Polarity of Xylem Formation in Isolated Stem Segments of Pinus silvestris

The Seasonal dynamics of changes in the endogenous cytokinin level was investigated in the tissue of the stem cambial region, The results of the soybean test and Amaranthus test show that marked variations occur. in the course of the year in cytokinin activity in five fractions obtained from tissue of the cambial region. These variations characterized by a spring maximum and late-summer maximum may be correlated in time with changes in cambial activity and the course of annual ring differentiation in the pine stem during the vegetation season.

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Inhibition and Requirement of Natural Stimulator for Cambial Xylem Production in Isolated Stem Segments of Pinus silvestris

Physiologia Plantarum ◽

10.1111/j.1399-3054.1975.tb03768.x ◽

1975 ◽

Vol 33 (1) ◽

pp. 71-74 ◽

Cited By ~ 4

Author(s):

STEFAN ZAJACZKOWSKI ◽

TOMASZ J. WODZICKI

Keyword(s):

Pinus Silvestris ◽

Natural Stimulator ◽

Stem Segments

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Apical control of xylem formation in the pine stem. II. Responses of differentiating tracheids

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1982.018 ◽

2014 ◽

Vol 51 (2) ◽

pp. 203-214 ◽

Cited By ~ 7

Author(s):

Jarosław Porandowski ◽

Krzysztof Rakowski ◽

Tomasz J. Wodzicki

Keyword(s):

Radial Growth ◽

Inductive Effect ◽

Secondary Xylem ◽

Regulatory System ◽

Continuous Control ◽

Pinus Silvestris ◽

Daily Rate ◽

Xylem Formation ◽

Tracheid Differentiation ◽

Cell Wall Deposition

The effect of auxin supplied to the main stem of 5-year-old <em>Pinus silvestris</em> trees during various periods after decapitation upon differentiation of the secondary xylem tracheids was investigated. The results revealed the complexity of auxin involvement in the regulatory system of tracheid differentiation of secondary xylem. It is manifested both as the inductive effect to which the cells respond in the meristematic phase and in the continuous control during the consecutive stages of radial growth and maturation. A lack of auxin during the meristematic phase resulted in smaller cell diameters and reduced the daily rate of cell wall deposition even though these cells progressively grew and matured in the presence of auxin. The intensity of these two processes increased and the cells deposited thicker walls when auxin was supplied during all stages of tracheid differentiation even though the period of maturation decreased. Under these conditions tracheids of compression wood type differentiated. Continuous availability of auxin causes earlier termination of tracheid maturation while lack of auxin results in a delay of autolysis of protoplasts. In this case auxin probably functions in a system specifying information concerning the position of the cells in respect to the cambial layer.

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The effect of cambial zone isolation upon the autolytic system in maturing tracheids of pine (Pinus silvestris L.)

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1987.037 ◽

2014 ◽

Vol 56 (3) ◽

pp. 399-405 ◽

Cited By ~ 1

Author(s):

Jacek Zakrzewski ◽

Krzysztof Rakowski

Keyword(s):

Proteolytic Activity ◽

Concentration Gradient ◽

Specific Activity ◽

Positional Information ◽

Small Degree ◽

Pinus Silvestris ◽

Surgical Methods ◽

Xylem Formation ◽

Cambial Zone ◽

Applied Auxin

The autolytic protease system in maturing tracheids of the main stem of <em>Pinus silvestris</em> was investigated after separation (using surgical methods) of the cambial zone from the layer of differentiating xylem, in combination with decapitation and IAA application. Separation of the cambium prevented autolysis of the protoplast in maturing tracheids, although the specific activity of proteases was little reduced. It was found that a radial or longitudinal concentration gradient of exogenously applied auxin was not responsible for autolysis, but that it could influence the level of extracted protein, and proteolytic activity. Similarly, decapitation modified, only to small degree, the effects of the cambium separation. Thus, the data from this experiment lead to the conclusion that integration of all cells in the region of xylem formation is a crucial factor for the start of autolytic protoplast breakdown. Possible involvement of auxin waves in the transfer of the positional information for this process is suggested.

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