Browsing by Author "Calamandrei, Daniele"
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- Evaluation of exhausted bentonite for pruning wound protection in grapevinePublication . Calamandrei, Daniele; Ferreira, Ricardo Boavida; Nascimento, TeresaGrapevine trunk diseases (GTDs) are a group of fungal wood diseases caused by several pathogens that actively colonize the perennial vine organs causing wood necrosis, discoloration, vascular infections, and white decays. Among them, the esca complex is one of the most widespread and damaging grapevine diseases, causing great economic damages in terms of both yield quality and quantity, eventually leading to vine’s death. Symptoms are inconsistent in time and there are no effective known treatments, the only defence is prevention. Being pruning wounds one of the main infection sites, a considerable proportion of the undergoing research focuses on the search for pruning wound protective agents. One of the recently studied wound protective agents is bentonite. Bentonite is a montmorillonite clay used in winemaking to prevent protein casse formation; thanks to its swelling ability and negative charge at the wine pH, it acts as a cation exchanger and adsorbs the positively charged (at the wine pH) haze forming proteins, mainly Pathogenesis-Related (PR) proteins. The PR proteins are synthesized both as part of the inducible (typically before veraison) and constitutive (typically after veraison) pathogen defence mechanisms. Using exhausted bentonite (typically containing PR proteins) in an attempt to protect grapevine pruning wounds, a systemic acquired resistance, an elicitor effect and an antifungal effect are expected. This research main objectives are: (i) to evaluate the efficiency of exhausted bentonite as pruning wound protection agent against the esca disease pathogen Phaeomoniella chlamydospora, and (ii) to assess the changes in protein and phenolic profiles induced by treatments and disease. A field trial was set up, testing three types of sodium bentonite as wound protector: exhausted bentonite after fininig a red wine, exhausted bentonite after fining a white wine and hydrated neutral bentonite as the control; and collecting a symptomatic pool as further control. None of the treatment was able to reduce the internal symptoms by a statistically significant amount. However, all treatments showed the ability to reduce the incidence (up to 33%) and severity (up to 40%) of the disease. Our results show that, with some improvements, bentonite might became an useful tool in GTD's management. Protein and phenolic wood profiles were evaluated. The symptomatic pool displayed the highest content in total phenols due to the correlation between symptoms and phenolic production. The symptomatic pool and the positive control showed the highest relative non-flavonoids content, while the negative control showed the lowest. Highlighting a correlation between the infection and the production rate of flavonoids and non-flavonoids phenols. The sds-page showed differences between the controls, the treatments and the symptomatic pool, we can affirm that the infection interacts whit the protein metabolism.