botany to describe a cluster of flowers

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed. The modifications can involve the length and the nature of the internodes and the phyllotaxis, as well as variations in the proportions, compressions, swellings, adnations, connations and reduction of main and secondary axes. Inflorescence can also be defined as the reproductive portion of a plant that bears a cluster of flowers in a specific pattern.

Apical dominance

In botany, apical dominance is the phenomenon whereby the main, central stem of the plant is dominant over other side stems; on a branch the main stem of the branch is further dominant over its own side branchlets.

Vascular cambium part of a plant

The vascular cambium is the main growth layer in the stems and roots of many plants, specifically in dicots such as buttercups and oak trees, and gymnosperms such as pine trees. It produces xylem on the inside and phloem on the outside. In herbaceous plants, it occurs in the vascular bundles which are often arranged like beads on a necklace forming an interrupted ring inside the stem. In woody plants, it forms a continuous ring and grows new wood on the inside.

Meristem tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place

A meristem is the tissue in most plants containing undifferentiated cells, found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of a plant and are responsible for growth.

Plant hormone class of chemical compounds

Plant hormones are signal molecules produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of growth and development, from embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and through to reproductive development. Unlike in animals each plant cell is capable of producing hormones. The term 'phytohormone' was coined by Went and Thimann and used in the title of their book in 1937.

Phyllotaxis Arrangement of leaves on the stem of a plant

In botany, phyllotaxis or phyllotaxy is the arrangement of leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature.

Cytokinin class of chemical compounds

Cytokinins (CK) are a class of plant growth substances (phytohormones) that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence. Folke Skoog discovered their effects using coconut milk in the 1940s at the University of Wisconsin–Madison.

Organogenesis is the phase of embryonic development that starts at the end of gastrulation and continues until birth. During organogenesis, the three germ layers formed from gastrulation: the ectoderm, endoderm, and mesoderm form the internal organs of the organism.

Gravitropism growth in reaction to gravity

Gravitropism is a coordinated process of differential growth by a plant or fungus in response to gravity pulling on it. Gravity can be either "artificial gravity" or natural gravity. It is a general feature of all higher and many lower plants as well as other organisms. Charles Darwin was one of the first to scientifically document that roots show positive gravitropism and stems show negative gravitropism. That is, roots grow in the direction of gravitational pull and stems grow in the opposite direction. This behavior can be easily demonstrated with any potted plant. When laid onto its side, the growing parts of the stem begin to display negative gravitropism, growing upwards. Hebaverns (non-woody) stems are capable of a small degree of actual bending, but most of the redirected movement occurs as a consequence of root or stem growth outside.

ABC model of flower development

The ABC model of flower development is a scientific model of the process by which flowering plants produce a pattern of gene expression in meristems that leads to the appearance of an organ oriented towards sexual reproduction, a flower. There are three physiological developments that must occur in order for this to take place: firstly, the plant must pass from sexual immaturity into a sexually mature state ; secondly, the transformation of the apical meristem’s function from a vegetative meristem into a floral meristem or inflorescence; and finally the growth of the flower’s individual organs. The latter phase has been modelled using the ABC model, which aims to describe the biological basis of the process from the perspective of molecular and developmental genetics.

Lateral roots extend horizontally from the primary root (radicle) and serve to anchor the plant securely into the soil. This branching of roots also contributes to water uptake, and facilitates the extraction of nutrients required for the growth and development of the plant.

Polar auxin transport is the regulated transport of the plant hormone auxin in plants. It is an active process, the hormone is transported in cell-to-cell manner and one of the main features of the transport is its directionality (polarity). The polar auxin transport has coordinative function in plant development; the following spatial auxin distribution underpins most of plant growth responses to its environment and plant growth and developmental changes in general.

Plant morphology part of botany

Plant morphology or phytomorphology is the study of the physical form and external structure of plants. This is usually considered distinct from plant anatomy, which is the study of the internal structure of plants, especially at the microscopic level. Plant morphology is useful in the visual identification of plants.

Evolutionary developmental biology (evo-devo) is the study of developmental programs and patterns from an evolutionary perspective. It seeks to understand the various influences shaping the form and nature of life on the planet. Evo-devo arose as a separate branch of science rather recently. An early sign of this occurred in 1999.

Plants produce new tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant always has embryonic tissues. By contrast, an animal embryo will very early produce all of the body parts that it will ever have in its life. When the animal is born, it has all its body parts and from that point will only grow larger and more mature.

Lateral shoot

Commonly called a branch. It develops from axillary buds on the stem's surface, extending laterally from the plant's stem.

Plant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. Plant tissue culture is widely used to produce clones of a plant in a method known as micropropagation. Different techniques in plant tissue culture may offer certain advantages over traditional methods of propagation, including:


  2. Noble, R.; T. R. Fermor; S. Lincoln; A. Dobrovin-Pennington; C. Evered; A. Mead; R. Li (2003). "Primordia Initiation of Mushroom (Agaricus bisporus) Strains on Axenic Casing Materials". Mycologia. 95 (4): 620. doi:10.2307/3761938. ISSN   0027-5514.
  3. 1 2 Heisler, Marcus G.; Carolyn Ohno; Pradeep Das; Patrick Sieber; Gonehal V. Reddy; Jeff A. Long; Elliot M. Meyerowitz (2005). "Patterns of Auxin Transport and Gene Expression during Primordium Development Revealed by Live Imaging of the Arabidopsis Inflorescence Meristem". Current Biology. 15 (21): 1899–1911. doi:10.1016/j.cub.2005.09.052. ISSN   0960-9822. PMID   16271866.