Influence of arbuscular mycorrhizal fungi and treated wastewater on water relations and leaf structure alterations of Viburnum tinus L. plants during both saline and recovery periods.

Nowadays, irrigation with low quality water is becoming an alternative to satisfy the needs of crops. However, some plant species have to deal with high salinity of reclaimed water, by adapting their physiological behaviour during both saline and recovery periods and developing morphological changes in their leaves. The application of arbuscular mycorrhizal fungi (AMF) could also be a suitable option to mitigate the negative effects of this kind of water, although the effectiveness of plant-AMF association is influenced by many factors. In this work, during forty weeks, the combined effect of Glomus iranicum var. tenuihypharum and two types of water: control, C, EC<0.9 dS m(-1) and reclaimed water, RW (with EC: 4 dS m(-1) during a first saline period and EC: 6 dS m(-1) during a second saline period) was evaluated for laurustinus plants (Viburnum tinus L.) transplanted in soil. This was followed by a recovery period of eight weeks, when all the plants were irrigated in the control irrigation conditions. Seasonal and daily changes in stem water potential (Ψstem), stomatal conductance (gs), photosynthesis (Pn) and leaf internal CO2 concentration (Ci) of laurustinus plants were evaluated. Leaf structure alterations, nutrient imbalance, height and leaf hydraulic conductivity (Kleaf) were also determined. Due to the high difficulty of absorbing water from the soil, RW plants showed a high volumetric water content (θv) in soil. The stem water potential and the stomatal conductance (gs) values were reduced in RW plants throughout the second saline period. These decreases were also found during the day. Leaf Ca(2+)/Na(+) and K(+)/Na(+) ratios diminished in RW plants respect to the C plants due to the Na(+) accumulation, although height and chlorophyll content values did not show statistical differences. Leaves from RW plants showed a significantly thicker mesophyll than Control leaves as a consequence of high EC. The area of palisade parenchyma (PP) increased while the area of spongy parenchyma (SP) decreased in RW leaves with respect to the C leaves. These structural changes could be considered as a strategy to maximize photosynthesis potential in saline conditions. Mycorrhizal inoculation improved the water status of both C and RW plants by increasing their Ψstem and gs values. As regards leaf structure, AMF showed an opposite effect to salinity for PP and SP. At the end of the recovery period, hardly any statistical differences of physiological parameters were found between treatments, although a tendency to improve them was observed in inoculated plants. In any case, the leaf structural changes and the great reduction in Kleaf observed at Ψleaf below -1.5 MPa would constitute an important mechanism for laurustinus plants to reduce the water loses produced by salinity.

Protective effects of Glomus iranicum var. tenuihypharum on soil and Viburnum tinus plants irrigated with treated wastewater under field conditions.

Currently, irrigation using recycled water is increasing, especially in semiarid environments, but a potential problem of using reclaimed wastewater is its elevated salt levels. The application of arbuscular mycorrhizal fungi (AMF) could be a suitable option to mitigate the negative effects produced by the salinity. In this work, the combined effect of Glomus iranicum var. tenuihypharum and two types of water: Control, C, with EC <0.9 dS m(-1) and reclaimed water (wastewater previously treated in a sewage treatment plant) with EC 4 dS m(-1) during a first saline period (11 weeks) and with EC 6 dS m(-1) during a second saline period (25 weeks), was evaluated for laurustinus (Viburnum tinus) plants under field conditions. This plant is a popular shrub very used for gardening. Chemical properties of soil as well as physiological behavior, leaf nutrition, and esthetic value of plants were evaluated. Due to the high salinity from wastewater at 6 dS m(-1), laurustinus plants decreased their stem water potential values and, to a lesser extent, the stomatal conductance. Also, the visual quality of the plants was diminished. The inoculated AMF satisfactorily colonized the laurustinus roots and enhanced the structure of the soil by increasing the glomalin and carbon contents. Furthermore, G. iranicum var. tenuihypharum inoculation decreased Na and Cl content, stimulated flowering and improved the stem water potential of the plants irrigated with both types of reclaimed water. The AMF also had a positive effect as a consequence of stimulation of plant physiological parameters, such as the stem water potential and stomatal conductance. Effective AMF associations that avoid excessive salinity could provide wastewater reuse options, especially when the plants grow in soils.

α-Glucosidase and lipoxygenase inhibitory derivatives of cryptosporioptide from the endophytic fungus Cryptosporiopsis sp.

Two new cryptosporioptide-derived polyketides cryptosporioptides A (2) and B (3) were isolated from the extract of endophytic fungus Cryptosporiopsis sp. associated with the shrub, Viburnum tinus. The structures of the isolates were determined through spectral analysis including 1D NMR ((1)H, (13)C) and 2D NMR (HSQC, HMBC, COSY) techniques, HR-FAB-MS and by comparison with the reported data of cryptosporioptide (1). The relative stereochemistry was assigned with the help of NOESY analysis, the molecular model, and comparison of the optical rotation values with the reference compound 1.

Depsitinuside: a new depside galactoside from an endophytic fungus isolated from Viburnum tinus.

Chromatographic purification of the extract of an endophytic fungal culture yielded depsitinuside (1), a new phenolic ester together with ergosterol (2) and (22E,24S)-24-methyl-5-α-cholesta-7,22-diene-3ß,5,6ß-triol (3). The structure of 1 was elucidated based on 1D, 2D NMR spectroscopy and high-resolution mass spectrometry, whereas the known compounds (2 and 3) were identified by (1)H NMR, mass spectrometry, and in comparison with the literature values. Compound 1 was evaluated for its enzyme inhibitory potential against acetylcholinesterase, butyrylcholinesterase and lipoxygenase, and was found inactive (10%-40% inhibition at a concentration of 2 mg/ml).

A test system to quantify inoculum in runoff from Phytophthora ramorum-infected plant roots.

Foliar hosts of Phytophthora ramorum are often susceptible to root infection but the epidemiological significance of such infections is unknown. A standardized test system was developed to quantify inoculum in runoff from root-infected Viburnum tinus ?Spring Bouquet? or Rhododendron ?Cunningham's White? cuttings. Cuttings of both species gave off a maximum amount of inoculum 1 to 3 weeks after inoculation. The greatest amount of inoculum was recovered from Viburnum roots that were 48 to 70 days old at the time of inoculation, or roots incubated at 15 to 20?C rather than 25?C. Inoculum in runoff from inoculated Viburnum roots was similar for four different isolates of P. ramorum representing both the NA1 and EU1 lineages. When Rhododendron cuttings were inoculated with P. ramorum, P. citricola, or P. cactorum, inoculum of all three pathogens was recovered from runoff, with the highest amount recovered from plants inoculated with P. citricola, followed by the other two. Compared with the other two pathogens, P. ramorum colonized root tissue to a smaller extent. The epidemiology of root infection by P. ramorum is important in itself but the assay might lend itself for use in risk analysis for root infection of other plant species and evaluation of control measures, and also shed light on other root-infecting Phytophthora spp.

Biodiversity and new records of microfungi in the Ruhrarea (north Rhine Westfalia), Germany.

During our investigations of the microflora in NRW (Duisburg, Düsseldorf and Essen incl. the greenhouse of the Botanical Garden) in 2007 and 2008, we were able to collect and identify about 55 species on trees, bushes and ornamental plants as parasites and saprophytes. Some of these species are new for Germany or have been only rarely found until now. Most of the species belong the Ascomycotina, Basidiomycotina and Deuteromycotina for example Arthrocladiella mougeotii (Lév.) Vassilkov. on Lycium barbarum L., Caudospora taleola (Fr.) Starb on Quercus robur L., Colletotrichum coffeanum F. Noak on Coffea arabica L. (new for Germany) Colletotrichum trichellum (Fr.) Duke on Hedera helix L., Erysiphe buhrii U. Braun on Lychnis cf. coronaria (L.) Desr. (Anamorph. Oidium dianthi Jacz.), Erysiphe spec. on Acer opalus Mill (new host), Erysiphe flexuosa (Peck) U. Braun & S. Takam. on Aesculus spec. (new for Europe)), Erysiphe heraclei DC. on Tinguarra montana (Webb ex Christ ) A.Hansen & G.Kunkel, Erysiphe necator Schwein. = Uncinula necator (Schwein.) Burrill on Cissus cf. rhombifolia Vahl. (new for NRW), Erysphe trifolii Grev. on Trigonella caerulea (L.) Ser., Golovinomyces cichoracearum (DC.) V.P.Gelyuta (Oidium spec.) on Argyranthemum pinnatifidum (L.f.) R.T. Lowe (new host), Lobatopedis foliicola P.M. Kirk on Quercus robur L. (new for NRW), Lophodermium juniperinum (Fr.) de Not. on Juniperus communis L., Mamiania coryli De Not. on Corylus avellana L., Marssonina juglandis (Lib.) Magnus on Juglans regia L., Oidium hortensia Jørst on Philadelphus coronarius L., Oidium spec. on Dahlia variabilis (Willd.) Desf. (new for Germany), Oidium longipes Noordeloos & Loerak on Petunia hybrida Vilm., Oidium pedilanthi M. Yen on Pedilanthus titymaloides (L.) Poit, Oidium pedaliacearum H.D. Shin sp. nov. (= Oidium sesami H.D. Shin) on Ibicella lutea (Lindl.) van Eselt. (= Martynia lutea Lindl.), Passalora pastinacae (Sacc.) U. Braun = Pseudocercosporella pastinacae (P. Karst.) U. Braun (new for Germany) on Pastinaca sativa L., Podosphaera tridactyla (WalIr.) de Bary on Prunus laurocerasus L., Septoria cornicola Desm. on Cornus sanguinea L., Stigmina tinea (Sacc.) M.B.Ellis on Viburnum opulus L., Torula herbarum (Pers.) Link on Potentilla argentea L., etc. All species are located in the herbarium Mycotheca parva collection G.B. Feige and N. Ale-Agha.

Stromata, sporangiomata and chlamydosori of Phytophthora ramorum on inoculated Mediterranean woody plants.

Three types of multihyphal structures, stromata, sporangiomata and chlamydosori, are described for the plant pathogen Phytophthora ramorum. Their morphology, morphogenesis and position on the host organ were observed by dissecting, compound and scanning electron microscopy. Stromata were consistently formed one to two weeks after zoospore inoculation of detached leaves and fruits of an assortment of Mediterranean sclerophyll shrubs. Stroma initials appeared subcuticularly or subepidermally and developed as small hyphal aggregates by repeated branching, budding, swelling and interweaving, eventually forming a prosenchyma. They always emerged through the adaxial side of the leaf by rupture of the overlying host tissue. Occasionally sporangia and chlamydosori (packed clusters of chlamydospores) were formed on the stromata. Sporangiomata bore short sporangiophores and clusters of 20-100 sporangia and resembled sporodochia of the mitosporic fungi. The biological significance of these multihyphal structures is discussed. Some epidemiological aspects were also studied: several understorey species of the holm oak (Quercus ilex) woodland were susceptible to in vitro infection with three isolates of P. ramorum originally collected from different ornamental hosts. The risk of spread to this ecosystem is evaluated.

Phytopthora ramorum in Belgium: 2002 survey results and research efforts.

Phytophthora ramorum is a new and aggressive Phytophthora species that causes leaf blight and dieback symptoms on Viburnum and Rhododendron plants in Europe. A variant of this fungus is responsible for Sudden Oak Death (SOD) in California and Oregon. In Europe, problems so far are mostly restricted to nursery plants of Rhododendron and Viburnum while in the US, the fungus has been isolated from over 20 host species and is responsible for massive killing of oak trees (mostly Quercus agrifolia and Lithocarpus densiflorus) in forest and park settings. The potential for infection of native tree species in Europe and the recent detection of the fungus in nurseries of several European countries has lead to the implementation of EU emergency phytosanitary measures. As a result, most European countries have conducted surveys and are doing research as part of risk assessment efforts. The first part of this paper focuses on the plant diagnoses of the 2002 survey of P. ramorum in Belgian nurseries. The data from the survey indicates P. ramorum is present in Belgium at similar rates as in the neighbouring countries, in an apparent random distribution. The second part of this paper describes research results relating to the in vitro effect of oomycete fungicides on P. ramorum, Rhododendron cultivar susceptibility, the determination of the leaf infection site, and pathogen survival. Some fungicides had excellent in vitro activity against P. ramorum and should be tested further on plants. Use of host resistance as a control strategy may be limited as little difference in cultivar sensitivity was observed. Infection studies showed that wounds and the lower sides of the leaves are most susceptible to infection. Once the pathogen gets inside, it can survive well on detached leaves, especially when they are kept cool and moist. These data can contribute to management decisions of P. ramorum at the level of nurseries as well as the government.