Does mycorrhization influence herbivore-induced volatile emission in Medicago truncatula?

Symbiosis with mycorrhizal fungi substantially impacts secondary metabolism and defensive traits of colonised plants. In the present study, we investigated the influence of mycorrhization (Glomus intraradices) on inducible indirect defences against herbivores using the model legume Medicago truncatula. Volatile emission by mycorrhizal and non-mycorrhizal plants was measured in reaction to damage inflicted by Spodoptera spp. and compared to the basal levels of volatile emission by plants of two different cultivars. Emitted volatiles were recorded using closed-loop stripping and gas chromatography/mass spectrometry. The documented volatile patterns were evaluated using multidimensional scaling to visualise patterns and stepwise linear discriminant analysis to distinguish volatile blends of plants with distinct physiological status and genetic background. Volatile blends emitted by different cultivars of M. truncatula prove to be clearly distinct, whereas mycorrhization only slightly influenced herbivore-induced volatile emissions. Still, the observed differences were sufficient to create classification rules to distinguish mycorrhizal and non-mycorrhizal plants by the volatiles emitted. Moreover, the effect of mycorrhization turned out to be opposed in the two cultivars examined. Root symbionts thus seem to alter indirect inducible defences of M. truncatula against insect herbivores. The impact of this effect strongly depends on the genetic background of the plant and, hence, in part explains the highly contradictory results on tripartite interactions gathered to date

Growth and carbohydrate status of Pyrus communis L plantlets inoculated with Glomus sp

The effects of an arbuscular mycorrhizal fungus (Glomus sp) on development and carbohydrate metabolism of micropropagated plantlets of a pear clonal rootstock (OH x F 51) were examined during the first vegetative growth and at the beginning of the second growing year. Plant growth was assessed in terms of stem height, leaf number, root length, fresh and dry weight of the whole plant, stem, leaves and root mass at different times following inoculation. The levels of soluble (fructose, glucose, sucrose and sorbitol) and insoluble (starch) sugars were analyzed in stems, leaves and roots using gas-chromatographic techniques. Inoculation with Glomus sp was effective in promoting plant growth causing a strong increase in shoot height, root length and a greater growth rate of dry matter. Colonization of rootstock roots with Glomus sp altered the carbohydrate metabolism and partitioning within the plant.Croissance et état des glucides chez des microplantes de Pyrus communis L inoculées avec Glomus sp. Les effets d'un champignon mycorhizogène à arbuscule (Glomus sp) sur la croissance et sur le métabolisme glucidique d'un porte-greffe micropropagé de poirier (OH x F 51) ont été examinés pendant les premiers stades et au début de la deuxième année de développement. La croissance des plantes a été évaluée, à différentes périodes après inoculation, par des mesures de hauteur de tige, de nombre de feuilles, de longueur de racines et de poids de matière fraîche et sèche. Le contenu en glucides solubles (fructose, glucose, saccharose et sorbitol) et insolubles (amidon) a été mesuré dans les tiges, les feuilles et les racines par chromatographie gazeuse. L'inoculation avec Glomus sp s'est révélée efficace pour stimuler la croissance des plantes en induisant une forte augmentation de la hauteur des tiges, de la longueur des racines et du taux de matière sèche par rapport aux témoins. La colonisation des racines de porte-greffes par Glomus sp a provoqué aussi un changement au niveau du métabolisme des glucides et de leur répartition dans la plante

New method for the devitalization of imported horsetail (Equisetum hyemale)

Despite being rated as one of the world’s worst weeds, Equisetum hyemale was until recently imported into New Zealand for use by the floristry industry, subject to devitalization. It was subsequently found that imported stems were not being successfully devitalized and importation was banned. This study, in two trials, used different dilutions of six herbicides, including Roundup, the one listed in the MAF Biosecurity NZ standard, to investigate if it were possible to render stems non-propagable without destroying their commercial use. This research found that a Sharpshooter (oryzalin) formulation at 1 and 1:2 dilutions of the field application strength was the only herbicide that completely devitalized the stem material with minimal impact on stem quality. Roundupat the concentration required by MAF Biosecurity NZ destroyed the stems, while 1:5 and 1:10 dilutions reduced the ability of the stems to be propagated, but still caused stem damage. AGPRO activated amitrole, Duplosan, Agritone and Kamba were not successful as devitalization agents

comportamento ambientale degli erbicidi impiegati nelle colture orticole Atti

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Air purification by trees and their impact in urban environment

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