Patulin effects on wheat plants in field treatments

Summary Fall field patulin applications (500 µg/g of soil) to Cheyenne winter wheat seedlings at growth stages 0, 1, and 2, decreased germination, plant growth, winter survival, and tillering. Decreased tillering decreased the number of heads and grain yield. Spring patulin application of 250 and 500 µg/g of soil to wheat at growth stages 6, 7, 8, 9, and 10 decreased yields by decreasing the number of heads, kernels per head, and kernel weight. With fall patulin applications, yields were decreased more when patulin was applied near seeding. Spring patulin applications to wheat during sensitive heading stages decreased yield the most.Stages of wheat growth especially susceptible to patulin are the germination, stem-elongation, and flowering, which occur during the fall and spring when soil Penicillium urticae Bainier numbers are maximun and patulin has been extracted from the soil.Contribution from the Soil, Water, and Animal Waste Management Research Unit, North Central Region, Agricultural Research Service, U.S. Department of Agriculture, in cooperation with the Nebraska Agricultural Experiment Station, Lincoln. Published as Paper No. 4071, Journal Series, Nebraska Agricultural Experiment Station.Microbiologist, USDA, A.R.S. University of Nebraska, Lincoln; Soil Scientist, USDA, A.R.S. Fort Collins, Colorado; and Microbiologist, USDA, A.R.S. University of Nebraska, Lincoln, respectively.     

Growth and patulin formation byPenicillium urticae Bainier in pure and mixed cultures

Penicillium urticae Bainier synthesized patulin in potato-dextrose medium at temperatures ranging from 5 to 30°C. Maximum patulin yield was 2700 μg/ml of culture fluid in 14 days at 25°C. Two distinctive intervals affected patulin formation: 15 to 20°C and 30 to 35°C, the former favorable and the latter detrimental. An incubation period of 11 to 14 days made a nonsterile mixture of weathered wheat straw and soil a favorable medium for patulin formation. Autoclaved weathered wheat straw, inoculated withP. urticae alone, or in combination withTrichoderma sp., was a medium comparable to nonsterile, incubated weathered wheat straw in soil. Both carbon source and accessory growth factors were important for patulin formation. Of seven media tested, potato-dextrose was superior to potatodextrose supplemented with 70 ppm Zn-ions and 16 ppm Fe-ions, potatosucrose, Raulin-Thom, autoclaved weathered wheat straw in pure culture, weathered wheat straw in nonsterile soil, and autoclaved weathered wheat straw in mixed culture, in that order. Patulin production ranged from 337.5 to 0.2 mg/g of C in the medium. Contribution from the Northern Plains Branch, Soil and Water Conservation Research Division, Agricultural Research Service, U.S. Department of Agriculture, in cooperation with the Nebraska Agricultural Experiment Station, Lincoln. Published as Paper No.2621, Journal Series, Nebraska Agricultural Experiment Station.     

DNA-damaging activity of patulin in Escherichia coli

At a concentration of 10 micrograms/ml, patulin caused single-strand DNA breaks in living cells of Escherichia coli. At 50 micrograms/ml, double-strand breaks were observed also. Single-strand breaks were repaired in the presence of 10 micrograms of patulin per ml within 90 min when the cells were incubated at 37 degrees C in M9-salts solution without a carbon source. The same concentration also induced temperature-sensitive lambda prophage and a prophage of Bacillus megaterium. When an in vitro system with permeabilized Escherichia coli cells was used, patulin at 10 micrograms/ml induced DNA repair synthesis and inhibited DNA replication. The in vivo occurrence of DNA strand breaks and DNA repair correlated with the in vitro induction of repair synthesis. In vitro the RNA synthesis was less affected, and overall protein synthesis was not inhibited at 10 micrograms/ml. Only at higher concentrations (250 to 500 micrograms/ml) was inhibition of in vitro protein synthesis observed. Thus, patulin must be regarded as a mycotoxin with selective DNA-damaging activity.     

DNA-damaging activity of patulin in Escherichia coli.

At a concentration of 10 micrograms/ml, patulin caused single-strand DNA breaks in living cells of Escherichia coli. At 50 micrograms/ml, double-strand breaks were observed also. Single-strand breaks were repaired in the presence of 10 micrograms of patulin per ml within 90 min when the cells were incubated at 37 degrees C in M9-salts solution without a carbon source. The same concentration also induced temperature-sensitive lambda prophage and a prophage of Bacillus megaterium. When an in vitro system with permeabilized Escherichia coli cells was used, patulin at 10 micrograms/ml induced DNA repair synthesis and inhibited DNA replication. The in vivo occurrence of DNA strand breaks and DNA repair correlated with the in vitro induction of repair synthesis. In vitro the RNA synthesis was less affected, and overall protein synthesis was not inhibited at 10 micrograms/ml. Only at higher concentrations (250 to 500 micrograms/ml) was inhibition of in vitro protein synthesis observed. Thus, patulin must be regarded as a mycotoxin with selective DNA-damaging activity.     

The isoepoxydon dehydrogenase gene PCR profile is useful in fungal taxonomy

This study evaluates the specificity of PCR isoepoxydon dehydrogenase (idh) primers on fungi associated with patulin production. The DNAs of 93 strains were extracted and analysed by PCR using primers of the idh gene of patulin biosynthesis. A single band at 620 bp was obtained on 17% of the analysed strains. Different molecular weight amplicons were observed in other strains. These were employed as binary characters for numerical analysis to obtain a dendrogram. Clusters were observed, which corresponded to morphological identifications in some cases. Amplicons at 400 and/or 500 bp were related to patulin non-detection for strains, whereas a 450 bp amplicon was associated with some Aspergillus and both of the Byssochlamys nivea strains tested. Hence, the idh primers are not specific for the gene and provide other amplicon products in other species. These results were useful providing (a) profiles of DNA to identify and classify fungi and (b) insights into patulin production. The DNA profiles in this study may be useful for the potential of patulin producing fungi. Obtaining multiple bands in culture-independent PCR of environmental samples by using the primers could indicate that more than one species is present.     

镁、锰、活性炭和石灰及其交互作用对小麦镉吸收的影响

采用盆栽试验,研究了在镉污染土壤上施用石灰、硫酸镁、硫酸锰和活性炭不同用量以及交互作用对小麦生长和吸收重金属镉的影响.研究结果表明,在试验条件下施用适量的硫酸镁、硫酸锰或与石灰配合能明显提高小麦籽粒产量,单施石灰或与活性炭配合施用降低了小麦籽粒产量;与对照(CK)相比,所有处理秸秆产量均下降.施用硫酸镁能显著降低小麦籽粒和秸秆中Cd浓度,且随用量的增加两增大.低量硫酸锰能有效降低小麦籽粒和秸秆中Cd浓度,高量反而增加小麦对Cd的吸收.石灰、活性炭单独施用或配合施用都能明显减少小麦对Cd的吸收,但籽/杆中Cd比却随石灰用量的增加呈明显的上升趋势.叶面喷施硫酸镁对降低小麦吸收镉的效果与土施相当,但叶面喷施硫酸锰却比土施硫酸锰显著降低了小麦籽粒中的镉浓度与吸收量.硫酸镁与硫酸锰,或石灰、硫酸镁和硫酸锰3种物质配合施用,对小麦籽粒镉浓度和吸收量的降低表现出明显的正交互作用,对抑制小麦体内镉从秸秆向籽粒的转移具有显著效果.     

Effect of copper on stem melanosis and yield of wheat: Sources,rates and methods of application

Park wheat (Triticum aestivum cv. Park) is susceptible to stem melanosis when grown on Cu-deficient soils. Three field experiments were conducted to evaluate the effectiveness of various Cu sources, using different methods and rates of application for reducing the incidence of stem melanosis and increasing the grain yield of Park wheat on a Cu-deficient Black Chernozemic soil in central Alberta. A fourth experiment determined the residual effect of Cu over 4 years. In the first experiment, Park wheat had less disease and higher grain yield when Cu-chelate solution at 2 and 4 kg Cu ha⁻¹ or Cu-sulfate solution at 10 and 20 kg Cu ha⁻¹ was applied to the soil surface and incorporated to a depth of 8 cm or was applied at these rates as a foliar spray. The foliar application, however, was phytotoxic and delayed maturity by approximately two weeks. Sidebanding Cu (4 cm to the side and 4 cm below the seed row) was least effective. In the second experiment, Cu-sulfate solution incorporated into the soil was more effective than the soil incorporated granular Cu-sulfate in reducing disease incidence and increasing grain yield in the year of application. In the following year the granular Cu was as effective as solution Cu. The third experiment showed that Cu seed dressings did not have any effect on disease incidence or grain yield of Park wheat. In the fourth experiment, the residual effect of Cu-chelate was evident four years after application. The grain yield in the fourth year was about four times that of the control. Contribution No. 564     

旋转磁场对小麦种子萌发及幼苗生长的影响

以“淮麦19”小麦种子为研究对象,采用磁场强度为11 mT的旋转磁场进行处理,设定不同的时间梯度(10、20、30、60 min),以未经磁场处理的为对照,研究了不同处理时间下旋转磁场对小麦种子发芽指标及幼苗生理特性的影响。结果表明：旋转磁场处理对小麦种子萌发具有促进作用,不同处理时间下,种子的发芽势、发芽率、发芽指数均有显著提高,随着时间的增加呈现先上升后下降的趋势,以处理30 min为最高,分别比对照提高了8.24％、7.37％、11.24％。经旋转磁场处理后,小麦根系发达,根长、根数均显著高于对照;幼苗生长加快,株高除处理60 min外,其他处理均显著高于对照,以处理30 min为最大,高出对照11.13％;叶片数除处理10 min外,其他处理均高于对照,以处理30 min为最大,比对照高出38.89％,且差异显著。旋转磁场处理显著增加了小麦幼苗的物质积累,不同处理时间表现出不同的效果,对幼苗生物积累量影响最佳的是处理20 min。这说明旋转磁场处理提高了小麦种子的萌发能力,加快了小麦幼苗的生长速度。     

Insights on the role of tillering in salt tolerance of spring wheat from detillering

Tillering is reduced by salinity, with the primary and secondary tillers being more affected than is the mainstem. To understand the importance of tillering in the salt tolerance of wheat plants, two contrasting genotypes of spring wheat (Triticum aestivum L.) were grown in a greenhouse under saline or non-saline conditions and were subjected to five progressive levels of detillering. Regardless of the genotype and salinity, shoot dry weight, seed yield and seed number per plant were all significantly decreased in the treatments where only one or two tillers per plant remained compared with the untouched treatment (more than three tillers), whereas these same variables per tiller tended to be increased on a per tiller (mainstem or substem tiller) basis. The increased seed yield per tiller observed with tiller reduction may be attributed to the enhanced seed number within the spikelet. Under saline conditions, the reductions in shoot dry weight, seed yield and seed number per plant for the salt-tolerant genotype Kharchia were of a greater magnitude in the treatments where only one or two tillers per plant were present compared with the untouched treatment, whereas the magnitude of this reduction in the salt-sensitive genotype Sakha 61 was decreased.     

外源一氧化氮对铅胁迫下小麦种子萌发及幼苗生理特性的影响

利用室内水培实验,研究了外源一氧化氮（NO）供体硝普钠（SNP）对Pb²⁺处理下小麦（Triticum aestivum L.）种子萌发、幼苗生长及相关生理指标变化的影响。结果表明,Pb²⁺处理使小麦种子发芽势、发芽率、幼苗根长和茎长均显著降低,诱导叶绿素a、叶绿素b含量减少及叶绿素荧光参数F_v/F_m和F_v/F_o的比值减小,25 μmol·L^-1 SNP明显缓解Pb²⁺胁迫对种子萌发及幼苗生长的抑制作用,提高Pb²⁺胁迫下叶绿素a、叶绿素b含量及F_v/F_m和F_v/F_o的比值,而100 μmol·L^-1SNP无明显缓解作用。此外,25和100 μmol·L^-1SNP诱导Pb²⁺胁迫下小麦幼苗叶片过氧化氢酶（CAT）活性增强和可溶性蛋白含量增多,但100 μmol·L^-1SNP处理降低了过氧化物酶（POD）活性。结果说明,外源NO促进Pb²⁺胁迫下小麦种子萌发及幼苗生长,提高叶绿素和可溶性蛋白含量,诱导CAT活性升高,从而增强小麦对Pb²⁺胁迫的适应性。     

Production of Patulin by Penicillium expansum

Twenty-seven isolates of Penicillium expansum Lk. ex Thom obtained from Europe, Australia, and North America from seven different fruit hosts all produced patulin in culture. Six isolates were essentially nonpathogenic in apple fruits. In culture, patulin generally accumulated to much higher levels than in apple fruits. At all temperatures permitting fungus growth, patulin was produced. However, only small amounts were observed near the maximal temperature for growth (30 C). At 0 C, patulin accumulated but slowly in culture. Modified atmospheres suppressed both fungus growth and patulin accumulation in apples. After varying incubation periods to obtain similar total growth, the patulin concentration was low in modified atmospheres and high in air.     

Arabinoxylans from rye and wheat seed that interact with ice

Arabinoxylans that interfere with growth of ice crystals have been purified from rye (Secale cereale L., Rosen) and two varieties of wheat (Triticum aestivum L., Genesee and Hillsdale) seed. The most active polysaccharide from each seed type was homogeneous in the sense that all the molecules were in the same size range, they contained the same sugar residues, and they reacted similarly in chemical characterization experiments. Structural studies showed that the polysaccharides consist of a xylan chain to which are attached side-chains that contain a single, terminal arabinose residue. The polysaccharides differ with respect to the number of arabinose residues. The xylose:arabinose ratios in the most active fractions from rye, Genesee wheat, and Hillsdale wheat are 1.26, 1.54, and 2.08, respectively. Gel-permeation column chromatography showed that the most active polysaccharide from each seed type has a molecular weight greater than 2 x 10(6) and that the rye polysaccharide is slightly larger than the Hillsdale wheat polysaccharide. The rye polysaccharide is a better inhibitor of ice-crystal growth than is the Hillsdale wheat polysaccharide.     

Thermodynamic and kinetic processes during the unfolding of BSA in the presence of the mycotoxin patulin

The effects of the mycotoxin patulin on the thermodynamics and kinetics of the transition of bovine serum albumin (BSA) in aqueous solution were studied by Differential Scanning Calorimetry and Photoluminescence methods. Results show that in the presence of patulin, the free enthalpy change during the transition of BSA was decreased by an average of ～ 46 kJ/mol, the free energy change was decreased by ～ 4 kJ/mol, and the activation energy fell from ～ 1546 to ～ 840 kJ/mol. These results indicate that the bioactivity of patulin is based on the kinetic rather than on the thermodynamic properties of the transition. This is the first evidence of the direct interaction of patulin with the free thiol-containing BSA, a process which could contribute to the adverse cyto- and genotoxic effects induced by patulin.     

施氮水平对小麦籽粒发育过程中氨基酸含量的影响

施氮能提高小麦籽粒蛋白质氨基酸的含量,并与施氮水平呈正相关;但对普通小麦必需氨基酸与蛋白质氨基酸的比值没有影响,而硬粒小麦4286随施氮水平的提高,该比值下降。在开花后32d以前,籽粒发育过程中游离氨基酸与施氮水平呈正相关,以后,籽粒中游离氨基酸趋于相近,表明施氮增加了游离氨基酸的库源,不同基因型小麦对施氮水平的反应不同,在同等施氮水平和栽培条件下,籽粒中蛋白质氨基酸和游离氨基酸含量为硬粒小麦4286＞小偃6号＞小偃107,不同施氮水平下,籽粒中氨基酸含量为高氮＞中氮＞低氮。     

Physiological and biochemical effects of the mycotoxin patulin on Chang liver cell cultures.

Patulin exhibits both cytotoxic and cytopathic effects on cultured Chang liver cells. The LD50 found was 1.85 mug per ml of patulin. Effects on growth were observed with as little as 0.1 mug per ml of patulin; a 50% reduction in growth was observed at 0.38 mug per ml of patulin. Using a challenge dose of 2.5 mug per ml of patulin, the cytotoxic effect was reversible after an exposure of 10 min, but was not reversible after 20 min. Protein synthesis was depressed after 60 min and RNA synthesis after 20 min of contact with patulin. Neither protein nor RNA synthesis was completely inhibited after 260 min.     

Effect of Penicillium expansum culture conditions on patulin production.

Penicillium expansum strains grown on Capek-Dox liquid medium excreted patulin to the medium. Its amount increased until day 12, then smaller amounts of the toxin were observed. Maximum patulin excretion took place at 25 degrees C, pH 6, although at 5 degrees C, pH 3 the presence of this mycotoxin was also observed. The highest amount of patulin produced was observed in medium containing fructose.     

Plant competition and disease in genetically diverse wheat populations

Summary The direct and indirect effects of plant genetic diversity on epidemics and the influence of disease on plant competition were investigated using the wheat (Triticum aestivum)/stripe rust (Puccinia striiformis) system. Replacement series consisting of a susceptible and a resistant wheat genotype or two wheat genotypes susceptible to different races of stripe rust were grown in the presence and absence of the pathogen. Stripe rust severity, number of seed heads, seed yield, and seed weight were determined separately for each wheat genotype in the mixtures and the pure stands. The frequency of susceptible genotypes in a mixture explained up to 67% of the variation in disease severity. However, competitive interactions among plant genotypes sometimes appeared to alter susceptibility and obscured the relationship. In pure stands of single genotypes, disease severity explained between 52 and 58% of the variation in seed yield. In mixtures, coefficients of determination were only 10 and 31%, suggesting a strong influence of plant-plant interactions on seed yield. These results suggest that host-parasite coevolutionary models need to account for the strong effect that specific plant genotype combinations may have on disease severity and plant reproduction.Paper No. 9818 of the journal series of the Oregon Agricultural Experiment Station     

Mycotoxin production and evolutionary relationships among species of Aspergillus section Clavati

Aspergillus clavatus is a commonly encountered fungus in the environment, producing a number of mycotoxins including patulin, kojic acid, cytochalasins and tremorgenic mycotoxins. A. clavatus belongs to Aspergillus section Clavati together with six other species, all of which possess clavate-shaped vesicles. Patulin production was analysed by thin layer chromatography and high performance liquid chromatography, while a primer pair developed for the detection of an iso-epoxydon dehydrogenase gene involved in the biosynthesis of patulin in penicillia was used to detect the ability of patulin production in the isolates examined. A good correlation was observed between patulin producing properties, and the presence of an iso-epoxydon dehydrogenase gene fragment among the isolates tested. A. longivesica was found for the first time to produce patulin. Ribotoxin production was also examined using a PCR-based approach. Ribotoxins were detected for the first time in an A. pallidus and a Hemicarpenteles acanthosporus isolate. A phylogenetic analysis of intergenic transcribed spacer sequence data indicated that most isolates belong to two main clades that have also been identified earlier based on 26 S rDNA sequence data. A. pallidus isolates clustered together with A. clavatus strains. Although A. clavatus isolates produced highly homogeneous random amplified polymorphic DNA profiles, phylogenetic analysis of these data let us cluster A. clavatus isolates into distinct clades. Correlations were not observed between either patulin or ribotoxin production, and the taxonomic position of the isolates tested, indicating that patulin and ribotoxin producing abilities were lost several times during evolution of Aspergillus section Clavati. Although patulin was earlier found to inhibit mycovirus replication, one of the mycovirus carrying isolates also produced patulin, and both carried the iso-epoxydon dehydrogenase gene. This revised version was published online in June 2006 with corrections to the Cover Date.     

Chemical control of wheat bulb fly (Delia coarctata) attacking winter wheat in Eastern England, 1969–1981

Dry powder, liquid and microencapsulated formulations of organophosphate and synthetic pyrethroid insecticidal seed treatments were tested as possible alternatives to the standard organochlorine seed treatments for autumn-sown wheat in mineral and organic soils heavily infested with wheat bulb fly eggs and (subsequently) larvae. Retention of insecticides on the seed coat varied from 40% to 120% of the target dose; it was usually good when microencapsulated formulations were used. Chlorfenvinphos, fonofos, isofenphos and triazophos, each applied at 2-0 g a.i./kg seed, were phytotoxic, the symptoms varying from a slight delaying effect upon germination to an adverse effect upon grain yield. Chlorfenvinphos at 0–2 to 2-0 g a.i./kg seed was consistently effective against wheat bulb fly larvae in both mineral and organic soils. Athidathion 0–8 g a.i./kg, carbophenothion 1–2 g a.i./kg, ethion 1–7 g a.i./kg and fonofos (microencapsulated formulations) at 1-0 or 2-0 g a.i./kg were also effective in mineral and organic soils. Of the synthetic pyrethroids tested as seed treatments, permethrin gave excellent results in mineral soils at 1-0 g a.i./kg or in synergised formulations at 0–12 or 0–24 g a.i./kg but was disappointing in organic soils. In a single comparison of seed treatments applied to wheat sown early (14 October) and late (20 November), chlorfenvinphos was effective at both sowing dates whereas athidathion, ethion and pirimiphos-ethyl gave better results in late-sown wheat. A single trial compared deep with shallow sowing of treated seed. Most insecticides performed better on shallow-sown wheat, but chlorfenvinphos was equally effective against the pest at both sowing depths. Most insecticides restricted the numbers of larvae entering host plants but had little or no subsequent effect upon larval survival within attacked shoots. Fonofos and isofenphos, and to a lesser extent chlorfenvinphos, seed treatments additionally killed many larvae within plant shoots.     

Phosphorus speciation in mature wheat and canola plants as affected by phosphorus supply

Background and aims

As plants approach maturity and start to senesce, the primary sink for phosphorus (P) is the seed but it is unclear how plant P status affects the resulting P concentration and speciation in the seed and remaining plant parts of the residues. This study was established to measure how P speciation in different parts of wheat and canola is affected by plant P status.

Methods

Wheat and canola grown in the glasshouse were supplied three different P rates (5, 30 and 60 kg P ha^?1 equivalent). At physiological maturity, plants were harvested and P speciation was determined for all plant parts (root, stem, leaf, chaff/pod and seed) and rates of P application, using solution ³¹P nuclear magnetic resonance (NMR) spectroscopy.

Results

Phytate was the dominant form of P in seed whereas orthophosphate was the dominant form of P in other plant parts. The distribution of P species varied with P status for canola but not for wheat. The phytate content of wheat chaff increased from 10 to 45 % of total P as the P rate increased. Canola pods did not show a similar trend, with most P present as orthophosphate.

Conclusions

Although minor differences were observed in P speciation across the three P application rates and plant parts, the effect of this on P cycling from residues into soil is likely to be relatively minor in comparison to the overall contribution of these residues to soil P pools. This glasshouse experiment shows the dominant P form in crop residues that is returned to soil after harvest is orthophosphate, regardless of plant P status.