Vessel Anatomical Features of 'Picual' and 'Frantoio', Two Olive Cultivars Different in Resistance against Verticillium Wilt of Olive.

The olive tree (Olea europaea), a non-tropical woody crop that occupies the largest area in the world, is severely affected by the fungus Verticillium dahliae worldwide. In this regard, there is currently detailed information on the level of resistance to this pathogen in the main olive varieties. However, there is little information on quantitative aspects of its anatomy and on the existence of anatomical differences between varieties that could be related to the differential resistance response observed. In the present work, a quantitative study of the xylem of 'Picual', susceptible, and 'Frantoio', resistant, to V. dahliae is carried out. This study also provides quantitative data on the xylem in different areas of the plant, an aspect on which there is not much information for the olive tree. Among the parameters evaluated, it is probably the greater conductive capacity in the xylem tissue that 'Frantoio' presents, mainly due to the greater density of its vessels, which has a more relevant role in the resistance and natural recovery that this cultivar manifests to the disease. In any case, these constitutive anatomical differences, and those others that can be induced in plants during infections, should be investigated in future work that includes inoculation with the pathogen.

High Input of Nitrogen Fertilization and Short Irrigation Frequencies Forcefully Promote the Development of Verticillium Wilt of Olive.

It is known that high N doses, N/K imbalances, and frequent irrigation favor Verticillium wilt. The influence of fertilization and its interaction with the frequency of irrigation on the development of Verticillium wilt of olive (VWO) has been evaluated. A split-split-plot design in microplots with two naturally infested soils of different texture was established for studying three fertilization treatments (NO3Ca, NPK and without fertilization), plus two irrigation frequencies (daily and deficit). The treatments were applied by means of fertigation, evaluating the susceptible cultivar Picual. Final disease incidence in plants subjected to NO3Ca daily treatment was 100% regardless of soil texture. However, final mortality in these plants was 37% and 85.2% in clay and sandy loam soils, respectively. In addition, the area under the disease progress curve values were significantly higher (49.1%) in plants subjected to NO3Ca fertilization compared to those not fertilized or fertilized with N-P-K when plants were grown in clay soil. This value in the sandy loam soil was significantly higher in the NO3Ca daily irrigation treatment (94.3%), followed by the N-P-K-daily treatment (61.1%) which also was significantly higher than the unfertilized daily, N-deficit and NPK-deficit treatments (37.8, 42.6 and 44.9%, respectively). The plants submitted to unfertilized-deficit treatment reached the lowest value (9.6%). In this work it can be concluded that the application of fertilizer or the application of fertilizer with daily irrigation in naturally infested soils increases the development of VWO in Picual.

Effect of Previous Crops and Soil Physicochemical Properties on the Population of Verticillium dahliae in the Iberian Peninsula.

The soil infestation of Verticillium dahliae has significant Verticillium wilt of olive (VWO) with epidemiological consequences which could limit the expansion of the crop. In this context, there is a misunderstood history of the crops and soil property interactions associated with inoculum density (ID) increases in the soil. In this study, the effect of the combination of both factors was assessed on the ID of V. dahliae in the olive-growing areas of the Iberian Peninsula. Afterwards, the relationship of the ID to the mentioned factors was explored. The detection percentage and ID were higher in Spain than Portugal, even though the fields with a very favourable VWO history had a higher ID than that of the fields with a barely favourable history, regardless of the origin. The soil physicochemical parameters were able to detect the degree to which the ID was increased by the previous cropping history. By using a decision tree classifier, the percentage of clay was the best indicator for the V. dahliae ID regardless of the history of the crops. However, active limestone and the cation exchange capacity were only suitable ID indicators when <2 or 4 host crops of the pathogen were established in the field for five years, respectively. The V. dahliae ID was accurately predicted in this study for the orchard choices in the establishment of the olive.

The Influence of In Vitro Gastrointestinal Digestion on the Chemical Composition and Antioxidant and Enzyme Inhibitory Capacities of Carob Liqueurs Obtained with Different Elaboration Techniques.

Carob liqueur is a traditional Mediterranean alcoholic beverage obtained via a wide range of production techniques contributing to the different organoleptic attributes of the final product. The aim of this research was to evaluate the stability of the chemical composition and biological capacities (antioxidant and enzyme inhibition) under in vitro simulated gastrointestinal digestion of liqueurs prepared by flavouring the fig spirit with carob pulp by maceration, distillation, percolation, or aqueous and hydro-alcoholic infusions. For this purpose, the phenolic and furanic compositions, the total phenolic (TPC) and flavonoid (TFC) contents, antioxidant capacity (AC), and enzyme inhibitory potential against acethylcholinesterase, tyrosinase, α-glucosidase and α-amylase enzymes were evaluated. The content of gallic acid decreased after gastrointestinal digestion, while TPC, TFC, and AC significantly increased after each digestion phase. Overall, no significantly different enzyme inhibitions (p < 0.05) were observed among digested liqueurs, with moderate inhibition against acethylcholinesterase and tyrosinase (enzymes related with neurodegenerative diseases), and potent and low inhibitory capacities for α-glucosidase and α-amylase, respectively (ideal conditions employed in antidiabetic therapy). The study indicates that hydro-alcoholic infusion and maceration were the most appropriate methods to obtain liqueurs with higher values of the aforementioned parameters and safe levels of toxic furanics.