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Maria Beatriz P. Calheiros

Bio: Maria Beatriz P. Calheiros is an academic researcher. The author has contributed to research in topics: Somatic embryogenesis & Coffea canephora. The author has an hindex of 2, co-authored 2 publications receiving 171 citations.

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Journal ArticleDOI
TL;DR: At concentrations between 30–60 μM, AgNO3 improved embryo yield for the genotypes evaluated, while higher doses negatively affected the regenerative capacity, and the substitution of maltose, glucose or fructose for sucrose produced different responses depending on the genotype.
Abstract: The response of five Coffea canephora Pierre genotypes with regard to somatic embryogenesis was tested on media containing silver nitrate (AgNO3) and different carbohydrates (sucrose, fructose, maltose and glucose). The presence of AgNO3 caused only small modifications to the ionic equilibrium of the media. At concentrations between 30–60 μM, AgNO3 improved embryo yield for the genotypes evaluated, while higher doses negatively affected the regenerative capacity. The substitution of maltose, glucose or fructose for sucrose produced different responses depending on the genotype. Fructose significantly increased somatic embryo production in genotypes N91 and N128, while maltose was highly effective for N75. In addition, more synchronous embryo development was observed in genotype N91 when glucose was used instead of sucrose.

169 citations

01 Jan 1994
TL;DR: The effects of the polyamines putrescine, spermidine and spermine on direct somatic embryogenesis of Coffeea conephora and Coffea arabica were examined and interactions with genotypes were found when applied in combination with high dose of sperMidine.
Abstract: The effects of the polyamines putrescine, spermidine and spermine on direct somatic embryogenesis of Coffea conephora and Coffea arabica were examined. With spermidine and spermine, the number of somatic embryos produced by "less responsive" genotypes of C. canephora decreased. However, spermidine was not inhibitory in the highly embryogenic genotype (N123). This general negative effect was also observed in C. arabica. Putrescine alone was not detrimental to embryo formation, but interactions with genotypes were found when applied in combination with high dose of spermidine. Explants originated from leaves of different orthotropic branches on the same plant showed distinct embryogenic response. The role of endogenous polyamines on direct somatic embryogenesis and the possible effects of exogenous polyamines on ethylene synthesis are discussed. Additional index terms: Coffea arabica, Coffea canephora, putrescine, spermidine, spermine, tissue culture.

15 citations


Cited by
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Journal ArticleDOI
TL;DR: This review compiles published reports of silver nitrate-mediated in vitro and in vivo studies and focuses on fundamental and applied aspects of plant growth modulation under the influence ofsilver nitrate.

201 citations

Journal ArticleDOI
TL;DR: The present communication attempts to overview the progress in tissue culture, genetic transformation and biotechnological applications in the last decade and future implications.
Abstract: Trees are an integral part of human life, and a vital component of biodiversity. Forest trees in particular are renewable sources of food, fodder, fuel wood, timber and other valuable non-timber products. Due to the rapid growth of population and the human desire to progress, there has been a tremendous reduction in forest cover from the earth’s surface. To maintain and sustain forest vegetation, conventional approaches have been exploited in the past for propagation and improvement. However, such efforts are confronted with several inherent bottlenecks. Biotechnological interventions for in vitro regeneration, mass micropropagation and gene transfer methods in forest tree species have been practised with success, especially in the last decade. Against the background of the limitations of long juvenile phases and life span, development of plant regeneration protocols and genetic engineering of tree species are gaining importance. Genetic engineering assumes additional significance, because of the possibility of introducing a desired gene in a single step for precision breeding of forest trees. There are no comprehensive and detailed reviews available combining research developments with major emphases on tissue culture and basic genetic transformation in tree species. The present communication attempts to overview the progress in tissue culture, genetic transformation and biotechnological applications in the last decade and future implications.

178 citations

Journal ArticleDOI
TL;DR: It seems that specific PAs at specific concentration ranges are required during critical stages of growth and morphogenetic events and the effects of PA biosynthesis inhibitors vary considerably at different developmental stages of the same tissue.
Abstract: Alterations in free and conjugated polyamines (PAs) and the enzymes involved in their biosynthesis, namely arginine decarboxylase, ornithine decarboxylase and S-adenosyl methionine decarboxylase have been reported to occur during cell division, growth, embryogenesis and rhizogenesis in an array of plant materials However, the relationship, if any, between them and all these processes has not yet been established It seems that specific PAs at specific concentration ranges are required during critical stages of growth and morphogenetic events Furthermore, the effects of PA biosynthesis inhibitors vary considerably at different developmental stages of the same tissue The present review deals with the available information about the possible role of PAs in aforesaid physiological processes

174 citations

Journal ArticleDOI
TL;DR: The present article reviews the past and current findings on carbon sources and their sustainable utilization for in vitro plant tissue culture to achieve better growth rate and development.
Abstract: In vitro plant cells, tissues and organ cultures are not fully autotrophic establishing a need for carbohydrates in culture media to maintain the osmotic potential, as well as to serve as energy and carbon sources for developmental processes including shoot proliferation, root induction as well as emission, embryogenesis and organogenesis, which are highly energy demanding developmental processes in plant biology. A variety of carbon sources (both reducing and non-reducing) are used in culture media depending upon genotypes and specific stages of growth. However, sucrose is most widely used as a major transport-sugar in the phloem sap of many plants. In micropropagation systems, morphogenetic potential of plant tissues can greatly be manipulated by varying type and concentration of carbon sources. The present article reviews the past and current findings on carbon sources and their sustainable utilization for in vitro plant tissue culture to achieve better growth rate and development.

169 citations

Journal ArticleDOI
TL;DR: Molar concentrations should be used to carbohydrate concentrations reference because it isolates the osmotic variable influence that acts concomitantly with the nutritional variable.

116 citations