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Topic: Periderm

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	Angiosperms
		Periderm, the term first used by von Mohl (1845), is a protective tissue of secondary origin which replaces the epidermis in stems and roots that have continual secondary growth.
		As trees age, sequent periderms may arise at successively greater depths thus causing an accumulation of dead tissues on the surface of the stem or root and contributing to the formation of rhytidome on rough-barked species or simply outer bark on smooth-barked species.
		In angiosperms, wound periderms are distinct from the first periderms based on their dissimilar histochemical reactions to lignin reagents (Biggs 1984b, Rittinger et al 1987) and the formation of a ligno-suberized boundary as a prerequisite to barrier differentiation (Mullick 1997, Soo 1977, Biggs 1984a,b).
	www.caf.wvu.edu /bark/angiospe1.htm (7636 words)

	Immunocytological Comparison of Native and Wound Periderm Maturation in Potato Tuber American Journal of Potato ...
		In contrast, as we previously described, native periderm maturation and resistance to excoriation (skinning) is accompanied by an increase in relatively un-esterifled and esterified homogalacturonan pectin epitopes in the walls of phellogen cells.
		In native tuber periderm, the phellogen layer differentiates from the hypodermis early during development of the tuber (Artschwager 1924; Peterson and Barker 1979).
		As is the case with native periderm, an immature wound periderm is susceptible to excoriation.
	www.findarticles.com /p/articles/mi_qa4069/is_200403/ai_n9369924 (861 words)

	Apoptosis in Down Feathers and Periderm
		We investigated the role of apoptosis in early feather morphogenesis and shedding of the late-stage periderm in chick embryos.
		Periderm sections of 14- and 16-day chicks showed no marked cells, whereas periderm sections from 18-day chicks showed abundant and very clearly marked apoptotic cells.
		As is the case with cell differentiation within the feather, apoptosis seems to move proximally along the longitudinal axis of the feather as development progresses.
	academics.hamilton.edu /biology/smiller/feather&periderm.html (590 words)

	PG-IV: P287 - Identification of Periderm-Specific Genes in Sweetpotato (Ipomoea batatas) using differential display RNA ... (Site not responding. Last check: 2007-10-25)
		Periderm in sweetpotato (Ipomoea batatas L. Lam.), is the outer layer of cells ('skin') that provide a protective coat to the storage roots.
		Multiple fragment cDNA from the periderm and flesh of the storage roots were amplified by RT-PCR using random 6- and 10-mer primers.
		Analysis of gene expression patterns for the periderm and the flesh revealed some transcripts present only in the periderm while many were present in both periderm and the flesh.
	www.intl-pag.org /4/abstracts/p287.html (274 words)

	More on Morphology of the Seed Plants (Site not responding. Last check: 2007-10-25)
		Periderm is the other product of secondary growth; it is produced by the cork cambium, a cylindrical layer of cells which develops not far under the outer skin (epidermis) of the plant.
		There are a number of other groups which do develop secondary tissues, such as some extinct lycophytes and sphenophytes, and their secondary growth occurs by a similar process, though it differs in a number of important details.
		The extinct scale trees, for instance, produced woody growth enough to reach heights of several dozen meters, but their primary support was their periderm (bark, not wood), and both cambia were unifacial, that is they divided new cells only toward one side of the cambium, and not to both sides as in seed plants.
	www.ucmp.berkeley.edu /seedplants/seedplantsmm.html (844 words)

	ARS \| Publication request: Biochemical and Physical Changes in Tuber Periderm Upon Skin-Set
		It was previously determined that the phellogen walls of immature native periderm are thin and prone to fracture during harvest, leading to periderm abrasion (excoriation).
		Maturation of native periderm is accompanied by an apparent increase in unesterified pectins in the walls of phellogen cells, which may allow for the strengthening of phellogen cell walls via calcium pectate formation.
		Since peroxidase is known to catalyze the cross-linking of cell wall polymers, we stained native and wound periderm for the presence of peroxidase utilizing guaiacol as a substrate.
	www.ars.usda.gov /research/publications/Publications.htm?seq_no_115=169140 (469 words)

	ARS \| Publication request: Immunocytological Comparison of Native and Wound Periderm Maturation in Potato Tuber
		Consequently, wound periderm development is often used as a convenient model for year-round research on the biochemical processes associated with native periderm development during growth.
		While both types of periderm form from a phellogen layer which serves as a lateral meristem, there has been little research done on comparing the biochemical processes and steps involved in the maturation of the two types of periderm.
		We demonstrated previously that maturation of native periderm and resistance to excoriation (skinning) is accompanied by an increase in relatively un-esterified and esterified homogalacturonan polymers in the walls of phellogen cells.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=150697&pf=1 (553 words)

	Cankers
		Cankers on trees are the visible manifestation of necrotic periderm, cortex, phloem and vascular cambium tissues (Figs 1- 4).
		Several lines of evidence indicate that periderms function to prevent desiccation of internal layers, prevent inward movement of pathogen toxins or enzymes, and serve as physical barriers to colonization.
		In wound periderms, as many as ten layers of thin-walled phellem formed prior to the formation of thick-walled phellem in comparison to normal periderm which formed a minimum of three layers of thin-walled cells.
	www.caf.wvu.edu /bark/cankers.htm (6976 words)

	Chitin-protein complex in theOrdovician organic fossil Byronia (Scyphozoa).
		In the present note the first though slightly doubtful finding of chitin-protein complex in the periderm of an organic microfossil is described.
		The fine structure of this type is typical for periderm of scyphopolips and the cuticle of Arthropoda, i.e.
		periderm as well as "self-staining" and "selffixation" of fine structure during the process of fossilization.
	www.graptolite.net /Chitin.html (467 words)

	Silver Scurf of Potato fact sheet (Site not responding. Last check: 2007-10-25)
		Severe browning of the surface layers of tubers may occur, followed by sloughing-off of the outer layers of the periderm (fig.
		In contrast, infection of russet-skinned tubers is masked by the dark thick periderm.
		These conidia are washed off the seed tuber and through the soil by rain or irrigation; some of these are deposited near or on the surfaces of the daughter tubers.
	vegetablemdonline.ppath.cornell.edu /factsheets/Potato_SilverScurf.htm (1194 words)

	Changes in Gap Junction Distribution and Connexin Expression Pattern During Human Fetal Skin Development -- Arita et ...
		Cx26 was detected mainly within the periderm and Cx43 between the intermediate cells at 96 days' EGA.
		At 152 days' EGA, the periderm had already degenerated and the majority of gap junctions were between the intermediate cells.
		cell layer and the periderm, are observed in the primitive epidermis.
	www.jhc.org /cgi/content/full/50/11/1493 (3598 words)

	Periderm
		Many of the periderm cells seen in this scanning electron micrograph have more than one bleb projecting from their surface.
		The formation of the blebs greatly increases the cell surface area exposed to amniotic fluid.
		This is considered the pinnacle of development of the periderm.
	courses.washington.edu /hubio567/devbio/peri16.html (64 words)

	Periderm (Site not responding. Last check: 2007-10-25)
		As differentiation of the underlying epidermal cell layers approaches completion, the periderm is sloughed into the amniotic fluid.
		The 'basket weave' pattern of darkly staining material above the nucleated cells is the first appearance of a comified cell layer in interfollecular epidermis.
		To understand what has been transpiring underneath the periderm, and why it is no longer needed, select stratification from the main index.
	courses.washington.edu /hubio567/devbio/peri24.html (81 words)

	rhabdo
		The periderm surface is patchy (as defined by Urbanek 1986, p.210) and rough (Fig.
		Urbanek, A. and Towe, K.M. Ultrastructural studies on graptolites, 1: The periderm and its derivatives in the Dendroidea and in Mastigograptus.
		Fissure in the periderm; arrow indicates a presumably bunch of cortical fibrils.
	www.graptolite.net /rhabdo.htm (6535 words)

	Origin of Outer Bark (Site not responding. Last check: 2007-10-25)
		A cell wall forms parallel to the surface of the organ (i.e., periclinal), initially in a group of cells and then expanding to neighboring cells until the sheet of cells is continuous around the stem.
		For some species, the initial periderm arises deep in the cortex or parenchyma cells of the phloem, for which the term superficial would not be appropriate.
		The initial periderm of a root arises deep within the axis, not near the surface.
	www.botgard.ucla.edu /html/botanytextbooks/generalbotany/barkfeatures/originofouterbark.html (451 words)

	[No title]
		Lenticels are portions of the periderm with many air spaces in between the cells and may appear as raised round, oval or elongated areas.
		In older portions of the stem, lenticels form at the bottom of cracks in the bark where new periderm is being formed.
		Eventually, new periderm appears in between the old crushed secondary phloem and newer secondary phloem The old phloem is separated from the newer phloem and is sloughed.
	www.cbu.edu /~esalgado/BIOL216/ch6.doc (2520 words)

	American Chemical Society: Journal of Agricultural and Food Chemistry
		However, utilizing periderm tissue may result in incorporation of chemical components that present potential quality and flavor problems.
		The purpose of this investigation was to determine the feasibility of processing carrot puree with periderm tissue as influenced by preprocessing conditions and storage at an elevated temperature.
		By determining the physicochemical and sensory changes that occur after thermal processing and prolonged storage, the influence of periderm tissue and processing parameters on antioxidant compounds was evaluated.
	pubs.acs.org /hotartcl/jafcau/inthenews/jf9910178_rev.html (187 words)

	Symptoms of Pierce's Disease on Grapevines
		Another diagnostic symptom of PD is the abscission of leaf blades from shoots with retention of leaf petioles.
		This periderm formation usually begins at the basal portion of a shoot and progresses toward the growing tip.
		In infected grapevines, periderm formation is not uniform, usually resulting in green "islands" at the nodal area while the internodal portion of the stem becomes brown.
	winegrapes.tamu.edu /grow/diseases/piercesphoto3.shtml (119 words)

	Wood and Bark (Site not responding. Last check: 2007-10-25)
		The periderm consists of a cork cambium and its derivatives.
		Divisions of the cork cambium initials tangentially and radially allow the periderm to keep up with later years of expansion in the trunk caused by the activity of the vascular cambium and its derivatives.
		Bark is the combination of dead epidermis, periderm, cortex, phloem (primary and secondary), and vascular cambium.
	koning.ecsu.ctstateu.edu /Plants_Human/secondary.html (1550 words)

	Feather Germ Morphogenesis (Site not responding. Last check: 2007-10-25)
		Morphological accounts of feather germ morphogenesis that described areas where cells were being "resorbed" or where layers "disintegrated" did not have the benefit of current immunocytochemical techniques to clarify processes associated with what could be seen.
		Ephemeral periderm is continuous with feather sheaths and is similarly incompletely described.
		Our results suggest that apoptosis is part of the formation of natal down barbs and barbules, is responsible for cavitation in pulp, and that PCD precedes shedding of periderm.
	academics.hamilton.edu /biology/smiller/featherapop.html (263 words)

	Nikon MicroscopyU: SMZ1500 Fluorescence Digital Image Gallery - Generalized Plant Stem Cell
		The primary dermal tissue, the epidermis, is found on young parts of a plant such as new growth of stems and leaves.
		Epidermis is eventually replaced by the secondary periderm, which is composed of phellem, phellogen, and phelloderm.
		Cork and bark are common examples of periderm tissue.
	www.microscopyu.com /galleries/smz1500/generalizedplantcellstemsmall.html (389 words)

	Botany Glossary "P"
		Periderm cells are cork cells in the stems of
		periderm is produced by the phellogen (cork cambium) toward the outside of the stem.
		periderm towards the outside of the stem and one layer of
	www.puc.edu /Faculty/Gilbert_Muth/botglosp.htm (1313 words)

	Post-harvest deterioration of cassava ... - Physiological deterioration in cassava: biochemistry of the processes ...
		Enzymes associated with the phenylpropanoid pathway, such as phenylalanine ammonia-lyase and chalcone synthase, lead to the biosynthesis of phenolics which may act directly as defence compounds (quinones, phytoalexins) or can form polymers, such as lignin, that render cell walls more resistant to water loss and attack from microbial enzymes.
		This response is notably slower than in the other tropical root crops, such as yam, which form a periderm in four to five days at 35°C (Passam, Read and Rickard, 1976).
		Booth (1976), however, demonstrated that periderm formation in cassava roots occurred around small v-shaped cuts within four to seven days at 35°C, indicating that the magnitude of the wound sustained can affect the time required for periderm formation.
	www.fao.org /docrep/v4510e/V4510E05.htm (2285 words)

	Unit 6 (Site not responding. Last check: 2007-10-25)
		Describe and discuss the processes involved in the initiation of phellogen activity and be able to describe the patterns of cell distribution of periderm and storied cork.
		Using wood anatomy features discussed in Unit 4, be able to compare and contrast the wood of different species based on cell types and their distribution.
		This stem is curious because it consists of several parallel vascular cylinders enclosed in a common periderm.
	trc.ucdavis.edu /plb/PLB105/html/Un6.html (3280 words)

	transition_to_landSecGrow
		The outermost Secondary Phloem is converted into Periderm in many large trees.
		A dynamic equilibrium is established with the Vascular Cambium which produces new phloem while old phloem is converted into Periderm.
		Periderm forms an impervious barrier between the outer environment and internal plant cells.
	www.biologie.uni-hamburg.de /b-online/library/webb/BOT201/Transition/transitiontolandsecgrow.htm (245 words)

	Periderm and its Cell Types (Site not responding. Last check: 2007-10-25)
		Each cork cambium produces a sector of cells called a periderm.
		The dividing cells (initials) of the cork cambium (phellogen) divide to produce cells, most of which are "pushed" toward the outside, and some may be pushed toward the inside.
		Cells pushed from the cork cambium to the inside are called phelloderm, and these can remain alive because they have unthickened and unspecialized cell walls and, hence, can exchange gases and obtain nutrients.
	www.botgard.ucla.edu /html/botanytextbooks/generalbotany/barkfeatures/periderm.html (154 words)

	The anatomy of a tree trunk - the bark
		In a mature tree there are two main tissues types in the bark the secondary phloem and the periderm.
		The periderm is the outer layer of the bark which replaces the epidermis and is formed by the cork cambium.
		The inner periderm effectively cuts the outer periderm off from water and nutrients and the outer periderm layers die.
	www.botany.uwc.ac.za /ecotree/trunk/woodanatomy3.htm (393 words)

	Distinguish between these 3 root types:
		Suberin – waterproof substance found in the Casparian Strip and Cork (periderm).
		Periderm – the outer tissue of the secondary plant body consisting of the cork cambium and cork.
		Without the periderm, the vascular cambium and living phloem would be exposed to damage.
	www.mvhs.fuhsd.org /debbie_frazier/Web/VocabCardKey2.htm (373 words)

	Coulombe Laboratory at JHU/Under the Spotlight
		We investigated the developmental regulation of a lacZ reporter transgene fused to the promoter region of the human keratin 6a gene.
		In mouse embryos, the transgene is expressed in the periderm (the outermost layer of embryonic epidermis), as are the endogenous keratin 6 a and b genes.
		A subset of periderm cells, localized to temporary epithelial fusions, is known to contain keratin 6 protein, and we find that these cells also harbor LacZ enzymatic activity.
	www.hopkinsmedicine.org /coulombelabpage/spotlight.htm (119 words)

	Phloem parenchyma cells are involved in local and distant defense responses to fungal inoculation or bark-beetle attack ...
		Note that the PP cells exterior to the wound periderm have lost their phenolic bodies, compared to those internal to the periderm.
		Enlargement of a region of a wound periderm showing phellogen, phellem with thin-walled cells and thick-walled lignified cells, and phelloderm with parenchyma, many of which contain phenolic bodies.
		Note the very thin periderm, relative to the size of the beetles, at the top of the micrograph (between arrowheads).
	www.amjbot.org /cgi/content/full/87/3/314 (7381 words)

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