Yeast polysaccharide affects fusaric acid content in maize root rot

Protective action of sulfoethyl glucan (SEG), a derivative of the cell wall glucan prepared from the baker's yeast Saccharomyces cerevisiae, was investigated in the maize seedlings infected by a plant pathogen Fusarium verticillioides (Sacc.). Several markers were assayed with the SEG addition and in the control experiments. Two evaluations were performed on the 7th and the 14th days. Addition of SEG led to the increased productivity parameters of the infected plants and maintained them at the level of non-infected plants during the 14 days of experiment. After seven days of cultivation, concentration of fusaric acid (=5-butylpyridine-2-carboxylic acid; FA) decreased in all infected plants cultivated in the presence of SEG when compared to that detected in the infected plants grown in the absence of SEG. After 14 days of cultivation, polysaccharide addition resulted in the reduction of FA concentration almost to 75% in comparison to the infected plants grown without polysaccharide addition. In the experiment, when exogenous FA was added to the growth medium, its concentration decreased up to 60% in the presence of SEG. Thus, it is feasible to assume that SEG binds and adsorbs FA, and, in this way, reduces its content and exerts protective action in plants against its toxic effect.     

Root distribution and morphology of maize seedlings as affected by tillage and fertilizer placement

Suboptimal soil conditions are known to result in poor early growth of maize (Zea mays L.) in no-tillage (NT) systems in contrast with conventional tillage (CT) systems. However, most studies have generally focused on maize roots at later growth stages and/or do not give details on root morphology. In a 2-year field study at two locations (silt loam and loam soils) in the Swiss midlands, we investigated the impacts of tillage intensity, NT vs. CT, and NP-fertilizer sidebanding on the morphology, vertical and horizontal distribution, and nutrient uptake of maize roots at the V6 growth stage. The length density (RLD) and the length per diameter-class distribution (LDD) of the roots were determined from soil cores taken to a depth of 0.5 m and at distances of 0.05 and 0.15 m from both sides of the maize row. The temperature of the topsoil was lower, and the bulk density and penetration resistance were greater in the topsoil of NT compared with CT. The growth and the development of the shoot were slower in NT. RLD was greater and the mean root diameter smaller in CT than in NT, while the vertical and horizontal distribution of roots did not differ between CT and NT. RLD increased in the zone enriched by the sidebanded fertilizer, independent of the tillage system, but LDD did not change. The poorer growth of the roots and shoots of maize seedlings was presumably caused by the lower topsoil temperature in NT rather than by mechanical impedance. The placement of a starter fertilizer at planting under NT is emphasized.     

水肥耦合对玉米籽粒全氮含量的影响

采用四因素五水平(1/2实施)二次通用旋转组合设计,选取灌水、施氮肥、施磷肥和秸秆覆盖四因素作为试验因素,在辽西半干旱区褐土农田进行了水肥耦合效应长期定位试验。按照二次通用旋转组合设计统计分析方法建立回归模型,分析了水肥耦合对玉米籽粒全氮含量的影响。结果表明:水肥单因子对籽粒全氮的含量有较明显的影响,影响顺序为施氮秸秆覆盖施磷灌水;当灌水量为700m3.hm-2、施氮量为180kg.hm-2、施磷量为120kg.hm-2和秸秆覆盖量为7500kg.hm-2时,它们每个因素对玉米籽粒全氮含量的影响都集中11.7g·kg-1,此时籽粒蛋白质含量为73g·kg-1,产量为12000kg.hm-2,表明该处理组合下,玉米的经济效益和生态效益达到最佳,推荐生产上以此进行施肥。     

Toxic levels of soil and plant zinc for maize and wheat

Summary Maize and wheat crops grown for 60 days and maturity respectively in soils with a range of available zinc (0.4 to 109 ppm DTPA extractable) indicated 7 ppm Zn in soil and 60 ppm in plant being toxic for wheat. These limits for maize were 11 ppm Zn in soil and 81 ppm Zn in plant. Wheat crop is more susceptible to Zn toxicity as compared to maize.     

Nitrogen placement at sowing affects root growth,grain yield formation,N use efficiency in maize

Plant and Soil - DNA methylation is an important form of epigenetic modification. It has a vital role in regulating plant growth and development, and also participates in plant response to various...     

Soil-sodicity-induced zinc deficiency in maize

Summary Maize (Zea mays L. cv. Ganga-2) plants were grown in pot culture on a loamy alluvial soil of Lucknow district (India) alkalinized to graded levels of ESP (Exchangeable Sodium Percentage) ranging from 15.5 to 55.3. Before sowing maize seeds the soil was fertilised with NPK, Fe, Mn and Cu. At and above ESP 34 Zn-deficiency symptoms first appeared at 30 days. The symptoms gradually became pronounced with increase in age and at 60 days they were found even at ESP 15.5. The severity of symptoms was related to increase in sodicity. Alkalinization of soils depressed available soil Zn and tissue Zn and increased tissue ratios of Na/Zn and P/Zn. It also decreased the total plant content of Zn, Fe, Mn, Cu and even Na. Increase in soil sodicity increased both tissue concentration and total content of P in plants upto ESP 34 beyond which it decreased it. Among different extractants, 0.1N HCl, DTPA pH 7.3 and EDTA-(NH₄)₂ CO₃ pH 8.6, for measuring available soil Zn the latter showed best correlations with soil ESP (−), tissue P (−), P/Zn ratio (−), dry matter yield (+) and tissue Zn (+). Tissue Zn was related to yield (+), tissue Na (−) and soil ESP (−). Mild, moderate, severe and very severe Zn deficiency in maize was induced by soil ESP levels, 18, 25, 33 and 45, respectively.     

Manganese deficiency in maize affects pollen viability

Maize (Zea mays L. cv. G2) was grown with 0.55 mg L^–1 (sufficient), or 0.0055 mg L^–1 (deficient) manganese in sand. Manganese-deficient plants developed visible deficiency symptoms and showed poor tasseling and delayed anther development. Compared to Mn-sufficient plants, Mn-deficient plants produced fewer and smaller pollen grains with reduced cytoplasmic contents. Manganese deficiency reduced in vitro germination of pollen grains significantly. Ovule fertility was not significantly affected by Mn. But in Mn-deficient plants seed-setting and development was reduced significantly.     

Zinc content in lymphocytes and the activity of zinc ion efflux from lymphocytes in primary arterial hypertension

Clinical observations and experimental data show that zinc (Zn) plays a role in regulating arterial blood pressure and in arterial hypertension etiopathogenesis. To determine the direction of changes in Zn metabolism in primary arterial hypertension, Zn absorption from the alimentary tract, Zn levels in blood serum, its content in lymphocytes, Zn efflux rate constants from lymphocytes, and urinary Zn excretion in patients with hypertension and in healthy subjects were studied. In this article, Zn levels in blood serum, its content in lymphocytes, and Zn efflux rate constants from lymphocytes are presented. In primary arterial hypertension, on the basis of this study, decreasing Zn levels in blood serum and its decreasing content in lymphocytes were found. The Zn efflux rate constants from lymphocytes increased at the initial stage of hypertension (mild arterial hypertension) and decreased in the late stage of the hypertension disease (severe arterial hypertension). Taking into consideration all of the directions of changes and the fact that Zn can be a factor that increases arterial blood pressure, the changes in Zn distribution can be regarded as having, to a certain extent, a protective character leading to weakening of the pressor reaction, assuming a genetic existence of relative or absolute Zn excess in the body. The changes of Zn distribution can lead, after some time, to Zn deficiency and the resulting metabolic changes (e.g., carbohydrate intolerance).     

Nystatin affects zinc uptake in human fibroblasts

The mechanism(s) by which zinc is transported into cells has not been identified. Since zinc uptake is inhibited by reducing the temperature, zinc uptake may depend on the movement of plasma membrane micoenvironments, such as endocytosis or potocytosis. We investigated the potential role of potocytosis in cellular zinc uptake by incubating normal and acrodermatitis enteropathica fibroblasts with nystatin, a sterol-binding drug previously shown to inhibit potocytosis. Zinc uptake was determined during initial rates of uptake (10 min) following incubation of the fibroblasts in 50 μg nystatin/mL or 0.1% dimethyl-sulfoxide for 10 min at 37°C. The cells were then incubated with 1 to 30 μM ⁶⁵zinc. Michaelis-Menten kinetics were observed for zinc uptake. Nystatin inhibited zinc uptake in both the normal and AE fibroblasts. Reduced cellular uptake of zinc was associated with its internalization, not its external binding. In normal fibroblasts, nystatin significantly reduced theK _m 56% and theV _max 69%. In the AE fibroblasts, nystatin treatment significantly reduced theV _max 59%, but did not significantly affect theK _m. The AE mutation alone affected theV _max for cellular zinc uptake. The control AE fibroblasts exhibited a 40% reduction inV _max compared to control normal fibroblasts. We conclude that nystatin exerts its effect on zinc uptake by reducing the velocity at which zinc traverses the cell membrane, possibly through potocytosis. Furthermore, the AE mutation also effects zinc transport by reducing zinc transport.     

The maize Brown midrib1 locus affects cell wall composition and plant development in a dose-dependent manner

The four brown midrib (bm) mutants of maize have a reduced content and altered subunit composition of the cell wall polymer lignin. The bm mutations have traditionally been considered completely recessive, because the brown midrib phenotype is only apparent in plants homozygous for the mutation. In addition to an effect on cell wall composition, some bm mutations have been shown to affect flowering time. We had preliminary evidence for a dosage effect of the Bm1 locus on flowering time, which prompted this detailed study on the Bm1 locus. In this study, near-isogenic lines (in an A619 background) with zero, one or two bm1 mutant alleles were compared. The bm1 heterozygotes flowered significantly earlier than both the wild-type plants and bm1 mutants. This difference can at least be partly attributed to an accelerated growth rate in the later stages of plant development. Furthermore, Fourier transform infrared spectroscopy revealed that the cell wall composition of the bm1 heterozygous plants is distinct from both the bm1 and wild-type homozygotes. The combination of the data on flowering time and the data on cell wall composition provide evidence for a dosage effect at the Bm1 locus.     

Zinc availability from zinc lipoate and zinc sulfate in growing rats

The purpose of this study was to investigate the effect of zinc lipoate and zinc sulfate on zinc availability in growing rats. 6 . 6 male albino rats were fed purified diets based on corn starch, egg albumen, sucrose, soy bean oil and cellulose over a 4-week period (diet Ia: 10 mg Zn/kg as zinc sulfate, diet Ib: 10 mg Zn/kg as zinc lipoate, diet IIa: 10 mg Zn/kg as zinc sulfate +0.4% phytic acid, diet IIb: 10 mg Zn/kg as zinc lipoate +0.4% phytic acid, diet IIIa: 20 mg Zn/kg as zinc sulfate + 0.4% phytic acid, diet IIIb: 20 mg Zn/kg as zinc lipoate + 0.4% phytic acid). Zinc lipoate and zinc sulfate both proved to be highly available zinc sources. When 0.4% phytic acid were present in the diets, apparent zinc absorption was generally depressed but was higher from zinc lipoate in tendency than from zinc sulfate. Comparable results were evident for femur zinc, plasma zinc and metallothionein concentrations in liver tissues. This indicates that zinc lipoate could be a valuable zinc source under conditions of low zinc availability. Nevertheless the absence or presence of phytic acid was a more important factor influencing zinc availability than the type of zinc source investigated.     

Zinc coordination sphere in biochemical zinc sites

Zinc is known to be indispensable to growth and development and transmission of the genetic message. It does this through a remarkable mosaic of zinc binding motifs that orchestrate all aspects of metabolism. There are now nearly 200 three dimensional structures for zinc proteins, representing all six classes of enzymes and covering a wide range of phyla and species. These structures provide standards of reference for the identity and nature of zinc ligands in other proteins for which only the primary structure is known. Three primary types of zinc sites are apparent from examination of these structures: structural, catalytic and cocatalytic. The most common amino acids that supply ligands to these sites are His, Glu, Asp and Cys. In catalytic sites zinc generally forms complexes with water and any three nitrogen, oxygen and sulfur donors with His being the predominant amino acid chosen. Water is always a ligand to such sites. Structural zinc sites have four protein ligands and no bound water molecule. Cys is the preferred ligand in such sites. Cocatalytic sites contain two or three metals in close proximity with two of the metals bridged by a side chain moiety of a single amino acid residue, such as Asp, Glu or His and sometimes a water molecule. Asp and His are the preferred amino acids for these sites. No Cys ligands are found in such sites. The scaffolding of the zinc sites is also important to the function and reactivity of the bound metal. The influence of zinc on quaternary protein structure has led to the identification of a fourth type of zinc binding site, protein inteface. In this case zinc sites are formed from ligands supplied from amino acid residues residing in the binding surface of two proteins. The resulting zinc site usually has the coordination properties of a catalytic or structural zinc binding site.     

The effect of local application of fertilizer on the content of cytokinins in the xylem sap of maize

Cytokinin content in xylem sap was higher in plants grown under local supply of fertilizers as compared to those grown under homogenous distribution of nutrients in soil. The separate assay of cytokinins in xylem exudate from split root system showed that roots, which were in contact with fertilizer mainly contributed to cytokinins transported from roots to shoots. This revised version was published online in July 2006 with corrections to the Cover Date.     

Soil fertility management effects on maize productivity and grain zinc content in smallholder farming systems of Zimbabwe

Biochar is produced as a by-product of the low temperature pyrolysis of biomass during bioenergy extraction and its incorporation into soil is of global interest as a potential carbon sequestration tool. Biochar influences soil nitrogen transformations and its capacity to take up ammonia is well recognized. Anthropogenic emissions of ammonia need to be mitigated due to negative environmental impacts and economic losses. Here we use an isotope of nitrogen to show that ammonia-N adsorbed by biochar is stable in ambient air, but readily bioavailable when placed in the soil. When biochars, containing adsorbed ¹⁵N labelled ammonia, were incorporated into soil the ¹⁵N recovery by roots averaged 6.8% but ranged from 26.1% to 10.9% in leaf tissue due to differing biochar properties with plant ¹⁵N recovery greater when acidic biochars were used to capture ammonia. Recovery of ¹⁵N as total soil nitrogen (organic+inorganic) ranged from 45% to 29% of ¹⁵N applied. We provide a proof of concept for a synergistic mitigation option where anthropogenic ammonia emissions could be captured using biochar, and made bioavailable in soils, thus leading to nitrogen capture by crops, while simultaneously sequestering carbon in soils.     

Zinc content in organs of dogfish (Scyliorhinus canicula L.) subject to sublethal experimental aquatic zinc pollution

1. Zn content of liver, pancreas, spleen, kidney, and muscle of zinc-treated and untreated dogfish were analysed.2. Liver and spleen accumulate Zn after 14 days of treatment; liver, spleen and pancreas, after 25 days.3. According to the Wilcoxon test, liver Zn accumulation was significantly higher than spleen at 14 days. The pancreas accumulate significantly more Zn than liver and spleen at 25 days.4. Comparing the results with our work on the effect of Zn in gills, we conclude that when working in sublethal conditions (15 ppm) Zn toxicity would be bound to organs injury.     

Zinc treatment affects superoxide dismutase activity in growth retardation

Children with growth dysfunction present complex diagnostic challenges. The purpose of this study was to determine the effects of oral zinc treatment on red cell copper/zinc superoxide dismutase (Cu/Zn-SOD) activity and copper and zinc concentrations in children with “growth retardation.” Twenty-nine patients, average age of 11 yr, whose percentile was under 3% of the National Center of Health Statistics parameters were selected. For the control group, 10 children whose average age was 10 yr were included. Red cell Cu/Zn-SOD activity was determined by spectrophotometer. Red cell copper and zinc concentrations were measured by atomic absorption spectrophotometer. Red cell Cu/Zn-SOD activity was higher than the control group before zinc treatment (p<0.001). There was a decrease in the Cu/Zn-SOD activity after zinc treatment, but the mean value of the Cu/Zn-SOD activity of patients was still higher than the control values (p<0.001). After zinc treatment, there was an increase in red cell zinc concentration (p<0.01) and a decrease in copper concentration (p<0.001), which were statistically significant. The results of this study suggested that Cu/Zn-SOD activity was increased significantly during growth retardation and zinc treatment appeared to ameliorate the enzyme activity. There were also insignificant alterations in red cell copper and zinc concentrations. Presented at the 23rd Congress of Endocrinology and Metabolic Diseases of Turkey Joint Meeting with the European Federation of Endocrine Societies, Bilkent Hotel, Ankara, 7–9 September, 2000.     

Soil heterogeneity affects ramet placement of Hydrocotyle vulgaris

Aims Soil heterogeneity is common in natural habitats. It may trigger foraging responses (placing more ramets and/or roots in nutrient-rich patches than in nutrient-poor patches) and further affect the growth of plants. However, the impact of soil heterogeneity on competitive interactions has been little tested.Methods We conducted a greenhouse experiment to investigate the effects of soil heterogeneity on intraspecific competition with a stoloniferous herb Hydrocotyle vulgaris. We grew one (without competition) or nine ramets (with competition) of H. vulgaris under a homogeneous environment and two heterogeneous environments differing in patch size (large or small patches). In the heterogeneous treatment, the soil consisted of the same number of nutrient-rich and nutrient-poor patches arranged in a chessboard manner, and in the homogeneous treatment, the soil was an even mixture of the same amount of the nutrient-rich and the nutrient-poor soil.Important findings Irrespective of intraspecific competition, H. vulgaris showed foraging responses to soil heterogeneity in the large patch treatment, e.g. it produced significantly more biomass, ramets, aboveground mass and root mass in the nutrient-rich patches than in the nutrient-poor patches. In the small patch treatment, foraging responses were observed when intraspecific competition was present, but responses were not observed when there was no competition. However, we find a significant effect of soil heterogeneity on neither overall growth nor competitive intensity of H. vulgaris. Our results suggest that foraging responses to soil heterogeneity may not necessarily be adaptive and intraspecific competition may not be influenced by soil heterogeneity.     

Variation of DIMBOA and related compounds content in relation to the age and plant organ in maize

We report the variation of all 1,4-benzoxazin-3-one derivatives content detectable in maize with plant age in roots and aerial parts. Our results show that the concentration of hydroxamic acids, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc) and its 8-methoxylated analogue (DIM2BOA-Glc) is high after seed germination and then decreases with plant age. Nevertheless, these compounds continue to be biosynthesised during 6-10 days after germination. Variation in concentration of N-O-methylated DIMBOA-Glc (HDMBOA-Glc) is similar to the one of hydroxamic acids in aerial parts. On the contrary, in roots, its concentration remains relatively stable with plant age. After 10 days, HDMBOA-Glc becomes the main compound in roots. This compound is also present in higher concentration than hydroxamic acids in the oldest leaf of 20-day-old maize. The presence of four other DIMBOA related compounds in maize plants depends on variety, age and tissue. The role of these compounds in plant resistance to aphids is discussed.