Current insights into the development, structure, and chemistry of the endodermis and exodermis of roots

2003 ◽  
Vol 81 (5) ◽  
pp. 405-421 ◽  
Author(s):  
Fengshan Ma ◽  
Carol A Peterson
Keyword(s):  
Passive Movement ◽  
Root Tip ◽  
Main Function ◽  
Casparian Bands ◽  
Fluorescence And Electron Microscopy ◽  
Suberin Lamellae ◽  
Apoplastic Barriers ◽  
Molecular Aspects ◽  
Development Structure ◽  
Future Work

The endodermis and exodermis are the inner- and outermost cortical layers, respectively, of a root. Both are characterized by the development of Casparian bands in their anticlinal walls. Endodermal Casparian bands normally appear within 10 mm of the root tip, while exodermal Casparian bands are typically deposited farther from the tip. All Casparian bands contain the biopolymers lignin and suberin, allowing the endodermis and exodermis to serve as filtration sites for the passive movement of ions between the soil solution and the stele. Later in development, suberin lamellae are frequently deposited as secondary walls, which will reduce the transmembrane transport of ions and water. In some species, tertiary walls are also formed; their main function is postulated to be mechanical support of the root. Recent research with fluorescence and electron microscopy has revealed some important details of development and structure of these wall modifications. Further, chemical analyses of enzymatically isolated wall modifications have shown the chemical basis for the endodermis and exodermis as apoplastic barriers. Studies of Arabidopsis at the molecular level are shedding light on the genetic control of endodermal morphogenesis. In contrast, molecular aspects of exodermal development are totally unknown. Future work will benefit from a combined molecular and biochemical approach to the endodermis and exodermis.Key words: Casparian band, endodermis, exodermis, lignin, molecular biology, suberin, suberin lamella, tertiary wall.

Development of Casparian bands and suberin lamellae in the endodermis of onion roots

1992 ◽  
Vol 70 (11) ◽  
pp. 2233-2237 ◽  
Author(s):  
Alban D. Barnabas ◽  
Carol A. Peterson
Keyword(s):  
Allium Cepa ◽  
Small Region ◽  
Root Tip ◽  
Radial Wall ◽  
Casparian Bands ◽  
Suberin Lamellae ◽  
Casparian Band ◽  
Apoplastic Barrier ◽  
Endodermal Cells ◽  
Suberin Lamella

The endodermal Casparian band in onion (Allium cepa L.) roots is first evident 10 mm from the apex. It occupies a small region (20–30%) in the middle of the radial wall for a distance of 70 mm from the apex. However, with the development of suberin lamellae in most cells at greater distances from the root tip, the band expands symmetrically through the wall until, at 80 mm from the root tip, it fills the entire radial wall. Passage cells overlying some xylem poles have a delayed development of suberin lamellae, and in these cells the Casparian bands remain narrow. The sensitive stain, Fluorol yellow 088, detects precursors of the suberin lamellae in the outer tangential walls of the endodermal cells. The presence of complete lamellae is indicated by Sudan red 7B staining and resistance to acid digestion. Growth of the Casparian band during suberin lamella development may play a role in maintaining the apoplastic barrier in this layer by enlarging the contact area between the band and the lamellae. Key words: Casparian band, endodermis, suberin lamella, Allium cepa.

scholarly journals Suberized transport barriers in plant roots: the effect of silicon

2020 ◽  
Vol 71 (21) ◽  
pp. 6799-6806 ◽  
Author(s):  
Tino Kreszies ◽  
Victoria Kreszies ◽  
Falko Ly ◽  
Priya Dharshini Thangamani ◽  
Nandhini Shellakkutti ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Barley Root ◽  
Plant Roots ◽  
Growth And Survival ◽  
Casparian Bands ◽  
Suberin Lamellae ◽  
Transport Barriers ◽  
Seminal Roots ◽  
Apoplastic Barriers ◽  
Promote Plant Growth

Abstract Plant roots are the major organs that take up water and dissolved nutrients. It has been widely shown that apoplastic barriers such as Casparian bands and suberin lamellae in the endo- and exodermis of roots have an important effect on regulating radial water and nutrient transport. Furthermore, it has been described that silicon can promote plant growth and survival under different conditions. However, the potential effects of silicon on the formation and structure of apoplastic barriers are controversial. A delayed as well as an enhanced suberization of root apoplastic barriers with silicon has been described in the literature. Here we review the effects of silicon on the formation of suberized apoplastic barriers in roots, and present results of the effect of silicon treatment on the formation of endodermal suberized barriers on barley seminal roots under control conditions and when exposed to osmotic stress. Chemical analysis confirmed that osmotic stress enhanced barley root suberization. While a supplementation with silicon in both, control conditions and osmotic stress, did not enhanced barley root suberization. These results suggest that enhanced stress tolerance of plants after silicon treatment is due to other responses.

Deposition of Casparian bands and suberin lamellae in the exodermis and endodermis of young corn and onion roots

1986 ◽  
Vol 64 (9) ◽  
pp. 1873-1878 ◽  
Author(s):  
C. J. Perumalla ◽  
Carol A. Peterson
Keyword(s):  
Growth Rate ◽  
Age And Growth ◽  
Root Tip ◽  
Casparian Bands ◽  
Corn Roots ◽  
Suberin Lamellae ◽  
Casparian Band ◽  
The Individual ◽  
Suberin Lamella ◽  
Individual Root

The Casparian band of the exodermis of corn and onion roots matures further from the root tip than its counterpart in the endodermis. A complete suberin lamella in the exodermal cells usually develops about 10 mm proximal to the exodermal Casparian band. The distance between the exodermal Casparian band and suberin lamella in the endodermis was usually much greater than in the exodermis. Both the exodermal Casparian band and suberin lamella matured closer to the tip in onion than in corn roots. The distance from the root tip at which the exodermal Casparian band matured increased with root age during the 5-day period studied in corn grown in hydroponics and vermiculite, and onion grown in hydroponics. This difference was most pronounced in corn, in which the Casparian band matured 20 mm from the root tip when the root was 20 mm long but matured 120 mm from the tip 4 days later when the root was 170 mm long. When the growth rate of corn roots was drastically inhibited by adding polyethylene glycol to the hydroponic medium, the exodermal Casparian band and suberin lamellae were present within 10 mm of the root tip. The position in the root at which the exodermis matures is thus highly variable and can depend on the plant species, and the age and growth rate of the individual root.

scholarly journals Morphological structures and histochemistry of roots and shoots in Myricaria laxiflora (Tamaricaceae)

2021 ◽  
Vol 16 (1) ◽  
pp. 455-463
Author(s):  
Linbao Li ◽  
Di Wu ◽  
Qiaoling Zhen ◽  
Jun Zhang ◽  
Liwen Qiu ◽  
...  
Keyword(s):  
Riparian Zone ◽  
Epifluorescence Microscopy ◽  
Mature Stage ◽  
Three Gorges ◽  
Casparian Bands ◽  
The Three Gorges ◽  
Suberin Lamellae ◽  
Terrestrial Environments ◽  
Apoplastic Barriers ◽  
Young Stage

Abstract Myricaria laxiflora (Tamaricaceae) is an endangered plant that is narrowly distributed in the riparian zone of the Three Gorges, along the Yangtze River, China. Using bright-field and epifluorescence microscopy, we investigated the anatomical and histochemical features that allow this species to tolerate both submerged and terrestrial environments. The adventitious roots of Myr. laxiflora had an endodermis with Casparian bands and suberin lamellae; the cortex and hypodermal walls had lignified thickenings in the primary structure. In the mature roots, the secondary structure had cork. The apoplastic barriers in stems consisted of a lignified fiber ring and a cuticle at the young stage and cork at the mature stage. The leaves had two layers of palisade tissue, a hyaline epidermis, sunken stomata, and a thick, papillose cuticle. Aerenchyma presented in the roots and shoots. Several Myr. laxiflora structures, including aerenchyma, apoplastic barriers in the roots and shoots, were adapted to riparian habitats. In addition, shoots had typical xerophyte features, including small leaves, bilayer palisade tissues, sunken stomata, a thick, papillose cuticle, and a hyaline epidermis. Thus, our study identified several anatomical features that may permit Myr. laxiflora to thrive in the riparian zone of the Three Gorges, China.

Development of cell wall modifications in the endodermis and exodermis of Allium cepa roots

2001 ◽  
Vol 79 (5) ◽  
pp. 621-634 ◽  
Author(s):  
Fengshan Ma ◽  
Carol A Peterson
Keyword(s):  
Electron Microscopy ◽  
Allium Cepa ◽  
Plasma Membranes ◽  
Casparian Bands ◽  
Transmission Electron ◽  
Allium Cepa L ◽  
Suberin Lamellae ◽  
Pit Field ◽  
Casparian Band ◽  
Suberin Lamella

The cytological events of wall modification in the endodermis and exodermis of Allium cepa L. roots were examined with fluorescence and transmission electron microscopy. In the endodermis, Casparian bands, suberin lamellae, and tertiary walls developed in succession. At the site of the future Casparian band, the plasma membrane was bound to the wall before deposition of detectable hydrophobic components in the radial wall. Suberin lamellae were deposited on the inner faces of the primary walls, first along the outer tangential walls and then the inner tangential walls. On both walls, segments of the lamellae were formed earlier in primary pit fields than at nonprimary pit field regions. Suberin lamellae then extended to the radial walls. When they reached the Casparian bands, the lamellae intruded between the bound plasma membranes and the walls, so that the cells' plasma membranes remained intact. In this way, suberin lamellae that were continuous around the cells were laid down. Later, tertiary walls were deposited internal to the suberin lamellae. None of the wall modifications interrupted the symplastic connections of the endodermis. During suberin lamella and tertiary wall formation, more dictyosomes and ER profiles appeared than during Casparian band development. In the exodermis, although Casparian bands were readily detected with fluorescence microscopy, they were rarely detected with electron microscopy. Suberin lamellae were formed in long cells severing their plasmodesmata. As in the endodermis, dictyosomes and ER were prominent during suberin lamella formation. Tertiary walls were not formed in the exodermis.Key words: Allium cepa, Casparian band, endodermis, exodermis, suberin lamella, ultrastructure.

Suberin deposition and band plasmolysis in the corn (Zea mays L.) root exodermis

1997 ◽  
Vol 75 (7) ◽  
pp. 1188-1199 ◽  
Author(s):  
Daryl E. Enstone ◽  
Carol A. Peterson
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Lateral Roots ◽  
Root Surface ◽  
Casparian Bands ◽  
Suberin Lamellae ◽  
Tight Connection ◽  
Casparian Band ◽  
Apoplastic Barrier ◽  
Suberin Lamella

The exodermal Casparian band in corn (Zea mays L.) was first seen 10 mm distal to the kernel 4 days after planting. From its inception, the band usually occupied most of the radial wall (as seen in a cross section of the root). Subsequent maturation of the band around the root was asynchronous into the region of emerging lateral roots. Thus, a continuous apoplastic barrier would have been absent over much of the young root surface. Suberin lamellae development was also asynchronous, as these structures formed in those cells which had Casparian bands. Frequently, a lamella was initially deposited in patches, progressing centripetally until a continuous lipid layer was formed around the cell protoplast. Many instances of band plasmolysis (typical of the endodermis) were observed in the developing uniform exodermis. It could occur in cells with no detectable Casparian bands, suggesting that the tight connection between the plasmalemma and the wall that causes this phenomenon is not due to hydrophobic attractions. The results are consistent with the idea that there are strong attractions between proteins of the membrane and wall in the region of the Casparian band. The tight connection between the plasmalemma and the wall was broken during the later stages of suberin lamella development. Key words: Zea mays L., Poaceae, band plasmolysis, exodermis, Casparian band, suberin lamella.

The effect of suberin lamellae on the vitality and symplasmic permeability of the onion root exodermis

1996 ◽  
Vol 74 (8) ◽  
pp. 1220-1226 ◽  
Author(s):  
Carol A. Peterson ◽  
Janet L. Waite
Keyword(s):  
Cell Types ◽  
Ion Transfer ◽  
Onion Root ◽  
Cell Vitality ◽  
Casparian Bands ◽  
Allium Cepa L ◽  
Suberin Lamellae ◽  
Form Part ◽  
Wall Permeability ◽  
Suberin Lamella

The onion exodermis is made up of two cell types, i.e., long and short cells. Both form Casparian bands, but suberin lamella development is absent or delayed in the short cells. Long cells did not accumulate fluorescein, a common test for cell vitality, because of reduced wall permeability due to suberin lamella development. Immature, long cells without lamellae stained in 15 min, whereas mature cells with lamellae required a 3.5- to 4-h treatment before staining was visible. Long exposure to fluorescein was needed to show that mature long cells were alive. Their vitality appeared to decline slowly with age but was not affected by drought stress. Fluorescein staining was apparent in the long cells only after treatment of paradermal sections; when dye was applied only externally to root segments, it did not enter the long cells from the epidermis or from the neighbouring short cells. This result indicates that the long cells were connected symplasmically to the cells of the cortex but were either unconnected, or connected by plasmodesmata of small functional diameter, to the epidermal and short cells. If they were unconnected, they would not form part of the symplasmic path of ion transfer into the root. Keywords: Allium cepa L., drought, exodermis, suberin lamella, vitality.

scholarly journals CHANGE IN CONTRIBUTION OF AQUAPORINS TO THE HYDRAULIC CONDUCTIVITY OF PLANTS DURING THE FORMATION OF APOPLASTIC BARRIERS UNDER SALINITY

ÈKOBIOTEH ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 249-254
Author(s):  
R.S. Ivanov ◽  
◽  
G.V. Sharipova ◽  
G.R. Akhiyarova ◽  
◽  
...  
Keyword(s):  
Salt Stress ◽  
Hydraulic Conductivity ◽  
Water Movement ◽  
Mercury Chloride ◽  
Casparian Bands ◽  
Barrier Formation ◽  
Apoplastic Barriers ◽  
Apoplastic Barrier ◽  
Apoplastic Pathway ◽  
Chloride Treatment

The study of plant adaptation mechanisms during the salt stress is required to provide an increase in plant productivity under such conditions. Along with a decrease in the availability of water for plants, the NaCL-induced inhibition of plant growth is associated with the toxic effect of sodium ions. The formation of apoplastic barriers due to the deposition of suberin and lignin restricts passive ion diffusion. However, the formation of such barriers reduces the capacity of the apoplastic pathway for water movement. In these conditions the role of transmembrane water transport is increased. This process is provided by aquaporin water channels. Thus the purpose of this work was to determine the contribution of aquaporins to hydraulic conductivity of peas plants under salinity-induced apoplastic barrier formation. An only slight decrease in plants transpiration caused by mercury chloride in the absence of salinization was in accordance with the ideas the apoplast is the dominant pathway when the Casparian bands is not formed yet. Salt stress in our experiments accelerated the development of the Casparian bands formation which could be visualized as an appearance of suberin strips in root endodermis which in turn was accompanied by a decrease in hydraulic conductivity. The decrease in hydraulic conductivity in 2 times during the mercury chloride treatment under salinity confirmed that contribution of aquaporins to the total hydraulic conductivity was increased under conditions when Casparian bands have had formed.

Sign in / Sign up

Export Citation Format

Share Document