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Esca is a multi-fungal disease affecting grapevines. The objective of the study was to evaluate the physiological and molecular response of the grapevine cv. Tempranillo to esca disease, carried out in a vineyard under Mediterranean climatic conditions in western Spain. The photosynthetic pigments in the leaves decreased, with a strong decrease in the photosynthetic efficiency. The proline content increased significantly in the early stages of affected leaves, being possibly involved in the maintenance of lipid peroxidation levels in leaves, which do not increase. The phenol, flavonoid, and phenylpropanoid content decreased in esca-affected leaves, as does the total antioxidant capacity (FRAP), while the polyphenol oxidase (PPO) activity suffers a strong increase with the development of the disease. In affected grapes, the lipid peroxidation and the total phenol content decrease, but not the anthocyanin content. The ascorbate pool decreases with the disease and with time. On the other hand, pool GSH + GSSG is lower in affected leaves, but increases with time. These alterations show a clear change in the redox homeostasis. The expression of genes phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), superoxide dismutase (SOD), and chalcone synthase (ChaS1 and ChaS3) become considerably higher in response to esca, being even higher when the infection time increases. The alteration of AsA and GSH levels, phenolic compounds, PPO activity, proline content, and FRAP, together with the increase of the PAL, PPO, SOD,ChaS1, and ChaS3 gene expression, are clearly implicated in the esca response in plants. The expression of these genes, similar to the PPO activity, can be used as markers of state in the development of the disease. [ABSTRACT FROM AUTHOR]

• Several biochemical compounds concentrations were significantly correlated with tolerance to P. expansum, such as the PPO enzymatic activity. • The transcription of Mal d 1.03, PAL1, PAL3/4/6/7, PAL5, PPO and POX64 genes was induced by the inoculation and infection of apples with P. expansum. • The relative gene expression of LDOX and Mal d 1.03 at 14 dpi in inoculated fruits were significantly and positively correlated with tolerance to Penicillium expansum. The so-called blue mold is one of the most important fungal pathologies causing major pome fruits postharvest losses. To understand apple defense mechanisms, great interest has been put on aspects such as changes in fruit tissue gene expression or biochemical composition during infections. In the present study, the expression patterns of 15 genes and isoforms previously reported to be involved in the defense response of apple against Penicillium expansum were analyzed. Thus, 28 apple accessions from the germplasm bank of the Experimental Station of Aula Dei (EEAD-CSIC) (NE Spain) were wounded and artificially inoculated with P. expansum. At 14 days post inoculation (dpi), lesion diameter and lesion extension were measured, ranking apple accessions according to their susceptibility/tolerance. In addition, several biochemical components were assessed in healthy fruits at the moment of inoculation (0 dpi) and after two weeks of incubation (14 dpi). Sugar and organic acid concentrations, total flavonoids content and ascorbic acid levels were measured. Enzyme activities, including phenylalanine ammonia-lyase (PAL), peroxidase (POX), and polyphenol oxidase (PPO), were also assessed. In summary, some parameters exhibited significant negative correlations with susceptibility, such as PPO enzymatic activity at 0 dpi and total sugars at harvest. Furthermore, positive correlations were identified, including total sugars at 0 dpi and 14 dpi, α-ketoglutaric acid at 14 dpi, total organic acids, and quinic acid at harvest. Notably, the variation in some biochemical components during infection, such as PPO activity, significantly correlated with 'lesion diameter'. Concerning gene expression, 10 accessions were studied. The PAL1 and the allergen Mal d 1.03 were found to be induced by the inoculation with P. expansum. Furthermore, LDOX and Mal d 1.03 were differentially expressed between tolerant and susceptible cultivars at 14 dpi. In addition, their expression level was positively correlated with tolerance, making them potential biomarkers for future selection programs. [ABSTRACT FROM AUTHOR]

The main Spanish table olive varieties supplied by different olive cooperatives were investigated for their polyphenol compositions and the endogenous enzymes involved in their transformations during two growing seasons. Olives of the Manzanilla variety had the highest concentration in total polyphenols, followed by the Hojiblanca and Gordal varieties. The Gordal and Manzanilla cultivars showed the highest polyphenol oxidase activities. The Gordal cultivar presented a greater β-glucosidase and esterase activity than the others. An important influence of pH and temperature on the optimal activity of these enzymes was also observed. The polyphenol oxidase activity increased with temperature, and peroxidase activity was optimal at 35 °C. The β-glucosidase and esterase activities were at their maximum at 30 and 55 °C, respectively. The oxidase and β-glucosidase activities were at their maximum at the pH of the raw fruit. These results will contribute to the knowledge of the enzyme transformation of oleuropein in natural table olives.