Effects of Azospirillum brasilense Sp245 on grapevine propagation

Azospirillum brasilense Sp245, a well known PGPR (plant growth-promoting rhizobacteria), has been considered in order to evaluate the effects on the nursery propagation, and especially to test the ability of the inoculated bacterium to improve rooting parameters for some rootstocks which do not easily root by means of conventional techniques. Nursery trials, laboratory trials, growth observations of the obtained vines, and experiments on the drought resistance of inoculated plants, were performed along three years, from 2008 to 2010. The nursery trials were executed in a conventional nursery and in an organic one, during the scheduled daily work of the host nurseries; plant material was furnished by the nurseries as well. A significant increase in the callus diameter was observed in inoculated grafted cuttings at the end of the grafted cuttings forcing (a two-weeks period at 25°C and high humidity rate). As to the rooting parameters, while the rooting percentage was not significantly affected, an improved quality of the root system was observed in the second year, especially as to the number of roots and the total biomass of the rooted vines. The chemical analyses of plant material revealed that roots of inoculated plants had greater dry matter, and greater concentrations of total phenols (in this case in leaves as well). Laboratory trials comprised also the isolation and morphological and molecular characterization of bacterial cells found in the grapevine tissues; different bacterial species were identified, some of these (such as Stenotrophomonas sp., and Lysobacter sp.) not yet known to be capable of living as endophytes in grapevine tissues. No cells of Azospirillum brasilense were found inside the examined tissues, suggesting that the observed inoculation effects might not depend on the penetration of the bacterial cells inside the plants. Growth measures on obtained vines, whether in pots or in field, showed that the number of nodes was in general higher in inoculated plants, even if not significantly. The stomatal conductance of the leaves of the treated plants was lower than the control, suggesting an increased resistance of the treated plants to drought stress (for the rootstocks 420A and 775P - second year trials), and, possibly, to plant pathogens. Moreover, the experiments of drought simulation showed that the shoots growth in the treated plants was not affected by the stress, nor was the stomatal conductance, implying that the bacterial treatment could somehow protect plants during drought conditions. This effect of the bacterial inoculation could be ascribed to the induction of systemic resistance in the host plant, possibly via a bacterial MAMP (microbial-associated molecular pattern), which elicited a variety of plant defence responses; some of the typical plant defence responses to MAMPs have been actually found in this work, such as the accumulation of phenolic compounds, and the stomatal closure. The possibility that the Azospirillum brasilense Sp245 treatment could induce systemic resistance to biotic and abiotic stresses in grapevine could be of great importance, whether in nursery propagation or in grape production

Biodiversity of wine yeast in response to environmental stress

Alcoholic fermentation is generally performed by Saccharomyces spp., especially by the principal wine yeast Saccharomyces cerevisiae. The wide variety of natural yeasts reflects the biodiversity, in most grape musts. During spontaneous fermentation, dynamics of microbial population results in successions of different strains, which contribute to the aromatic complexity and diversity of the wine. In the present work, Saccharomyces cerevisiae strains were isolated in 2009 during the harvest from biodynamic wine farms of Tuscany, starting from Syrah musts with zero or low levels of added sulphite, according to the tendency of “natural wines” producers to abate every invasive operation during wine making. By means of molecular techniques, thirteen different profiles of Saccharomyces cerevisiae strains were identified from a hundred isolates. The collected Saccharomyces cerevisiae strains were characterized, in order to verify the effect of low sulphite addition on biodiversity, pursuing information about stress-adaptation mechanisms that allow the survival in the challenging environment of fermenting must. Sulphite addition may act as a selective factor to induce the presence and the activity of strains with diverse features about sulphite metabolism. The different additions of sulphite induced a considerable variability among strains. Moreover, increasing levels of ethanol limited considerably the activity of the selected strains. Further gene-specific investigation may contribute to reveal the complex mechanism of resistance to environmental stress condition

Effectiveness of Azospirillum brasilense Sp245 on young plants of Vitis vinifera L

Information about the influence of the plant growth promoting rhizobacteria Azospirillum brasilense Sp245 on the development of grapevine plants could be promoted to enhance sustainable agricultural practices for globally important fruit crops such as grapes. Thus, this study was initiated to evaluate the potential influence of A. brasilense Sp245 on two separate experimental trials, A) potted young grape plants: cv. 'Colorino' grafted onto two rootstocks 420A and 157/11 which received a fixed volume of inoculum at different times of vegetative cycle; B) hardwood cuttings from rootstock mother-plants of 420A and 775P inoculated during the phase of hydration, before bench-grafting in a specialized nursery. Overall, our results revealed that A. brasilense Sp245 has considerable potential to enhance the root apparatus and vegetative development in grapevines. Potted plants inoculated with A. brasilense Sp245 showed an improved development. Repeated supply was revealed to be more effective, inducing a greater accumulation of dry mass. Interesting findings were obtained in nursery experiments resulting from a considerable enhancement of the final quality of roots. The stimulating effect of A. brasilense Sp245 on vegetative development of rootstocks and vines may indeed improve sustainability in viticulture, through the promotion of healthy growth and a reduced dependence on fertilizers and other chemicals

Effetto dei trattamenti con Azospirillum brasilense Sp245 sull’accrescimento di giovani piante di vite (Vitis vinifera L.)

The aim of this study was to evaluate the effects of the plant growth-promoting rhizobacteria (PGPR) Azospirillum brasilense Sp245 on vegetative development and phenological changes of young grape plants Vitis vinifera L. cv. ‘Colorino’ grafted onto two rootstocks 420A and 157/11 (V. berlandieri x V. riparia). Roots of the grapevine rootstocks were immersed in a bacterial suspension in water (107 CFU/mL) by dipping overnight, and transplanted into pots. The inoculated plants were distributed in two groups differently treated adding a fixed volume of inoculum: the first group received only one treatment (end of May), the second group was treated three times, from the end of May to July. Overall results revealed that A. brasilense Sp245 seems to have considerable potential in enhancing the root apparatus, vegetative development and plant survival

Effectiveness of Azospirillum brasilense Sp245 on young plants of Vitis vinifera L.

Information about the influence of the plant growth promoting rhizobacteria Azospirillum brasilense Sp245 on the development of grapevine plants could be promoted to enhance sustainable agricultural practices for globally important fruit crops such as grapes. Thus, this study was initiated to evaluate the potential influence of A. brasilense Sp245 on two separate experimental trials, A) potted young grape plants: cv. ‘Colorino’ grafted onto two rootstocks 420A and 157/11 which received a fixed volume of inoculum at different times of vegetative cycle; B) hardwood cuttings from rootstock mother-plants of 420A and 775P inoculated during the phase of hydration, before bench-grafting in a specialized nursery. Overall, our results revealed that A. brasilense Sp245 has considerable potential to enhance the root apparatus and vegetative development in grapevines. Potted plants inoculated with A. brasilense Sp245 showed an improved development. Repeated supply was revealed to be more effective, inducing a greater accumulation of dry mass. Interesting findings were obtained in nursery experiments resulting from a considerable enhancement of the final quality of roots. The stimulating effect of A. brasilense Sp245 on vegetative development of rootstocks and vines may indeed improve sustainability in viticulture, through the promotion of healthy growth and a reduced dependence on fertilizers and other chemicals

LA SOPRAVVIVENZA DI GIOVANI PIANTE DI VITIS VINIFERA L. AUMENTA IN SEGUITO A TRATTAMENTI A BASE DI AZOSPIRILLUM BRASILENSE SP245

Azospirillum brasilense è un batterio PGPR (plant growth-promoting rhizobacteria) che produce fitormoni e molecole con atitivtà antimicrobica; in particolare il ceppo Sp245 è stato dimostrato possedere effetti positivi specifici nella propagazione di diverse specie arboree e sull'architettura radicale. Il suo impiego nella propagazione della vite porta a miglioramenti nella qualità delle radici in termini numero di radici, architettura degli apparati radicali e biomassa totale. Lo studio presentato ha riguardato la valutazione degli effetti di A. brasilense Sp245 su giovani piante di vite allevate in vaso e su talee di portinnesti di piante madri inoculate nella fase d'idratazione, che precede l'innesto, effettuato in un vivaio specializzato. Sono stati evidenziati effetti positivi del rizobatterio sui parametri di crescita delle viti, in particolar modo nelle piante in cui la somministrazione del batterio è stata ripetuta. È stata inoltre rilevata una percentuale di sopravvivenza significaticamente maggiore nelle piante trattate rispetto ai controlli non trattati. La migliorata capacità di sopravvivenza delle viti trattate è di notevole interesse in quanto può essere messa in relazione ad una possibile influenza di A. brasilense Sp245 sulla tolleranza a stress biorici e abiotici. In conclusione, gli effetti di A. brasilense Sp245 sullo sviluppo vegetativo di portiennesti e delle piante di vite può contribuire a migliorare la sostenibilità in viticoltura.Azospirillum brasilense is a well-known PGPR (plant growth-promoting rhizobacteria) that produces phytohormones and molecules with an antimicrobial activity; in addition A. brasilense strain Sp245 has shown a specific effect on woody plant propagation and root architecture. Its use on grapevine nursery propagation has been found to improve quality of the root system in terms of number of roots, root architecture and the total biomass. A study was conducted in order to evaluate the influence of A. brasilense Sp245 on potted young grape plants on different rootstocks and on hardwood cuttings from rootstock mother-plants inoculated during the phase of hydration, before the bench-grafting performed in specialized nursery. A positive effect of rhizobacterium on the growth parameters of roots and shoots of vine plants was observed, specifically in the plants that were subjected to repeated bacterial suspension inoculation. In addition, a significant higher survival percentage was revealed in comparison to control plants. In conclusion, the effect of A. brasilense Sp245 on vegetative development of rootstocks and vines, may contribute to enhanced sustainability in viticulture. Moreover, the better survival ability of treated vines is an interesting finding indicating a possible influence of A. brasilense Sp245 on stress tolerance to biotic and abiotic factors