ENDODERMIS & POLARITY

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1 ENDODERMIS & POLARITY Niloufar Pirayesh PCDU SEMINAR

(in and out of vascular system) Store starch Saturated with Hydrophobic

2 2 What is Endodermis? It helps with Regulate the movement of water ions and hormones. (in and out of vascular system) Store starch Saturated with Hydrophobic substances (Casparian Strip) Involved in perception of gravity Protect the plant against toxins moving into vascular system

3 3 What is casparian strip? Angiosperms In plant anatomy the casparian strip is band of cell wall material Deposited on the radial and transverse walls of endoermis. Ferns

4 4 Endodermal cells of the primary root develops in 2 stages: 1. Primary 2. Secondary Characterized by deposition of specific cell wall material This helps to: 1. form the barrier controlling radial uptake and loss of water and solvents between the vascular cylinder and peripheral tissues 2. barrier against potential pathogen invasion

5 Formation of the root endodermis: periclinal (in botany) Parallel http://www.ext.colostate.edu/mg/gardennotes/images/132-3.

In periclinal cell division the plane of division is parallel to the surface of the plant body. http://www.mun.

html The periclinal division, generates 4 Concentric angles to the surface of an organ or Rings of cells that each differentiat

5 5 Formation of the root endodermis: periclinal (in botany) Parallel to the surface of an organ or part. In periclinal cell division the plane of division is parallel to the surface of the plant body. The periclinal division, generates 4 Concentric angles to the surface of an organ or Rings of cells that each differentiat into a part. In anticlinal cell division the Different cell: plane of division is at right angles to 1.Lateral root cap the surface of the plant body. 2. Epidermis 3.Cortex 4.Endodemris Anticlinal: (in botany) At right Asymmetric (although an unequal distribution of components before or during division has not been demonstrated.)

Formation of the root endodermis: 6 After germination, the cortex and endodermis ground tissue organization is maintained by the stereotypical cell division of

6 Formation of the root endodermis: 6 After germination, the cortex and endodermis ground tissue organization is maintained by the stereotypical cell division of the cortex/endodermis initials (CEIs) and their immediate daughter cells (CEIDs) cortex/endodermis initials (CEIs) cortex/endodermis immediate daughter cells (CEIDs)

Formation of the root endodermis: 7 An unidentified signal that possibly emanates from the adjacent quiescent center (QC) maintains the pluripotent

The CEID divides periclinally to give rise to two daughter cells, each of which differentiates into either an endodermis or cortex cell, depending

7 Formation of the root endodermis: 7 An unidentified signal that possibly emanates from the adjacent quiescent center (QC) maintains the pluripotent stem cell capacity of the CEI. The CEID divides periclinally to give rise to two daughter cells, each of which differentiates into either an endodermis or cortex cell, depending on its position relative to the stele. The CEI divides transversely to give rise to a CEID at the distal position from the QC, whereas the daughter cell abutting the QC maintains its CEI identity.

8 Formation of the root endodermis: Two GRAS-type transcription factors, SHORT-ROOT (SHR) and SCARECROW (SCR), play key roles in the formation and maintenance of the root endodermis. SHR proteins are produced in the stele and move to the adjacent cell layer, which is composed of the QC, CEI, CEID and endodermis In the CEID, the SHR-SCR complex activates the transcription of a cell cycle regulator, Cyclin D6;1, which in turn is required for the periclinal division of CEID 8 Loss of SCR protein results in increased SHR movement and ectopic periclinal divisions, indicating that SCR captures SHR protein in the nucleus of the recipient cell layer, and thereby inhibits further cell-cell movement of SHR.

9 9 Endodermal differentiations: *Entering the elongation zone: Where cells start to grow up: transit-amplifying zone: is the place which cells of a certain cell fate make more cells of their own type. After formation of CEID a transversal division will take place v15/n5/fig_tab/nrm3790_f1.html

CS: Casparian Strip CW: Cell Wall IS: Intercellular Space M:Mitochondria Pd: Plastid V: Vacuole

10 10 Casparian strip Casparian strip is situated in the center of the transversal and anticlinal walls. CS: Casparian Strip CW: Cell Wall IS: Intercellular Space M:Mitochondria Pd: Plastid V: Vacuole Endodermal cell layers with casparian strip in radial walls. Drawing by Robert Caspary An overview of an endodermal cell in a transversal cut With the casparian strip visible in the radial walls.

11 11 Nondigested vascular elements. Net like structure of the casparian strip (after complete digestion with cell wall degrading enzymes ) Fish net like structure that surrounds the xylem tissue of the stele. In complete cell wall digestion only the resistant walls of the xylem and the Casparian strips are left intact. In digestions, the casparian strip forms a supracellular network between endodermal cells.

12 12 Localization of Casparian strip: Electron micrograph of casparian strip in Arabidopsis. CS: Casparian Strip PM: Plasma Membtrane CSD: both Casparian sides of Strip the Casparian membrane Domain strip CW: Cell Wall PMS: Plasmolysis-generated Space Gold particles are visible at the plasma membranes on The primary cell wall, including the middle lamella, appears homogenous and slightly thickened. The plasma membrane adheres to the cell wall Immunogold localization of CASP1-GFP

13 Secondary stage Endodermis & formation of Passage cells: Secondary stage of differentiation is is characterized by the formation of suberin lamellae all around endodermis surface, i.e., not restricted to the narrow band of the Casparian strip 13 Patchy appearance of suberin lamellae (yellow)

It has been shown that suberin is inefficient in providing Then what propose does it serve? an effective diffusion barrier in young endodermal cells 1.

14 It has been shown that suberin is inefficient in providing Then what propose does it serve? an effective diffusion barrier in young endodermal cells 1.Direct uptake into the endodermis is blocked by the presence of suberin lamellae between the plasma membranes and primary cell walls of endodermal cells, forcing the symplastic passage of nutrients Efficient way to protect cells against Pathogens such as bacteria and fungi

15 15 Tertiary stage & Death of the Endodermis: The inner preclinical and The radial wall appear thickened. Outer periclinal wall remains thin.

16 Key words: Anticlinal division: (In botany) At right angles to the surface of an organ or part. In anticlinal cell division the plane of division is at right angles to the surface of the plant body. Apoplastic : Within a plant, the apoplast is the free diffusional space outside the plasma membrane. It is interrupted by the Casparian strip in roots, by air spaces between plant cells and by the plant cuticle. Casparian strip: Is a band of cell wall material deposited on the radial and transverse walls of the endodermis, and is chemically different from the rest of the cell wall. Endodermis: The central inner most layer of cortex in some land plants. Periclinal division: (in botany) Parallel to the surface of an organ or part. In periclinal cell division the plane of division is parallel to the surface of the plant body. symplastic : The symplastic of a plant is the inner side of the plasma membrane in which water (and low-molecular-weight solutes) can freely diffuse. Xylem : Xylem is one of the two types of transport tissue in vascular plants, phloem being the other. The basic function of xylem is to transport water, but it also transports some nutrients.

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Roots and Soil Chapter 5

Roots and Soil Chapter 5 Plant Organs Plant organs are groups of several types of tissues that together perform a particular function. Vegetative organs roots, stems, leaves make and use food, absorb water