scholarly journals Physiological Comparisons of Pith Callus With Crown-Gall and Genetic Tumors of Nicotiana glauca, N. langsdorffii, and N. glauca-langsdorffii Grown in Vitro. I. Tumor Induction and Proliferation

1969 ◽  
Vol 44 (7) ◽  
pp. 1069-1072 ◽  
Author(s):  
W. R. Sharp ◽  
J. E. Gunckel
Keyword(s):  
Crown Gall ◽  
Nicotiana Glauca ◽  
Tumor Induction ◽  
Genetic Tumors

Crown gall: effect of temperature on tumorigenesis in pea seedlings

1969 ◽  
Vol 47 (5) ◽  
pp. 803-808 ◽  
Author(s):  
A. Kurkdjian ◽  
P. Manigault ◽  
R. Beardsley
Keyword(s):  
Crown Gall ◽  
Regression Line ◽  
Normal Growth ◽  
Tumor Formation ◽  
Effect Of Temperature ◽  
Time Interval ◽  
Tumor Weight ◽  
Pea Seedlings ◽  
Lateral Shoots

The development of crown gall tumors on decapitated pea seedlings grown in vitro is evaluated in terms of the mean weight of excised tumors. Reproducible quantitative results are obtained when mean weights of tumors are adjusted for the growth of lateral shoots. The regression line for tumor weight on the length of lateral shoots suggests that the growth of tumors and shoots is competitive. Optimal tumor formation occurs when seedlings are inoculated either immediately or within a few hours after decapitation of the seedlings. Wound healing after decapitation is not accompanied by the appearance of cells in stages of active division. Dividing cells are not observed in tissues below decapitation sites unless seedlings are inoculated with the crown gall bacterium. In darkness, large tumors develop within 2 weeks on inoculated seedlings kept at 24 °C. However, although normal growth continues, tumor formation is almost completely inhibited at 15 °C. When inoculated seedlings are held at 24 °C and 15 °C for alternate periods of varying duration, the adjusted tumor weight decreases as the duration of the period at the lower temperature increases. However, tumor size is not determined simply by the time interval during which plants are exposed to the inhibiting temperature, but also by the order of exposure to the two temperatures.

Histological study of organogenesis in vitro from callus cultures of two Nicotiana species

1981 ◽  
Vol 59 (11) ◽  
pp. 1969-1977 ◽  
Author(s):  
V. Nuti Ronchi
Keyword(s):  
Vascular Tissue ◽  
Histological Study ◽  
Parenchyma Cell ◽  
Shoot Formation ◽  
Callus Cultures ◽  
Nicotiana Glauca ◽  
Meristematic Tissue ◽  
Nicotiana Langsdorffii ◽  
Physical And Chemical

The histological events leading to shoot formation in Nicotiana glauca and in the nontumorous Nicotiana glauca × Nicotiana langsdorffii hybrid have been studied. Organized development begins from a single vacuolated parenchyma cell which divides and precociously differentiates tracheidal cells, forming a growth center with nodular structures with xylem in the center and phloem outside. The vascular tissue is precociously separated from the surrounding callus by a layer of cells which are shown to be endodermal by position and by histochemical reactions. Further growth leads to the formation of a mound of meristematic tissue which later forms shoot apical meristems. The sequences of events are discussed in relation to other known systems of regeneration in calluses.The system described could be suitable for evaluating the effects of various physical and chemical agents on the different steps of differentiation.

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