Tonoplast cytochrome b561 is a transmembrane ascorbate-dependent monodehydroascorbate reductase: functional characterization of electron currents in plant vacuoles.

Ascorbate (Asc) is a major redox buffer of plant cells, whose antioxidant activity depends on the ratio with its one-electron oxidation product monodehydroascorbate (MDHA). The cytoplasm contains millimolar concentrations of Asc and soluble enzymes that can regenerate Asc from MDHA or fully oxidized dehydroascorbate. Also, vacuoles contain Asc, but no soluble Asc-regenerating enzymes. Here, we show that vacuoles isolated from Arabidopsis mesophyll cells contain a tonoplast electron transport system that works as a reversible, Asc-dependent transmembrane MDHA oxidoreductase. Electron currents were measured by patch-clamp on isolated vacuoles and found to depend on the availability of Asc (electron donor) and ferricyanide or MDHA (electron acceptors) on opposite sides of the tonoplast. Electron currents were catalyzed by cytochrome b561 isoform A (CYB561A), a tonoplast redox protein with cytoplasmic and luminal Asc binding sites. The Km for Asc of the luminal (4.5 mM) and cytoplasmic site (51 mM) reflected the physiological Asc concentrations in these compartments. The maximal current amplitude was similar in both directions. Mutant plants with impaired CYB561A expression showed no detectable trans-tonoplast electron currents and strong accumulation of leaf anthocyanins under excessive illumination, suggesting a redox-modulation exerted by CYB561A on the typical anthocyanin response to high-light stress.

Improvement in fruit yield and tolerance to salinity of tomato plants fertigated with micronutrient amounts of iodine.

Iodine is an essential micronutrient for humans, but its role in plant physiology was debated for nearly a century. Recently its functional involvement in plant nutrition and stress-protection collected the first experimental evidence. This study wanted to examine in depth the involvement of iodine in tomato plant nutrition, also evaluating its potential on salt stress tolerance. To this end, iodine was administered at dosages effective for micronutrients to plants grown in different experimental systems (growth chamber and greenhouse), alone or in presence of a mild-moderate NaCl-salinity stress. Plant vegetative fitness, fruit yield and quality, biochemical parameters and transcriptional activity of selected stress-responsive genes were evaluated. In unstressed plants, iodine increased plant growth and fruit yield, as well as some fruit qualitative parameters. In presence of salt stress, iodine mitigated some of the negative effects observed, according to the iodine/NaCl concentrations used. Some fruit parameters and the expressions of the stress marker genes analyzed were affected by the treatments, explaining, at least in part, the increased plant tolerance to the salinity. This study thus reconfirms the functional involvement of iodine in plant nutrition and offers evidence towards the use of minute amounts of it as a beneficial nutrient for crop production.

Quality of intimate relationships, dyadic coping, and psychological health in women with endometriosis: Results from an online survey.

OBJECTIVE: To explore the associations between intimate relationships, psychological health, and endometriosis-related variables such as pelvic pain and infertility. METHODS: In this cross-sectional study, data were collected with an online survey delivered through Qualtrics and posted on the Facebook page and website of a patient association (Associazione Progetto Endometriosi-APE) in August 2020. The survey was composed of a researcher-made questionnaire and four validated questionnaires assessing relational satisfaction (adapted Quality of Marriage Index), dyadic coping (Dyadic Coping Questionnaire), and psychological health (Hospital Anxiety and Depression Scale and Rosenberg Self-Esteem Scale). RESULTS: Participants were 316 women (age: 35.9 ± 6.7) with endometriosis, who reported being in an intimate relationship from at least one year. A greater perceived negative impact of the disease on past and current intimate relationships was associated with poorer psychological health, lower relational satisfaction and worse dyadic coping. Women who perceived their partner as more informed about endometriosis, more informed about and interested in their health conditions, and more likely to accompany them to the medical appointments, showed greater relational satisfaction and dyadic coping. Relational satisfaction and dyadic coping were associated with psychological health. A greater perceived negative impact of endometriosis on intimate relationships was associated with more severe pelvic pain (especially dyspareunia). CONCLUSION: Endometriosis has a negative impact on intimate relationships, which is associated with poorer psychological health. For the women with the disease, partner's support is important, and our findings suggest that effort should be made to involve both members of the couple in multidisciplinary treatment.

Evidences for a Nutritional Role of Iodine in Plants.

Little is known about the role of iodine in plant physiology. We evaluated the impact of low concentrations of iodine on the phenotype, transcriptome and proteome of Arabidopsis thaliana. Our experiments showed that removal of iodine from the nutrition solution compromises plant growth, and restoring it in micromolar concentrations is beneficial for biomass accumulation and leads to early flowering. In addition, iodine treatments specifically regulate the expression of several genes, mostly involved in the plant defence response, suggesting that iodine may protect against both biotic and abiotic stress. Finally, we demonstrated iodine organification in proteins. Our bioinformatic analysis of proteomic data revealed that iodinated proteins identified in the shoots are mainly associated with the chloroplast and are functionally involved in photosynthetic processes, whereas those in the roots mostly belong and/or are related to the action of various peroxidases. These results suggest the functional involvement of iodine in plant nutrition.