Ultrastructural changes in sunflower root cells in relation to boron deficiency and added auxin

The responses of sunflower root cells to conditions of boron deficiency and to the addition of exogenous auxin were studied on the ultrastructural level. Although gross morphological effects such as inhibition of root elongation and a change in the direction of cell expansion from longitudinal to radial are similar in both auxin-treated and boron-deficient seedling roots, ultrastructural changes are different in the two treatments. An increase in cell wall thickness and a loss of membrane integrity are seen as early as 6 h in seedlings grown without boron. Auxin-treated root cells do not show this response. A role for boron may involve maintenance of membrane integrity rather than determining endogenous auxin levels.

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Physiological Responses of Downy Brome (Bromus tectorum) Roots toPseudomonas fluorescensStrain D7 Phytotoxin

Weed Science ◽

10.1017/s004317450005222x ◽

1993 ◽

Vol 41 (3) ◽

pp. 483-489 ◽

Cited By ~ 11

Author(s):

Patrick J. Tranel ◽

David R. Gealy ◽

Gerald P. Irzyk

Keyword(s):

Root Elongation ◽

Membrane Integrity ◽

Lipid Synthesis ◽

Significant Inhibition ◽

Downy Brome ◽

Similar Treatment ◽

Physiological Processes ◽

Treatment Conditions ◽

Dose Dependent ◽

Inhibition Of Root Elongation

Effects of a crude preparation of a phytotoxin fromPseudomonas fluorescensstrain D7 (D7) on various physiological processes were evaluated in roots of downy brome seedlings. Cell division, respiration, and synthesis of protein, RNA, and DNA were not inhibited or only slightly inhibited under treatment conditions that caused substantial inhibition of root elongation. Significant inhibition of each of these processes was detected by known inhibitors included in each study to verify sensitivity of the procedures used. Disruption of lipid synthesis and membrane integrity by the crude phytotoxin preparation was significant and might account for inhibition of root elongation. Additional studies on these two possible target sites were conducted with partially purified phytotoxin. In intact roots, incorporation of [14C]acetate and [14C]malonic acid into lipophilic fractions was reduced by 50% or greater during a 1-h treatment with concentrations between 10 and 100 μg ml−1of the partially purified phytotoxin preparation. In a membrane integrity study, a similar treatment increased radioactivity efflux 250% from seedlings preloaded withscyllo-[R-3H]inositol. Additionally, disruption of lipid synthesis and membrane integrity by the partially purified phytotoxin was dose dependent. Collectively, these findings indicate that the D7 phytotoxin may inhibit downy brome root elongation through its effects on lipid synthesis and membrane integrity.

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PARTICIPATION OF ENT3 TRANSPORTER IN CYTOKININ DISTRIBUTION BETWEEN THE ROOT AND THE SHOOT AND IN REGULATION OF GROWTH RESPONSE OF ARABIDOPSIS PLANTS TO INCREASED LEVEL OF MINERAL NUTRITION

ÈKOBIOTEH ◽

10.31163/2618-964x-2020-3-4-741-749 ◽

2020 ◽

Vol 3 (4) ◽

pp. 741-749

Author(s):

A.V. Korobova ◽

◽

Z.A. Akhtyamova ◽

B.R. Kuluev ◽

G.R. Kudoyarova ◽

...

Keyword(s):

Mineral Nutrition ◽

Root Elongation ◽

Growth Response ◽

Zeatin Riboside ◽

Root Cells ◽

Endogenous Cytokinins ◽

Nitrogenous Base ◽

Regulation Of Growth ◽

Adaptive Role ◽

Inhibition Of Root Elongation

The nitrogenous base riboside transporter ENT3 is known for its ability to transport ribosylated cytokinins across the membrane. However, its role in the distribution of cytokinins between plant organs has not yet been studied. For this purpose, we compared the content and distribution of either endogenous cytokinins or the exogenous trans-zeatin riboside introduced into the nutrient solution in mutant ent3-1 plants and the parent genotype Columbia. In the mutant, the accumulation of endogenous cytokinins in the roots was suppressed, and the ability to deliver exogenous trans-zeatin riboside to shoots increased. The roots of ent3-1 were about 15% longer and had a lower cytokinin concentration. A thirtyfold increase in the concentration of macronutrients led to inhibition of root elongation in the original Columbia line, but not in ent3-1 plants. This growth response occured in accordance with the content of cytokinins in the roots: in Columbia plants, cytokinins accumulated in these organs. The increase in the level of hormones in the roots of ent3-1 was to a lesser extent and was not significant. It was concluded that the ENT3 transporter is involved in the distribution of endogenous cytokinins between the apoplast and symplast, facilitating their uptake by root cells, thereby limiting the export of cytokinins to shoots through the xylem, and can play an important adaptive role in changing the level of mineral nutrition.

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The cytotoxic influence of aluminium on Cucumis sativus L seedling roots

Acta Agrobotanica ◽

10.5586/aa.1995.019 ◽

2013 ◽

Vol 48 (2) ◽

pp. 83-93 ◽

Cited By ~ 1

Author(s):

Maria Szymańska ◽

Jolanta Molos

Keyword(s):

Apical Meristem ◽

Root Elongation ◽

Lateral Roots ◽

Outer Side ◽

Main Root ◽

Root Primordia ◽

Cucumis Sativus L ◽

Lateral Root Primordia ◽

Seedling Roots ◽

Inhibition Of Root Elongation

The roots of 5-days old cucumber seedling cv. Wisconsin were incubated in the Al solutions (AICl3) of pH 4,2. AI was applied in the following concentrations: 20, 30 and 40 mg/dm3. All the Al concentrations caused both the inhibition of root elongation and reduction of mitotic activity of apical meristem. The complete inhibition of mitoses and elongation growth was determined in the presence of 30 and 40 mg Al/dm3 after 4 and 3 days of incubation. After 5 incubation days the changes in the morphology of seedling roots, resulting mainly from the inhibition of the main root elongation and formation of a greater number of lateral roots, were noted. The reduction of root cap dimensions was accompanied by the apical meristem shortening and in short distance, differentiation of numerous lateral root primordia. The meristematic cell got elongated while their nuclei and nucleoli enlarged (particularly at 20 and 30 mg Al/dm3) and cytoplastn vacuolized. In the region of elongation and lateral roots differentiation, the cells of epidermis and primary cortex got shrunk, degenerationed and after falling off the tissue they made bigger (40 mg Al/dm3) or smaller (20 and 30 mg Al/dm3) hollows and cracks on the outer side of the root.

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Ultrastructural Changes of the Symbiotic Chlorella-Like Alga Isolated from Hydra Viridis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054212 ◽

1982 ◽

Vol 40 ◽

pp. 320-321

Author(s):

K.W. Lee ◽

R.H. Meints ◽

D. Kuczmarski ◽

J.L. Van Etten

Keyword(s):

Time Course ◽

Reciprocal Cross ◽

Ultrastructural Level ◽

Ultrastructural Changes ◽

Symbiotic Relationship ◽

Cell Recognition ◽

Green Hydra ◽

Different Strains ◽

Hydra Viridis

The physiological, biochemical, and ultrastructural aspects of the symbiotic relationship between the Chlorella-like algae and the hydra have been intensively investigated. Reciprocal cross-transfer of the Chlorellalike algae between different strains of green hydra provide a system for the study of cell recognition. However, our attempts to culture the algae free of the host hydra of the Florida strain, Hydra viridis, have been consistently unsuccessful. We were, therefore, prompted to examine the isolated algae at the ultrastructural level on a time course.

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Ultrastructural changes in sciatic nerve tissue: Effects of passive maternal smoking

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076858 ◽

1983 ◽

Vol 41 ◽

pp. 650-651

Author(s):

Amankwah K.S. ◽

A.D. Weberg ◽

R.C. Kaufmann

Keyword(s):

Sciatic Nerve ◽

Maternal Smoking ◽

Ultrastructural Level ◽

Uranyl Acetate ◽

Nerve Tissue ◽

Ultrastructural Changes ◽

Cacodylate Buffer ◽

And Control ◽

Spontaneous Delivery

Previous research has revealed that passive (involuntary inhalation) tobacco smoking during gestation can have adverse effects upon the developing fetus. These prior investigations did not concentrate on changes in fetal morphology. This study was undertaken to delineate fetal neural abnormalities at the ultrastructural level in mice pups exposed in utero to passive maternal smoking.Pregnant study animals, housed in a special chamber, were subjected to cigarette smoke daily from conception until delivery. Blood tests for determination of carbon monoxide levels were run at 15-18 days gestation. Sciatic nerve tissue from experimental and control animals were obtained following spontaneous delivery and fixed in 2.5% gluteraldehyde in 0.1M cacodylate buffer pH 7.3. The samples were post-fixed in osmium ferrocyanide (1:1 mixture of 1.5% aqueous OSO4 and 2.5% K4 Fe(CN)6). Following dehydration, the tissues were infiltrated with and embedded in Spurr. Sections were stained with uranyl acetate and lead citrate.

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Comparative Time-Course Physiological Responses and Proteomic Analysis of Melatonin Priming on Promoting Germination in Aged Oat (Avena sativa L.) Seeds

International Journal of Molecular Sciences ◽

10.3390/ijms22020811 ◽

2021 ◽

Vol 22 (2) ◽

pp. 811

Author(s):

Huifang Yan ◽

Peisheng Mao

Keyword(s):

Antioxidant Capacity ◽

Avena Sativa ◽

Proteomic Analysis ◽

Time Course ◽

Intact Cell ◽

Membrane Integrity ◽

Acid Synthesis ◽

Ultrastructural Changes ◽

Oat Seeds ◽

Aged Seeds

Melatonin priming is an effective strategy to improve the germination of aged oat (Avena sativa L.) seeds, but the mechanism involved in its time-course responses has remained largely unknown. In the present study, the phenotypic differences, ultrastructural changes, physiological characteristics, and proteomic profiles were examined in aged and melatonin-primed seed (with 10 μM melatonin treatment for 12, 24, and 36 h). Thus, 36 h priming (T36) had a better remediation effect on aged seeds, reflecting in the improved germinability and seedlings, relatively intact cell ultrastructures, and enhanced antioxidant capacity. Proteomic analysis revealed 201 differentially abundant proteins between aged and T36 seeds, of which 96 were up-accumulated. In melatonin-primed seeds, the restoration of membrane integrity by improved antioxidant capacity, which was affected by the stimulation of jasmonic acid synthesis via up-accumulation of 12-oxo-phytodienoic acid reductase, might be a candidate mechanism. Moreover, the relatively intact ultrastructures enabled amino acid metabolism and phenylpropanoid biosynthesis, which were closely associated with energy generation through intermediates of pyruvate, phosphoenolpyruvate, fumarate, and α-ketoglutarate, thus providing energy, active amino acids, and secondary metabolites necessary for germination improvement of aged seeds. These findings clarify the time-course related pathways associated with melatonin priming on promoting the germination of aged oat seeds.

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