Coleoptiles Of Wheat Seedlings Research Articles

Induction of Low Temperature Tolerance in Wheat by Pre-Soaking and Parental Treatment with Melatonin

Low temperatures seriously depress germination and seedling establishment in wheat and it is of great significance to explore approaches to improve wheat tolerance to low temperatures. In this study, the effects of seed pre-soaking and parental treatment with melatonin on seed germination and low temperature tolerance during the early growing stage in wheat were studied. The results showed that pre-soaking with melatonin increased the germination rate, improved antioxidant capacity and accelerated starch degradation under low temperature, which alleviated low temperature-induced damage to the chloroplasts in coleoptiles of wheat seedlings. Parental melatonin treatment during grain filling stage significantly decreased the grain weight. Seeds from parental melatonin-treated plants showed higher germination rates and higher antioxidant enzyme activity than the control seeds under low temperature. In addition, parental treatment with melatonin modulated the activities of carbohydrate metabolism enzymes, which contributes to enhanced low temperature tolerance in wheat offspring. It was suggested that both seed pre-soaking and parental treatment with melatonin could be the effective approaches for low temperature tolerance induction in wheat.

Estimation of dynamical changes in the superoxide anion radical producing rate and quantitative alterations of nucleic acid and protein synthesis in coleoptiles of wheat seedlings (Triticum aestivum L.)

Estimation of dynamical changes in the superoxide anion radical producing rate and quantitative alterations of nucleic acid and protein synthesis in coleoptiles of wheat seedlings (Triticum aestivum L.)

The effect of bioproducts on organically grown winter wheat

The study was aimed to examine the effect of the bioproducts Biokal 01 and Fitokondi on the germination of organically grown winter wheat (Triticum aestivum L.) cultivar ‘Širvinta 1’ seed and its contamination with microscopic fungi as well as the impact on the occurrence of foliar diseases, plant bio­metric indicators and grain quality. Laboratory analyses showed that the tested bioproducts did not exert any significant effect on seed vigour and germination. Fitokondi gave the highest efficacy against pathogens of seeds, its biological efficacy against Fusarium and Alternaria spp. fungi was 50.0% and against Penicillium spp. it was 20.0%. Biokal 01 statistically significantly reduced only grain contamination with Mucor spp. and Aspergillus spp. The bioproducts significantly decreased the incidence of crown rot diseases in the coleoptiles of wheat seedlings and roots. In the field conditions, the bioproducts did not have any significant effect on the incidence of Septoria leaf blotch (Mycosphaerella graminicola (Fuckel) J. Schröt. anamorph Zymoseptoria tritici (Desm.) Quaedvlieg & Crous) and tan spot (Helminthosporium tritici-repentis Died.). A significant increase in plant height and ear length, grain number per ear and 1000 grain weight was recorded. Grain yield increased by 0.66–0.79 t ha–1 or 18.64–22.32%, as well as protein, wet gluten and dry gluten content in response to both bioproducts.

Anthocyanins Participate in the Protection of Wheat Seedlings against Cadmium Stress

Due to anthropogenic activity, the environment is contaminated with high levels of cadmium, which is a dangerous heavy metal. At very low concentrations, cadmium is bioaccumulative and toxic to animals and plants, generating reactive oxygen species (ROS) that are destructive to cells of organisms. Anthocyanin pigments are natural antioxidants produced in various plant tissues and play a protective role under different environments. In the present study, the putative role of anthocyanins that accumulate in the grains and shoots of bread wheat (Triticum aestivum L.) in response to cadmium-induced toxicity (25 and 50 µM CdCl2) was studied at the seedling stage. For this purpose, a set of near-isogenic lines carrying different alleles of the Pp (purple pericarp) and Rc (red coleoptile) genes was used. The lines responded differently to Cd treatment. The observed changes in anthocyanin metabolism under stress conditions were dependent on the alleles of the Rc genes that determine coleoptile pigmentation and on CdCl2 concentration. In less-colored line carrying the Rc-A1 allele, the antioxidant system was unable to fully cope with oxidative stress and thus induced the synthesis of additional antioxidants, whereas in the most tolerant lines, which have dark-purple coleoptile pigmentation predetermined by Rc-A1 + Rc-D1, the level of anthocyanins in the coleoptiles was independent of stress. A protective role of anthocyanins presented in the coleoptiles of wheat seedlings was observed under moderate Cd stress (25 µM), whereas anthocyanins seemed to be ineffective as protective compounds under heavier stress.

CNG site-specific and methyl-sensitive endonuclease WEN1 from wheat seedlings

Endonuclease WEN1 with apparent molecular mass about 27 kDa isolated from cytoplasmic vesicular fraction of aging coleoptiles of wheat seedlings has expressed site specificity action. This is a first detection and isolation of a site-specific endonuclease from higher eukaryotes, in general, and higher plants, in particular. The enzyme hydrolyzes deoxyribooligonucleotides of different composition on CNG (N is G, A, C, or T) sites by splitting the phosphodiester bond between C and N nucleotide residues in CNG sequence independent from neighbor nucleotide context except for CCCG. WEN1 prefers to hydrolyze methylated λ phage DNA and double-stranded deoxyribooligonucleotides containing 5-methylcytosine sites (m(5)CAG, m(5)CTG) compared with unmethylated substrates. The enzyme is also able to hydrolyze single-stranded substrates, but in this case it splits unmethylated substrates predominantly. Detection in wheat seedlings of WEN1 endonuclease that is site specific, sensitive to the substrate methylation status, and modulated with S-adenosyl-L-methionine indicates that in higher plants restriction--modification systems or some of their elements, at least, may exist.

Effect of “External” Superoxide Anion on Apoptosis in Coleoptiles of Wheat Seedlings

A derivative of phthalic acid, dibutylphthalate (DBP), which has gametocidal effect at the concentration of approximately 10(-4) M, increased apoptosis in coleoptiles of wheat seedlings. This was associated with activation of chromatin margination and generation of mitochondria-containing vesicles. At the same concentration, DBP activated the release by the coleoptiles of superoxide anion into the environment. Lower (10(-5) M) and higher (10(-3) M) concentrations of DBP virtually had no effect on either process. A probable mechanism of effect of the "external" superoxide anion on apoptosis within the plant cell is discussed.

Effect of ethylene producer ethrel and antioxidant ionol (BHT) on the proteolytic apparatus in coleoptiles of wheat seedlings during apoptosis.

It was established that total proteolytic activity in etiolated wheat seedlings changes in ontogenesis in cycles: peaks of proteolytic activity correspond to the 3rd, 5th, and 8th days of seedling growth, respectively. The maximum of proteolytic activity preceded the maximum of nuclease activity, which may be due to activation of nucleases by proteolytic enzymes. According to inhibitory analysis the cysteine and serine proteases play the main role in apoptosis in wheat coleoptiles. Growing of seedlings in the presence of ethrel stimulated apoptosis in the coleoptile, and it increased (almost 6-fold) the proteolytic activity in its cells. On the other hand, the antioxidant ionol (BHT) suppressed the induction of proteases, particularly at the second stage of coleoptile development, and it slowed down the increase in the nuclease activity after 6th day of the seedling life. It is suggested that phytohormones and antioxidants participate in regulation of apoptosis in the ageing coleoptile, directly or indirectly effecting the proteolytic apparatus in the coleoptile cells.

Effect of the antioxidant ionol on proteolytic apparatus of aging coleoptiles of wheat seedlings grown in light

The dynamics of changes in total proteolytic activity and activities of various groups of proteases in the coleoptiles of 3- to 12-day-old wheat seedlings grown in light with and without antioxidant BHT (2,6-di-tert-butyl-4-methylphenol) was studied. It was established that the specialized proteases that easily hydrolyze specific synthetic substrates and the enzymes actively hydrolyzing histone H1 dominate in young coleoptiles of 3- to 4-day-old seedlings. Proteases that degrade equally well the majority of the studied substrates are accumulated in the cells of old coleoptiles of 11- to 12-day-old seedlings. Under the effect of BHT, the plants grown in light (in comparison with etiolated seedlings) demonstrated a somewhat changed dynamics of proteolytic activity in young coleoptiles and the disappearance of proteases active toward histone H1. An inhibitory analysis revealed a relative domination of cysteine proteases in young coleoptiles at the initial development stage of seedlings, whereas the fraction of serine proteases markedly increased in old coleoptiles. We presume that the revealed quantitative and qualitative changes in the proteolytic apparatus of the coleoptile cells induced by BHT may be largely responsible for the retardant and geroprotective effect of this antioxidant in plants.

Proline accumulation induced by weak acids and IAA in coleoptiles of wheat seedlings

Proline accumulation in coleoptiles of wheat seedlings or in excised coleoptile segments incubated under shaking for a 24 h period was studied. There was no increase of proline content of coleoptiles after incubation of the seedlings in 5 mM citric acid (a relatively strong and slowly penetrating organic acid) in a pH range from 4.5 to 7.0 and only a slight increase of proline content after incubation in phosphate buffer at pH 7.0 to 7.5 duo to the higher osmotic concentration of phosphate buffer in this pH range. Quite different results were obtained with seedlings incubated in 10 mM acetic acid, a weak and easily penetrating organic acid. With increasing proton concentrations, proline accumulation increased. Application of 400 mM mannitol or higher concentrations of IAA (more than 10−5M) additionally increased proline accumulation in the presence of 10 mM acetic acid in the pH range from 6.0 to 7.5 in which acetic acid alone was loss effective. It is suggested that a decrease of cytosolic pH causes stress—induced proline accumulation.