Growth Rate Of Coleoptiles Research Articles

Growth processes of Triticum durum Dest. on the formaldehyde concentration gradient in microcosmic models

Under modern conditions, against the background of military invasion of the Russian Federation in Ukraine, there is an increase in threats to ecological security of the state, including as a result of violation of technological regime of operation of numerous potentially dangerous objects. Particular attention should be paid to such impurities as suspended substances (aerosols, dust), carbon monoxide, nitrogen dioxide, formaldehyde, the concentrations of which in the air have been rapidly increasing recently. Formaldehyde is one of the most well-known air pollutants, which is a permanent component of the atmosphere. The average content of formaldehyde in the air in the cities of Ukraine in the pre-war period exceeded the maximum permissible concentration. Its significant growth depends significantly on meteorological conditions. In comparison with other impurities, a clear seasonal dynamics is manifested with an increase in concentration in the summer period. The course of monthly concentrations of formaldehyde varies depending on the air temperature and the intensity of direct solar radiation on a horizontal surface. The article summarizes scientific data on specifics of formaldehyde effect on the growth processes of Triticum durum Dest. Phytotesting was carried out by forming microcultivators and planting calibrated seeds of Favorit wheat in them. The subject of the study was coleoptiles (model objects sensitive to the influence of exogenous factors, separated from three-day-old ethylated seedlings). Based on application of microcosm models method, it is shown inhibition of the growth of the aerial part of T. durum Dest. seedlings on the formaldehyde concentration gradient, which affects the growth rate of coleoptiles. It was established that the growth of coleoptiles decreases with increasing concentration. It is substantiated that the value of the effective concentration (EC50) is 0.875 MPC. Inhibition of T. durum Dest. seed germination at the formaldehyde concentration gradient under the influence of all studied concentrations was shown. The smallest percentage of germinated seeds (5.6%) was found at a concentration that corresponds to the maximum permissible one. The reaction of wheat seeds to the concentration of formaldehyde, corresponding to 0.1 MPC and 2 MPC, was almost the same (28.6% and 30.3%, respectively). The highest percentage of seed germination (82.2%) was observed under the influence of formaldehyde at a concentration of 0.5 MPC.

Detection of Fusarium langsethiae on wheat in Belgium

In 2010, the populations of Fusarium sp. and Microdochium sp. were monitored in Belgium and 16 strains were identified as Fusarium langsethiae on wheat in Belgium. The other species identified from the sampling were F. poae, F. tritinctum, F. graminearum, F. avenaceum and Microdochium nivale. The pathogenicity potential of the F. langsethiae strains was assessed via an in vitro coleoptile growth rate test on wheat seedlings and compared with strains of F. poae, F. tritinctum, F. graminearum and F. avenaceum known to cause Fusarium head blight. The results showed the ability of F. langsethiae to cause retardation in the wheat coleoptile growth rate, but at a lower rate than F. graminearum, F. avenaceum, F. poae and F. tricinctum. A test for mycotoxin production in vitro showed the ability of the four strains tested to produce T-2 and HT-2 toxins at a rate of up to 290 mg kg−1. This is the first report on the potential pathogenicity of F. langsethiae on wheat in Belgium, a species known to produce T-2 and HT-2 toxins, which are highly toxic for humans and animals.

Initial seedling growth rates in a semi-dwarf spring wheat collection.

A relationship was observed between seedling growth rate and seedling emergence under conditions of soil capping. Coleoptile and root growth rates were strongly influenced by the origin of the seed sample and the genotype involved, whereas genotype × environment interactions were small and not significant. A test-cross analysis revealed the presence of strong epistatic effects for the characters coleoptile growth rate and coleoptile diameter. Both additive and dominance variation contributed strongly to the total genetic variation for coleoptile growth rate, while the - dominance appeared to be ambidirectional. Genetic variation for coleoptile diameter was found to be predominantly additive. Whereas both traits were expected to respond well to selection, no consistent correlations with simple plant characteristics could be established, a situation that may limit the utilization of the observed genetic differences through indirect selection.

Correlation between black point symptoms and fungal infestation and seedling viability of wheat kernels

The level of occurrence of black point, the spectrum of fungal species and damage to wheat seedling vigour associated with it were assessed during 2003 and 2004 in the Slovak Republic. The incidence of black point kernels ranged between 0.2–2.4% in 2003 and 24.2–34.3% in 2004. The kernels’ fungal contamination varied from 60% to 100%. <i>Alternaria</i> spp., <i>F. poae</i> and <i>F. culmorum</i> were isolated from all localities and all subsamples. <i>Stemphylium vesicarium</i>, <i>Fusarium culmorum</i>, <i>F. graminearum</i>, <i>F. avenaceum</i>, <i>F. sporotrichioides</i>, <i>Microdochium nivale</i>, <i>Epicoccum nigrum</i>, <i>Penicillium</i> spp., <i>Aspergillus niger</i>, <i>Rhizopus nigricans</i> and <i>Cochliobolus sativus</i> were isolated less frequently. Fungi of the genus Alternaria were the most dominant, followed by <i>Fusarium</i> and <i>Microdochium</i> among which <i>F. poae</i> was dominant. Irrespective of incubation temperature, the germinative capacity and coleoptile growth rate of discolored kernels were affected more in the wet and cold year 2004. The inhibition of germination and seedling viability was more pronounced at the incubation temperature 22°C than at 15°C. Inhibition of coleoptile growth rate was 0.12–3.12% in black point kernels collected in 2003, and 0.24–9.28% in those collected in 2004.

Pathogenicity of fungi associated with wheat and barley seedling emergence and fungicide efficacy of seed treatment

Presented study focused on the influence of Cochliobolus sativus isolates origin on pathogenicity towards wheat and barley seedlings in comparison with pathogenicity of certain Fusarium species and Microdochium nivale. The efficacy of fungicide seed treatment against C. sativus was estimated. The C. sativus isolates were collected from different locations and were isolated from wheat, barley and sunflower seeds. The pathogenicity of C. sativus, Fusarium species and M. nivale towards germinating seedlings were expressed as germination (GA) retardation and coleoptile growth rate retardation (CGR). Of wheat only, the CGR was significantly influenced by the isolate origin. The C. sativus isolates obtained from sunflower seeds were the most aggressive. Of the barley seeds, the barley isolates were the most aggressive. Barley was significantly more susceptible to damage by C. sativus isolates than wheat. The pathogenicity of tested fungal species declined in the order: F. culmorum, F. graminearum, C. sativus, F. avenaceum, M. nivale, F. poae for both barley and wheat. The results highlighted high pathogenicity potential of C. sativus equal to that of F. avenaceum and M. nivale. The symptoms of C. sativus on coleoptile and roots were very similar or the same as the symptoms caused by Fusarium species and M. nivale, except of white, pink or red colours.

Studies on in vitro growth and pathogenicity of European Fusarium fungi

The effect of temperature on the in vitro growth rates and pathogenicity of a European Fusarium collection consisting of isolates of Fusarium graminearum,F. culmorum,F. avenaceum, F. poae and Microdochium nivale was examined. Irrespective of geographic origin, the optimum temperature for the growth of F. graminearum, F. culmorum and F. poae was 25 °C, while that for F. avenaceum and M. nivale was 20 °C. In general, the growth rates of F. graminearum, F. culmorum and F. poae increased between 10 and 25 °C and those of F. avenaceum and M. nivale increased between 10 and 20 °C. Pathogenicity tests were carried out by examining the effect of the five species on the in vitro coleoptile growth rate of wheat seedlings (cv. Falstaff). Irrespective of geographic origin, the temperature at which F. avenaceum, F. culmorum and F. graminearum caused the greatest retardation in coleoptile growth ranges 20–25 °C (>89.3% reduction), whilst for F. poae and M. nivale it was 10–15 °C (>45.6% retardation), relative to uninoculated control seedlings. In general, F. culmorum and F. graminearum were the most pathogenic of the five species, causing at least a 69% reduction in coleoptile growth at 10, 15, 20 and 25 °C. General linear model analysis (GLIM) showed that species accounted for 51.3–63.4% of the variation in isolate growth and from 19.5% to 44.3% of the variation in in vitro pathogenicity. Country of origin contributed from 22.6% to 51.9% to growth rate variation and from 0.73% to 7.61% to pathogenicity variation. The only significant correlation between in vitro growth and pathogenicity was that observed for M. nivale at 15 °C (r = -0.803, P < 0.05).

Effects of temperature on the cell wall and osmotic properties in dark-grown rice and azuki bean seedlings.

The mechanism inducing the difference in growth rate under various temperature (10-50 degrees C) conditions was analyzed using rice and azuki bean seedlings. The growth rate of rice coleoptiles and azuki bean epicotyls increased as temperature increased up to 40 and 30 degrees C, respectively, and the elongation was retarded at a higher temperature. The cell wall extensibility of rice coleoptiles and azuki bean epicotyls also showed the highest value at 40 and 30 degrees C, respectively, and became smaller as the temperature rose or dropped from the optimum. The opposite tendency was observed in the minimum stress-relaxation time of the cell wall. On the other hand, the cellular osmotic concentration of rice coleoptiles and azuki bean epicotyls was lower at the temperature optimum for growth at 40 and 30 degrees C, respectively. When rice and azuki bean seedlings grown at 10, 20, 40, or 50 degrees C were transferred to the initial temperature (30 degrees C), the growth rate of coleoptiles and epicotyls was mostly elevated, concomitant with an increase in the cell wall extensibility. The growth rate was correlated with the cell wall mechanical parameters in both materials. These results suggest that the environmental temperature modulates the growth rate of plant shoots by affecting mainly the mechanical properties of the cell wall.

Stress-relaxation Analysis of Submerged and Air-grown Rice Coleoptiles: Correlations with Cell Wall Biosynthesis and Growth

Summary The growth rate of rice coleoptiles grown under water was decreased by exposure to air. In parameters of the stress-relaxation of cell walls, water-grown coleoptiles had a larger pre-extension time (Tp) and a smaller stress-relaxation rate (b) as compared with those exposed to air. Tp and b were significantly correlated with the growth rate of coleoptiles grown under different conditions. The amounts of cell wall components, such as hemicellulose, cellulose, diferulic acid (DFA) and ferulic acid (FA), in air-exposed coleoptiles increased rapidly as compared with those in submerged ones. When 7-h air-exposed seedlings were submerged again, the growth rate of re-submerged coleoptiles was still lower as compared with that of continuously submerged ones during the subsequent incubation under water. The decrease in Tp, the increase in b, and the increases in the amounts of those wall components by air-exposure were not completely recovered even when coleoptiles were re-submerged after 7h. There were close correlations between the amounts of cell wall components per unit length of coleoptile and Tp and b. These results indicate that Tp and b can represent the ability of rice coleoptiles to grow under different conditions and that those wall components are involved in determining Tp and b of cell walls.

Protective effect of exogenous nitrate on the mitochondrial ultrastructure ofOryza sativa coleoptiles under strict anoxia

The effect of exogenous KNO3, the terminal acceptor of electrons in oxygen-free medium, on mitochondrial ultrastructure and on the growth rate of 4-day-old rice coleoptiles under strictly anoxic conditions was studied. Exogenous nitrate (10 mM) did not exert any significant effect on the growth rate of coleoptiles of intact seedlings compared to their growth in KNO3-free medium. Anaerobic incubation of detached coleoptiles in KNO3-free medium for 48 h resulted in the complete destruction of mitochondrial and other cell membranes. In the presence of KNO3, no mitochondrial-membrane destruction was observed even after 48 h anoxia although the mitochondrial ultrastructure was modifed. Cristae were arranged in parallel rows and elongated dumbbell-shaped mitochondria appeared in some cells. The data obtained indicate a protective role of exogenous nitrate as electron acceptors in oxygen-free medium. The results of the present investigation are discussed and compared with reports of either markedly damaging or favorable effects of exogenous nitrate on the growth, metabolism, and energetics of rice and other plants under hypoxic and anoxic conditions.

Changes in amounts and molecular mass distribution of cell-wall polysaccharides of wheat ( Triticum aestivum L.) coleoptiles under water stress

Summary Polyethylene glycol (PEG)-induced water stress suppressed growth of wheat ( Triticum aestivum L.) coleoptiles. When PEG was removed, the growth rate of coleoptiles rapidly increased, and the length reached the same level as that of the unstressed coleoptiles. The amounts of cell-wall polysaccharides, such as hemi-cellulose and cellulose, per coleoptile increased under unstressed conditions as coleoptiles grew. The suppression of growth by water stress led to the reduction of the increases in the amounts of hemicellulose and cellulose. In response to the PEG removal, the increases in cell-wall polysaccharides recovered, and the amounts became close to those of unstressed coleoptiles. A close correlation was observed between the amounts of hemicellulose and cellulose and the length of coleoptiles. These results indicate that coleoptile cells keep their ability to grow even under water-stress conditions, and that cellulose and hemicellulose are produced in parallel with the cell elongation. The gel permeation chromatography of the hemicellulose fraction showed that PEG treatment reduced the increases in the amounts of middle and low molecularmass polysaccharides. However, the increases in high *nolecular-mass polysaccharides, such as β-glucans and arabinoxylans, were not affected by the suppression of growth. The synthesis of high molecular-mass portion of hemicellulosic polysaccharides seems to be related to preserving the ability of the cell walls to extend rather than to cell elongation.

A critical statistical study of experimental data on the effect of minute electric currents on the growth rate of the coleoptile of barley

A study of the effect of very minute electric currents on the rate of growth of the coleoptile of barley was published recently by one of us (F. G. G.) in collaboration. In this paper the mean rate of a number of control coleoptiles was compared with the mean rate of a number exposed to a minute electric discharge. The growth rate of individual coleoptiles showed, naturally, considerable divergences, so the mean result was in each case based on the observation of a large number of coleoptiles, the increments of growth of individual coleoptiles being stated as percentages of the rate of growth during the first hour of observation. It was assumed that the distribution of growth rates in a comparatively large sample of a pure-line barley would conform with the normal distribution; the probable errors of the mean results were therefore calculated in the ordinary way. During the continuation of this work positive results have been obtained in further experimental sets, but a number of these, though significant in the mass, were individually without significance. This suggested that a careful statistical study of the data on which the results were based might show how the accuracy of the method could be increased. Such a study has accordingly been undertaken, and it seems probable that methods employed are likely to be of use in the treatment of similar data.