INFLUENCE OF SOME ENVIRONMENTAL CONDITIONS ON THE GROWTH OF EXCISED ROOT TIPS OF WHEAT SEEDLINGS IN LIQUID MEDIA

Growth chamber studies using one soil investigated the effects of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 0.0, 0.4, and 0.8 ppmw on the root development and the mineral status of wheat (Triticum aestivumL. ‘Neepawa’) seedlings. The 0.8-ppmw trifluralin rate increased the number of seminal roots, reduced lateral root production, decreased root extension, caused root tips to swell (club-like appearance), and reduced root dry weights. However, 0.4-ppmw trifluralin caused only slight damage to the seedlings. Towards the end of the two-week growth period, damaged seedlings showed signs of recovery, which included an increased number of seminal roots, development of normal root extensions from clubbed root tips, and development of normal lateral root patterns. Trifluralin increased percent calcium and magnesium and decreased percent nitrogen, phosphorus, and potassium in wheat plants. The nutrient concentrations were more affected in 21-day-old plants than in 35-day-old plants, indicating the wheat seedlings were able to recover from trifluralin injury.

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An Inhibitory Effect of Propolis on Germination and Cell Division in the Root Tips of Wheat Seedlings

Bee Products ◽

10.1007/978-1-4757-9371-0_17 ◽

1997 ◽

pp. 129-135

Author(s):

K. Sorkun ◽

S. Bozcuk ◽

A. N. Gömürgen ◽

F. Tekin

Keyword(s):

Cell Division ◽

Inhibitory Effect ◽

Root Tips ◽

Wheat Seedlings

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The ·SH radical and some other sources of sulfur as affecting growth of isolated root tips of wheat seedlings

PROTOPLASMA ◽

10.1007/bf01606170 ◽

1933 ◽

Vol 19 (1) ◽

pp. 132-135 ◽

Cited By ~ 5

Author(s):

Philip R. White

Keyword(s):

Root Tips ◽

Wheat Seedlings

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The physiological regulation of macropinocytosis during Dictyostelium growth and development

10.1101/227983 ◽

2017 ◽

Author(s):

Thomas D. Williams ◽

Robert R. Kay

Keyword(s):

Amino Acids ◽

Flow Cytometry ◽

High Throughput ◽

Environmental Conditions ◽

Growth And Development ◽

Minimal Medium ◽

Liquid Media ◽

Isolated Cells ◽

Flow Cytometry Assay ◽

Physiological Regulation

AbstractMacropinocytosis is a conserved endocytic process used by Dictyostelium amoebae for feeding on liquid medium. To further Dictyostelium as a model for macropinocytosis, we developed a high-throughput flow cytometry assay for macropinocytosis, and used it to identify inhibitors and investigate the physiological regulation of macropinocytosis. Dictyostelium has two feeding states: phagocytic and macropinocytic. When cells are switched from phagocytic growth on bacteria to liquid media, the rate of macropinocytosis slowly increases, due to increased size and frequency of macropinosomes. Upregulation is triggered by a minimal medium of 3 amino acids plus glucose and likely depends on macropinocytosis itself. Bacteria suppress macropinocytosis while their product, folate, partially suppresses upregulation of macropinocytosis. Starvation, which initiates development, does not of itself suppress macropinocytosis: this can continue in isolated cells, but is shut down by a conditioned-medium factor or activation of PKA signalling. Thus macropinocytosis is a facultative ability of Dictyostelium cells, regulated by environmental conditions that are identified here.SummaryA high-throughput flow cytometry assay shows that macropinocytosis in D. discoideum is upregulated in the presence of nutrients and absence of bacteria. Development and bacteria induce cells to downregulate macropinocytosis.

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Effects of Anoxia on Uptake and Loss of Solutes in Roots of Wheat

Functional Plant Biology ◽

10.1071/pp9920233 ◽

1992 ◽

Vol 19 (3) ◽

pp. 233 ◽

Cited By ~ 14

Author(s):

H Greenway ◽

I Waters ◽

J Newsome

Keyword(s):

Amino Acids ◽

Free Amino Acids ◽

Free Amino ◽

Soluble Sugars ◽

Membrane Integrity ◽

Root Tip ◽

Root Tips ◽

Wheat Seedlings ◽

Root Tissues ◽

Irreversible Injury

This paper reports on leakage of K+, Cl-, free amino acids and soluble sugars from roots of 4-5-day-old intact wheat seedlings, exposed to anoxia. Leakages were slower from hypoxically than from aerobically pretreated roots. For the first 24 h of anoxia, leakage of K+ and free amino acids was similar, while sugar leakage was slow. Subsequently, leakage of all three solutes usually increased with time. Net losses of K+ and Cl-, after 48 or 72 h exposure of intact seedlings to anoxia, were faster, and/or occurred earlier: (i) in expanding than in expanded root tissues; (ii) at 25� than at 15�C. Re-aeration showed that expanded root tissues retained their capacity to take up K+ and accumulate Cl-, for at least 12 h after the root tips had lost their ability to elongate. Roots which had lost their elongation potential after 20 h of anoxia, as diagnosed by microscopic observation, still had high solute concentrations in the 1-5 mm and 10-20 mm segments from the root tip, but the 0-1 mm apices had lost 70-90% of their K+, free amino acids and soluble sugars. In contrast, solute concentrations were still high in 0-1 mm tips which had not yet lost their elongation potential. Thus, either irreversible injury of the apices is caused by sudden loss of membrane integrity, or there is another cause of death leading to rapid leakage.

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STUDIES ON "BROWNING" ROOT ROT OF CEREALS: I. THE ASSOCIATION OF LAGENA RADICICOLA N.GEN.; N.SP., WITH ROOT INJURY OF WHEAT

Canadian Journal of Research ◽

10.1139/cjr30-014 ◽

1930 ◽

Vol 2 (3) ◽

pp. 171-194 ◽

Cited By ~ 15

Author(s):

T. C. Vanterpool ◽

G. A. Ledingham

Keyword(s):

Root Rot ◽

New Genus ◽

Maize Seedlings ◽

Root Tips ◽

Complex Type ◽

Diagnostic Features ◽

Wheat Seedlings ◽

Pythium Root Rot ◽

Root Injury ◽

Physiological Characters

A specific root rot of wheat and other cereals is described which is widespread over Saskatchewan, and occasions severe losses in some seasons. In early June, the outer leaves of the young plants become discolored, the number of tillers is reduced, growth delayed, and the yield considerably lessened. One of the chief diagnostic features is the presence of lesioned root tips containing oospores of the Pythium type. Although the disease is worst in a cool, wet spring, followed by warm, dry weather, the plants recover markedly when the remainder of the growing season is favorable. In preliminary work, "isolation strains" of various fungi from lesioned roots of field material collected in mid-summer failed to produce the disease under greenhouse methods of inoculation.A fungus belonging to the lower Phycomycetes, hitherto not described, was found associated with rootlet injury of wheat, barley, rye and maize seedlings grown in Regina clay soil from infested fields of southern Saskatchewan. Its life-history, morphology and physiological characters are given in detail; it is believed to be an obligate parasite which, under conditions favorable to its development, is capable of causing definite injury to wheat. It is not considered one of the major causes of browning root rot, but in the section where it is common it is likely one of the contributing causes in some seasons. It is regarded as belonging to the Ancylistaceæ, close to the genus Lagenidium, but the erection of a new genus Lagena is recommended. The binomial Lagena radicicola has been assigned to the fungus.More recently several "isolation strains" of Pythiaceous fungi have been secured from infected roots of wheat seedlings grown in soil collected from browning root-rot fields. A few of these in pot experiments in the greenhouse are shown to be definitely parasitic on the roots of wheat plants. There is some evidence that the particular root-rot concerned belongs to the Pythium root-rot complex type.

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Effect of Nitric Oxide on Ions Absorption in Excised Root Tips of Wheat Seedlings under Drought Stress

ACTA AGRONOMICA SINICA ◽

10.3724/sp.j.1006.2009.00530 ◽

2009 ◽

Vol 35 (3) ◽

pp. 530-534

Author(s):

Li-Qun ZHAO ◽

Yu-Liang LIU ◽

Bao-Teng SUN ◽

Cai-Qin WANG

Keyword(s):

Nitric Oxide ◽

Drought Stress ◽

Root Tips ◽

Wheat Seedlings

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The kinetics of pycnospore liberation in Septoria tritici

Canadian Journal of Botany ◽

10.1139/b71-157 ◽

1971 ◽

Vol 49 (7) ◽

pp. 1095-1099 ◽

Cited By ~ 19

Author(s):

Z. Eyal

Keyword(s):

Environmental Conditions ◽

Wheat Cultivar ◽

Infected Host ◽

Septoria Tritici ◽

Wetting And Drying ◽

Wheat Seedlings ◽

Flag Leaves ◽

Green Leaves ◽

Non Linear ◽

Kinetics Of

Productivity and rate of liberation of spores from pycnidia of Septoria tritici on green detached flag leaves of field origin and from pycnidia on artificially inoculated wheat seedlings were studied. About 40% of the total spores within a pycnidium were exuded after the initial wetting, but the final percentage of spores which oozed naturally from the pycnidium ranged from 60 to 80% of the total spores, depending on the wheat cultivar and the environmental conditions in which the infected host was grown. The pycnidia were ellipsoid and their volume was calculated for both dried and wet pycnidia. The volume of wet pycnidia varied within the range of 0.012 to 0.019 mm3, which is about a 30% increase over the dry pycnidia, whose volume varied within the range of 0.003 to 0.006 mm3. The correlation between pycnidial volume and total number of pycnospores per pycnidium was non-linear. Wetting and drying treatments had little effect on pycnospore production and liberation rate, and did not cause the production of new pycnidia on detached green leaves.

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Interaction between reactive oxygen species and nitric oxide in drought-induced abscisic acid synthesis in root tips of wheat seedlings

Functional Plant Biology ◽

10.1071/pp00143 ◽

2001 ◽

Vol 28 (10) ◽

pp. 1055 ◽

Cited By ~ 17

Author(s):

Zhiguang Zhao ◽

Guocang Chen ◽

Chenglie Zhang

Keyword(s):

Nitric Oxide ◽

Reactive Oxygen Species ◽

Abscisic Acid ◽

Reactive Oxygen ◽

Acid Synthesis ◽

Oxygen Species ◽

Root Tips ◽

Wheat Seedlings ◽

Acid Accumulation ◽

Oxide Synthase

Abscisic acid accumulation and oxidative stress are two common responses of plants to environmental stresses. However, little is known about their relationships. The purpose of this article is to investigate the effects of reactive oxygen species and nitric oxide on the plant hormone abscisic acid synthesis in root tips of wheat (Triticum aestivum L.) seedlings under drought stress. Detached root tips were subjected to drought stress by naturally evaporating until 20% of their fresh weights were lost. The activities of superoxide synthases and nitric oxide synthase (EC 1.14.13.39) increased after 20 min of treatment and abscisic acid began to accumulate 60 min later. The induction of abscisic acid by drought was strongly blocked by pretreating the root tips with reactive oxygen species eliminators tiron or ascorbate acid, and with nitric oxide synthase inhibitor Nω-nitro-L-arginine or nitric oxide eliminator 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide. Consistent with these results, reactive oxygen species generators diethyldithiocarbamic acid, xanthine–xanthine oxidase and triazole or nitric oxide donor sodium nitroprusside can also induce abscisic acid accumulation in root tips of wheat seedlings. While potentiated by reactive oxygen species, the effect of sodium nitroprusside on abscisic acid accumulation was blocked by 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide. Based on these results, we suggest that reactive oxygen species and nitric oxide play important roles in drought-induced abscisic acid synthesis in plant, they may be the signals through which the plant can ‘sense’ the drought condition.

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