The structure of the stem endodermis in etiolated pea seedlings

1987 ◽  
Vol 65 (7) ◽  
pp. 1514-1519 ◽  
Author(s):  
Fred D. Sack

Differentiation of the endodermis was examined in third internodes of etiolated Pisum sativum L. cv. Alaska seedlings. The endodermis in young internodes contains large, sedimented amyloplasts; in older internodes, a casparian strip differentiates and the endodermis becomes depleted of starch except for the proximal region of the stem, which retains sedimented amyloplasts and remains graviresponsive. Sedimentation occurs in the hook but does not occur consistently until cells reach the base of the hook, where the axis becomes vertical, rapid cell elongation starts, and amyloplast diameter increases substantially. Contact between endoplasmic reticulum and amyloplasts was observed. Endoplasmic reticulum is not distributed polarly with respect to gravity. No symplastic or apoplastic blockages exist in the endodermis at the level of the stem where lateral gradients may be established during tropic curvature.

Planta ◽  
1973 ◽  
Vol 110 (2) ◽  
pp. 173-182 ◽  
Author(s):  
D. A. Morris ◽  
Golben Othman Kadir ◽  
A. J. Barry

Horticulturae ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 125
Author(s):  
Nisreen A. AL-Quraan ◽  
Zakaria I. Al-Ajlouni ◽  
Nima F. Qawasma

The physiological and biochemical role of the γ-aminobutyric acid (GABA) shunt pathway in green pea seedlings (Pisum sativum L.) was studied in response to soil water holding capacity levels: 80%, 60%, 40%, 20%, and 10% grown under continuous light at 25 °C for 7 days and 14 days, separately. Characterization of seeds germination pattern, seedlings growth (plant height, fresh and dry weight, and chlorophyll contents), GABA shunt metabolite (GABA, glutamate, and alanine) levels, total protein and carbohydrate levels, and oxidative damage (MDA level) were examined. Data showed a significant effect of drought stress on seed germination, plant growth, GABA shunt metabolites level, total protein and carbohydrate contents, and MDA level. A significant decline in seed germination percentage was recorded at a 20% drought level, which indicated that 20% of soil water holding capacity is the threshold value of water availability for normal germination after 14 days. Seedling fresh weight, dry weight, and plant height were significantly reduced with a positive correlation as water availability was decreased. There was a significant decrease with a positive correlation in Chl a and Chl b contents in response to 7 days and 14 days of drought. GABA shunt metabolites were significantly increased with a negative correlation as water availability decreased. Pea seedlings showed a significant increase in protein content as drought stress was increased. Total carbohydrate levels increased significantly when the amount of water availability decreased. MDA content increased slightly but significantly after 7 days and sharply after 14 days under all water stress levels. The maximum increase in MDA content was observed at 20% and 10% water levels. Overall, the significant increases in GABA, protein and carbohydrate contents were to cope with the physiological impact of drought stress on Pisum sativum L. seedlings by maintaining cellular osmotic adjustment, protecting plants from oxidative stress, balancing carbon and nitrogen (C:N) metabolism, and maintaining cell metabolic homeostasis and cell turgor. The results presented in this study indicated that severe (less than 40% water content of the holding capacity) and long-term drought stress should be avoided during the germination stage to ensure proper seedling growth and metabolism in Pisum sativum L.


1965 ◽  
Vol 13 (2) ◽  
pp. 171 ◽  
Author(s):  
MC Wark ◽  
TC Chambers

An ontogenetic study of secondary phloem sieve elements of Pisum sativum L., fixed on the intact plant for electron microscopy, indicates that the connecting strands across the sieve plates are continuities of the endoplasmic reticulum. Each connecting strand is surrounded by a callose cylinder. The peripheral cytoplasm of the nucleate "young" sieve elements contains longitudinally oriented tubules of endoplasmic reticulum. As the sieve elements develop, nuclear material is extruded into the cytoplasm by way of a fibrotubular body which is structurally distinct from the slime body. When the cells are fully expanded the slime bodies disperse. This process is followed by breakdown of a number of organelles including the nucleus and tonoplast. This apparently leaves the endoplasmic reticulum free in the cell lumen.


2011 ◽  
Vol 52 (No. 12) ◽  
pp. 559-563 ◽  
Author(s):  
H. Fišerová ◽  
J. Šebánek ◽  
J. Hradilík ◽  
S. Procházka

This study compares effects of 2,3,5-triiodobenzoic acid (TIBA) and flavonoid quercetine (Q). In spite of the fact that both these compounds are inhibitors of the polar transport of auxin, a number of experiments demonstrated that their properties are different. If the flax seedlings were decapitated and one cotyledon was removed, the axillary bud of the remaining cotyledon grew up more intensively while TIBA (0.5% applied in the form of a lanolin paste on the remaining cotyledon) induced a correlative reversal so that axillars of removed cotyledons grew up more intensively. However, when Q (0.5%) was applied on the remaining cotyledon in the form of a lanolin paste, this inhibition was not significant. In the lamina-deprived petioles of apple trees TIBA accelerated abscission while Q caused an inhibiting effect similar to that of auxin. TIBA applied on epicotyls of pea seedlings inhibited their growth by 35% while Q only by 15%. As far as the release of ethylene by pea seedlings is concerned, both compounds showed promoting effects similar to the effect of auxin.


1999 ◽  
Vol 77 (5) ◽  
pp. 611-622 ◽  
Author(s):  
Philip J Villani ◽  
Darleen A DeMason

The leaf blade of Pisum sativum L. possesses proximal leaflets and distal tendrils and is altered by two recessive mutations that affect pinna identity, afila (af) and acacia/tendrilless (tl). Using morphological and histology features we characterized the variation in leaf form and pinna anatomy of the Af and Tl heterozygous genotypes. Our goal was to identify the specific interactions of these genes and the relative influence of each in regulating all structural components of the leaf and pinna phenotypes. The Tl/tl genotypes possess broad tendril - narrow leaflets in the distal region that are histologically more similar to leaflets than to tendrils. The afafTltl leaves have simple tendrils in the distal region and branching complexity that is intermediate between that of aftl and af leaves in the proximal region. Only the most distal tips are slightly expanded. Because the Af and Tl genes interact to affect almost all aspects of leaf and pinna form, they affect development at multiple levels of organization.Key words: acacia, afila, Fabaceae, leaf morphology, leaf anatomy, Pisum sativum.


1977 ◽  
Vol 81 (4) ◽  
pp. 308-313 ◽  
Author(s):  
S. Procházka ◽  
H. Schraudolf ◽  
J. Šonka

2019 ◽  
Vol 17 (4) ◽  
pp. 5-14
Author(s):  
Anna V. Tsyganova ◽  
Viktor E. Tsyganov

Background. The endoplasmic reticulum (ER) is the largest membrane-bound organelle, which plays an important role in the functioning of a plant cell and participates in its differentiation. Materials and methods. Using the methods of transmission electron microscopy, the morphological features and dynamics of structural changes in the ER in symbiotic nodules of pea (Pisum sativum L.) wild-type and mutants blocked at different stages of nodule development were studied. Results. ER developed from a network of individual tubules in meristematic cells, to a developed network of cisterns around the nucleus and plasmalemma, and a network of granular and smooth tubules accompanying infection structures in colonized and infected cells and symbiosomes in infected cells. Conclusions. A correlation was found between the level of development of the ER network and the degree of bacteroid differentiation.


2008 ◽  
Vol 20 (2) ◽  
pp. 159-163 ◽  
Author(s):  
Eric Guevara ◽  
Víctor M. Jiménez ◽  
Jorge Herrera ◽  
Fritz Bangerth

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