A. Francini

Phenolic Compounds in Apple (Malus x domestica Borkh.): Compounds Characterization and Stability during Postharvest and after Processing

This paper summarizes the information on the occurrence of phenolic compounds in apple (Malus x domestica Borkh.) fruit and juice, with special reference to their health related properties. As phytochemical molecules belonging to polyphenols are numerous, we will focus on the main apples phenolic compounds with special reference to changes induced by apple cultivar, breeding approaches, fruit postharvest and transformation into juice.

Ethylene Role in Plant Growth, Development and Senescence: Interaction with Other Phytohormones

The complex juvenile/maturity transition during a plant’s life cycle includes growth, reproduction, and senescence of its fundamental organs: leaves, flowers, and fruits. Growth and senescence of leaves, flowers, and fruits involve several genetic networks where the phytohormone ethylene plays a key role, together with other hormones, integrating different signals and allowing the onset of conditions favorable for stage progression, reproductive success and organ longevity. Changes in ethylene level, its perception, and the hormonal crosstalk directly or indirectly regulate the lifespan of plants. The present review focused on ethylene’s role in the development and senescence processes in leaves, flowers and fruits, paying special attention to the complex networks of ethylene crosstalk with other hormones. Moreover, aspects with limited information have been highlighted for future research, extending our understanding on the importance of ethylene during growth and senescence and boosting future research with the aim to improve the qualitative and quantitative traits of crops.

Biological monitoring of ozone: the twenty-year Italian experience

Tropospheric ozone is a growing environmental menace in Italy and in the whole Mediterranean basin. The importance of active biomonitoring of this pollutant with hypersensitive Bel-W3 tobacco plants is stressed, and several examples of field studies carried out in Italy with this technique are presented. Current limitations are discussed, with special emphasis on data quality assessment and the opportunity of adopting easy-to-use kits based on tobacco germlings instead of adult plants. A standardization of methodologies (from cultivation to scoring and data elaboration), also at an international level, is strongly felt to be needed, in order to get official acknowledgement of biomonitoring procedures. Potential educational implications, with the active involvement of students and environmentalists, are shown. Other biological indicators are used, namely sensitive and resistant white clover (Trifolium repens) clones (as descriptors of biomass reduction in crops species) and Centaurea jacea (brown knapweed) as a model species to evaluate the relationship between ozone exposure and effects on the performance and injury symptoms of native plants which are largely used in the framework of European programmes.

Ingestion toxicity of three Lamiaceae essential oils incorporated in protein baits against the olive fruit fly, Bactrocera oleae (Rossi) (Diptera Tephritidae).

The ingestion toxicity of three Lamiaceae essential oils (EOs) – Hyptis suaveolens, Rosmarinus officinalis and Lavandula angustifolia – incorporated in protein baits was evaluated against Bactrocera oleae, a worldwide pest of olive fruits. In laboratory conditions, all the tested EOs showed dose-dependent toxicity on B. oleae, with mortality rates ranging from 12% (EO concentration: 0.01% w:v) to 100% (EO concentration: 1.75% w:v). Semi-field results highlighted the toxicity of L. angustifolia and H. suaveolens EOs, which exerted more than 60% of flies mortality at a concentration of 1.75% (w:v). Gas Chromatography-Electron Impact Mass Spectrometry analyses of the three EOs showed that H. suaveolens EO was dominated by monoterpene and sesquiterpene hydrocarbons. Oxygenated monoterpenes were the main chemical class in R. officinalis and L. angustifolia EOs. Further research is needed to evaluate the efficacy of these EOs plus food bait against the olive fruit fly in the open field.

White clover clones as a cost-effective indicator of phytotoxic ozone: 10 years of experience from central Italy

Data collected at one site in central Italy using the NC-S/NC-R clover (Trifolium repens) biotype system during 1997-2007 were analysed in order to assess: (a) its performance under Mediterranean conditions; (b) variations of ozone damage linked with meteorological conditions; (c) if critical level approach is a good predictor of ozone risk on vegetation. NC-S dry biomasses were systematically lower than those of NC-R, the mean ratio being 0.7. Relevant relationship between ozone visible injury and cumulated values of AOT40 were also reported. Temperature and number of rainy days were the most important factors associated with ozone presence and, as a consequence, with leaf injury index. Photosynthetic gas exchange properties indicate that NC-S has higher values of stomatal conductance.

Role of ethylene in responses of plants to nitrogen availability.

Ethylene is a plant hormone involved in several physiological processes and regulates the plant development during the whole life. Stressful conditions usually activate ethylene biosynthesis and signaling in plants. The availability of nutrients, shortage or excess, influences plant metabolism and ethylene plays an important role in plant adaptation under suboptimal conditions. Among the plant nutrients, the nitrogen (N) is one the most important mineral element required for plant growth and development. The availability of N significantly influences plant metabolism, including ethylene biology. The interaction between ethylene and N affects several physiological processes such as leaf gas exchanges, roots architecture, leaf, fruits, and flowers development. Low plant N use efficiency (NUE) leads to N loss and N deprivation, which affect ethylene biosynthesis and tissues sensitivity, inducing cell damage and ultimately lysis. Plants may respond differently to N availability balancing ethylene production through its signaling network. This review discusses the recent advances in the interaction between N availability and ethylene at whole plant and different organ levels, and explores how N availability induces ethylene biology and plant responses. Exogenously applied ethylene seems to cope the stress conditions and improves plant physiological performance. This can be explained considering the expression of ethylene biosynthesis and signaling genes under different N availability. A greater understanding of the regulation of N by means of ethylene modulation may help to increase NUE and directly influence crop productivity under conditions of limited N availability, leading to positive effects on the environment. Moreover, efforts should be focused on the effect of N deficiency or excess in fruit trees, where ethylene can have detrimental effects especially during postharvest.

Salt stress induces differential regulation of the phenylpropanoid pathway in Olea europaea cultivars Frantoio (salt-tolerant) and Leccino (salt-sensitive)

Olive tree (Olea europaea L.) is an important crop in the Mediterranean Basin where drought and salinity are two of the main factors affecting plant productivity. Despite several studies have reported different responses of various olive tree cultivars to salt stress, the mechanisms that convey tolerance and sensitivity remain largely unknown. To investigate this issue, potted olive plants of Leccino (salt-sensitive) and Frantoio (salt-tolerant) cultivars were grown in a phytotron chamber and treated with 0, 60 and 120mM NaCl. After forty days of treatment, growth analysis was performed and the concentration of sodium in root, stem and leaves was measured by atomic absorption spectroscopy. Phenolic compounds were extracted using methanol, hydrolyzed with butanol-HCl, and quercetin and kaempferol quantified via high performance liquid-chromatography-electrospray-mass spectrometry (HPLC-ESI-MS) and HPLC-q-Time of Flight-MS analyses. In addition, the transcripts levels of five key genes of the phenylpropanoid pathway were measured by quantitative Real-Time PCR. The results of this study corroborate the previous observations, which showed that Frantoio and Leccino differ in allocating sodium in root and leaves. This study also revealed that phenolic compounds remain stable or are strongly depleted under long-time treatment with sodium in Leccino, despite a strong up-regulation of key genes of the phenylpropanoid pathway was observed. Frantoio instead, showed a less intense up-regulation of the phenylpropanoid genes but overall higher content of phenolic compounds. These data suggest that Frantoio copes with the toxicity imposed by elevated sodium not only with mechanisms of Na+ exclusion, but also promptly allocating effective and adequate antioxidant compounds to more sensitive organs.

Heavy Metals Stress on Poplar: Molecular and Anatomical Modifications

Heavy metal stress responses vary from plant to plant depending on the type of heavy metals and require a coordinated interplay of complex physiological and biochemical processes, gene expression, protein modification and changes in metabolites compositions leading to proper stress signal and tolerance.

Degradation of exogenous caffeine by Populus alba and its effects on endogenous caffeine metabolism

This is the first study reporting the presence of endogenous caffeine, theobromine, and theophylline in all organs of poplar plants. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used in order to evaluate the uptake, translocation, and metabolism of caffeine-(trimethyl-13C) in Populus alba L. Villafranca clone grown in hydroponic conditions. We investigated the remediation of caffeine since it is one of the most widely consumed drugs and it is frequently detected in wastewater treatment plant effluents, surface water, and groundwater worldwide. Our results demonstrated that poplar can absorb and degrade exogenous caffeine without negative effects on plant health. Data showed that concentrations of all endogenous compounds varied depending on caffeine-(trimethyl-13C) treatments. In particular, in control conditions, endogenous caffeine, theobromine, and theophylline were mainly distributed in roots. On the other hand, once caffeine-(trimethyl-13C) was provided, this compound and its dimethy-13C metabolites are mainly localized at leaf level. In conclusion, our results support the possible use of Villafranca clone in association with other water treatment systems in order to complete the process of caffeine remediation.

COPPER EFFECTS ON PRUNUS PERSICA IN TWO DIFFERENT GRAFTING COMBINATIONS (P. PERSICA × P. AMYGDALUS AND P. CERASIFERA)

Growth, chlorophyll content, biomass dry weight (DW), nutrient uptake and copper (Cu) accumulation were evaluated in BigTop® peach (Prunus persica L. Batsch) grafted onto two different rootstocks [GF677 (P. persica × P. amygdalus) and Mr.S2/5 (P. cerasifera)] when grown in the presence of 0.1, 10 or 100 μM copper sulfate (CuSO4). Although scion shoot length varied significantly in response to Cu concentration only with Mr.S2/5 rootstock (40%reduction at 100 μM Cu compared with control), Cu concentration in the scion grafted on GF677 was higher (18.2 mg kg−1) compared to that grafted on Mr.S2/5 (10.5 mg kg−1). In both graft combinations, the Cu concentrations in leaves were not statistically different although values ranged between 4.7 and 8.1 mg kg−1. The DW of leaves and stems was not statistically different from control plants in both graft combinations. On the contrary, root DW of Mr.S2/5 increased, about 13% at 10 μM Cu and 43% at 100 μM Cu. In contrast, DW of GF677 roots at higher Cu treatment was significant lower than control. Chlorophyll reduction Cu induced was not found, suggesting that the degradation of these pigments is maintained at low levels. The uptake of sodium (Na), zinc (Zn), and iron (Fe) changed during Cu stress. The different behavior observed between GF677 and Mr.S2/5 regarding Cu accumulation proves that these two rootstocks have a different ability in translocation and accumulation of Cu in presence of this heavy metal. The use of GF677 rootstocks, in substrates particularly rich of Cu, insures a better development of scion growth when compared to Mr.S2/5, but determines a higher Cu concentration in the stem, while Mr.S2/5 seems to be able to stabilize the Cu concentrations in the scion.