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Phytoplasmas are phytopathogenic bacteria that cause serious damage to agriculture. A quarantine pathogen, the flavescence dorée phytoplasma (FDp), often associated with grapevine yellows disease, affects viticultural production across Europe. However, the mechanisms of FDp pathogenicity are not still elucidated. In this study, symptomatic and asymptomatic grapevine (Vitis vinifera L. var. ‘Pinot gris’) leaves were sampled. Two different FDp genotypes (M38 and M54) were identified, and genotype-dependent changes to grapevine physiological responses through the development of FDp infection were analysed. Correlation analyses established a potential link between measured physiological parameters and relative FDp DNA abundance. Increased malondialdehyde levels pointed to the oxidative stress in infected leaves, and highly correlated with the activation of L-ascorbic acid synthesis. Levels of hydrogen peroxide were reduced in infected leaves, possibly as an FDp mechanism to avoid plant-derived oxidative damage. Genotype M54 was associated with a lower accumulation of soluble sugars and lower damage to photosynthetic pigments while retaining a higher titre than M38. Therefore, pronounced phytoplasma genotype-dependent changes in grapevine physiology, potentially caused by the differences between M54 and M38 on the level of the efficiency of their effectors should be further investigated. Altogether, results provide data on certain targets of FDp in grapevine and could assist in the identification of potential specific effectors of this phytoplasma to aid the efforts of FDp management in European vineyards. [ABSTRACT FROM AUTHOR]

Due to extreme climate changes, plants are exposed to severe soil water content, i.e. flooding and drought. The aim of this study was to assess the effect of different soil water content on the nutritional potential of young Chinese cabbage (Brassica rapa ssp. pekinensis) on the level of phenolics, sugars, photosynthetic pigments and antioxidant capacity. Total phenolic acids were induced in plants grown under drought conditions. Both types of stress increased soluble sugars in Chinese cabbage but reduced total tannins. Plants grown under drought had more L-ascorbic acid than the control group; however, the concentration of ferulic acid and quercetin was reduced. On the other hand, excess of water increased the amount of sinapic and ferulic acid, main hydroxycinnamic acids in Chinese cabbage. Photosynthetic pigments were more susceptible to flooding (reduced amount) than drought, the only exception was chlorophyll b whose concentration was significantly higher in plants grown under drought. In addition, among all the measured parameters, chlorophyll b reacted most specifically against flooding (decreased) and drought (increased). Chinese cabbage grown under flooding had reduced amount of porphyrins compared to the one grown under normal and drought conditions, but showed higher antioxidant capacity (ABTS). Based on the results, the use of excess water could be considered as a possibility when growing young Chinese cabbage since it increased the concentration of antioxidants sinapic and ferulic acid and resulted in higher antioxidant capacity, recorded by ABTS assay, compared to control plants. [ABSTRACT FROM AUTHOR]

Spectrophotometric and chromatographic analysis of phenolics in water and ethanolic extracts of wild asparagus, butcher's broom and black bryony from Croatia was conducted. Their antioxidant capacity (ABTS, DPPH and FRAP assay) and energy content were determined. The gastrointestinal stability of detected phenolics was determined using a two-phase in vitro digestion method with human enzymes. The highest phenolics yield, radical scavenging activity and ferric reducing antioxidant potential were recorded in 40 % ethanolic extract of black bryony, with glycosylated forms of kaempferol as dominant components. Quercetin-3- O-rutinoside and isorhamnetin-3- O-rutinoside were dominant phenolics in all wild asparagus extracts, and salicylic acid was predominant in butcher's broom 40 % ethanolic extract. Phenolic acids of the three species were not stable during gastric and duodenal phases of simulated digestion. Two main black bryony kaempferol glycosides were best preserved after digestion (50 % of each). Black bryony contains more energy than wild asparagus and butcher's broom. Accordingly, we propose black bryony as a valuable source of antioxidant kaempferol glycosides with relevant gastrointestinal stability and higher energy content than so far more conventional vegetable wild asparagus. [ABSTRACT FROM AUTHOR]