1,721,009 research outputs found
Contributo della micropropagazione alla valorizzazione del sorbo da legno
Full text linkNell’attività di micropropagazione di selezioni autoctone da legno di S. torminalis e S. domestica la fase di radicazione si è rivelata critica per S. torminalis e quella d’ambientamento per entrambe. Nel presente lavoro si evidenzia l’influenza del genotipo e della citochinina sulla fase di radicazione di S. torminalis e si descrive l’evoluzione dell’apparato fogliare durante la fase di ambientamento delle colture.Sorbus spp. is particularly important for timber production as the price of its good-quality wood is extremely high and its demand is increasing on the European market. The use of in vitro propagation allows the large-scale production of interesting accessions as those selected at DIPROVE of Milan University. Whereas rooting was critic for S. torminalis accessions acclimatization appeared critical also for S. domestica. S. torminalis gave better rooting and in vivo survival when preconditioned on BA free medium. Changes in the morphological and histological features and in the development of the mesophyll layer of persistent (ex vitro) leaves as compared to both in vitro and new formed ones were observed
Morphological and physiological behaviour of sweet cherry 'somaclone' HS plants in field
No full textThe somaclonal variant HS (HS), regenerated from Prunus avium `Hedelfinger’ (H) leaf explants, had previously been molecularly and physiologically characterized both in vitro and in early ex vitro condition showing reduced apical dominance.
Somaclone HS, here assessed for several morphological and physiological field performances
showed reduced vegetative vigour as determined by trunk circumference and tree height nevertheless natural architecture of the tree was preserved. HS canopy was less crowded compared to H as leaves were shorter with a shorter petiole, they were better spaced out as indicated by internodes length and they had a significantly thinner cuticle and wax layer compared to that found on H leaves surface. Leaf histological analysis also evidenced that HS had thicker mesophyll and palisade the latter composed of more than one layer which, together with increased stomatal density, are distinguishing signs of extensively sun exposed leaves. HS showed a reduction in leaf chlorophyll b and β-carotene content. On the other hands no significant differences were found between the two genotypes in terms of net photosynthesis, intercellular CO2 concentration, leaf transpiration and water use efficiency. HS flowered one year later than H and fertility parameters such as floral buds and number of flowers per bud were reduced. In consideration of the fact that the large size of trees has contributed to make P. avium commercial cultivars unpopular with modern orchardists, HS could be used as either germplasm in breeding programs aiming to reduce tree vigour or a rootstock
Chemical-induced resistance against powdery mildew in barley : the effects of chitosan and benzothiadiazole
No full textChitosan (CHT), a deacetylated chitin derivative, and benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), a non toxic synthetic functional analogue of salicylic acid, were applied as foliar spray to barley plants (Hordeum vulgare L.), to compare their effectiveness in inducing resistance against Blumeria graminis f. sp. hordei
and to investigate the underlying defence response. After an induction phase of 3 days (IP, time elapsed between treatment and fungal inoculation) both compounds reduced significantly the infection on the primary leaf, namely of 55.5% for CHT and of 68.9% for BTH, showing the induction of a good level of local resistance (LAR). A 5-day IP further
reduced the infected areas in BTH treated plants ( 77.2%) but not in CHT treated ones ( 47.1%). Furthermore, both CHT and BTH also induced SAR, being the infection in the second non treated leaves reduced of 57% and 76.2%, respectively, as evaluated at 10-day IP. Both BTH and CHT induced oxidative burst and phenolic compound deposition in
treated leaves, creating an hostile environment that slowed down the fungal spreading by
impairing haustorium development. However, the greater efficacy of BTH was possibly due to: i) a greater reinforcement of papilla; ii) a higher level and the more homogeneous diffusion of H2O2 in the treated leaf tissues and iii) an induced hypersensitive-like response in many penetrated cells
Activity of synthetic and natural compounds for phytoplasma control
Full text linkA sustainable and rational procedure to evaluate the activity of synthetic and natural substances towards phytoplasma agents of important tree diseases was developed with the aim of finding new strategies of control. The method of testing is based on 1) the utilization of Catharanthus roseus; 2) the artificial infection of periwinkles with two phytoplasma strains; 3) scion dipping, selected as the most suitable method of applying the substances.
A series of natural and synthetic compounds were chosen among a) new agrochemical entries, registered as plant-resistance inducers; b) secondary metabolites of fungal and plant origin; c) new and known biologically active substances never tested before for their antiphytoplasmal properties. The activity of this series of compounds on healthy and phytoplasma-infected periwinkles was evaluated on the basis of several parameters: phytotoxicity, evolution of symptoms and microscope observations. The in-volvement of the third component in the triangular interaction between phytoplasma, plant and compound is discussed
Indagini preliminari sull’interazione tra Plasmopara viticola e ibridi di vite resistenti alla peronospora
No full textIn vivo antibiogram to test the action of synthetic and natural compounds on phytoplasmas
No full textWith the aim of finding new strategies to control phytoplasmal diseases, a series of natural and synthetic compounds were tested to study their activity in Catharanthus roseus L. healthy and graft-infected with two phytoplasmas (Candidatus Phytoplasma
asteris and Candidatus Phytoplasma ulmi). A preliminary investigation was carried out by testing the responses of plants to treatment with tetracycline. The compound was applied in several ways (spraying, root absorption and scion dipping), and at different concentrations and number and timing of treatments. The results obtained showed that scion dipping was the most suitable method in our experimental conditions, as it needed the lowest amount of compound and permitted the uantification of the compound absorbed. Thus, this procedure was adopted to test some natural substances never assayed before in this hostpathogen system: (i) Cercosporin, Spirolaxin and Cladosporol, organic compounds of fungal origin with antibiotic activity against phytopathogenic bacteria; (ii) Carvone and Pulegone, two active terpenoids of plant origin; (iii) the mineral salt Potassium Alum; (iv) the synthetic basic Dienes stain and (v) a Methionin-Riboflavin mixture. The activity of these compounds was evaluated on the basis of phytotoxicity, symptom evolution and microscope observations. This testing method is likely to provide a sustainable and rational procedure for investigating the triangle host-phytoplasma-compound. It will be adopted in further research to estimate the anti-phytoplasmal activity of other known and novel chemicals, both synthetic and natural
Activity of chitosan, antibiotics and phosethyl-Al on healthy and phytoplasma-experimentally infected periwinkles.
No full textUromyces appendiculatus Infection in BTH-Treated Bean Plants: Ultrastructural Details of a Lost Fight
No full textThe mechanisms of BTH [benzo-(1,2,3)-
thiadiazole-7-carbothioic acid S-methyl ester]-induced resistance against bean rust caused by Uromyces appendiculatus have been explored in Phaseolus vulgaris by light and transmission electron microscopy, following the infection progression in plants challenged 7 days after treatment. While BTH did not affect
uredospore germination and fungal penetration in the substomatal cavity, a first impairment to the colonization
appeared evident about 48–96 h after inoculation, with alterations of infection hypha structure and reduction in mycelium expansion. No differences were found in this phase regarding the formation and
ultrastructure of haustoria in untreated andBTH-treated plants, except for the deposition of electron-opaque material in the extrahaustorial matrix of the latter. A second and decisive impairment in fungal progression was observed at 7–10 days after inoculation when host cell penetrated, or in close contact with the fungal hyphae, were impregnated by phenolic compounds
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