GreenUPorto - Research Center in Sustainable Agri-food Production

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Early pathogen recognition and antioxidant system activation contributes to actinidia arguta tolerance against pseudomonas syringae pathovars actinidiae and actinidifoliorum

Publication . Nunes da Silva, M.; Vasconcelos, M. W.; Gaspar, M.; Balestra, G. M.; Mazzaglia, A.; Carvalho, Susana M. P.

Actinidia chinensis and A. arguta have distinct tolerances to Pseudomonas syringae pv. actinidiae (Psa), but the reasons underlying the inter-specific variation remain unclear. This study aimed to integrate the metabolic and molecular responses of these two kiwifruit species against the highly pathogenic Psa and the less pathogenic P. syringae pv. actinidifoliorum (Pfm) bacterial strains. Disease development was monitored weekly till 21 days post inoculation (dpi), analysing a broad number and variety of parameters including: colony forming units (CFU), foliar symptoms, total chlorophylls, lipid peroxidation, soluble polyphenols, lignin and defense-related gene expression. At the end of the experimental period A. chinensis inoculated with Psa presented the highest endophytic bacterial population, whereas A. arguta inoculated with Pfm showed the lowest values, also resulting in a lower extent of leaf symptoms. Metabolic responses to infection were also more pronounced in A. chinensis with decreased total chlorophylls (up to 55%) and increased lipid peroxidation (up to 53%), compared with non-inoculated plants. Moreover, at 14 dpi soluble polyphenols and lignin concentrations were significantly higher (112 and 26%, respectively) in Psa-inoculated plants than in controls, while in A. arguta no significant changes were observed in those metabolic responses, except for lignin concentration which was, in general, significantly higher in Psa-inoculated plants (by at least 22%), comparing with control and Pfm-inoculated plants. Genes encoding antioxidant enzymes (SOD, APX and CAT) were upregulated at an earlier stage in Psa-inoculated A. arguta than in A. chinensis. In contrast, genes related with phenylpropanoids (LOX1) and ethylene (SAM) pathways were downregulated in A. arguta, but upregulated in A. chinensis in the later phases of infection. Expression of Pto3, responsible for pathogen recognition, occurred 2 dpi in A. arguta, but only 14 dpi in A. chinensis. In conclusion, we found that A. arguta is more tolerant to Psa and Pfm infection than A. chinensis and its primary and secondary metabolism is less impacted. A. arguta higher tolerance seems to be related with early pathogen recognition, the activation of plant antioxidant system, and to the suppression of ET and JA pathways from an earlier moment after infection.

2020Journal article

Open access

Factors influencing food waste during lunch of fourth-grade school children

Publication . Martins, Margarida Liz; Rodrigues, Sara S.P.; Cunha, Luís M.; Rocha, Ada

This study aims to explore the factors that influence plate waste at lunches served in primary schools. Data was collected for all fourth-grade children attending 21 primary schools from the city of Porto (Portugal) (n = 463). Plate waste was evaluated by the weighing method and factors influencing plate waste were collected by observation of menu and canteen characteristics and through the application of a questionnaire to children aiming to evaluate factors related to preferences and dietary patterns. Logistic regression was performed to identify predictors of plate waste. It was observed that fish menus and composed dishes showed a higher tendency for increased plate waste. However, this effect was not observed when adjusted for other variables. Soups without pulses and blended soups were less likely to be discarded by children. The presence of the teacher during meals and the possibility for children to leave the canteen whenever they wish, protected both the main dish and the soup from being wasted. A higher number of children in the canteen was associated with increased soup waste. As expected, children more pleased with the sensory characteristics of the main dish and soup were less likely to waste food. Children who consumed high-saturated fat content mid-morning snacks were more likely to waste soup. The main factors associated with plate waste were related to the presence of teachers during the mealtime, school meal policies and the meals’ sensory characteristics. Additionally, soup waste was determined by its composition, mid-morning snacks and the number of children in the canteen.

2020Journal article

Restricted access

Iron metabolism in soybean grown in calcareous soil is influenced by plant growth-promoting rhizobacteria: a functional analysis

Publication . Roriz, Mariana; Pereira, Sofia I.A.; Castro, Paula M.L.; Carvalho, Susana M.P.; Vasconcelos, Marta W.

Iron deficiency results in severe yield losses, particularly in calcareous soils. Recent evidences suggest that biofertilizers with plant growth-promoting rhizobacteria (PGPR) may be an efficient strategy for enhancing iron (Fe) nutrition in legumes. This work aimed at evaluating the capacity of PGPR strains to enhance Fe uptake-related processes in soybean grown in calcareous soil. From the studied 24 PGPR, Sphingobium fuliginis ZR 1–6 and Pseudomonas jessenni ZR 3–8 strains were selected for the inoculation experiment based on their in vitro ability to produce indole-3-acetic acid, 1-aminocyclopropane-1-carboxylic acid deaminase, siderophores, and organic acids, to tolerate high pH, and to reduce Fe3+. The effect of bacterial inoculation on improving Fe uptake was tested using each isolate alone or combined and through the evaluation of several morphological, physiological, and molecular parameters. Inoculation with S. fuliginis showed beneficial effects particularly at the root level by the improvement of ferric chelate activity (111%) and FRO2 expression (646%), resulting in increased Fe root content (62%). Inoculation with P. jessenii increased Zn and Mn concentrations in the trifoliates (463% and 51%, respectively), decreased Zn concentration in the roots (88%), and increased the expression of FER4 in the trifoliates (5260%). Combined inoculation of both strains fostered Fe accumulation in the trifoliates and increased the expression of IRT1 and FER4 genes, indicating an improved capacity of Fe translocation to the shoots. These results suggest that inoculation with selected PGPR strains could be effective in improving Fe uptake and accumulation in soybean grown under Fe-deficient conditions.

2021Journal article

Restricted access