1,721,115 research outputs found
Stimulation of growth in Daucus carota L. cell cultures by Brassinosteroid.
No full textIn Daucus corota L. cell culture, the steroid hormone 24-epibrassinolide (BR) induces cell enlargement at 10−6 M, without having any effect on cell multiplication when tested on suspension cultured cells, and increases the plating efficiency when diluted cell suspensions are plated onto agarized culture medium. This improvement of the plating efficiency may be a direct consequence of cell enlargement
Evidence for the presence of a second conditioning factor in plant cell cultures.
No full textPlating efficiency (P.E.) of Daucus carota cells in culture is strongly dependent on cell density, either in the absence or presence of a conditioning factor (CF) previously described. The decrease of plating efficiency with cell dilution is not abolished by an increase of CF concentration or by CFs produced from different species. The dependence of the multiplication on cellular density is unchanged also after addition of Brassinosteroid, a hormone which increases the plating efficiency synergistically with CF. Direct contact of seeded cells with callus cultures, separated by a dialysis membrane, completely abolishes the phenomenon providing evidence for the presence of a second conditioning factor
Stimulation of growth induced by Brassinosteroid and Conditioning Factors in plant cell cultures.
No full text
High plating efficiency with plant cell cultures.
No full textIn this paper we describe a simple method to improve the plating efficiency in plant cell cultures.
Two-stage plating is used; in the first stage the cells are inoculated at high density in 0.2% agarized culture medium for ten days to facilitate growth; under this condition, each cell produces a single micro-colony trapped in the agar network. In the second stage the colonies are plated at different densities in 1% agarized medium.
These colonies are self-sufficient and able to improve the cell growth by conditioning the medium
Methyl esterification of pectin plays a role during plant-pathogen interactions and affects plant resistance to diseases
No full textThe cell wall is a complex structure mainly composed by a cellulose-hemicellulose network embedded in a cohesive pectin matrix. Pectin is synthesized in a highly methyl esterified form and is de-esterified in muro by pectin methyl esterases (PMEs). The degree and pattern of methyl esterification affect the cell wall structure and properties with consequences on both the physiological processes of the plants and their resistance to pathogens. PME activity displays a crucial role in the outcome of the plant-pathogen interactions by making pectin more susceptible to the action of the enzymes produced by the pathogens. This review focuses on the impact of pectin methyl esterification in plant-pathogen interactions and on the dynamic role of its alteration during pathogenesis. (c) 2012 Elsevier GmbH. All rights reserved
The impact of homologous and heterologous nurse cells on the division capability of sparsely plated cells.
No full textThe growth-promoting effects of nurse cells of carrot, tomato, patato, maize, bean, carnation and two species of tobacco were studied on carrot, tomato, tobacco and potato cells plated at low densities. In an area immediately below the nurse cells the plating efficiency was very high and found to be independent of cell density. In an area outside the nurse cells, in some cases, the plating efficiency tended to be much higher in combinations with cells from a heterologous source as compared with those from a homologous source. Moreover, in the same area with some combinations the plating efficiency decreased when cell density was lowered, while with other combinations this phenomenon did not occur. This decrease was independent of the absolute value of plating efficiency. In experiments in which the concentration of conditioning factors was presumably changed, no significant difference in the plating efficiency was noticed. We therefore suggest that different plating efficiencies observed with heterologous nurse cells were not due to a higher level of conditioning factors, but rather to the production of different types of conditioning factors that are presumably degraded with different efficiency
MMS-induction of different types of genetic damage in Aspergillus nidulans: A comparative analysis in mutagenesis
No full textMethyl methanesulphonate (MMS) was used to test the induction of gene mutation, somatic crossing-over and mitotic non-disjunction in A. nidulans. Gene mutation was tested by inducing mutants resistant to 8-azaguanine and revertants of methG1 in a haploid strain. Somatic crossing-over was tested in heterozygous diploids, both with a selective method, i.e. inducing homozygosis to FPA resistance in a heterozygous fpa A1/+ strain, and with a non-selective method, i.e. identifying the frequencies of colour sectors. This latter method was also used to estimate the induction of non-disjunction because additional markers were present which permitted us to distinguish the two types of colour segregant. Generally, 3 different experimental procedures were used, namely the "plate test", i.e. plating of conidia in agar media containing MMS, and two types of "liquid test", i.e. brief treatment of quiescent or pre-germinated conidia in MMS solution before they were plated on agar media. Point mutations were induced with about equal efficiency with each method, whereas crossing-over was induced preferentially when germinating conidia were exposed to MMS. On the other hand, non-disjunction was induced in germinating and quiescent spores with equal efficiency, but such segregants were not recovered with the selective (fpa) method. The results are discussed for both their practical use in the mutagenic testing procedure and their theoretical implication
- …
