Loading...
13 results
Search Results
Now showing 1 - 10 of 13
- Effects of high temperature on mitotic index, microtubule and chromatin organization in rye (Secale cereale L.) root-tip cellsPublication . Neves, Vanda; Viegas, Wanda; Caperta, AnaStressful high temperatures on plants can limit whole-plant function and decrease crop productivity. However, little is known regarding heat stress effects on microtubule cytoskeleton and chromatin in roots from intact plants. Here we studied high temperature effects on cell division, microtubule and chromatin organization patterns in rye root tips from intact plants subjected to 40ºC for 4 h and after different recovery periods (0RT, 7RT, 24 RT). We showed that heat stress induced changes in nuclear morphology as detected by the unusual presence of interphase cells with irregularly shaped nuclei, probably associated with changes in chromosome segregation at anaphase, leading to micronuclei formation as well as changes in the mitotic index. These alterations were associated to differential effects in microtubules organization in both heat-stressed interphase and mitotic cells at 0RT and 7RT. Although no changes in the distribution of H3 phosphorylation of Ser 10 residues on chromatin were found in cells from heat-stressed plants, marked alterations in chromatin DNA methylation patterns were detected. These effects included higher agglutination of 5-methylcytosine domains in both interphase and metaphase cells compared to controls. Taken together these results seem to suggest that alterations in microtubule conformation upon heat stress influences nuclear chromatin organization and cell cycle progression. However, when seedlings recovered from stress (24RT), root tip cells presented microtubule configurations and chromatin organization patterns similar to controls. We conclude that in spite of heat stress markedly altered cell cycle progression and distribution of epigenetic marks, these responses are transient to cope with such stress conditions in the roots
- Inquiry in higher education for sustainable development: crossing disciplinary knowledge boundariesPublication . Galvão, Cecília; Faria, Cláudia; Viegas, Wanda; Branco, Amélia; Goulao, LuisPurpose – This paper aims to understand if a project work methodology proposed to students, based on an inquiry perspective and dealing with different dimensions of sustainable development, contributed to creating an interdisciplinary solution for a problem on sustainability challenged by food production and consumption, and also to understand if this methodological approach is perceived as important to their learning as professionals and citizens. Data were collected by direct observation, a questionnaire applied to the students and students’ individual reflections. Design/methodology/approach – This paper aims to present the research results of the impact of a pedagogical approach on students, implemented as a part of the Doctoral Programme in Sustainability Science, which was designed following an innovative model at the University of Lisbon, Portugal. The main drivers include building a new body of interdisciplinary knowledge leading to the application of science to address real problems towards transdisciplinary education. Findings – The results suggest great potential for an inquiry perspective in trying to solve a real problem. Students’ proposals were realistic, viable and complementary enough to collectively contribute in response to the global problem. The use of approaches acquired from different areas of knowledge was clear, and the project methodology was well understood. Students considered the experience very rewarding in terms of learning and contributing positively to their personal and professional development. Originality/value – This Doctoral programme is anchored in a progressive continuum encompassing holistic debates with a multidisciplinary team of professors in environments that promote interdisciplinary attitudes and new knowledge, and also project work aimed at guiding students to transdisciplinary learning, which constitutes an innovative form of dealing with the complex challenges created by the science of sustainability
- Grain transcriptome dynamics induced by heat in commercial and traditional bread wheat genotypesPublication . Tomás, Diana; Viegas, Wanda; Silva, ManuelaHigh temperature (HT) events have negative impact on wheat grains yield and quality. Transcriptome profiles of wheat developing grains of commercial genotypes (Antequera and Bancal) and landraces (Ardito and Magueija) submitted to heatwavelike treatments during grain filling were evaluated. Landraces showed significantly more differentially expressed genes (DEGs) and presented more similar responses than commercial genotypes. DEGs were more associated with transcription and RNA and protein synthesis in Antequera and with metabolism alterations in Bancal and landraces. Landraces upregulated genes encoding proteins already described as HT responsive, like heat shock proteins and cupins. Apart from the genes encoding HSP, two other genes were upregulated in all genotypes, one encoding for Adenylate kinase, essential for the cellular homeostasis, and the other for ferritin, recently related with increased tolerance to several abiotic stress in Arabidopsis. Moreover, a NAC transcription factor involved in plant development, known to be a negative regulator of starch synthesis and grain yield, was found to be upregulated in both commercial varieties and downregulated in Magueija landrace. The detected diversity of molecular processes involved in heat response of commercial and traditional genotypes contribute to understand the importance of genetic diversity and relevant pathways to cope with these extreme events
- Unravelling the hidden inter and intra-varietal diversity of durum wheat commercial varieties used in PortugalPublication . Bento, Miguel; Pereira, Sónia Gomes; Viegas, Wanda; Silva, ManuelaAssessing durum wheat genomic diversity is crucial in a changing environmental particularly in the Mediterranean region where it is largely used to produce pasta. Durum wheat varieties cultivated in Portugal and previously assessed regarding thermotolerance ability were screened for the variability of coding sequences associated with technological traits and repetitive sequences. As expected, reduced variability was observed regarding low molecular weight glutenin subunits (LMW-GS) but a specific LMW-GS allelic form associated with improved pasta-making characteristics was absent in one variety. Contrastingly, molecular markers targeting repetitive elements like microsatellites and retrotransposons – Inter Simple Sequence Repeat (ISSR) and Inter Retrotransposons Amplified Polymorphism (IRAP) – disclosed significant inter and intra-varietal diversity. This high level of polymorphism was revealed by the 20 distinct ISSR/IRAP concatenated profiles observed among the 23 individuals analysed. Interestingly, median joining networks and PCoA analysis grouped individuals of the same variety and clustered varieties accordingly with geographical origin. Globally, this work demonstrates that durum wheat breeding strategies induced selection pressure for some relevant coding sequences while maintaining high levels of genomic variability in non-coding regions enriched in repetitive sequences
- Halotolerant endophytes promote grapevine regrowth after salt-induced defoliationPublication . Navarro-Torre, Salvadora; Ferrario, Sara; Caperta, Ana D.; Victorino, Gonçalo; Bailly, Marion; Sousa, Vicelina; Viegas, Wanda; Nogales, AmaiaSalinity is an important problem for agriculture in the Mediterranean area, and thus, it is essential to develop mitigation strategies to reduce its impact. The main objective of this study was to test the effectiveness of halotolerant plant growth-promoting bacteria (H-PGPB) in improving grapevine salt stress tolerance. Grapevines grafted onto a salt-sensitive rootstock were inoculated with a consortium of H-PGPB. The substrate of half of the plants of each treatment was salinized up to 2 dS m−1 . Plants grew for six days under these conditions, and afterward, NaCl was removed to assess plant recovery through growth, physiology, and canopy temperature measurements. Inoculation with H-PGPB had a positive effect on plant physiology, but after salt treatment, grapevines stopped their photosynthetic metabolism, leading to severe defoliation. Remarkably, after salt stress removal, inoculated plants re-sprouted faster, demonstrating that H-PGPB inoculation could be a good practice to increase vineyard resilience to salt stress
- School and family ecosystem: Incentives and barriers to school–family communicationPublication . Guedes, Fábio Botelho; Cerqueira, Ana; Marques-Pinto, Alexandra; Branco, Amélia; Galvão, Cecília; Sousa, Joana; Goulão, Luis F.; Bronze, Rosário; Viegas, Wanda; Gaspar, Tania; Moreno, Carmen; Matos, Margarida Gaspar deThe aim of the study was to explore the factors and barri- ers related to the incentive and opportunity of school–fam- ily communication. This work is part of the HOUSE-Colégio F3 Project, ULisbon, which included 1,143 first-year uni- versity students from the University of Lisbon, with aver- age age of 19.61 ± 3.96 years. The young people who had better communication with their parents, greater family support and better family relationship were the ones who reported greater incentives for school–family communica- tion. School–family communication and relationship were associated with the incentives for school–family communi- cation and greater parental monitoring. These results align with the literature stating that parents' communication and presence in all areas of young people's lives, including the school context, foster better social and family relationships and academic results. This result should not be read as a call for non-autonomy. Instead, it highlights that monitoring and supporting family presence promotes that autonomy.
- Dynamic regulation of Grapevine’s microRNAs in response to Mycorrhizal Symbiosis and high temperaturePublication . Campos, Catarina; Coito, João Lucas; Cardoso, Hélia; Silva, Jorge Marques da; Pereira, Helena Sofia; Viegas, Wanda; Nogales, AmaiaMicroRNAs (miRNAs) are non-coding small RNAs that play crucial roles in plant development and stress responses and can regulate plant interactions with beneficial soil microorganisms such as arbuscular mycorrhizal fungi (AMF). To determine if root inoculation with distinct AMF species affected miRNA expression in grapevines subjected to high temperatures, RNA-seq was conducted in leaves of grapevines inoculated with either Rhizoglomus irregulare or Funneliformis mosseae and exposed to a high-temperature treatment (HTT) of 40 C for 4 h per day for one week. Our results showed that mycorrhizal inoculation resulted in a better plant physiological response to HTT. Amongst the 195 identified miRNAs, 83 were considered isomiRs, suggesting that isomiRs can be biologically functional in plants. The number of differentially expressed miRNAs between temperatures was higher in mycorrhizal (28) than in non-inoculated plants (17). Several miR396 family members, which target homeobox-leucine zipper proteins, were only upregulated by HTT in mycorrhizal plants. Predicted targets of HTT-induced miRNAs in mycorrhizal plants queried to STRING DB formed networks for Cox complex, and growth and stress-related transcription factors such as SQUAMOSA promoter-binding-like-proteins, homeobox-leucine zipper proteins and auxin receptors. A further cluster related to DNA polymerase was found in R. irregulare inoculated plants. The results presented herein provide new insights into miRNA regulation in mycorrhizal grapevines under heat stress and can be the basis for functional studies of plant-AMF-stress interactions.
- Assessment of four portuguese wheat landrace diversity to cope with global warmingPublication . Tomás, Diana; Coelho, Luís Pinto; Rodrigues, José Carlos; Viegas, Wanda; Silva, ManuelaWheat is a dietary staple consumed worldwide strongly responsible for proteins and carbohydrate population intake. However, wheat production and quality will scarcely fulfill forward demands, which are compounded by high-temperature (HT) events as heatwaves, increasingly common in Portugal. Thus, landraces assume crucial importance as potential reservoirs of useful traits for wheat breeding and may be pre-adapted to extreme environmental conditions. This work evaluates four Portuguese landrace yield and grain composition through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, particularly protein content, and their responses to HT treatment mimicking a heatwave. Landraces showed distinct yield traits, especially plant height and first spike grain number, and a similar pattern in FTIR spectra, although revealing differences in grain components’ proportions. Comparison between spectra band intensity indicates that Ardito has the highest protein-related peaks, contrary to Magueija, which appears to be the landrace with higher lipid content. In plants submitted to 1 week of HT treatment 10 days after anthesis, the first spike grain size and weight were markedly reduced in all landraces. Additionally, it was observed that a general increase in grain protein content in the four landraces, being the increment observed in Ardito and Grécia, is statistically significant. The comparative assessment of control and HT average FTIR spectra denoted also the occurrence of alterations in grain polysaccharide composition. An integrated assessment of the evaluations performed revealed that Ardito and Magueija landraces presented diverse yield-related characteristics and distinct responses to cope with HT. In fact, the former landrace revealed considerable grain yield diminution along with an increase in grain protein proportion after HT, while the latter showed a significant increase in spikes and grain number, with grain quality detriment. These results reinforce the relevance of scrutinizing old genotype diversity seeking for useful characteristics, particularly considering HT impact on grain production and quality
- Mycorrhizal inoculation differentally affects grapevine's performance in copper contaminated and non-contaminated soilsPublication . Nogales, Amaia; Santos, Erika S.; Abreu, Maria Manuela; Arán, Diego; Victorino, Gonçalo; Pereira, Helena Sofia; Lopes, C.M.; Viegas, WandaPlant inoculation with arbuscular mycorrhizal fungi (AMF) is increasingly employed to enhance productivity and sustainability in agricultural ecosystems. In the present study, the potential benefits of AMF inoculation on young grapevines replanted in pots containing vineyard soil with high Cu concentration were evaluated. For this purpose, one-year-old cv. Touriga Nacional grapevines grafted onto 1103P rootstocks were further inoculated with Rhizoglomus irregulare or Funneliformis mosseae, or left non-inoculated, and maintained in a sterilized substrate under greenhouse conditions for three months. After this time, half of the plants were transplanted to containers filled with an Arenosol from a vineyard which had been artificially contaminated or not with 300mg kg−1 of Cu. At the end of the growing season, soil nutrient concentration, soil dehydrogenase activity and mycorrhizal colonization rate were analyzed. Grapevine performance was assessed bymeasuring several vegetative growth and physiological parameters as well as nutrient concentrations in leaves and roots. In the non-contaminated soil, R. irregulare- and F. mosseae-inoculated plants had significantly greater root biomass than the non-inoculated ones. However, the opposite effect was observed in the Cu-contaminated soil, where non-inoculated plants performed better regarding shoot and root development. Concerning nutrient levels, an increase in Cu, Mg and Mn concentrations was observed in the roots of plants growing in the contaminated soil, although only Mn was translocated to leaves. This led to a large increase in leaf Mn concentrations, which was significantly higher in noninoculated and F. mosseae- inoculated plants than in the R. irregulare- inoculated ones. Copper contamination induced a general decrease in leaf N, P and Fe concentrations as well as chlorosis symptoms. The largest decrease in N and P was observed in F. mosseae- inoculated plants, with 73 and 31.2%, respectively. However, these plants were the ones with the least decrease in Fe concentration (10% vs. almost 30% in the other two inoculation treatments). In conclusion, this study indicates that soil Cu levels can modify the outcome of AMF inoculations in young grapevines, disclosing new AMF-plant associations potentially relevant in vineyards with a tradition of Cu-based fungicide application
- Genetic diversity and structure of the portuguese pear (Pyrus communis L.) germplasmPublication . Queiroz, Álvaro; Guimarães, Joana Bagoin; Sánchez, Claudia; Simões, Fernanda; Sousa, Rui Maia; Viegas, Wanda; Veloso, Maria ManuelaA rich heritage of traditional pear varieties is kept in national Portuguese collections. Out of these varieties, “Rocha” dominates national pear production. Although a noticeable phenotypic variation among clones of this variety has been reported, little is known about its genetic variability, as to date molecular studies have been performed on a single “Rocha” clone. Eleven Simple Sequence Repeats (SSR) markers were used to assess the genetic diversity of 130 local cultivars, 80 of them being “Rocha” clones. The results allowed the di erentiation of 75 genotypes of which 29 are “Rocha”. Three synonyms groups and four homonymous groups of other local varieties were confirmed. A Bayesian model-based clustering approach identified two distinct clusters. Using flow cytometry, six cultivars were found to be triploids. These results show high genetic variability among “Rocha” clones. In conclusion, there is a need for di erent “Rocha” clones to be preserved to enable the correct selection of the multiplication material