Metabolic changes in wheat (Triticum aestivum L.) plants under action of bioregulator stifun

Under action of growth-stimulating concentrations of bioregulator stifun on wheat plants, an increase of functional activity of nucleoli of meristematic cells; contents of lectin (wheat germ agglutinin); and activity of proteinases, tripsin inhibitors, and ATPase activity was established. The pool of free amino acids was increased under bioregulator use. Levels of methionine, phenylalanine, cysteine, lysine, and tyrosine were increased. It is likely that stifun could activate protein biosynthesis in wheat plants.     

The uptake,transport and metabolism of the bioregulator 2-(3,4-dichlorophenoxy) ethyldimethylamine in guayule

The bioregulator 2-(3,4-dichlorophenoxy) ethyldimethylamine was applied to five-month-old summer and winter guayule plants. Uptake of this molecule depended on the presence of viable trichomes and a well-developed cuticle, in the leaves. Winter plants absorbed the bioregulator more successfully than summer plants. The stem proved to be an active absorption site in young plants. Six days after bioregulator application, transport of the molecule was restricted to the lower stem in summer plants, and stem and leaves in winter plants. Transport was governed by the availability and development of conduits. The intact molecule was recovered two days after application but was not detectable after 4 and 6 days indicating that it is metabolized fairly rapidly. The significance of these findings is discussed in terms of the use of bioregulators to stimulate rubber production in guayule plants.     

Decreased lipolysis in peanuts by a pyridazinone bioregulator

Peanut,Arachis hypogaea, plants were treated in the field with the bioregulator BAS 105 00W, 4-chloro-5-dimethylamino-2-phenylpyridazin-3-one, a substituted pyridazinone, at different times of development. The seeds were harvested, dried, hand-shelled, and analyzed for lipoxygenase activity and conjugated diene hydroperoxide content. Reduced lipoxygenase activity occurred when the bioregulator was applied to the plants at flowering and pegging. The conjugated diene hydroperoxide content decreased the most in peanuts when the bioregulator was applied at pegging. The apparent K_m for lipoxygenase of treated peanuts with linoleic acid as substrate was the same as that for untreated peanuts.     

Decreased lipolysis in peanuts by a pyridazinone bioregulator

Peanut,Arachis hypogaea, plants were treated in the field with the bioregulator BAS 105 00W, 4-chloro-5-dimethylamino-2-phenylpyridazin-3-one, a substituted pyridazinone, at different times of development. The seeds were harvested, dried, hand-shelled, and analyzed for lipoxygenase activity and conjugated diene hydroperoxide content. Reduced lipoxygenase activity occurred when the bioregulator was applied to the plants at flowering and pegging. The conjugated diene hydroperoxide content decreased the most in peanuts when the bioregulator was applied at pegging. The apparent K_m for lipoxygenase of treated peanuts with linoleic acid as substrate was the same as that for untreated peanuts.     

Effect of <Emphasis Type="Italic">Pseudomonas</Emphasis> Bacteria on Peroxidase Activity in Wheat Plants when Infected with <Emphasis Type="Italic">Bipolaris sorokiniana</Emphasis>

We investigated the effect of treating soft wheat seeds (Triticum aestivum L.) with two Pseudomonas bacteria strains, isolated from earthworm coprolites, showing a significant antifungal and growth-promoting action in preliminary screening on the activity of guaiacol-dependant peroxidase under phytopathogenic load in the presence of Bipolaris sorokiniana (Sacc.) Shoemaker as a mechanism for inducing plant resistance to the pathogen. We established a statistically significant decrease (P < 0.05) in root rot disease incidence and severity during bacterization, which is indicative both of antifungal activity of the used bacterial isolates and of their successful colonizing the rhizosphere of wheat plants. We noted a response of free and weakly bound peroxidase of wheat plants to infection with B. sorokiniana: the enzyme activity increased during pathogenesis. Bacterization also increased peroxidase activity in plant leaves and roots, the greatest differences from non-bacterized plants being observed in wheat roots in the presence of the pathogen. We detected a direct link between peroxidase activity in wheat roots and leaf tissues in the absence of the pathogen and the feedback between peroxidase activity and plant infestation by the root rot pathogen. In the presence of the phytopathogen, there is a lack of correlation between peroxidase activity in wheat roots and leaves, and there is a shift of activity towards its increase in roots, which plays an important role in the development of systemic resistance against the root rot pathogen that penetrates into plants through the roots and root collar.     

Identification of a new bioregulator acting in ultralow doses in bulb onion (<Emphasis Type="Italic">Allium cepa</Emphasis> L.)

A bioregulator that has physicochemical and biological properties similar to a group of bioregulators isolated from various animal tissues has been found in the bulb onion (Allium cepa L.). It was determined that the biological action of the plant bioregulator is determined by a peptide with molecular weight of 4036 ± 2 Da whose 18-C-terminal amino acid sequence consisted of 18 residues. On models of seed germination of some vegetable cultures, the ability of the bioregulator isolated from supernatant of onion extract in ultralow doses (10⁻¹³ mg of protein/ml) to inhibit growth and development was demonstrated.     

Structural-functional characteristics of a new bioregulator isolated from bovine pigmented epithelium tissue

A new bioregulator operating in ultralow doses corresponding to 10^?17 mg/ml has been isolated from tissue of pigmented epithelium of bovine eyes. It has been established that the functional basis of this bioregulator is a complex of a low molecular weight regulatory peptide (4372 Da) and a modulator consisting of a mixture of proteins with molecular weights of 14.980–66.283 kDa. It has been shown that the regulatory peptide is responsible for membranotropic activity of the bioregulator, and the modulator proteins are responsible for biological action in ultralow doses. The data demonstrate an interrelation between nanocondition of the bioregulator and its ability to show activity in ultralow doses.     

Bioregulator from rat liver tissue

It has been shown that the membranotropic homeostatic tissue-specific bioregulator isolated from rat liver tissue contains a nanosized peptide-protein complex consisting of low-molecular peptides (1–6.5 kDa) and a protein from the serum albumin family. This bioregulator modulated the peptide biological activity and determined the tissue specificity.     

Ammonia-excreting mutant strain of the cyanobacterium Anabaena variabilis supports growth of wheat

Summary Growth of wheat in a nitrogen-free hydroponic co-culture with a mutant strain of the cyanobacterium Anabaena variabilitis (strain SA-1) was enhanced over plants grown with the parent strain SA-0. This increase was achieved in the dry weight, grain yield, and total nitrogen content of the plants. Nitrogenase activity of the mutant strain SA-1 was increased in a co-culture of the cyanobacterial mutant with wheat plants compared to the activity of the wild-type strain in association with wheat. Offprint requests to: M. Gunasekaran     

NaHSO3对盐胁迫下小麦幼苗氮同化酶及脯氨酸含量的影响

以普通小麦(Triticum aestivumL.)为材料,研究了NaHSO3对不同盐度胁迫下小麦幼苗氮素同化酶和脯氨酸含量的调节。结果表明,盐胁迫降低了叶片中硝酸还原酸(NR)的活性,加入NaHSO3之后,NR活性表现出进一步的降低。谷氨酰胺合成酶(GS)在低浓度盐胁迫下活性增加,在高浓度盐胁迫下活性降低;NaHSO3加入时,即便在低盐浓度下GS活性也降低。依赖于NADH的谷氨酸脱氢酶(NADH-GDH)和依赖于NADP的异柠檬酸脱氢酶(NADP-ICDH)的变化趋势一致,在盐胁迫下它们的活性都明显增加;NaHSO3加入促进了它们活性的进一步增加,尤其对NADH-GDH活性的促进更为明显。游离脯氨酸在高浓度盐胁迫下大量积累,在低浓度盐胁迫下含量增加不明显;NaHSO3促进了盐胁迫下脯氨酸的积累,提示了NaHSO3促进了盐胁迫下小麦幼苗碳氮营养元素的贮存。     

The effect of humic acid on transamination in winter wheat plants

A very low, for the most part unmeasurable glutamic-aspartio transminase activity and a very high glutamic-alanine transaminase activity was found in the overground parts and roots of young wheat plants. The roots had a higher glutamic-alanine transaminase activity than the overground parts in the first and second leaf stage. Plants cultivated in Knop’s nutrient solution (variant with humate and without) showed a higher glutamic-alanine transaminase activity than poorly growing plants, cultivated in distilled water (with humate and without). In plants cultivated in nutrient solutions, transaminase activity increased with the age of the wheat plants. As in the previous experiments, the effect of humate was only significant, in the roots of plants cultivated in distilled water with humate, where transamination activity was greater than in the control without humate. The roots of this variant with a stimulatory growth effect showed a large accumulation of free sugars in the previous experiments. The connection between these effects of humate on the roots of young winter wheat plants is discussed.     

Helicoverpa armigera (Hübner): can wheat stubble protect cotton plants against attack?

Abstract  When investigating strategies for Helicoverpa armigera (Hübner) control, it is important to understand oviposition behaviour. Cotton ( Gossypium hirsutum ) was sown into standing wheat ( Triticum astivum L.) stubble in a closed arena to investigate the effect of stubble on H. armigera moth behaviour and oviposition. Infrared cameras were used to track moths and determine whether stubble acted as a physical barrier or provided camouflage to cotton plants, thereby reducing oviposition. Searching activity was observed to peak shortly before dawn (03:00 and 04:00 h) and remained high until just after dawn (4 h window). Moths spent more time resting on cotton plants than spiralling above them, and the least time flying across the arena. While female moths spent more time searching for cotton plants growing in wheat stubble, the difference in oviposition was not significant. As similar numbers of eggs were laid on cotton plants with stubble (3.5/plant SE ±0.87) and without stubble (2.5/plant SE ±0.91), wheat stubble does not appear to provide camouflage to cotton plants. There was no significant difference in the location of eggs deposited on cotton plants with and without stubble, although more eggs were laid on the tops of cotton leaves in wheat stubble. As the spatial and temporal distribution of eggs laid on the cotton plant is a crucial component of population stability, eggs laid on the upper side of leaves on cotton plants may be more prone to fatalities caused by environmental factors such as wind and rain. Therefore, although stubble did not influence the number of eggs laid, it did affect their distribution on the plant, which may result in increased mortality of eggs on cotton plants sown into standing wheat stubble.     

Exogenous Ca<Superscript>2+</Superscript> alleviates nitrogen and water deficit,and improves growth of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) seedlings exposed to high temperature

This study was designed to examine whether exogenous Ca²⁺ would improve nitrogen nutrition, water status and growth of high temperature (HT)-stressed wheat (Triticum aestivum) seedlings. Wheat plants were exposed to 35/30 and 25/20°C as temperature control. Some of HT-stressed plants were simultaneously treated with 4 mM Ca²⁺. External Ca²⁺ could obviously improve growth of HT-exposed wheat seedlings indicated by the biomass. Compared with Ca²⁺-untreated plants, total nitrogen content showed a significant increase in Ca²⁺-treated plants under HT stress, this primarily resulted from enhanced nitrate reductase activity and depressed loss of ammonium through photorespiration. External Ca²⁺ application could also increase leaf relative water content and alleviate osmotic stress via increased K⁺ ion and water-soluble carbohydrates in HT-stressed plants. Whereas free proline content showed remarkable decline in Ca²⁺-treated plants at HT stress.     

Characterization of inhibitor(s) of β-glucuronidase enzyme activity in <Emphasis Type="Italic">GUS</Emphasis>-transgenic wheat

The uidA gene, encoding for β-glucuronidase (GUS), is the most frequently used reporter gene in plants. As a reporter enzyme, GUS can be assayed both qualitatively and quantitatively. In wheat, there are numerous reports of failure in detecting GUS enzyme activity in tissues of transgenic plants, while other reports have suggested presence of β-glucuronidase inhibitor(s) in wheat tissues. In the present study, we show that the β-glucuronidase enzyme activity is not only tissue-specific but also genotype-dependent. Our data demonstrate that the glucuronic acid could be the candidate inhibitor for β-glucuronidase enzyme activity in wheat leaves and roots. It should be noted that the assays to detect β-glucuronidase enzyme activity in wheat should be interpreted carefully. Based on the data of our present study, we recommend studying the chemical pathways, the unintended effects and the possible loss-of-function of any candidate transgene prior to transformation experiments.     

Ovary co-culture improves embryo and green plant production in anther culture of Australian spring wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

A simple anther culture protocol for Australian spring wheat cultivars was developed using ovary co-culture. The inclusion of ovaries in the induction medium significantly increased the production of embryo-like structures (ELS), green and albino plants in two spring wheat cultivars tested. When five ovaries were added to the induction medium, the mean number of ELS per spike increased from 7.6 to 50.1 and green plants per spike increased from 0.6 to 8.9. The addition of 10 ovaries, however, did not further increase the production of ELS or green plants. The growth regulator combination of 2,4-D and KIN was compared with IAA and BA. There were no significant differences in the numbers of ELS or green plants although significantly fewer albino plants were produced with IAA and BA. Eight additional cultivars were screened using the protocol with either 5 or 10 ovaries in the induction medium. Green plants were obtained from nine varieties at frequencies ranging from 0.3 to 33.0 green plants per spike. Regenerant plants at maturity exhibited chromosome fertility rates in different cultivars ranging from 15% to 100%.     

Significance of<Emphasis Type="Italic">Herbaspirillum seropedicae</Emphasis> inoculation and/or straw amendment on growth and dinitrogen fixation of wheat using<Superscript>15</Superscript>N-dilution method

The effect of Herbaspirillum seropedicae inoculation and/or maize straw (0, 5 and 10 Mg/hm2) amendment on the growth and N2 fixation of wheat was determined in pot experiments using 15N-dilution method. Inoculation resulted in accumulation of fixed nitrogen, and % N from atmosphere being 24.6 and 26.5% in wheat shoot and grain, respectively. Straw amendment reduced % Natm to 16.1 and 20.2% at high straw level (10 Mg/hm2). Rational nitrogen fertilization (180 kg N/hm2) completely inhibited N2 fixation by H. seropedicae inoculation. Bacterial inoculation increased dry shoot and grain yield up to 23 and 31%, respectively. The highest levels of shoot and grain dry mass (46.5 and 42.4%) were obtained by N-fertilization in both inoculated and uninoculated plants. Total shoot and grain N-yield increased irrespective of organic matter amendment by inoculation up to 9 and 25%, respectively. N-fertilized plants recorded a maximum increase in N-yield (57 and 51%). H. seropedicae was reisolated from inoculated wheat histosphere after harvesting (90 d from sowing). Neither organic matter nor mineral nitrogen applications had any marked effect on bacterial total counts colonizing wheat histosphere. Moreover, no symptoms of mottled stripe disease were observed on leaves and stems of inoculated plants.     

Impact of aggressiveness of <Emphasis Type="Italic">Fusarium graminearum</Emphasis> and <Emphasis Type="Italic">F. culmorum</Emphasis> isolates on yield parameters and mycotoxin production in wheat

Plant-associated isolates from Fusarium graminearum and F. culmorum were inoculated on wheat in field experiments in 2007 and 2008 to ascertain their influence on fungal colonization of the ears, as well as mycotoxin contamination (deoxynivalenol, DON; nivalenol, NIV; zearalenone, ZEA) and yield parameters in the mature crop after inoculation with or without irrigation. The isolates were assigned to four different groups of aggressiveness on the basis of pathogenic symptom development and mycotoxin production in vitro. Increased levels of trichothecene-producing Fusarium DNA in the ears indicated a successful inoculation of the plants, which resulted in increased DON content in the wheat kernels in 2007. Dry conditions at anthesis markedly suppressed fungal colonization as well as mycotoxin accumulation. However, due to precipitation during the ripening period, yield and thousand-kernel weight were similar whether or not irrigation was applied at the time of inoculation. The level of aggressiveness among the isolates as determined in vitro was not reflected in the field experiment. The activity of the extracellular invertase in developing ears increased as a plant response to pathogen infection, especially when the plants were irrigated at the time of inoculation. In 2008, the Fusarium inoculation of wheat heads did not cause fungal growth and mycotoxin contamination in the grain, because of the dry weather conditions that occurred over the entire period of anthesis and ripening. The risk of future mycotoxin contamination in grains was discussed based on climate change prognosis.     

根瘤菌在小麦与紫云英混作中的作用

采用盆钵实验,在小麦与紫云英混作系统中,通过对紫云英接种根瘤菌,研究了小麦与紫云英生长过程中植株生长、植株生物量、植株与土壤氮素变化情况及根瘤菌的酶活性．结果表明,在有根瘤菌接种的混作体系中,植株的生长得到促进,植株及土壤全氮均有增加,酶活性比单作也有所提高．     

Change in the activity of lectins in cell structure of winter wheat crown under the action of low-temperature hardening and fusicoccin

Haemagglutinating activity was determined in cell walls and total cell organelles of crown cells of Winter wheat (Triticum aestivum L. ) plants. The effect of fusicoccin (FC) was investigated using fractions obtained from plants hardened for 7 days at 2 degrees C and from untreated plants. FC concentration (5x10(-7) m) increased the frost resistance of the plants. The temporal pattern of lectin activity during hardening could be described by a single-peak curve. In the cell wall fraction, the highest activity manifested itself after one-day hardening, and in the fraction of organelles it peaked after five-days hardening. The carbohydrate specificity of lectins also changed during hardening; cell wall lectins completely lost their capacity for interaction with uridine diphosphoglucose, glucose 6-phosphate, D-galactosamine, and N-acetylglucosamine and the lectins of organelles retained some affinity only for amino sugars. After hardening the test plants, the activity of the lectins increased substantially in the cell walls and plastids, decreased in the nuclei, and was practically flat in mitochondria and microsomes. Consequently, low temperature and FC with their antistress effect improved frost resistance and stimulated the activity of the lectins of some cell structures of the tillering node of winter wheat. A similar action of low temperature and FC in increasing the activity of lectins of plastids was found. Further information was obtained on the subcellular localization of lectins providing additional information on their possible participation in the development of frost resistance of winter wheat.     

Drought tolerance and proteomics studies of transgenic wheat containing the maize C<Subscript>4</Subscript> phosphoenolpyruvate carboxylase (<Emphasis Type="Italic">PEPC</Emphasis>) gene

Enhancing drought tolerance of crops has been a great challenge in crop improvement. Here, we report the maize phosphoenolpyruvate carboxylase (PEPC) gene was able to confer drought tolerance and increase grain yield in transgenic wheat (Triticum aestivum L.) plants. The improved of drought tolerance was associated with higher levels of proline, soluble sugar, soluble protein, and higher water use efficiency. The transgenic wheat plants had also a more extensive root system as well as increased photosynthetic capacity during stress treatments. The increased grain yield of the transgenic wheat was contributed by improved biomass, larger spike and grain numbers, and heavier 1000-grain weight under drought-stress conditions. Under non-stressed conditions, there were no significant increases in these of the measured traits except for photosynthetic rate when compared with parental wheat. Proteomic research showed that the expression levels of some proteins, including chlorophyll A-B binding protein and pyruvate, phosphate dikinase, which are related to photosynthesis, PAP fibrillin, which is involved in cytoskeleton synthesis, S-adenosylmethionine synthetase, which catalyzes methionine synthesis, were induced in the transgenic wheat under drought stress. Additionally, the expression of glutamine synthetase, which is involved in ammonia assimilation, was induced by drought stress in the wheat. Our study shows that PEPC can improve both stress tolerance and grain yield in wheat, demonstrating the efficacy of PEPC in crop improvement.