Percorrer por autor "Carvalho, S. M. P."
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- Antimicrobial and antioxidant activity of different extracts of Mentha cervina from PortugalPublication . Rocha, J.; Carvalho, S. M. P.; Politi, M.; Castro, Paula M. L.; Pintado, M. E.
- Avaliação do contributo da expressão genética na tolerância à desidratação em Rosa × hybrida cultivada em humidade relativa elevadaPublication . Carvalho, D. R. A.; Vasconcelos, Marta; Koning-Boucoiran, C. F. S.; Krens, F. A.; Heuvelink, E; Carvalho, S. M. P.Cultivation of cut flowers with high postharvest longevity is of extreme importance for consumer’s satisfaction. A negative water balance is indicated as the most important factor reducing longevity. This problem is more severe in plants grown at high relative air humidity (i.e. RH > 85%) mainly due to a poor stomatal functioning associated to lower abscisic acid (ABA) concentrations, leading to higher water loss. In this paper it is analysed whether a sensitive cut rose cultivar to high RH show different gene expression related to ABA metabolism when grown at moderate (60%) or high (90%) RH. RNA was isolated from fully developed leaves, harvested 180 min after the beginning of the dark period (stomatal closing stimulus) and the relative gene expression was evaluated in genes involved in: biosynthesis (AAO3 and NCED1), oxidation (CYP707A1 and CYP707A3) and conjugation (UGT75B2) of ABA. The stomatal conductivity in the dark period was 5.6-fold higher in intact plants developed at high RH compared to moderate RH-grown plants, showing the reduced closure capacity of the stomata during darkness. After 4 h of leaflet desiccation, leaflets grown at high RH showed a relative water content (RWC) 69% lower than the moderate RH-grown leaflets, validating the sensitivity of K023 to high RH during growth. At last, from the five studied genes only the expression of CYP707A3 was significantly reduced by high RH, without significant differences found in the other genes. In conclusion, the sensitivity of the genotype K023 to high RH cannot be explained by the expression of the genes evaluated in this study, using leaves harvested 180 min after the beginning of the dark period (closing stimulus). We expect that after transferring the plants to the postharvest conditions, inducing water stress, a more contrasting gene expression among RH levels will appear.
- Avaliação do contributo da expressão genética na tolerância à desidratação em Rosa × hybrida cultivada em humidade relativa elevadaPublication . Carvalho, D. R. A.; Vasconcelos, Marta; Koning-Boucoiran, C. F. S.; Krens, F. A.; Heuvelink, E; Carvalho, S. M. P.
- Chemical characterization and antimicrobial activity of 6 plant essential oils against Pseudomonas syringae pv. actinidiae and P. syringae pv. actinidifoliorumPublication . Silva, M. Nunes da; Machado, J.; Mazzaglia, A.; Balestra, G. M.; Vasconcelos, M. W.; Carvalho, S. M. P.Introduction: Kiwifruit bacterial canker (KBC), caused by Pseudomonas syringae pv. actinidiae (PSA), is currently the most destructive disease of kiwifruit worldwide. It was introduced in Portugal in 2010, leading to drastic production losses and plant mortality. Conversely, a closely related pathovar, P. syringae pv. actinidifoliorum (PSAF), only causes necrotic spots, not being associated with plant mortality. Current control techniques are expensive, consisting in the application of copper- and antibiotics-based compounds, with serious risks of environmental contamination and development of resistant bacteria. Therefore, the aim of this work was to characterize six plant essential oils against (anise, basil, cardamom, cumin, fennel and laurel) by gas chromatography–mass spectrometry (GC-MS) and evaluate their antimicrobial potential against different strains of PSA and PSAF. Methods: 1. Two highly virulent PSA strains (CFBP 7286 and 1F, isolated from Italy and France, respectively) and two less virulent PSAF strains (ICMP 18804 and ICMP 19441, isolated from New Zealand and Australia, respectively) were grown overnight in LB broth at 27 ᵒC and with shaking. 2. Bacterial inoculum (1-2x107 CFU.mL-1) was plated onto Nutrient Sucrose Agar medium and 20 μL droplets of each essential oil concentration were placed in 5 mm diameter paper discs (N = 3). 3. Plates were incubated at 28 ᵒC for 48 h, after which the inhibition zone was measured. 4. Essential oils chemical characterization was performed by GC-MS. Conclusions: Plant essential oils differed in their composition; however, compounds such as 3-carene, eucalyptol, camphor, fenchone and 4-terpineol were detected transversely in all oils. Although cumin presented the most simple composition, it showed MIC as low as 0.1 % for PSA 19441. In general, basil, cardamom and fennel had higher MICs, whereas anise had the lowest. PSAF strain 19441 was the most sensitive to almost all essential oils tested.
- Conventional and novel approaches for managing “flavescence dorée” in grapevine: knowledge gaps and future prospectsPublication . Oliveira, M. J. R. A.; Roriz, M.; Vasconcelos, M. W.; Bertaccini, A.; Carvalho, S. M. P.“Flavescence dorée” (FD) is a grapevine quarantine disease associated with phytoplasmas and transmitted to healthy plants by insect vectors, mainly Scaphoideus titanus. Development of efficient methods for its control has been hampered by the lack of knowledge about phytoplasma biological properties, linked also to difficulties in its in vitro cultivation. Conventional management strategies rely mainly on the application of insecticide treatments, roguing of infected plants and production of phytoplasma‐free propagation material. However, these strategies are costly and could have undesirable environmental impacts. Novel approaches are being investigated using transcriptomic and proteomic tools that can assist in identifying key regulators expressed by diseased, recovered and healthy plants. These studies allowed the identification of molecular profiles linked to the grapevine cultivar‐diverse susceptibility that are of great interest for the development of FD less susceptible plants by breeding programmes. Other promising FD management strategies include the use of grapevine endophytic microorganisms with known biocontrol properties and endophytes living inside specialized insect cells, which can be potential candidates for FD vector control. Finally, the application of plant defence elicitors might be an interesting tool for FD containment, but more research is needed before it can be implemented. In this review, the methodologies used for detecting and confining FD diffusion are discussed, focusing mainly on conventional tools, current research perspectives and knowledge gaps.
- Cultivar differences in the stomatal characteristics of cut roses grown at high relative humidityPublication . Fanourakis, D.; Tapia, A.; Heuvelink, E.; Carvalho, S. M. P.High relative air humidity (RH>85%) during cultivation is known to reduce the vase life of cut roses, but the magnitude of such effect is cultivar dependent. The reasons behind this genotypic variation are not yet known. In this study, the stomatal density and stomatal responses to two closing stimuli (i.e. desiccation and abscisic acid (ABA) application) were evaluated using detached fully expanded leaves of two contrasting rose cultivars in their sensitivity to high RH (‘Frisco’ and ‘Prophyta’) which were grown at moderate (60%) and high (90%) RH. High RH significantly increased the stomatal density in both cultivars, but the effect was stronger in the tolerant cultivar (14% increase for ‘Frisco’, 8% increase for ‘Prophyta’). ‘Frisco’ also showed a higher stomatal density at moderate RH (53 stomata/mm2) as compared to the sensitive cultivar (43 stomata/mm2). Moreover, high RH decreased the speed and the degree to which stomata responded to different closing stimuli in both cultivars, resulting in higher transpiration rates. This effect was more pronounced in the sensitive cultivar. It was concluded that the tolerance to high RH during cultivation is related to more responsive stomata, while the stomatal density is apparently an irrelevant character. Furthermore, this study showed that the rose guard cell dimensions are not representative for the pore dimensions.
- Defence-related pathways, phytohormones and primary metabolism are key players in the distinct tolerance of Actinidia spp. to pseudomonas syringae pv. actinidiaePublication . Silva, M. Nunes da; Carvalho, S. M. P.; Vasconcelos, M. W.The kiwifruit bacterial canker (KBC), caused by Pseudomonas syringae pv. actinidiae (Psa), affects plant yield and requires strict orchard management routines. Actinidia arguta (kiwi berry) is more tolerant than A. chinensis (green-fleshed kiwifruit) to Psa, but the molecular mechanisms that underpin plant tolerance are not fully understood. We hypothesised that plant tolerance is linked to the differential regulation of genes involved in distinct defence strategies shortly following infection. Here, micropropagated plants from both kiwifruit species were inoculated with Psa, and 48 hours post-inoculation, whole-transcriptome sequencing was performed. Psa density was 10-fold higher in A. chinensis than in A. arguta, demonstrating the tolerant character of the later species. Sixty-nine and 51 differentially expressed genes (DEGs) related with plant defences (e.g., pathogen recognition, immunity, and defence regulation) were identified in A. chinensis and A. arguta, respectively. Fifty-two DEGs related to abscisic (ABA), jasmonic (JA) and salicylic acid (SA) pathways, and 28 DEGs involved in primary metabolism (e.g., glycolysis, tricarboxylic acid and ammonia assimilation cycles) were also identified in A. chinensis, whereas in A. arguta 21 and 16 DEGs related with these biological functions, respectively, were identified. Results suggest that A. chinensis’ higher susceptibility to Psa is due to an inefficient activation of plant defence mechanisms, with the involvement of ABA, JA and SA, leading to impairments in primary metabolism. A. arguta’s increased tolerance may result from the downregulation of the ABA pathway and the expression of specific genes involved in plant defence, including FOX1, SN2 and RBOHA.
- Effects of air humidity and air movement on growth, visual quality and post-production stress tolerance of pot Rose ‘Toril’Publication . Carvalho, D. R. A.; Torre, S.; Vasconcelos, Marta; Almeida, Domingos P. F.; Heuvelink, E.; Carvalho, S. M. P.This work aimed at assessing whether a high level of air movement would improve stomatal closure, counteracting the negative effect of high relative air humidity (RH > 85%) on plant growth, visual quality and postharvest stress tolerance to dark and drought (simulating shipping and/or retailing). Pot rose ‘Toril’ was grown at moderate (60%) and high (90%) RH, combined with no additional air movement or with a continuous additional air flow of 0.92 ± 0.03 m s-1 (MOV). At flowering stage, plants were transferred to continuous darkness and without irrigation. Total dry weight and time to flowering were not significantly affected by RH or MOV. MOV did not affect plant height nor flower dry weight, but it significantly increased peduncle diameter by 6%. Plants grown at elevated RH showed a six-fold higher initial transpiration rate at the start of the postharvest period and a reduced longevity (71%) as compared to moderate RH-grown plants. MOV decreased the initial transpiration rate in high RH-grown plants by 23%. In conclusion, high RH had a minimal effect on plant growth and visual quality parameters but it drastically reduced postharvest storability. MOV during growth slightly improved post-production storability in high RH-grown plants, having a minor effect on visual quality.
- Estimativa da área foliar em diferentes estados fenológicos baseada em descritores alométricos de rosas de corte cv 'Red Naomi'Publication . Costa, P. M.; Poças, I.; Alves, S.; Pereira, M.; Carvalho, S. M. P.; Cunha, M.A área foliar (AF) é uma variável fundamental para a fotossíntese, transpiração, e produtividade. Métodos expeditos e não destrutivos para a estimativa da AF ao longo do ciclo de produção são necessários para o desenvolvimento de modelos ecofisiológicos e apoiar práticas culturais, tais como a aplicação de fitofármacos e gestão da água. Existem diversos modelos para a estimativa da AF, mas por terem sido desenvolvidos para uma fase do ciclo de produção (geralmente a colheita) têm uma aplicabilidade limitada. Neste trabalho, estudamos como a área de folhas compostas da rosa de corte cv 'Red Naomi ' poderia ser estimada, em diferentes fases fenológicas, a partir de medições expeditas e não-destrutivas. A experiência realizou-se numa estufa localizada na região costeira do norte de Portugal, para a produção de roseiras em sistema sem solo, com uma densidade de 8 plantas/m2, em saco plástico com substrato de fibra de coco e turfa. Para estimativa da AF das roseiras, foi desenvolvido um modelo estatístico baseado em descritores alométricos tais como: comprimento da folha (CF), largura da folha (LF), posição da folha na haste (PF), número de folíolos (NF), assim como relações entre estas medições tais como: forma de folha (relação LL vs PV), e a posição relativa da folha na haste - (RF). A estimação do modelo, baseada na técnica de regressão “stepwise”, foi avaliado por diversos testes de qualidade de ajuste e de verificação da colinearidade entre variáveis. Para a estimativa do modelo foram utilizadas 176 folhas de 20 hastes colhidas em diferentes estados fenológicos. A AF, obtida por um método não-destrutivo, variou entre 7,5-111,8 cm2, a CF de 4,7- 18,9 cm, LF de 3,8-12,2 cm, o NF de 3 a 8 e a PF de 1 a 15. O modelo selecionado, baseado nas medidas de CF, LF, PF e NF, explicou 93% (R2 = 0,93; N = 176, p <0,000) da variabilidade da AF ao longo do ciclo de produção e a diferença média relativa entre a AF medida e modelada foi inferior a 9 %. A validação do modelo, realizada com dados independentes provenientes de 24 folhas, permitiu obter testes de ajustamento semelhantes aos obtidos para o modelo da serie de estimação. A precisão e operacionalidade do modelo desenvolvido para a obtenção da AF, justifica o seu uso em estudos de eco-fisiológicos, modelos de simulação do desenvolvimento, bem como para apoiar práticas culturais em rosas de corte.
- Estimativa da área foliar em diferentes estados fenológicos baseada em descritores alométricos de rosas de corte cv 'Red Naomi'Publication . Costa, P. M.; Poças, I.; Alves, S.; Pereira, M.; Carvalho, S. M. P.; Cunha, M.A number of models for estimating leaf area (LA) are available in the literature, but these were frequently developed for a specific phase of the production (generally the harvest). This study aimed at estimating the LA in different phenological stages using non-destructive allometric measurements of cut rose cv 'Red Naomi' grown in soilless system. A statistical model was developed based on the following allometric measures: leaf length (LL), leaf width (LW), leaf position (LP), number of leaflets (NL) and different combinations of these parameters. The estimated model based on 176 leaves obtained from 20 stalks harvested at different developmental stages explained 92% of the LA variance (R2 = 0.92, n = 176, p < 0.000).This model includes the numerical position of the leaf on the stem (PRFn), ln (LL*LW) and NL as parameters, and the mean absolute difference between measured and estimated LA was less than 11%. It is concluded that the obtained model shows a high accuracy and reliability in the LA estimation in very diverse situations of crop phenology.
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