Rosete Pescador

Bio: Rosete Pescador is an academic researcher from Universidade Federal de Santa Catarina. The author has contributed to research in topics: Somatic embryogenesis & Shoot. The author has an hindex of 14, co-authored 69 publications receiving 692 citations.

5-Azacytidine combined with 2,4-D improves somatic embryogenesis of Acca sellowiana (O. Berg) Burret by means of changes in global DNA methylation levels.

Abstract: DNA methylation is an epigenetic regulatory mechanism of gene expression which can be associated with developmental phases and in vitro morphogenetic competence in plants. The present work evaluated the effects of 5-azacytidine (AzaC) and 2,4-dichlorophenoxyacetic acid (2,4-D) on Acca sellowiana somatic embryogenesis (SE) and global DNA methylation levels by high-performance liquid chromatography mass spectrometry (HPLC/MS/MS). 2,4-D-free treatments revealed no somatic embryo formation in both accessions tested. Treatments supplemented with 2,4-D pulse plus AzaC in the culture medium resulted in increased embryo formation. In AzaC-free treatment, HPLC/MS/MS analysis showed a gradual increase in methylation levels in cultures of both accessions tested during SE induction. Treatment with AzaC and 2,4-D-free resulted in a marked decrease in methylation for both accessions, ranging from 37.6 to 20.8 %. In treatment with 2,4-D and AzaC combined, the 85 accession showed increasing global methylation levels. Otherwise, the 101X458 accession, in the same treatment, showed a decrease between 10 and 20 days, followed by an increase after 30 days (39.5, 36.2 and 41.6 %). These results indicate that 2,4-D pulse combined with AzaC improves SE induction. However, the conversion phase showed that although positively influencing SE induction, AzaC had a dysregulatory effect on the stage of autotrophic plant formation, resulting in significantly lower conversion rates. The results suggest that DNA methylation dramatically influences SE in Acca sellowiana, and global DNA methylation dynamics are related to morphogenetic response. Key message 5-Azacytidine combined with 2,4-D increases the number of Acca sellowiana somatic embryos. Global DNA methylation is directly affected by these compounds.

Thidiazuron influences the endogenous levels of cytokinins and IAA during the flowering of isolated shoots of Dendrobium.

Abstract: Summary This study reports the effects of thidiazuron (TDZ) on the endogenous levels of indoleacetic acid (IAA), zeatin, zeatin riboside ([9R]Z), isopentenyladenine and isopentenyladenosine ([9R]iP) as well as structural changes in the apical meristem of Dendrobium Second Love shoots during flower induction and initial development in vitro. The results revealed that the presence of 1.8 μM TDZ had a profound effect on the endogenous cytokinins (CKs) and IAA levels of the explants, when compared to those grown on a TDZ-free medium. A significant increase in CKs (especially [9R]iP and [9R]Z) and IAA in the first samples (taken at day 5) grown on TDZ-enriched medium was associated with flower induction, while a second increase in the level of these hormones after 25 d of culture was related to flower development. The histological changes detected in the shoot apical meristem of explants grown in the presence of 1.8 μM TDZ during 30 d of culture are also described. Based on these findings, it is suggested that both auxin and CKs seem to be involved with the floral transition of Dendrobium Second Love in vitro. However, a possible direct effect of TDZ on flower formation is not discarded.

Estabelecimento de um protocolo regenerativo para a micropropagação do abacaxizeiro

Abstract: No Laboratorio de Fisiologia do Desenvolvimento e Genetica Vegetal do CCA-UFSC, nos anos de 1993 a 1996, foram testadas 24 combinacoes de tratamentos envolvendo dois genotipos de abacaxizeiro (Ananas comosus (L.) Merr.), seis combinacoes dos fitorreguladores acido naftalenoacetico (ANA) e 6-benzilaminopurina (BAP), e os meios de cultura liquidos e geleificados, com o objetivo de estabelecer um protocolo regenerativo para a micropropagacao do abacaxizeiro. A taxa de regeneracao comportou-se de forma quadratica para a maioria das combinacoes testadas. O meio de cultura MS (Murashige & Skoog, 1962), liquido, adicionado de ANA (2,7 µM) e BAP (4,4 µM), proporcionou uma taxa media de regeneracao de 19,7 brotos/explante. A magnitude do efeito genotipico exibido pelas cultivares utilizadas foi intermediaria entre o efeito das combinacoes dos niveis de ANA e BAP (o maior) e o efeito da constituicao fisica do meio de cultura. A melhor combinacao de tratamentos foi testada em 17 acessos coletados no Estado de Santa Catarina, demonstrando-se a eficiencia do protocolo regenerativo. A taxa media de regeneracao foi de 15,3 brotos/explante, dos quais 40% apresentaram altura igual ou inferior a 3 cm. Brotos enraizados ou nao, com altura igual ou superior a 3 cm, apresentaram valores medios de 95,5% de sobrevivencia.

Asymbiotic seed germination and in vitro seedling development of the threatened orchid Hoffmannseggella cinnabarina

Abstract: Hoffmannseggella cinnabarina has not been found in the wild for the last 70 yr in the State of Sao Paulo and, therefore, wild populations of this native orchid are thought to be extinct. This investigation studied seed storage at a low temperature, in vitro germination, and seedling development of H. cinnabarina in order to establish an optimized protocol for propagation, and thus assure species conservation. Seeds of different ages were incubated on Knudson C (KC), Murashige and Skoog, and Vacin and Went media with or without 1 μM of N6-benzyladenine (BA) and exposed to either 12 or 16 h of light (30 μmol m−2 s−1 at 26 ± 2°C). Seed surface sterilization was deleterious to 3-mo-old seeds and severely reduced the viability of the 4-mo-old seeds. More mature seeds were not affected by the sterilization procedure. In general, the germination of 4-, 5-, 6-, and 7-mo-old seeds increased when BA was added to the culture medium especially under 16 h of light. Germination rates were highest with 8- and 9-mo-old seeds, and application of BA failed to enhance germination rates further. Developmental studies revealed that this cytokinin reduced seed and protocorm mortality rates; however, protocorm development was negatively affected in its presence. Seedling development was more pronounced when KC medium with 16 h of light was used. Long-term seed storage at 4°C did not provide promising results. The protocol described in this study proved to be efficient and relevant to in vitro seed germination and initial development of H. cinnabarina, and thus will contribute to conservation of this orchid species.

Propagation, growth, and carbohydrates of Dendrobium Second Love (Orchidaceae) in vitro as affected by sucrose, light, and dark

Abstract: In general, plant material grown in vitro has low photosynthetic ability to achieve positive carbon balances. Therefore, a continuous supply of carbohydrates from the culture medium is required, and sucrose has been the most commonly used carbon source. In this paper, we investigate the effects of different sucrose concentrations and the presence and absence of light on the endogenous levels of soluble carbohydrates and starch as well as on the proliferation and growth of Dendrobium Second Love (Orchidaceae) in vitro. The possibility of using etiolated stem segments as a means for micropropagating this hybrid was also verified. The results obtained indicated that the presence and absence of light and the sucrose concentrations used influenced the amounts of soluble carbohydrates and starch and the proliferation of D. Second Love shoots and roots. An increase in sucrose concentration caused a progressive increase in the amounts of total carbohydrates and starch. Under both light conditions, sucrose was the main sugar found in the shoots followed by glucose and fructose. The addition of sucrose to the culture medium up to 2% and 4% was advantageous to the number of shoots produced per explant and the root longitudinal growth in the presence and absence of light, respectively. Shoot and root dry matter and the number of roots formed per explant increased as sucrose concentration was raised up to 6% in both light treatments. The use of dark-grown shoot segments proved to be a useful and reliable alternative for the micropropagation of this hybrid.

Thidiazuron: A multi-dimensional plant growth regulator

Abstract: Thidiazuron (TDZ) has gained a considerable attention during past decades due to its efficient role in plant cell and tissue culture. Wide array of physiological responses were observed in response to TDZ-application in different plant species. TDZ has shown both auxin and cytokinin like effects, although, chemically, it is totally different from commonly used auxins and cytokinins. A number of biological (physiological and biochemical) events in cells are induced or enhanced by TDZ, but the mode of action of TDZ is yet unknown. However, varieties of underlying mechanisms were revealed by reports showing how morphogenic events were induced by application of TDZ. Other reports showed that TDZ may modify endogenous plant growth regulators, either directly or indirectly and produce reactions in cell/tissue, necessary for its division/regeneration. Other possibilities include modification in cell membrane, energy levels, nutrient absorption, transport and assimilation, etc. In this review, recent advancements in TDZ application in plant sciences are discussed. Key words: Thidiazuron, plant growth regulators, somatic embryogenesis, regeneration, cell cultures, metabolism.

Piper Species: A Comprehensive Review on Their Phytochemistry, Biological Activities and Applications.

Abstract: Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. These plants are rich in essential oils, which can be found in their fruits, seeds, leaves, branches, roots and stems. Some Piper species have simple chemical profiles, while others, such as Piper nigrum, Piper betle, and Piper auritum, contain very diverse suites of secondary metabolites. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In addition, Piper species could be used as natural antioxidants and antimicrobial agents in food preservation. The phytochemicals and essential oils of Piper species have shown strong antioxidant activity, in comparison with synthetic antioxidants, and demonstrated antibacterial and antifungal activities against human pathogens. Moreover, Piper species possess therapeutic and preventive potential against several chronic disorders. Among the functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions, based on preclinical in vitro and in vivo studies, besides clinical studies. Habitats and cultivation of Piper species are also covered in this review. In this current work, available literature of chemical constituents of the essential oils Piper plants, their use in traditional medicine, their applications as a food preservative, their antiparasitic activities and other important biological activities are reviewed.

Copper bioavailability, uptake, toxicity and tolerance in plants: A comprehensive review.

Abstract: Copper (Cu) is an essential element for humans and plants when present in lesser amount, while in excessive amounts it exerts detrimental effects. There subsists a narrow difference amid the indispensable, positive and detrimental concentration of Cu in living system, which substantially alters with Cu speciation, and form of living organisms. Consequently, it is vital to monitor its bioavailability, speciation, exposure levels and routes in the living organisms. The ingestion of Cu-laced food crops is the key source of this heavy metal toxicity in humans. Hence, it is necessary to appraise the biogeochemical behaviour of Cu in soil-plant system with esteem to their quantity and speciation. On the basis of existing research, this appraisal traces a probable connexion midst: Cu levels, sources, chemistry, speciation and bioavailability in the soil. Besides, the functions of protein transporters in soil-plant Cu transport, and the detrimental effect of Cu on morphological, physiological and nutrient uptake in plants has also been discussed in the current manuscript. Mechanisms related to detoxification strategies like antioxidative response and generation of glutathione and phytochelatins to combat Cu-induced toxicity in plants is discussed as well. We also delimits the Cu accretion in food crops and allied health perils from soils encompassing less or high Cu quantity. Finally, an overview of various techniques involved in the reclamation and restoration of Cu-contaminated soils has been provided.

Angiosperm ovules: diversity, development, evolution

Abstract: Background Ovules as developmental precursors of seeds are organs of central importance in angiosperm flowers and can be traced back in evolution to the earliest seed plants. Angiosperm ovules are diverse in their position in the ovary, nucellus thickness, number and thickness of integuments, degree and direction of curvature, and histological differentiations. There is a large body of literature on this diversity, and various views on its evolution have been proposed over the course of time. Most recently evo-devo studies have been concentrated on molecular developmental genetics in ovules of model plants. Scope The present review provides a synthetic treatment of several aspects of the sporophytic part of ovule diversity, development and evolution, based on extensive research on the vast original literature and on experience from my own comparative studies in a broad range of angiosperm clades. Conclusions In angiosperms the presence of an outer integument appears to be instrumental for ovule curvature, as indicated from studies on ovule diversity through the major clades of angiosperms, molecular developmental genetics in model species, abnormal ovules in a broad range of angiosperms, and comparison with gymnosperms with curved ovules. Lobation of integuments is not an atavism indicating evolution from telomes, but simply a morphogenetic constraint from the necessity of closure of the micropyle. Ovule shape is partly dependent on locule architecture, which is especially indicated by the occurrence of orthotropous ovules. Some ovule features are even more conservative than earlier assumed and thus of special interest in angiosperm macrosystematics.