Protoplast

About: Protoplast is a research topic. Over the lifetime, 5474 publications have been published within this topic receiving 122468 citations.

Structural analysis of the cell walls regenerated by carrot protoplasts.

Abstract: A procedure was developed to isolate protoplasts rapidly from carrot (Daucus carota L. cv. Danvers) cells in liquid culture. High purity of cell-wall-degrading enzymes and ease of isolation each contributed to maintenance of viability and initiation of regeneration of the cell wall by a great majority of the protoplasts. We used this system to re-evaluate the chemical structure and physical properties of the incipient cell wall. Contrary to other reports, callose, a (1 → 3)β-d-glucan whose synthesis is associated with wounding, was not a component of the incipient wall of carrot protoplasts. Intentional wounding by rapid shaking or treatment with dimethyl sulfoxide initiated synthesis of callose, detected both by Aniline blue and Cellufluor fluorescence of dying cells and by an increase in (1 → 3)-linked glucan quantified in methylation analyses. Linkage analyses by gas-liquid chromatography of partially methylated alditol-acetate derivatives of polysaccharides of the incipient wall of protoplasts and various fractions of the cell walls of parent cells showed that protoplasts quickly initiated synthesis of the same pectic and hemicellulosic polymers as normal cells, but acid-resistant cellulose was formed slowly. Complete formation of the wall required 3 d in culture, and at least 5 d were required before the wall could withstand turgor. Pectic substances synthesized by protoplasts were less anionic than those of parent cells, and became more highly charged during wall regeneration. We propose that de-esterification of the carboxyl groups of pectin uronic-acid units permits formation of a gel that envelops the protoplast, and the rigid cellulose-hemicellulose frame-work forms along with this gel matrix.

Somaclonal Variation: Mechanism and Applications in Crop Improvement

Abstract: Somaclonal variation refers to the variation arising in cell cultures, regenerated plants and their progenies, and this general term was given by Larkin and Scowcroft (1981). However, other types of variation arise by specific culture of cells or tissues, which include culture of: protoplasts (protoclonal); anthers and microspores (gametoclonal); callus (calliclonal); apical meristem (mericlonal); leaf, stem, root or other somatic tissues (somaclonal). There are different approaches to create somaclonal variation, which include: (1) growth of callus or cell suspension cultures for several cycles; (2) regeneration of a large number of plants from such long-term cultures; (3) screening for desirable traits in the regenerated plants and their progenies, e.g. in-vitro selection to select agronomically desirable somaclones for tolerance to various biotic and abiotic stresses using toxic levels of pathotoxins, herbicides, salts, etc.; (4) testing of selected variants in subsequent generations for desired traits; and (5) multiplication of stable variants to develop new breeding lines.

Variation amongst protoplast-derived potato plants (Solatium tuberosum cv. 'Maris Bard').

Abstract: Plants were obtained from protoplasts of shoot cultures of potato (Solarium tuberosum L. cv. 'Maris Bard') and from in situ calluses upon plants of cv. 'Majestic'. None of the protoplast-derived plants resembled each other in all of ten morphological characteristics scored and only one resembled the parental 'Maris Bard' type. As there were a number of plants regenerated from each of ten protoplast-derived calluses it is concluded that variation arose after protoplast isolation during the cell culture phase. Plants regenerated from in situ calluses of cv. 'Majestic' were quite uniform. Reported cases of variation and uniformity from cultured potato tissues are discussed. It is concluded that the variation is not a consequence of using protoplasts and that the expression or induction of variation is controllable.

Current Applications of Tissue Culture in Plant Propagation and Improvement

Abstract: Plant tissue culture involves the culture of all types of plant cells, tissues and organs under aseptic conditions. This definition also extends to the culture of excised embryos and to protoplast culture. An overview of tissue culture techniques and their applications in plant propagation and genetic improvement of plants is presented. The areas under review include: (1) embyro culture, (2) meristem culture, (3) micropropagation, (4) somatic embryogenesis, (5) somaclonal variation, (6) in vitro selection, (7) anther culture and (8) protoplast culture. Problems and limitations of each of the techniques are also discussed. Examples are given of work that has been undertaken or that is currently in progress on the application of these techniques to the improvement of Queensland's subtropical horticultural industries. Key examples are: (1) embryo culture to facilitate incorporation of genes conferring disease-resistance from wild Cucurbita species into cultivated varieties, (2) meristem culture for virus elimination in strawberries (Fragaria × ananassa) and sweet potato (Ipomoea batatas), (3) micropropagation for rapid increase in new varieties of ginger (Zingiber officinale) and pineapple (Ananas comosus) to enable more rapid field evaluation and early release, (4) micropropagation of disease-free, genetically uniform planting material of superior female papaya (Carica papaya) selections and banana (Musa spp.) selections and (5) the use of somaclonal variation and gamma-irradiation for the genetic improvement of banana. Finally, future opportunities for the utilisation of tissue culture in plant propagation and improvement in Queensland's horticultural industries are summarised.

Foreign gene expression in chloroplasts of higher plants mediated by tungsten particle bombardment.

Abstract: Publisher Summary Several approaches have been used in the past to manipulate genes in chloroplasts—that is, in the generation of chloroplast mutants, protoplast fusion, organelle inactivation, and chloroplast recombination Reports of the introduction of chloroplasts into albino protoplasts and the observation of variegated progeny with the transfer of only two chloroplasts open up the possibilities of introduction of transformed chloroplasts into recipient protoplasts Transient expression of foreign genes in chloroplasts of tobacco, sugar beet, and wheat cells, and in leaves or calli has been observed It is clear that chloroplast promoters are interchangeable among monocots and dicots; the cat gene driven by the maize rbcL promoter functions in tobacco chloroplasts and the uidA gene driven by the pea psbA promoter functions in wheat chloroplasts In addition, chloroplast vectors introduced into isolated protoplasts by the electroporation or polyethylene glycol (PEG)-mediated DNA uptake do not express foreign genes in the nuclear compartment