Genetic Structure of Cochliobolus sativus Populations Sampled from Roots and Leaves of Barley and Wheat in North Dakota

Common root rot (CRR) and spot blotch, caused by Cochliobolus sativus (Ito and Kurib.) Drechsl. ex Dast., are important diseases of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) worldwide. However, the population biology of C. sativus is still poorly understood. In this study, the genetic structure of three C. sativus populations, consisting of isolates sampled respectively from barley leaves (BL), barley roots (BR) and wheat roots (WR) in North Dakota, was analysed with amplified fragment length polymorphism (AFLP) markers. A total of 127 AFLP loci were generated among 208 C. sativus isolates analysed with three primer combinations. Gene diversity (H = 0.277–0.335) were high in all three populations. Genetic variation among C. sativus individuals within population accounted for 74%, whereas 26% of the genetic variation was explained among populations. Genetic differentiation was high (ØPT = 0.261, corrected = 0.39), whereas gene flow (Nm) ranged from 1.27 to 1.56 among the three populations analysed. The multilocus linkage disequilibrium (LD) (= 0.076–0.117) was moderate in C  sativus populations. Cluster analyses indicate that C. sativus populations differentiated according to the hosts (barley and wheat) and tissues (root and leaf) although generalists also exist in North Dakota. Crop breeding may benefit from combining genes for resistance against both specialists and generalists of C. sativus.     

Effectiveness of preharvest application of submicron chitosan dispersions for controlling Alternaria rot in postharvest jujube fruit

The efficacy of submicron chitosan dispersions (SCD) on Alternaria alternata rot of the ‘Lingwu changzao’ jujube (Zizyphus jujuba Mill. cv. Lingwu changzao) fruit and possible mechanisms involved were investigated in this study. When jujube fruit at the preharvest stage were sprayed twice with SCD (10 mg/ml) water solution and then natural infections were allowed to develop, there was a significant reduction in disease incidence and lesion index compared to control fruit during storage period, and similar results were obtained from postharvest fruit inoculated with the Alternaria rot pathogen. Scanning electron microscopy of the pathogen revealed that hyphae and spores were damaged and deformed when growing on the surface of fruit pretreated with SCD or CHO. The slowed softening of jujube fruit resulted from the protopectin content increasing compared with the control. Furthermore, SCD sprays inhibited cell wall hydrolysing enzymes, pectinase activity was decreased, and the increase in cellulase activity was postponed (from 30 days to 45 days).It was concluded that preharvest application of SCD was a more effective alternative to conventional chitosan for preventing postharvest from Alternaria rot of ‘Lingwu changzao’ jujube fruit.     

Variability of the Ramularia collo‐cygni Population in Central Europe

The genetic structure of the fungal barley pathogen Ramularia collo‐cygni (Rcc) population in Central Europe involving the isolates from the Czech Republic, the Slovak Republic, Germany and Swiss was determined using amplified fragment length polymorphism (AFLP) analysis. One hundred and eighty‐four markers were chosen to determine genetic and genotypic diversity and to test the hypothesis of random mating and population differentiation of Rcc isolates. Among the 337 isolates collected, the overall gene diversity was moderate ( = 0.216). The level of multilocus genotypic diversity was higher within populations than among them. All individuals had unique multilocus genotypes. Genetic differentiation was significant among populations in localities, but at a moderate level (θ = 0.12; P < 0.001), suggesting that gene flow is occurring among populations. The isolates from all twelve clusters produced by Structure were found in all local populations, although at different frequencies. Therefore, the inferred clusters did not represent geographical populations. Although the null hypothesis of random mating in Rcc populations was rejected, the high level of genotypic diversity suggests that the Rcc population structure appears to be generated by a mixed reproductive system including both asexual and sexual reproduction, along with a rather high migration rate.     

Logarithmic Transformation is Essential for Statistical Analysis of Fungicide EC50 Values

Half maximal (50%) effective concentration (EC50) values are widely used to express fungicide potency and sensitivity of plant pathogens. This study explored the necessity of logarithmic transformation for statistical analysis of EC50 values. The results demonstrated that without logarithmic transformation, none of the five sets of epoxiconazole EC50 data (n = 26–33) against Sclerotinia sclerotiorum fitted a normal distribution. But after logarithmic transformation, four of the five datasets became normally distributed. Of the five sets of pyraclostrobin EC50 data (n = 29–32), only one dataset fitted a normal distribution. After logarithmic transformation, four datasets became normally distributed. Logarithmic transformation transformed the heterogeneity of variance across the five sets of epoxiconazole EC50 data to homogeneity but failed to improve the heterogeneity of variance across the five sets of pyraclostrobin EC50 data. For 150 isolates' EC50 values to epoxiconazole and 153 isolates' EC50 values to pyraclostrobin, the intervals of arithmetic means ± standard deviations (SD) covered 85.3% and 90.2% of data points, respectively, whereas the intervals of geometric means (*) multiplied/divided by the multiplicative SD (S*) covered 69.3% and 70.9% of data points, respectively, which approximated the theoretical value of 68.3%. Distribution normality and homogeneity of variance are prerequisites for analysis of variance (anova ) and the two parameters could be improved by logarithmic transformation, therefore, power and efficiency of statistical tests on EC50 data will be greatly enhanced by this kind of transformation.     

Effect of an Antagonistic Yeast in Combination with Microwave Treatment on Postharvest Blue Mould Rot of Jujube Fruit

The potential of using an antagonistic yeast alone or in combination with microwave treatment for controlling blue mould rot of jujube fruit, and its effect on postharvest quality of fruit, was investigated. The results showed that the growth of Penicillium citrinum was completely inhibited by a 2450‐MHz microwave heating for 2 or more minutes in vitro. The population density of P. citrinum in surface wounds of fruit treated with microwave treatment for 2–3 min was significantly lower than that of controls. When tested on jujube fruit, antagonistic yeast or microwave treatment, as stand‐alone treatment, the disease incidence of infected wounds was reduced from 100% to 45.0% and 36.0%, and lesion diameters were reduced from 1.92 cm to 1.50 cm and 1.38 cm, respectively. However, in fruit treated with a combination of Metschnikowia pulcherrima and microwave treatment, the disease incidence of infected wounds and lesion diameters was only 21.0% and 1.00 cm, respectively. The natural decay incidence on jujube fruit treated with the combination of microwave treatment and M. pulcherrima was 6.2% after storage at 2 ± 1°C for 45 days and at 22°C for 7 days. None of the treatments impaired quality parameters of fruits. Thus, the combination of microwave treatment and M. pulcherrima could provide an alternative to synthetic fungicides for controlling postharvest blue mould rot of jujube fruit.     

Population Dynamics and Damage Potential of Meloidogyne hapla to Rose Rootstock Species

The relationship between initial population densities (Pi) of Meloidogyne hapla on growth of three rose rootstocks (Rosa corymbifera ‘Laxa’, R. multiflora and R. canina ‘Inermis’) and nematode population development was studied. Each plant species was inoculated with ranges of nematode densities of 0, 0.062, 0.125, 0.25, 0.50, 1, 2, 4, 8, 16, 32, 64 and 128 second‐stage juvenile/g soil and were allowed to grow for 9 weeks. Seinhorst yield model was fitted to total fresh biomass data of the rootstocks. The tolerance limits (T) were 0.04, 0.09 and 0.01 J2/g soil and the minimum yield (m) 0.65, 0.47 and 0.43 for R. corymbifera ‘Laxa’, R. multiflora and R. canina ‘Inermis’, respectively. The reproductive factor (Pf/Pi) was highest at low initial nematode densities for all rootstocks and then decreased to below maintenance level with increasing initial population densities. Root gall severity consistently increased with initial nematode population density. Furthermore, number of root galling showed a strong positive relationship with final nematode population per gram root fresh weight. The relation between Pi and Pf was also fitted to the Seinhorst population model (Pf = (M*Pi)/Pi + M/a). Rosa multiflora supported the population of M. hapla to a maximum population density (M) of 27.53 J2/g soil with an estimated average maximum multiplication rate (a) of 24.39. For R. corymbifera ‘Laxa’ and R. canina, the maximum multiplication rate was 4.34 and 3.62 and the maximum population density 6.08 and 4.78 J2/g dry soil, respectively. Hence, it was demonstrated that all three rootstocks were susceptible to even low initial nematode densities and therefore are considered good hosts for M. hapla.     

THE MAINTENANCE OF POLYGENIC VARIATION IN FINITE POPULATIONS

Models of the maintenance of genetic variance in a polygenic trait have usually assumed that population size is infinite and that selection is weak. Consequently, they will overestimate the amount of variation maintained in finite populations. I derive approximations for the equilibrium genetic variance, in finite populations under weak stabilizing selection for triallelic loci and for an infinite “rare alleles” model. These are compared to results for neutral characters, to the “Gaussian allelic” model, and to Wright's approximation for a biallelic locus under arbitrary selection pressures. For a variety of parameter values, the three-allele, Gaussian, and Wrightian approximations all converge on the neutral model when population size is small. As expected, far less equilibrium genetic variance can be maintained if effective population size, N, is on the order of a few hundred than if N is infinite. All of the models predict that comparisons among populations with N less than about 10⁴ should show substantial differences in . While it is easier to maintain absolute when alleles interact to yield dominance or overdominance for fitness, less additivity also makes more susceptible to differences in N. I argue that experimental data do not seem to reflect the predicted degree of relationship between N and . This calls into question the ability of mutation-selection balance or simple balancing selection to explain observed . The dependence of on N could be used to test the adequacy of mutation-selection balance models.     

The role of a cytosolic superoxide dismutase in barley–pathogen interactions

Reactive oxygen species (ROS), including superoxide ( / ) and hydrogen peroxide (H₂O₂), are differentially produced during resistance responses to biotrophic pathogens and during susceptible responses to necrotrophic and hemi‐biotrophic pathogens. Superoxide dismutase (SOD) is responsible for the catalysis of the dismutation of / to H₂O₂, regulating the redox status of plant cells. Increased SOD activity has been correlated previously with resistance in barley to the hemi‐biotrophic pathogen Pyrenophora teres f. teres (Ptt, the causal agent of the net form of net blotch disease), but the role of individual isoforms of SOD has not been studied. A cytosolic CuZnSOD, HvCSD1, was isolated from barley and characterized as being expressed in tissue from different developmental stages. HvCSD1 was up‐regulated during the interaction with Ptt and to a greater extent during the resistance response. Net blotch disease symptoms and fungal growth were not as pronounced in transgenic HvCSD1 knockdown lines in a susceptible background (cv. Golden Promise), when compared with wild‐type plants, suggesting that cytosolic / contributes to the signalling required to induce a defence response to Ptt. There was no effect of HvCSD1 knockdown on infection by the hemi‐biotrophic rice blast pathogen Magnaporthe oryzae or the biotrophic powdery mildew pathogen Blumeria graminis f. sp. hordei, but HvCSD1 also played a role in the regulation of lesion development by methyl viologen. Together, these results suggest that HvCSD1 could be important in the maintenance of the cytosolic redox status and in the differential regulation of responses to pathogens with different lifestyles.     

Free radical scavenging activity of novel thiazolidine‐2,4‐dione derivatives

Free radical activity towards superoxide anion radical (), hydroxyl radical (HO^?) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) of a series of novel thiazolidine‐2,4‐dione derivatives (TSs) was examined using chemiluminescence, electron paramagnetic resonance (EPR) and EPR spin trapping techniques. 5,5‐Dimethyl‐1‐pyrroline‐N‐oxide (DMPO) was applied as the spin trap. Superoxide radical was produced in the potassium superoxide/18‐crown‐6 ether dissolved in dimethyl sulfoxide. Hydroxyl radical was generated in the Fenton reaction (Fe(II) + H₂O₂. It was found that TSs showed a slight scavenging effect (15–38% reduction at 2.5 mmol/L concentration) of the DPPH radical and a high scavenging effect of (41–88%). The tested compounds showed inhibition of HO^? ‐dependent DMPO‐OH spin adduct formation (the amplitude of EPR signal decrease ranged from 20 to 76% at 2.5 mmol/L concentration. Our findings present new group compounds of relatively high reactivity towards free radicals. Copyright © 2012 John Wiley & Sons, Ltd.     

Superoxide anion radical scavenging property of catecholamines

The direct effect of the four catecholamines (adrenaline, noradrenaline, dopamine and isoproterenol) on superoxide anion radicals () was investigated. The reaction between 18‐crown‐6‐ether and potassium superoxide in dimethylsulfoxide was used as a source of . The reactivity of catecholamines with was examined using chemiluminescence, reduction of nitroblue tetrazolium and electron paramagnetic resonance spin‐trapping techniques. 5,5‐Dimethyl‐1‐pyrroline‐N‐oxide was included as the spin trap. The results showed that the four catecholamines were effective and efficient in inhibiting chemiluminescence accompanying the potassium superoxide/18‐crown‐6‐ether system in a dose‐dependent manner over the range 0.05–2 mm in the following order: adrenaline > noradrenaline > dopamine > isoproterenol, with, IC₅₀ = 0.15 ± 0.02 mm 0.21 ± 0.03 mm , 0.27 ± 0.03 mm and 0.50 ± 0.04 mm , respectively. The catecholamines examined also exhibited a strong scavenging effect towards when evaluated this property by the inhibition of nitroblue tetrazolium reduction (56–73% at 1 m concentration). A very similar capacity of scavenging was monitored in the 5,5‐dimethyl‐1‐pyrroline‐N‐oxide spin‐trapping assay. The results suggest that catecholamines tested may involve a direct effect on scavenging radicals. Copyright © 2013 John Wiley & Sons, Ltd.     

Postharvest biocontrol of Alternaria alternata in Chinese winter jujube by Rhodosporidium paludigenum

Aims:  This study was conducted to measure the efficacy of the marine antagonist Rhodosporidium paludigenum in the suppression of postharvest decay of Chinese winter jujube caused by Alternaria alternata and to explore the possible mode of action involved.
Methods and Results:  The efficacy of controlling postharvest diseases by R. paludigenum was examined. Rapid yeast colonization of wounds was observed during the first 48 h at 25°C. The yeast at 1 × 10⁸ cells ml⁻¹ of washed cells suspension provided better control of A. alternata than any other treatment. The concentration of the antagonist had significant effects on biocontrol effectiveness: as the concentration of R. paludigenum was increased, the disease incidence decreased. Meanwhile, R. paludigenum significantly inhibited the natural development of decay and did not damage fruit quality parameters including lightness values, hue angle, firmness, soluble solids, ascorbic acid and titratable acidity in 21 days' storage at 25°C.
Conclusions:  Rhodosporidium paludigenum was effective in controlling postharvest decay of Chinese winter jujube and did not impair fruit quality parameters.
Significance and Impact of the Study:  Rhodosporidium paludigenum can be used as a nonchemical agent in postharvest biological control of Chinese winter jujube.     

Studies on the antioxidant activities of some new chromone compounds

Recent reviews evidence that the naturally occurring compounds containing the chromone skeleton exhibit antiradical activities, providing protection against oxidative stress. The antioxidant activities of 13 new synthesized chromonyl‐2,4‐thiazolidinediones, chromonyl‐2,4‐imidazolidinediones and chromonyl‐2‐thioxoimidzolidine‐4‐ones were evaluated using in vitro antioxidant assays, including superoxide anion radical (), hydroxyl radical (), 2,2‐diphenyl‐1‐picryl‐hydrazyl free radical (DPPH^?) scavenging capacity and total antioxidant capacity ferric ion reducing activity. Superoxide anion radical was produced using potassium superoxide/18‐crown‐6‐ether dissolved in dimethylsulfoxide, and the Fenton‐like reaction (Fe(II) + H₂O₂) was a generator of hydroxyl radicals. Chemiluminescence, spectrophotometry, electron paramagnetic resonance (EPR) and 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO) as the spin trap were the measurement techniques. The results showed that the majority of the chromone derivatives tested showed a strong scavenging effect towards free radicals, similar to the chemiluminescence reaction with superoxide anion radical with a high activity, inhibition of the DMPO‐OOH radical EPR signal (24–58%), the DMPO‐OH radical EPR signal (4–75%) and DPPH radical EPR signal (6–100%) at 1 mmol/L. Several of the examined compounds exhibited the high reduction potentials. The results obtained show that the new synthesized chromone derivatives may directly scavenger reactive oxygen species and thus may play a protective role against oxidative damage. Copyright © 2014 John Wiley & Sons, Ltd.     

HEMOGLOBIN POLYMORPHISMS IN DEER MICE (PEROMYSCUS MANICULATUS): PHYSIOLOGY OF BETA-GLOBIN VARIANTS AND ALPHA-GLOBIN RECOMBINANTS

Wild populations of deer mice (Peromyscus maniculatus) contain hemoglobin polymorphisms at both alpha-globin (Hba, Hbc) and beta-globin (Hbd) loci. Population gene frequencies of beta-globin variants (d⁰ and d¹ haplotypes) are not correlated with altitude, whereas a¹c¹ alpha-globin haplotypes are fixed in low-altitude populations, and a⁰c⁰ haplotypes reach near fixation at high altitudes. We examined the effects of alpha- and beta-globin variants on blood oxygen affinity and on aerobic performance, measured as maximum oxygen consumption (). Exercise and cold exposure were used to elicit . Experiments were performed at low (340 m) and high (3,800 m) altitude to include the range of oxygen partial pressures encountered by wild deer mice. Beta-globin variants had little effect on blood oxygen affinity or . Oxygen-dissociation curves from a⁰c⁰ and a¹c¹ homozygotes and heterozygotes had similar shapes, but the P₅₀ of a⁰c⁰ homozygotes was significantly lower than that of other genotypes. Mice carrying a¹c¹/a¹c¹ genotypes had the highest at low altitude, but mice with a⁰c⁰/a⁰c⁰ genotypes had the highest at high altitude. Mice carrying rare recombinant alpha-globin haplotypes (a⁰c¹) had lower than nonrecombinant genotypes as a whole but in most cases were not significantly different from nonrecombinant heterozygotes (a⁰c⁰/a¹c¹). We conclude that genetic adaptation to different altitudes was important in the evolution of deer mouse alpha-globin polymorphisms and in the maintenance of linkage disequilibrium in the alpha-globin loci but was not a significant factor in the evolution of beta-globin polymorphisms.     

Phytochemical,Ecological and Antioxidant Evaluation of Wild Sicilian Thyme: Thymbra capitata (L.) Cav.

In a broad survey conducted throughout the Sicily region, 45 different sites were identified where thyme grows wild. All the biotypes collected were classified as Thymbra capitata (L.) Cav. (syn. Thymus capitatus (L.) Hoffmanns . & Link ). Cluster analysis based on the main morphological characteristics of the plant led to the division of the biotypes into 3 major groups. All samples were analyzed for their secondary phytochemical metabolites identified in the extracts and the essential oils. LC‐UV‐DAD/ESI‐MS and GC‐FID/GC‐MS have been applied to characterize the extracts and the essential oils, respectively. In the extracts, 15 flavonoid derivatives with taxifolin‐di‐O‐glucoside and thymusin as main components, and 2 organic acids, with a large predominance of rosmarinic acid, were identified. On the whole 37 compounds were fully characterized in the essential oils, carvacrol was identified as the main component with an average value of 73.93%. The total phenol content and the antioxidant activity of all phytochemical complexes were determined with the Folin–Ciocalteu (FC) assay, the UV radiation‐induced peroxidation in liposomal membranes (UV‐IP test), and the scavenging activity of superoxide radical ().     

Contributions of bats to the local economy through durian pollination in Sulawesi,Indonesia

Durian is economically important for local livelihoods in Indonesia. Our study investigated the identity of pollinators of semi‐wild durian and subsequently estimated the economic contribution of these pollination services. We conducted pollination exclusion experiments and deployed camera traps at durian trees from October 2017 to January 2018 in an area where the local economy depends on durian production in West Sulawesi, Indonesia. Durian flowers in the experiment that were accessible to bats had significantly higher fruit set compared with flowers that were completely closed to animal visitors or those that could only be visited by insects, suggesting that bats were the primary durian pollinator. The small, highly nectarivorous cave nectar bat (Eonycteris spelaea) visited more inflorescences (n = 25) and had visits of much longer duration ( = 116.87 sec/visit) than the two species of flying foxes: Pteropus alecto (n = 7 inflorescences visited,  = 11.07 sec/visit) and Acerodon celebensis (n = 6 inflorescences visited,  = 11.60 sec/visit). Visits by large and small bats were influential in differentiating successful durian fruit production from unsuccessful. Using a bioeconomic approach, we conservatively estimate that bat pollination services are valued at ~$ 117/ha/fruiting season. By demonstrating an ecological link between bats and the local economy, this research provides an urgent message for Southeast Asian governments regarding the need to promote bat conservation in order to increase the production of durian grown under semi‐wild conditions. Abstract in Indonesia is available with online material.     

Optimal design of the Wilcoxon–Mann–Whitney‐test

In scientific research, many hypotheses relate to the comparison of two independent groups. Usually, it is of interest to use a design (i.e., the allocation of sample sizes m and n for fixed ) that maximizes the power of the applied statistical test. It is known that the two‐sample t‐tests for homogeneous and heterogeneous variances may lose substantial power when variances are unequal but equally large samples are used. We demonstrate that this is not the case for the nonparametric Wilcoxon–Mann–Whitney‐test, whose application in biometrical research fields is motivated by two examples from cancer research. We prove the optimality of the design in case of symmetric and identically shaped distributions using normal approximations and show that this design generally offers power only negligibly lower than the optimal design for a wide range of distributions.     

Chitosan and hot water treatments reduce postharvest green mould in ‘Murcott’ tangor

This study aims to evaluate the efficacy of hot water and chitosan treatments to control green mould caused by Penicillium digitatum in 'Murcott' tangor. P. digitatum conidial germination and mycelial growth were evaluated in assays in vitro to verify whether chitosan (0.5, 1 and 2%) or hot water (45, 50, and 55°C, for 30 s, 1, 2, and 5 min) acts directly on fungus development. In vivo assays consisted of inoculating the fruit with P. digitatum (10⁵ conidia ml⁻¹) 4 hr before the chitosan and hot water treatments. Subsequently, green mould incidence and severity were evaluated in fruits stored at 25°C/80% RH for 4 days. Also, treatments combining chitosan and hot water were investigated for controlling green mould and the effect on postharvest quality of fruit stored at 5°C/90% RH. The results showed that P. digitatum conidia germination and mycelial growth were significantly reduced by the hot water treatments especially at 50°C/5 min and 55°C/2 or 5 min in the first case and 50 and 55°C/5 min in the second. These two treatments, when applied alone, 1 min dipping in 2% chitosan or hot water at 50°C/5 min, significantly reduced green mould development in fruit kept at 25°C/80% RH or refrigerated. However, the hot water dip combined with chitosan did not improve green mould control on ‘Murcott’ tangor at room temperature or under refrigeration. Besides, chitosan and hot water did not impair fruit quality. Thus, chitosan and hot water could be an alternative to synthetic fungicides to control green mould in citrus while also contributing to a decrease in the postharvest losses of ‘Murcott’ tangor.     

Encapsulation and release of a bacterial carotenoid from hydrogel matrix: Characterization,kinetics and antioxidant study

Various natural polymers with hydrophilic properties have been used to form hydrogels for the encapsulation and delivery of nutrients and drugs in food and pharmaceutical industries. Among them, chitosan (ChiHG)‐ and alginate (AlgHG)‐ based hydrogels have been extensively explored for delivery of several nutraceuticals in recent years. Release of natural canthaxanthin (CX) obtained from Dietzia maris NITD (accession number: HM151403) has been investigated with emphasis on biomedical applications. Significant changes (P < 0.05) in degree of swelling and moisture content (% dry basis) were found after encapsulation of bacterial canthaxanthin (BCX), but the gel content remained unchanged. BCX encapsulation efficiency was calculated to be 55.92% and 60.45% in ChiHG and AlgHG, respectively. A noticeable change in heat of fusion d melting point was recorded in ChiHG and AlgHG after BCX encapsulation. Swelling and BCX release from gel matrix was performed under two different pH (1.2 and 7.4). The results showed that swelling of hydrogel and BCX release was facilitated at higher pH (7.4) than acidic pH (1.2). With regard to the release kinetics data, it was found that BCX is released from bothand AlgHG in a diffusion transport method. In addition, antioxidant activity of BCX encapsulated hydrogels was found significantly higher (P < 0.001) in terms of DPPH, ABTS, nitrite, hydroxyl radical scavenging and reducing power assay. These results indicated that BCX can be successfully encapsulated into a polymeric hydrogel to obtain a dynamic biomaterial that may be used in drug delivery applications in future.