The effect of biologically active substances from coniferous plants on the L-phenylalanine ammonia lyase and peroxidase activities in wheat leaves

The effect of the preparations produced from needles and wood of various coniferous species on the activities of L-phenylalanine ammonia lyase (PAL; EC 4.3.1.5) and peroxidase (PO; EC 1.11.1.7), the enzymes involved in the development of plant defense response, was studied. It was demonstrated that treatment of soft wheat (Triticum aestivum L.) primary leaves with biological preparations produced from coniferous plants caused a transient increase in PAL and PO activities. The induction of these enzyme activities depends on the concentration of preparations and plant immune status. The results obtained suggest that coniferous metabolites are of interest as a source of plant extracts with the elicitor effect, increasing the resistance of plants to phytopathogens and adverse environmental factors.     

Plant growth regulator interactions results enhancement of antioxidant enzymes in Catharanthus roseus

Abstract

The present investigation was carried out with the objectives to understand the effect of paclobutrazol, gibberellic acid and Pseudomonas fluorescens on the enzymatic antioxidants like Ascorbate peroxidase (APX, EC: 1.11.1.11), Superoxide dismutase (SOD, EC: 1.15.1.1), Catalase (CAT, EC: 1.11.1.6), Peroxidase (POX, EC 1.11.1.7) and polyphenol oxidase (PPO, Ec 1.10.3.1) activities of Catharanthus roseus plants under field conditions. 10 mg l^?1 paclobutrazol, 5 µM gibberellic acid and 1 mg P. fluorescens concentrations were used for the treatments, and control plants were irrigated with well water. The treatments were given 38, 53, 68 and 83 days after planting (DAP) by soil drenching. The plants were taken randomly 45, 60, 75 and 90 DAP and separated into root, stem, leaves and flowers and used for estimating the antioxidant enzymes. The results showed that these plant growth regulators have significant effects on antioxidant enzymes of C. roseus.     

Exogenous application of mannitol and thiourea regulates plant growth and oxidative stress responses in salt-stressed maize (Zea mays L.)

Abstract

The mechanism of growth amelioration in salt-stressed maize (Zea mays L. cv., DK 647 F1) by exogenously applied mannitol (M) and thiourea (T) was investigated. Maize seedlings were planted in pots containing perlite and subjected to 0 or 100 mM NaCl in full strength Hoagland's nutrient solution. Two levels of M (15 and 30 mM) or T (3.5 and 7.0 mM) were sprayed to the leaves of maize seedlings 10 days after germination. Salinity stress caused considerable reduction in plant dry biomass, chlorophyll content, and relative water content in the maize plants. However, it increased the activities of catalase (CAT; EC 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1), and polyphenol oxidase (PPO; EC 1.10.3.1), and levels of hydrogen peroxide (H₂O₂) and electrolyte leakage, but it did not change peroxidase (POD; EC 1.11.1.7) activity. Foliar application of M or T was found to be effective in checking salt-induced shoot growth inhibition. Exogenously applied M or T reduced the activities of CAT, SOD, POD, and PPO in the salt-treated maize plants compared to those in the plants not fed with these organic compounds. Salinity increased Na⁺ contents but decreased those of K⁺, Ca^{2 +}, and P in the leaves and roots of the maize plants. Foliar-applied M or T increased the contents of K⁺, Ca^{2 +}, and P, but decreased that of Na⁺ in the salt-stressed maize plants with respect to those of the salt-stressed plants not supplied with mannitol or thiourea. Mannitol was found to be more effective than thiourea in improving salinity tolerance of maize plants in terms of growth and physiological attributes measured in the present study.     

Effect of sporophytic <Emphasis Type="Italic">PIRL</Emphasis>9 genotype on post-meiotic expression of the Arabidopsis <Emphasis Type="Italic">pirl1</Emphasis>;<Emphasis Type="Italic">pirl9</Emphasis> mutant pollen phenotype

Plant intracellular ras-group-related leucine-rich repeat proteins (PIRLs) are a novel class of plant leucine-rich repeat (LRR) proteins structurally related to animal ras-group LRRs involved in cell signaling and gene regulation. Gene knockout analysis has shown that two members of the Arabidopsis thaliana PIRL gene family, PIRL1 and PIRL9, are redundant and essential for pollen development and viability: pirl1;pirl9 microspores produced by pirl1/PIRL1;pirl9 plants consistently abort just before pollen mitosis I. qrt1 tetrad analysis demonstrated that the genes become essential after meiosis, during anther stage 10. In this study, we characterized the phenotype of pirl1;pirl9 pollen produced by plants heterozygous for pirl9 (pirl1;pirl9/PIRL9). Alexander’s staining, scanning electron microscopy, and fluorescence microscopy indicated that pirl1;pirl9 double mutants produced by pirl9 heterozygotes have a less severe phenotype and more variable morphology than pirl1;pirl9 pollen from pirl1/PIRL1;pirl9 plants. Mutant pollen underwent developmental arrest with variable timing, often progressing beyond pollen mitosis I and arresting at the binucleate stage. Thus, although the pirl1 and pirl9 mutations act post-meiosis, the timing and expressivity of the pirl1;pirl9 pollen phenotype depends on the pirl9 genotype of the parent plant. These results suggest a continued requirement for PIRL1 and PIRL9 beyond the initiation of pollen mitosis. Furthermore, they reveal a modest but novel sporophytic effect in which parent plant genotype influences a mutant phenotype expressed in the haploid generation.     

Phase and Period Responses of the Two-Peak Circadian Rhythm of Trigonoscelis gigas Reitter (Coleoptera: Tenebrionidae) for 6-hr Light Pulses

Abstract

Enzymatic activity of five lysosomal hydrolases: acid p‐nitrophenyl phosphatase (EC 3.1.3.2), acid β‐glycerophosphatase (EC 3.1.3.2), arylsulphatase (EC 3.1.6.1), β‐galactosidase (EC 3.2.1.23) and β‐N‐acetylhexosaminidase (EC 3.2.1.30) was studied in the supernatants of homogenates of hearts of unirradiated mice, serving as controls, and a group of U.V.‐irradiated mice.

In the control group, determinations made at 6‐hr intervals showed rhythmic diurnal changes in activities of three acid hydrolases. These changes were statistically significant in the case of acid p‐nitrophenyl phosphatase, acid β‐glycerophosphatase, and β‐N‐acetylhexosaminidase. The effect of U.V.‐irradiation was manifested mainly by depression of enzyme activities of the acid hydrolases during the first few hours after exposure. Depression of activities of arylsulphatase and β‐N‐acetylhexosaminidase by U.V. was statistically significant. Presumably, the fall in enzyme activities of the acid hydrolases was due to chemical mediators formed in the skin under the influence of U.V.‐irradiation and adrenal corticoids secreted into the blood.     

Host-related variability in arbuscular mycorrhizal fungal structures in roots of <Emphasis Type="Italic">Hedera rhombea</Emphasis>, <Emphasis Type="Italic">Rubus parvifolius</Emphasis>, and <Emphasis Type="Italic">Rosa multiflora</Emphasis> under controlled conditions

The arbuscular mycorrhizal (AM) morphology of three host plant species inoculated with single and mixed fungal culture and the distribution of AM fungal species in roots of the hosts treated with a mixed culture of AM fungi were determined. The aim was to investigate the effect of host plants and AM fungi on AM morphology of coexisting plant species. Noncolonized rooted cuttings of Hedera rhombea (Miq) Bean, Rubus parvifolius L., and Rosa multiflora Thunb. were inoculated with five fungal species as single and mixed culture inocula. The fungal species used were Gigaspora rosea and Scutellospora erythropa, previously isolated from H. rhombea; Acaulospora longula and Glomus etunicatum from R. parvifolius; and Glomus claroideum from both plant species. A few hyphal and arbusculate coils were seen in the mixed culture-inoculated roots of R. parvifolius; all fungal treatments produced this Paris-type AM in H. rhombea and Arum-type AM in R. parvifolius, and R. multiflora indicates that AM morphology is strongly controlled by the identity of the host plants used in this study. AM fungal rDNA was extracted separately from roots of each replicate plant species inoculated with the mixed fungal culture, amplified, cloned, sequenced, and analyzed to determine the AM fungal species and their respective proportions in roots of each plant species. Glomus etunicatum and G. claroideum of the family Glomaceae generally occurred more frequently in R. parvifolius and R. multiflora, which form Arum-types, whereas S. erythropa, of the family Gigasporaceae, was the most frequently detected species in H. rhombea, which produced Paris-type AM. Although the genotype of the plant species used appears to determine the AM morphologies formed, there was preferential association between the hosts and AM fungal inoculants.     

Effect of Preparations Exhibiting Cytokinin-like Activity on the Specific Density of Leaf in Grasses

The effects of synthetic preparations exhibiting cytokinin-like activity (6-benzylaminopurine, Thidiazuron, and kartolin-2) on the specific leaf area (SLA) were studied in plants of the family Gramineae (wheat, Triticum aestivum L.; meadow fescue, Festuca pratensis Huds.; and reed fescue, F. arindinacea Schreb.). At the early stages of ontogeny (until the leaf area reached 50–60% of the maximum value), treatment of plants of the three species with cytokinin-like preparations caused an increase in SLA. The SLA value in these plants was correlated with the rate of photosynthetic assimilation of carbon dioxide and activities of carbon metabolism enzymes: ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), NAD-malate dehydrogenase (EC 1.1.1.37), and NADP-glyceraldehydephosphate dehydrogenase complex, which includes phosphoglycerate kinase (EC 2.7.2.3) and glyceraldehydephosphate dehydrogenase (EC 1.2.1.13). However, there was no correlation of SLA with the activity of phospho(enol)pyruvate carboxylase (EC 4.1.1.31), an anaplerotic carboxylation enzyme of grasses. SLA is suggested to reflect the state and activity of the photosynthetic apparatus and can be recommended as a characteristic of photosynthesis variability (e.g., caused by cytokinin-like preparations).     

A cytosolic NADP-malic enzyme gene from rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) confers salt tolerance in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

NADP-malic enzyme (NADP-ME, EC 1.1.1.40) functions in many different pathways in plant and may be involved in plant defense such as wound and UV-B radiation. Here, expression of the gene encoding cytosolic NADP-ME (cytoNADP-ME, GenBank Accession No. AY444338) in rice (Oryza sativa L.) seedlings was induced by salt stress (NaCl). NADP-ME activities in leaves and roots of rice also increased in response to NaCl. Transgenic Arabidopsis plants over-expressing rice cytoNADP-ME had a greater salt tolerance at the seedling stage than wild-type plants in MS medium-supplemented with different levels of NaCl. Cytosolic NADPH/NADP⁺ concentration ratio of transgenic plants was higher than those of wild-type plants. These results suggest that rice cytoNADP-ME confers salt tolerance in transgenic Arabidopsis seedlings.     

Changes of antioxidative enzymes,lipid peroxidation and chlorophyll content in chickpea types colonized by different <Emphasis Type="Italic">Glomus</Emphasis> species under drought stress

In order to investigate the effects of Glomus species on some physiological characteristics of two chickpea types (Pirouz cultivar of Desi type and ILC-482 of Kabuli type) under non-stress (NS) and drought stress, an experiment was conducted using a factorial arrangement based on completely randomized design with three replications. Drought stress decreased shoot and total dry weight in plants. However inoculation of plants with mycorrhiza improved these traits. Leaf chlorophyll content was decreased, but leaf proline content and guaiacol peroxidases (EC 1.11.1.7) (POD), catalase (EC 1.11.1.6) (CAT), and ascorbate peroxidase (EC 1.11.1.11) (APX) activities were increased as a result of drought stress. Drought stress had no significant effect on soluble protein content and polyphenol oxidase (EC 1.10.3.1) (PPO) enzymatic activity in chickpea plants. In general, drought stress and especially severe drought stress increased membrane lipid peroxidation (MDA) in chickpea plants, which was more evident in non-inoculated than in inoculated plants. Inoculation of chickpea by AM significantly increased POD and PPO activities compared with non-inoculated chickpea, but had no effect on CAT activity and proline content of leaves. The reaction of chickpea cultivars to inoculation by AM species and irrigation levels were different. ILC-482 showed that antioxidant enzymes activities were more and thus less MDA compared with Pirouz cultivar. In general, the most POD and PPO activities were recorded for inoculated plants with G. etunicatum and G. versiform species, and the most APX activity was observed in plants inoculated with G. intraradices.     

Nematicidal activity of fervenulin isolated from a nematicidal actinomycete, <Emphasis Type="Italic">Streptomyces</Emphasis> sp. CMU-MH021, on <Emphasis Type="Italic">Meloidogyne incognita</Emphasis>

An isolate of the actinomycete, Streptomyces sp. CMU-MH021 produced secondary metabolites that inhibited egg hatch and increased juvenile mortality of the root-knot nematode Meloidogyne incognita in vitro. 16S rDNA gene sequencing showed that the isolate sequence was 99% identical to Streptomyces roseoverticillatus. The culture filtrates form different culture media were tested for nematocidal activity. The maximal activity against M. incognita was obtained by using modified basal (MB) medium. The nematicidal assay-directed fractionation of the culture broth delivered fervenulin (1) and isocoumarin (2). Fervenulin, a low molecular weight compound, shows a broad range of biological activities. However, nematicidal activity of fervenulin was not previously reported. The nematicidal activity of fervenulin (1) was assessed using the broth microdilution technique. The lowest minimum inhibitory concentrations (MICs) of the compound against egg hatch of M. incognita was 30 μg/ml and juvenile mortality of M. incognita increasing was observed at 120 μg/ml. Moreover, at the concentration of 250 μg/ml fervenulin (1) showed killing effect on second-stage nematode juveniles of M. incognita up to 100% after incubation for 96 h. Isocoumarin (2), another bioactive compound produced by Streptomyces sp. CMU-MH021, showed weak nematicidal activity with M. incognita.     

Impact of herbivory on performance of <Emphasis Type="Italic">Vincetoxicum</Emphasis> spp., invasive weeds in North America

The alien invasive vines Vincetoxicum rossicum and Vincetoxicum nigrum (swallow-wort) are of major concern in eastern North America, where both species invade forested landscapes and threaten faunal and plant diversity. Among the few native natural enemies reported in Eurasia, the specialist chrysomelid, Chrysochus (Eumolpus) asclepiadeus (Coleoptera; Chrysomelidae), feeds on Vincetoxicum both above ground (as adults) and below ground (as larvae). The goal of our study was to assess the potential for using this beetle to manage invasive Vincetoxicum spp. in North America by quantifying the impact of herbivory by C. asclepiadeus on Vincetoxicum and determining whether this effect was influenced by plant density (“Allee effect”). Experimental work was carried out using a split plot design in the field in southern France. Pots of V. nigrum and V. hirundinaria, a substitute for V. rossicum, were planted at high (255 plants/m²), medium (127 plants/m²), and low (32 plants/m²) plant densities, and received treatments of 0 (control), 2 or 4 C. asclepiadeus adult beetles/pot. Leaf damage, root and shoot biomass, and quantity of seeds were measured after 4 weeks of adult feeding. Densities of 2 and 4 beetles/pot caused similar damage, with significant reductions in plant biomass at low plant density. While V. hirundinaria increased allocation of resources to roots in response to herbivory, V. nigrum did not. Seed production was greatest for both species grown at low plant densities, but only V. nigrum produced fewer seeds in response to herbivory. Our results, based on the effects of herbivory by C. asclepiadeus adults, suggest that if this beetle were to be introduced into North America for the management of Vincetoxicum spp. such as V. rossicum, reductions in plant biomass and spread would be greatest if beetles were released on edges or in newly-established satellite populations at low plant densities. In the case of V. nigrum, beetles could be released irrespective of plant density as reproductive output and seed dispersal would be reduced similarly.     

Size-related auto-fragment production and carbohydrate storage in auto-fragment of <Emphasis Type="Italic">Myriophyllum spicatum</Emphasis> L. in response to sediment nutrient and plant density

Size-related asexual reproduction of submersed macrophytes is still poorly understood. Here, we investigate how size-related auto-fragmentation in Myriophyllum spicatum L. responds to sediment nutrients and plant density. An experiment was carried out with sediments containing two different nutrient levels and with two levels of plant density. The results show that sediment nutrients and plant density brought about a strong dependency of auto-fragment production and the amount of total non-structural carbohydrate (TNC) storage in auto-fragments on individual plant size (total plant biomass). However, these two factors acted differently on size dependency. Sediment nutrients positively affected auto-fragment production and the amount of TNC in auto-fragments of M. spicatum. High concentrations of sediment nutrients significantly increased these two traits in absolute value and the value relative to plant size. Although the auto-fragment biomass and the amount of TNC in auto-fragments did not differ between density treatments when plant size was considered, the absolute values of these two traits were much larger in the low plant density treatment than in the high plant density treatment, which suggested an indirect negative effect of plant density on the auto-fragmentation of M. spicatum. In addition, higher percentages of large auto-fragments (>100 mg) were produced by plants that grew in nutrient poor sediment and low plant density environment than plants in nutrient rich sediment and high plant density environment. These results do not solely highlight a size-dependent effect, but also a size-independent effect of auto-fragment production and the amount of TNC in auto-fragments of M. spicatum. Furthermore, such size-independent effects can be explained by the significant biomass partitioning differences and the similar TNC-concentrations in auto-fragments under different environmental conditions.     

Differential effects of water depth and sediment type on clonal growth of the submersed macrophyte <Emphasis Type="Italic">Vallisneria natans</Emphasis>

The response of clonal growth and ramet morphology to water depth (from 60 to 260 cm) and sediment type (sand versus organic clay) was investigated for the stoloniferous submersed macrophyte Vallisneria natans in an outdoor pond experiment. Results showed that water depth significantly affected clonal growth of V. natans in terms of clone weight, number of ramets, number of generations, clonal radius and stolon length. V. natans showed an optimal clonal growth at water depths of 110–160 cm, but at greater depths clonal growth was severely retarded. A high allometric effect was exhibited in ramet morphology. Along the sequentially produced ramet generations, ramet weight and plant height decreased while stolon length and the root:leaf weight ratio increased. When using ramet generations as covariate, sediment type rather than water depth more strongly affected the ramet characteristics. For plants grown in clay, ramet weight, ramet height and stolon length were greater, and plants exhibited lower root:leaf weight ratio. These data suggest that water depth and sediment type have differential effects on clonal growth of V. natans: Water depth appears primarily to affect numerical increase in ramets and spatial spread, whereas sediment type mainly affects biomass accumulation and biomass allocation. Handling editor: S. M. Thomaz     

Production and characteristics of antisera to Spiroplasma citri and clover phyllody-associated antigens derived from plants

Antisera were produced to clover phyllody- and Spiroplasma citri-associated antigens partially purified from infected Vinca rosea plants. Separate antisera were made to ‘membrane fraction’ (MF) preparations comprising the resuspended pellet obtained by high speed centrifugation, and to ‘soluble fraction’ (SA) preparations, comprising the supernatant from high speed centrifugation concentrated by freeze-drying. All antisera showed considerable activity against normal plant antigens but after cross-absorption with extracts of healthy plants the MF antisera were used in F(ab')₂based ELISA tests to detect S. citri- or clover phyllody-associated antigens in infected plants. The ‘clover phyllody’ antiserum also reacted specifically with extracts of clover plants with phyllody, and with naturally-infected strawberry plants showing symptoms of green petal disease. Both the ‘clover phyllody’ and S. citri antisera were specific for their respective homologous antigens. No cross-reactions were observed in heterologous tests or between either antiserum and extracts of V. rosea infected with various MLOs obtained from different host plants.     

Growth and reproduction of the alpine grasshopper <Emphasis Type="Italic">Miramella alpina</Emphasis> feeding on CO<Subscript>2</Subscript>-enriched dwarf shrubs at treeline

The consequences for plant-insect interactions of atmospheric changes in alpine ecosystems are not well understood. Here, we tested the effects of elevated CO₂ on leaf quality in two dwarf shrub species (Vaccinium myrtillus and V. uliginosum) and the response of the alpine grasshopper (Miramella alpina) feeding on these plants in a field experiment at the alpine treeline (2,180 m a.s.l.) in Davos, Switzerland. Relative growth rates (RGR) of M. alpina nymphs were lower when they were feeding on V. myrtillus compared to V. uliginosum, and were affected by elevated CO₂ depending on plant species and nymph developmental stage. Changes in RGR correlated with CO₂-induced changes in leaf water, nitrogen, and starch concentrations. Elevated CO₂ resulted in reduced female adult weight irrespective of plant species, and prolonged development time on V. uliginosum only, but there were no significant differences in nymphal mortality. Newly molted adults of M. alpina produced lighter eggs and less secretion (serving as egg protection) under elevated CO₂. When grasshoppers had a choice among four different plant species grown either under ambient or elevated CO₂, V. myrtillus and V. uliginosum consumption increased under elevated CO₂ in females while it decreased in males compared to ambient CO₂-grown leaves. Our findings suggest that rising atmospheric CO₂ distinctly affects leaf chemistry in two important dwarf shrub species at the alpine treeline, leading to changes in feeding behavior, growth, and reproduction of the most important insect herbivore in this system. Changes in plant-grasshopper interactions might have significant long-term impacts on herbivore pressure, community dynamics and ecosystem stability in the alpine treeline ecotone.     

Some hosts and properties of bulbous iris mosaic virus

Iris mosaic virus (IMV) was the only virus isolated from forty-six bulbous iris plants of twenty-two cultivars tested; it was common also in Iris danfordiae and I. reticulata but was not detected in any of fifty-two rhizomatous iris plants with mosaic symptoms. IMV was transmitted to healthy irises with difficulty by mechanical inoculation but was transmitted efficiently by Myzus persicae. IMV infected eight of forty-six plant species inoculated mechanically with partially purified virus preparations. Characteristic local lesions without subsequent systemic infection were produced in Amaranthus caudatus, six Chenopodium spp., and Tetragonia expansa; of these, C. quinoa and T. expansa were the best indicator and assay hosts. The virus was moderately stable in vitro and, unlike some similar filamentous viruses, was best purified by differentially centrifuging infective sap clarified with n-butanol. Partially purified preparations from several hosts were infective, produced one specific light-scattering zone after centrifuga-tion in sucrose density-gradient columns, were antigenic and contained particles of 760 mμ model length. IMV was not serologically related to any of nine similar aphid-transmitted, filamentous viruses.     

Bioactive secondary metabolites from <Emphasis Type="Italic">Nigrospora</Emphasis> sp. LLGLM003, an endophytic fungus of the medicinal plant <Emphasis Type="Italic">Moringa oleifera</Emphasis> Lam.

An endophytic fungus was isolated from the root of the medicinal plant Moringa oleifera Lam. Based on analyzing the rDNA sequence, the fungus was identified as Nigrospora sp. This is the first report of the isolation of endophytic Nigrospora from M. oleifera. By bioassay-guided fractionation, four antifungal secondary metabolites were isolated from liquid cultures of the fungus Nigrospora sp. LLGLM003, and their chemical structures were determined to be griseofulvin (1), dechlorogriseofulvin (2), 8-dihydroramulosin (3) and mellein (4) on the basis of spectroscopic analyses. Compound 2, 3 and 4 were isolated from Nigrospora sp. for the first time. In vitro antifungal assay showed that griseofulvin displayed clear inhibition of the growth of 8 plant pathogenic fungi. Dechlorogriseofulvin and mellein exhibited only weak antifungal activities, whereas 8-dihydroramulosin displayed no antifungal activities.     

Intercellular chitinase and peroxidase activities associated with resistance conferred by geneLr35to leaf rust of wheat

The effect of leaf rust (Puccinia triticina) infection on intercellular chitinase (EC 3.2.1.14) and peroxidase (EC 1.11.1.7) activities was studied in resistant [RL 6082 (Thatcher/Lr35)] and susceptible (Thatcher) near isogenic wheat (Triticum aestivum L.) lines at seedling, stem elongation and flag leaf stages of plant growth. The levels of activity of these enzymes were low during the seedling and stem elongation stages. Resistant plants at the flag leaf stage, during which the Lr35 resistance gene was maximally expressed, exhibited high constitutive levels of chitinase and peroxidase activities, in contrast to the lower constitutive levels of susceptible plants. The results suggest that chitinase and peroxidase, constitutively present in the intercellular spaces of Thatcher/Lr35 wheat leaves, may play a role in Lr35 mediated resistance to leaf rust.