Browsing by Author "Varanda, Carla"
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- Agricultura sustentável e as novas técnicas genómicasPublication . Belbute, D.; Gomes, S.; Carraço, T.; Farinha, Ana Paula; Materatski, P.; Varanda, CarlaAs Novas Técnicas Genómicas (NGTs) são técnicas desenvolvidas a partir de 2001, após a adoção da legislação sobre organismos gene ticamente modificados (OGM). Estas incluem a mutagénese dirigida, cisgénese, intragénese e transgénese. As NGTs permitem mutações genómicas precisas num organismo, podendo faze lo sem inserção de material genético estranho (mutagénese dirigida); ou com a inserção de material genético, diretamente (cisgénese) ou de uma cópia reorganizada (intragénese), proveniente de um organismo com o qual se poderia cruzar na natureza; ou ainda, por outro lado, com inserção de material genético de um organismo não cruzável na natureza (transgénese). Independentemente destas diferenças, atualmente todas as NGTs estão enquadradas na legislação dos OGMs, pelo que a sua aplicação em agricultura é bastante restritiva. Recentemente, e como já se verifica em vários outros países, a Europa tem mostrado abertura para excluir algumas NGTs da legislação dos OGM. Este artigo descreve as principais NGTs e o seu papel potencial para responder aos desafios atuais da agricultura. São ainda mostrados os avanços realizados na Europa para criação de uma legislação própria para algumas NGTs, assim como as vantagens que tal poderia trazer para a sustentabilidade da agricultura e a competitividade da economia europeia.
- Alternaria alternata an emerging pathogen with great impact on olive grovesPublication . Carvalho, Teresa; Materatski, Patrick; Osa, Nicolás; Patanita, Mariana; Varanda, Carla; Ribeiro, Joana A.; Albuquerque, André; Campos, Maria Doroteia; Félix, M.R.Downy mildew, powdery mildew, grey mould, black rot, and grapevine trunk diseases are among the most important fungal or oomycete diseases affecting grapevine, with a high economic impact in all growing areas. In recent decades, extensive efforts have been made to reduce the use of agrochemicals in viticulture, turning the management of these diseases a major challenge. Given the urgent need to identify and develop new sustainable and effective protection strategies, a better understanding of plant defence mechanisms is essential to develop more tolerant plants and provide valuable insights for disease management. Although recent advances in molecular technologies have allowed the identification of several resistance genes, little is known about the complexity of the molecular mechanisms involved in grapevine-pathogen interactions. This chapter aims to bring together the most up-to-date findings on the regulation of grapevine defence mechanisms against major fungal and oomycete diseases by enumerating promising candidate genes that offer broad possibilities for inducing resistance to specific pathogens. We also focus on the use of functional genomics as a tool to study grapevine immunity to different pathogens, with particular emphasis on new emerging molecular technologies that will undoubtedly contribute to a sustainable plant breeding.
- Biotecnologia vegetal: introdução de um gene de interesse num vetor binário utilizando a tecnologia GatewayPublication . Materatski, Patrick; Varanda, CarlaA Unidade Curricular (UC) de Biotecnologia Vegetal (LBBA1250), é uma UC obrigatória para o 2o ano da Licenciatura em Biologia e Biotecnologia Alimentar. Esta UC compreende, para além das aulas teóricas, uma componente teórico-prática e uma componente de prática-laboratorial, nas quais se pretende que os alunos aprofundem conhecimentos e obtenham competências no método de clonagem, mais especificamente na tecnologia Gateway®, que é um método de clonagem universal baseado nas propriedades de recombinação em local-específico do bacteriófago lambda (Landy, 1989). Esta tecnologia fornece uma forma rápida e altamente eficaz a capacidade de mover sequências de DNA para vários sistemas de vetores para análise funcional de genes e expressão de proteínas (Hartley et al., 2000). Pretende-se ainda que os alunos dominem técnicas de introdução de genes para a expressão de proteínas e silenciamento de genes em plantas indicadoras através de agroinfiltração, tecnologias estas que sustentam os vários domínios da biotecnologia em plantas e seus sistemas e processos. Assim, os protocolos aqui descritos, incluem as principais etapas realizadas num laboratório de biotecnologia vegetal, e uma vez que são transversais em biotecnologia, os estudantes aprendem de forma simples, as principais metodologias usadas rotineiramente num laboratório de biotecnologia vegetal. Este manual descreve os protocolos a realizar nas aulas práticas no ano letivo de 2024/25.
- Biotecnologia vegetal: isolamento e identificação de Colletotrichum spp.Publication . Materatski, Patrick; Varanda, Carla; Varanda, Carla; Materatski, PatrickA Unidade Curricular (UC) de Biotecnologia Vegetal (LBBA1250), é uma UC obrigatória do 2o ano da Licenciatura em Biologia e Biotecnologia Alimentar. Esta UC compreende, para além das aulas teóricas, uma componente teórico-prática e uma componente de prática laboratorial, nas quais se pretende que os estudantes aprofundem conhecimentos e obtenham competências no isolamento e cultura de organismos como bactérias e fungos de plantas de interesse para a região e o país. Pretende-se ainda que os alunos dominem técnicas de extração e identificação molecular que sustentam os vários domínios de aplicação tecnológica das plantas e dos seus sistemas e processos. Assim, os protocolos aqui descritos, incluem várias etapas realizadas num laboratório de biotecnologia vegetal, desde o isolamento de fungos de plantas, à extração e amplificação do DNA e identificação do organismos isolados. Uma vez que os protocolos usados em fungos de plantas são transversais em biotecnologia, os estudantes apreendem de forma simples, as várias das metodologias usadas rotineiramente num laboratório de biotecnologia vegetal. Este manual descreve os protocolos a realizar nas aulas práticas no ano letivo de 2024/25.
- Biotecnologia vegetal: silenciamento de genes em plantaPublication . Materatski, Patrick; Varanda, CarlaA Unidade Curricular (UC) de Biotecnologia Vegetal (LBBA1250), é uma UC obrigatória para o 2o ano da Licenciatura em Biologia e Biotecnologia Alimentar. Esta UC compreende, para além das aulas teóricas, uma componente teórico-prática e uma componente de prática-laboratorial, nas quais se pretende que os alunos aprofundem conhecimentos e obtenham competências no método de silenciamento de genes em planta com recurso a agroinfiltração através de Agrobacterium tumefaciens e que são compatíveis com o vetor binário pK7WG2 (Materatski e Varanda, 2025). Esta metodologia permite a realização de diversos estudos de análise funcional de genes de planta através do silenciamento dos mesmos, bem como a expressão de proteínas específicas. No caso de estudos em virologia, esta tecnologia possibilita também a análise funcional dos genes virais envolvidos na supressão do silenciamento, que é crucial para a correta descrição da biologia das doenças (Varanda, et al., 2018). Estas tecnologias sustentam os vários domínios da biotecnologia em plantas e seus sistemas e processos. Assim, os protocolos aqui descritos, incluem as principais etapas realizadas num laboratório de biotecnologia vegetal, e uma vez que são transversais em biotecnologia, os estudantes aprendem de forma simples, as principais metodologias usadas rotineiramente num laboratório de biotecnologia vegetal. Este manual descreve os protocolos a realizar nas aulas práticas no ano letivo de 2024/25.
- Bisifusarium lunatum causing cladode soft rot in pear cactus (Nopalea cochenillifera) in BrazilPublication . Xavier, L.M.S.; Farias, O.R.; Barbosa, P.R.R.; Varanda, Carla; Materatski, P.; Oliveira, V.S.; Porcino, M.M.; Barros, A.P.; Silva, H.F.; Batista, F.R.C.; Correia, K.C.; Nascimento, L.C.Cactus pear variety Miuda (Nopalea cochenillifera L. Salm-Dyck) is an important crop for the Northeast region of Brazil, composing one of the main sources of animal feed. By April 2021, cladode rot caused death of several cactus pear plants in a production area located in Itaporanga, Paraíba State, Brazil (7°21'55.35'S, 38°11'38.68'W). The infected cladodes showed brown circular necrotic spots and soft rot with perforations that extended throughout the cladode, followed by tipping over and death of the infected plants. The incidence of the disease ranged from 10 to 30% of the plants. Bisifusarium strains were isolated and cultured on potato dextrose agar (PDA) and synthetic nutrient-poor agar (SNA). The colonies were purple in color on PDA. On SNA, macroconidia (n = 100) were abundant, hyaline, slightly falcate, and three-septate, measuring 11.0 to 23.1 × 2.3 to 4.1 µm. Microconidia (n = 100) were oval and generally aseptate, measuring 4.1 to 8.7 × 2.3 to 3.0 µm. Conidiogenic cells formed into short monophialides. Chlamydospores were not observed. According to these morphological features, the pathogen was initially identified as Bisifusarium lunatum (Gryzenhout et al. 2017). For further confirmation of the identification, the partial sequences of translation elongation factor 1-alpha (TEF1-a) and the second largest subunit of RNA polymerase II (RPB2) genes were sequenced for a representative isolate (CMA 34; GenBank accession nos. OR536502 for TEF1-a and OR553509 for RPB2) and compared with other Bisifusarium species from the GenBank database. Subsequently, it was subjected to a phylogenetic analysis of maximum likelihood, including previously published sequences. According to BLAST searches, the TEF1-a and RPB2 sequences were 99% (637/640 nt) and 100% (312/312 nt) similar to B. lunatum (COUFAL0213: TEF1-a [MK640219] and RPB2 [MK301291]), respectively. The isolate was also clustered in a clade containing the ex-type of B. lunatum with 100% support (SH-aLRT and UFboot), being confidently assigned to this species. The pathogenicity test was performed as described by Medeiros et al. (2015) by using healthy 2-month-old cactus pear seedlings (n = 10) cultivated in a greenhouse. Sterile toothpicks were distributed over colonies of the representative isolate grown on PDA at 25 ± 2°C for 7 days. Seedling cladodes were stuck with the toothpicks, moistened with sterile water, and covered with transparent plastic bags for 24 h, thus simulating a humid chamber. Following 3 months, all control plants (stuck with sterile toothpicks) remained healthy, whereas those inoculated with the representative isolate exhibited rot symptoms. This test was performed two times. B. lunatum was reisolated from symptomatic cladodes and identified as previously described, thus fulfilling Koch’s postulates. To our best knowledge, this is the first report of B. lunatum causing soft rot on N. cochenillifera in Brazil. Besides N. cochenillifera, this species was also reported on Opuntia ficus-indica in India (Gryzenhout et al. 2017), which raises concern regarding its ability to infect other forage sources for cattle feed in Brazilian semiarid regions. The present study highlights that the precise identification of B. lunatum is a key factor to adjust control strategies and management of the disease to prevent the spread of this disease to other crops.
- Ciência e tecnologia no diagnóstico de doenças de plantas: avanços para uma agricultura sustentávelPublication . Varanda, Carla; Belbute, Diogo; Magrinho, Beatriz; Materatski, Patrick
- CRISPR/Cas13 system: a technology for the successful control of plant virusesPublication . Ribeiro, Joana A.; Varanda, Carla; Materatski, Patrick; Campos, Maria Doroteia; Albuquerque, André; Patanita, Mariana; Osa, Nicolás; Félix, M.R.Viruses are among the most important causal agents of infectious diseases, having relatively small genomes that comprise RNA or DNA. They have the ability to rapidly replicate and spread throughout a crop, being very difficult to monitor and causing devastating diseases in many agricultural systems. These can lead to significant losses in crop quality and yield, resulting in extreme economic impacts worldwide and threatening the provision of adequate nourishment for a continuous growing population. There are no efficient chemical products that can eliminate an infecting plant virus without perturbing host cells. Therefore, preventive sanitary measures, such as the use of viral resistant or tolerant plants, are usually the only options. Conventionally, these resistant/tolerant plants were generated through a very time- consuming classical breeding process. However, nowadays, molecular plant breeding plays a key role to prevent and control plant viruses. Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins systems allowed the development of a new technology that paves the way towards a new horizon for crop improvement. The first CRISPR/Cas systems studied were very useful for DNA-targeting, however, more recently identified types, such as CRISPR /Cas13, can specifically cleave single- stranded RNA in eukaryotic cells. Therefore, CRISPR/Cas13 is a promising tool for engineering plant immunity against a broad range of RNA viruses, which are the most abundant class of viruses in plants. The present work aims to bring together the most up-to-date information on CRISPR/Cas13 system to control plant viruses, discussing the limitations and future challenges for its application to produce virus resistant plants towards a more sustainable agriculture.
- Current context of Cannabis sativa cultivation and parameters influencing its developmentPublication . Saragoça, Andreia; Silva, Ana; Varanda, Carla; Materatski, Patrick; Ortega, Alfonso; Cordeiro, Ana; Gama, JoséCannabis sativa L. is a versatile plant with significant medicinal, industrial, and recreational applications. Its therapeutic potential is attributed to cannabinoids like THC and CBD, whose production is influenced by environmental factors, such as radiation, temperature, and humidity. Radiation, for instance, is essential for photosynthetic processes, acting as both a primary energy source and a regulator of plant growth and development. This review covers key factors affecting C. sativa cultivation, including photoperiod, light spectrum, cultivation methods, environmental controls, and plant growth regulators. It highlights how these elements influence flowering, biomass, and cannabinoid production across different growing systems, offering insights for optimizing both medicinal and industrial cannabis cultivation. Studies indicate that photoperiod sensitivity varies among cultivars, with some achieving optimal flowering and cannabinoid production under extended light periods rather than the traditional 12/12 h cycle. Light spectrum adjustments, especially red, far-red, and blue wavelengths, significantly impact photosynthesis, plant morphology, and secondary metabolite accumulation. Advances in LED technology allow precise spectral control, enhancing energy efficiency and cannabinoid profiles compared to conventional lighting. The photoperiod plays a vital role in the cultivation of C. sativa spp., directly impacting the plant’s developmental cycle, biomass production, and the concentration of cannabinoids and terpenes. The response to photoperiod varies among different cannabis cultivars, as demonstrated in studies comparing cultivars of diverse genetic origins. On the other hand, indoor or in vitro cultivation may serve as an excellent alternative for plant breeding programs in C. sativa, given the substantial inter-cultivar variability that hinders the fixation of desirable traits.
- Identification of candidate genes involved in olive response to anthracnose for a sustainable disease managementPublication . Inácio, Diogo; Félix, M.R.; Campos, Catarina; Patanita, Mariana; Ribeiro, Joana A.; Varanda, Carla; Materatski, Patrick; Albuquerque, André; Osa, Nicolás; Peixe, A.; Campos, Maria DoroteiaAnthracnose is a disease that affect the olive tree caused by fungi of the genus Colletotrichum. These fungi are responsible to premature fruit drop and a consequent decrease in the oil quality, and also cause defoliation of trees compromising the production of the following years. Currently the best control strategy is based on application of synthetic fungicides, with a regulatory pressure in agriculture worldwide to limit its use. Looking for a sustainable disease management, the present study reports the transcriptional changes of olive genes that encode enzymes directly associated with the maintenance of the balance of oxidative oxygen species (ROS), in response to Colletotrichum sp. infection. The cultivar selected for the studies was ‘Galega vulgar’, known to be extremely susceptible to this disease. Plants used in the experiments were from in vitro culture (to warranty their healthy status), transplanted to pots and maintained under controlled conditions. Leaves of the olive plants were inoculated with a spore suspension of Colletotrichum sp., and leaf samples were collected before fungi inoculation (T0) and at 10 days (T1) and 35 days (T2) after inoculation. Confirmation of the presence of the fungi in inoculated plants was performed following a real-time qPCR approach. The selected target genes for expression analysis were Superoxide dismutase (SOD), Endochitinase_EP3-like (CHI2), Glutathione S-transferase L3-like (TransFL3), Glutathione peroxidase 2 (PEROX2), Glutathione S-transferase THETA 1 (THETA), Glutathione S-transferase DHAR2-like (TransfDHAR), Glutathione peroxidase 5 (PEROX5) and Glutathione peroxidase 8 (PEROX8). Following a qPCR approach, a general up-regulation of the target genes was detected, but only CHI2 revealed a significantly up-regulation (p<0.005) between T0 and T2 in response to Colletotrichum sp. infection, being a promising candidate to be later used in functional analysis. We emphasize the importance of this study for the identification of candidate genes to incorporate new sources of resistance of olive trees to anthracnose with the promotion of the development of sustainable management strategies.