Defined Medium for Crown Gall Cells of Tobacco in Suspension Culture

Polymyxin-resistant (PBLr) mutants of Agrobacterium tumefaciens A6, B6, and B6M were isolated from polymyxin-sensitive (PBLs) parent strains in a defined medium containing 600 μg of polymyxin B sulfate per millilitre. The weight and number of tumors induced by PBLr mutants on a variety of host plants such as carrot, potato, and pinto bean were 45–75% less than those induced by PBLs wild types. The crude cell envelopes (CCE) prepared from both PBLs and PBLr bacteria were inhibitory for tumor initiation when they were applied before or during the inoculation of viable tumorigenic bacteria, but not when they were applied 30 min after the inoculation of infectious bacteria. The potency to inhibit the tumor initiation by the CCE prepared from PBLs cells was approximately 50% higher than that by the equal amount of the CCE prepared from PBLr cells. The concentration of CCE preparations required to reduce tumor induction 50% in carrot and pinto bean was determined to be 2.6 mg/mL and 4.0–6.2 mg/mL for the CCE derived from PBLs and PBLr cells, respectively. These data suggest that the envelope structure or composition of PBLs and PBLr cells is distinct, and that the acquisition of resistance to polymyxin by agrobacteria modifies envelope structure or components which are essential for tumor initiation.

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Changes in auxin level in the course of growth of a sunflower crown-gall suspension culture

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1983.032 ◽

2014 ◽

Vol 52 (3-4) ◽

pp. 285-294 ◽

Cited By ~ 1

Author(s):

Zofia Chirek

Keyword(s):

Suspension Culture ◽

Crown Gall ◽

Culture Medium ◽

Cell Mass ◽

Maximum Growth ◽

Maximal Growth ◽

Auxin Level ◽

Culture Cycle ◽

Crown Gall Tumour ◽

Further Development

The auxin level in the cell mass and culture medium was determined by means of the <em>Avena</em> straight caleoptile test in various periods of the suspension culture cycle of the sunflower crown-gall tumour. The investigations were performed in the course of the zero passage (PO) and first one (Pl), differing in their time of duration of maximum growth and its intensity. In both passages the intra- and extra-cellular auxin levels reach values of the same order. At the beginning of the maximal growth phase the activity corresponding to IAA in the cells prevails over that of the other auxin-like compounds. This disproportion diminishes with further development of the culture, and with the beginning of the stationary phase the cellular IAA level is lower than that of the remaining auxin-like compounds. The short phase of maximal growth (PO) occurs with an auxin level decreasing in the cell mass and increasing in the medium, and towards the end of the cycle these levels become equal. During the long phase of maximal growth (Pl) the total amount of auxins in the cells increases and is 2-3 times higher than in the medium, whereas IAA in the cells remains at a constant level. These results suggest that the participation of IAA in the intracellular pool of auxin-like substances is decisive for the mitotic activity of the cells and maintenance of growth in the culture.

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Culture of Chlamydomonas reinhardi Protoplasts in Defined Media

Functional Plant Biology ◽

10.1071/pp9760457 ◽

1976 ◽

Vol 3 (4) ◽

pp. 457

Author(s):

P.M Gresshoff

Keyword(s):

Suspension Culture ◽

Growth Cycle ◽

Defined Medium ◽

Cell Number ◽

Model System ◽

Plant Protoplasts ◽

Wild Type ◽

Higher Plant ◽

Defined Media ◽

Cell Densities

The cell-wall-deficient mutant CW15-9 of C. veinhavdi was grown in defined medium in suspension culture and on agar. Plating efficiencies of up to 95 % were achieved, even at low cell densities. In suspension culture, the correlation between cell number and absorbance over a large part of the growth cycle allowed easy monitoring of cell growth and division. Colony morphology on agar was flat, allowing microscopic observation of individual cells. Protoplasts grown in the absence of mannitol as an osmotic protectant did not burst, which suggests that the osmoregulation mechanism of the wild type has been retained by CW15 cells. Algal protoplasts have advantages as a model system for the study of higher plant protoplasts and cells in culture.

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