DEVELOPMENTAL STUDIES ON EUPHORBIA ESULA L.: APICES OF LONG AND SHORT ROOTS

1964 ◽  
Vol 42 (12) ◽  
pp. 1615-1628 ◽  
Author(s):  
M. V. S. Raju ◽  
T. A. Steeves ◽  
J. M. Naylor
Keyword(s):  
Cell Division ◽  
Root Apex ◽  
Root Cap ◽  
Field Conditions ◽  
Euphorbia Esula ◽  
Quiescent Center ◽  
Developmental Studies ◽  
Short Root ◽  
Root Apices ◽  
Root Axis

In both indeterminate long roots and determinate short roots of Euphorbia esula L., the promeristem usually consists of three meristematic layers. One of these represents the stelar pole, the second is continuous with the cortex, and the most distal appears to initiate the root cap – epidermis complex. Variations in this pattern are noted. Autoradiographs of apices of roots supplied with thymidine-H3 under field conditions demonstrate the existence of a region of low nuclear incorporation during a 24 or 48 hour period at the summit of the root axis in long roots. This region corresponds to the quiescent center described by previous authors. Short root apices consistently lack such a region. The pattern of nuclear incorporation of thymidine-H3 suggests that cell division is infrequent or absent in the center of the apex of long roots but not of short roots. Quiescence is thus a phenomenon which is superimposed upon the organization of the root apex in this species, and its presence or absence seems to be related to the developmental potentiality of the root. In many long roots the size of this quiescent region exceeds that of the region which may reasonably be designated the promeristem.

scholarly journals Morphoanatomic changes in shoot and root apices of banana Williams (AAA, Musa sp.) cultured on different N6- benzyladenine concentrations

1969 ◽  
Vol 92 (1-2) ◽  
pp. 53-72
Author(s):  
Maribel Ramírez-Villalobos ◽  
Helga Lindorf ◽  
Eva De García
Keyword(s):  
Lateral Roots ◽  
Root Apex ◽  
Transitional Zone ◽  
Root Cap ◽  
Anatomic Structure ◽  
Musa Sp ◽  
Tunica Layer ◽  
Vitro Development ◽  
Root Apices

Structural evidence about the in vitro growth of the shoot apex (SA) and root apex (RA) of banana is for the most part lacking.This paper presents an analysis of the morphoanatomic events that occur in the in vitro development of the SA, RA and explants of banana Williams cultured under different N6-benzyladenine (BA) concentrations. We examined the SA of explants (8 mm X 1.5 mm, shoot tip with part of rhizome) grown on 0, 2.5 and 5 mg /L of BA for 0, 3, 6, 9 and 12 d, and also the first emergent root (1 to 1.5 cm long) from these explants. Samples were sectioned (10 to 12 µm) and stained with safranin-fast green. The SA showed a dome shape with tunica-corpus organization (a single tunica layer). SA diameters were larger for explants growing in BA (93.75 to 142.05 µm) than in those growing without the cytokinin (73.87 to 85.83 µm), except for the diameter on the sixth day (127.84 µm). The noncultured initial explant without culture reached a diameter of 164.78 µm. The SA showed a cambium-like transitional zone in explants cultured with 2.5 mg/L of BA on the ninth day. This concentration also induced the highest number of shoots per explant (2.19) in 35 days. RA growing in media without BA showed protoderm, ground meristem, procambium, initial cells and root cap whereas with BA procambium, fundamental meristem and root cap (compressed) were distinguished. Benzyladenine decreased the number and length of the roots, inhibited the formation of lateral roots, increased the time for root emergence and caused distortion in their anatomic structure.

Localisation of aluminium in root apex cells of two Australian perennial grasses by X-ray microanalysis

1998 ◽  
Vol 25 (4) ◽  
pp. 427 ◽  
Author(s):  
Simon A. Crawford ◽  
Alan T. Marshall ◽  
Sabine Wilkens
Keyword(s):  
Significant Positive Correlation ◽  
Root Apex ◽  
Root Cap ◽  
Perennial Grasses ◽  
Elemental Distribution ◽  
X Ray ◽  
Positive Correlation ◽  
Distribution Maps ◽  
Meristematic Cells ◽  
Root Apices

To determine if an increased aluminium (Al) sensitivity is the result of greater accumulation of Al in root apices, the quantity and distribution of Al in root apex cells of Danthonia linkii Kunth and Microlaena stipoides (Labill.) R.Br. was investigated by X-ray microanalysis. Seedlings were grown in nutrient solution with 0, 185 and 370 µM total Al for 24 h after which the terminal 5 mm of the roots were excised, rapidly frozen and embedded using freeze-substitution. Elemental distribution maps of root apices showed that Al had accumulated in the nuclei of root cap and meristematic cells in Al-stressed roots of D. linkii but not in M. stipoides. Al appeared to be co-localised with phosphorous (P) in the nuclei of these cells. Quantitation of Al revealed that Al-stressed root apex cells of D. linkiiaccumulated significantly more Al than M. stipoides. Exposure of D. linkii roots to Al resulted in substantial increases in the P content of root apex cells, and a significant positive correlation was found between Al and P in both root cap and meristematic cells. Analysis of intracellular structures showed that the majority of Al had accumulated in the nuclei of cells. A significant positive correlation was found between Al and P in the nuclei, but not in the cytoplasm or cell walls. No positive correlation was found between Al and P in root apex cells of M. stipoides.

scholarly journals Developmental studies on Euphorbia esula: seasonal variation in the apices of long roots

1976 ◽  
Vol 54 (7) ◽  
pp. 605-610 ◽  
Author(s):  
M. V. S. Raju ◽  
T. A. Steeves ◽  
J. Maze
Keyword(s):  
Seasonal Variation ◽  
Growing Season ◽  
Large Percentage ◽  
Euphorbia Esula ◽  
Developmental Studies ◽  
Quiescent Centre ◽  
Root Apices

Long-root apices of Euphorbia esula L. were supplied with [3H]thymidine in the field on 11 occasions during the growing season. Autoradiographs of the root apices showed that the characteristic quiescent centre of long roots was absent in a large percentage of the roots in the early part of the growing season. It is suggested that the cells of the quiescent centre play an important role in the seasonal reactivation of the perennial roots of this species.

Cytological and histochemical characteristics of the axenic root surface of Alnus glutinosa

1986 ◽  
Vol 64 (10) ◽  
pp. 2216-2226 ◽  
Author(s):  
Yves Prin ◽  
Mireille Rougier
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Hairs ◽  
Root Apex ◽  
Alnus Glutinosa ◽  
Root Surface ◽  
Infection Process ◽  
Root Cap ◽  
A Cell ◽  
Histochemical Tests

The aim of the present study was to investigate the Alnus root surface using seedlings grown axenically. This study has focused on root zones where infection by the symbiotic actinomycete Frankia takes place. The zones examined extend from the root cap to the emerging root hair zone. The root cap ensheaths the Alnus root apex and extends over the root surface as a layer of highly flattened cells closely appressed to the root epidermal cell wall. These cells contain phenolic compounds as demonstrated by various histochemical tests. They are externally bordered by a thin cell wall coated by a thin mucilage layer. The root cap is ruptured when underlying epidermal cells elongate, and cell remnants are still found in the emerging root hair zone. Young emerging root hairs are bordered externally by a cell wall covered by a thin mucilage layer which reacts positively to the tests used for the detection of polysaccharides, glycoproteins, and anionic sites. The characteristics of the Alnus root surface and the biological function of mucilage and phenols present at the root surface are discussed in relation to the infection process.

scholarly journals Phosphorus and nitrogen interaction: loss of QC identity in response to P or N limitation is antecipated in pdr23 mutant

2011 ◽  
Vol 23 (3) ◽  
pp. 219-229 ◽  
Author(s):  
Cibele T. Costa ◽  
Mércio L. Strieder ◽  
Stephen Abel ◽  
Carla A. Delatorre
Keyword(s):  
Nucleic Acids ◽  
Lateral Roots ◽  
Adaptive Strategy ◽  
Quiescent Center ◽  
Wild Type ◽  
Short Root ◽  
Alternative Source ◽  
Low Phosphorus ◽  
Determinate Growth ◽  
Arabidopsis Mutant

Changes in root architecture are an important adaptive strategy used by plants in response to limited nutrient availability to increase the odds of acquiring them. The quiescent center (QC) plays an important role by altering the meristem activity causing differentiation and therefore, inducing a determinate growth program. The arabidopsis mutant pdr23 presents primary short root in the presence of nitrate and is inefficient in the use of nucleic acids as a source of phosphorus. In this study the effect of the pdr23 mutation on the QC maintenance under low phosphorus (P) and/or nitrogen is evaluated. QC identity is maintained in wild-type in the absence of nitrate and/or phosphate if nucleic acids can be used as an alternative source of these nutrients, but not in pdr23. The mutant is not able to use nucleic acids efficiently for substitute Pi, determinate growth is observed, similar to wild-type in the total absence of P. In the absence of N pdr23 loses the expression of QC identity marker earlier than wild-type, indicating that not only the response to P is altered, but also to N. The data suggest that the mutation affects a gene involved either in the crosstalk between these nutrients or in a pathway shared by both nutrients limitation response. Moreover loss of QC identity is also observed in wild-type in the absence of N at longer limitation. Less drastic symptoms are observed in lateral roots of both genotypes.

Developmental Studies ofArtemisia annua: Flowering and Artemisinin Production Under Greenhouse and Field Conditions

Planta Medica ◽  
1995 ◽  
Vol 61 (02) ◽  
pp. 167-170 ◽  
Author(s):  
Jorge Ferreira ◽  
James Simon ◽  
Jules Janick
Keyword(s):  
Field Conditions ◽  
Developmental Studies

Developmental studies of the stratification–germination process in sugar maple embryos

1985 ◽  
Vol 63 (5) ◽  
pp. 903-908 ◽  
Author(s):  
C. Y. Shih ◽  
E. B. Dumbroff ◽  
Carol A. Peterson
Keyword(s):  
Cell Division ◽  
Cell Elongation ◽  
Sugar Maple ◽  
Developmental Studies ◽  
Anatomical Changes ◽  
Germination Process ◽  
Radicle Protrusion ◽  
Xylem Elements ◽  
Food Reserves ◽  
Key Events

Changes in the anatomy, morphology, and stored food reserves of stratifying (5 °C) sugar maple embryos were followed from a strongly dormant state through germination. The correlation of cell division and cell elongation with radicle protrusion was also investigated. No morphological or anatomical changes were observed before first maturation of phloem elements on the 17th day of stratification. Mature xylem elements were first observed on day 37, and first germination was noted on day 38. Radicle protrusion was initiated by cell elongation, and cell division was not active for several days after emergence and a marked increase in lengths of the axes had occurred. Changes in amounts of protein, lipid, and starch were not observed during the stratification period, but mobilization of stored reserves was clearly evident with emergence of the radicles. Several of these key events appeared to be closely associated with previously described peaks and patterns of growth regulator activity.

Primary vascular patterns in root meristems of Pontederia cordata and their relevance to studies of root development

1980 ◽  
Vol 58 (12) ◽  
pp. 1351-1369 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Apical Meristem ◽  
Vascular System ◽  
Root Apex ◽  
Root Apical Meristem ◽  
Vascular Pattern ◽  
Quiescent Centre ◽  
Vascular Differentiation ◽  
Pontederia Cordata ◽  
Distribution Of Components ◽  
Root Apices

There are several files of metaxylem cells in root apices of Pontederia cordata L., each considered to consist of a series of prospective vessels with their ends in contact. Two longitudinally adjacent vessels may be in the same file of cells produced by the root apex or in adjacent files. As the root grows, successive prospective vessels are added to the apical ends of most of the files but not all files are continued. Addition of prospective vessels appears to take place within the "quiescent centre" of the root apical meristem. Where files are not continued there is no immediate readjustment of remaining files. The longitudinal and transverse distribution of components of the vascular system (including protophloem and protoxylem) is discussed in relation to the means by which the pattern of development may be controlled. Rates of production of vessels and the final lengths of the vessels are estimated. The observations and deductions are discussed in relation to other studies of root growth, vascular differentiation, and vascular pattern formation and maintenance.

DEVELOPMENTAL STUDIES ON EUPHORBIA ESULA L.: MORPHOLOGY OF THE ROOT SYSTEM

1963 ◽  
Vol 41 (5) ◽  
pp. 579-589 ◽  
Author(s):  
M. V. S. Raju ◽  
T. A. Steeves ◽  
R. T. Coupland
Keyword(s):  
Root System ◽  
Lateral Roots ◽  
Primary Root ◽  
Cambial Activity ◽  
Euphorbia Esula ◽  
Developmental Studies ◽  
Limited Growth ◽  
Mode Of Reproduction ◽  
Shoot Buds ◽  
Adverse Conditions

The significance of Euphorbia esula L. as a weed is related to its capacity to persist under adverse conditions and to its mode of reproduction. In both these properties, the root system plays an important role. The root system is initially established by seedlings. The seedling has a vigorous primary root with extensive longitudinal growth and considerable cambial activity. Such a root has been designated a "long" root. By contrast, the first lateral roots produced on the primary root have limited growth and no cambial activity. These roots have been termed "short" roots. Thus, the seedling exhibits a "heterorhizic" pattern. Lateral long roots also arise on the primary root of seedlings but their origin is delayed until cambial activity has begun. Such lateral long roots arise much earlier on seedlings growing in denuded areas than on those growing in areas covered by dense vegetation. The mature root system is described in terms of horizontal and vertical long roots, which make up the conspicuous framework of the system, and of the short roots which they produce. Long roots produce shoot-buds and the origin of these structures is delayed until cambial activity has started. Short roots do not give rise to shoot-buds. Cambial activity in long roots appears to be connected with bud production and its absence in short roots probably underlies their inability to produce buds.L'importance de Euphorbia esula L. comme mauvaise herbe est connexé a son capacité de persister dans les situations hostiles et à sa methode de reproduction. Dans ces deux caractéristiques, le système des racines a une signification profunde. Initialement le système des racines s'établit dans le semis. Le semis a une racine primaire très forte avec beaucoup de croissance longitudinale et avec une activité considérable du cambium. Une racine de cette espèce s'appelle une "longue" racine (long root). Par contre, les premières racines latérales que poussent sur la racine primaire ont croissance limité et aucun activité du cambium. Ces racines s'appellent les "courtes" racines (short roots). De cette façon, le semis montre un dessin "heterorhizique" (heterorhizic). Les longues racines latérales ont aussi leur origine sur la racine primaire du semis, mais l'origine est retardé jusqu'au commencement de l'activité du cambium. Les racines de cette espèce apparaissent beaucoup plus tôt sur les semis qui sont situés en terre sans autre végétation, que sur ceux qui sont situés au milieu des autres plantes. Le système adulte des racines se décrit sous forme des longues racines de l'espèce horizontale et verticale, lesquelles constituent la charpente bien visible du système, et des courtes racines que sont produites par les longues racines. Les longues racines produisent les bourgeons, mais l'origine des bourgeons est retardé jusqu'au commencement de l'activité du cambium dans les racines. Les courtes racines ne produisent pas les bourgeons. Il paraît que l'activité du cambium dans les longues racines soit corrélative avec l'initiation des bourgeons et l'absence du cambium dans les courtes racines explique probablement leur incapacité à produire les bourgeons.

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