MORPHOGENESIS OF CROWN
GALL
55
vitro, e.g., the number of new buds as well as the color of the tissue, is
largely dependent on light conditions.
Tumors have also the ability to affect each other. When slowly growing tumors are produced by a moderately virulent bacterial strain or by
a short treatment with a virulent strain, a more vigorously growing
tumor nearby increases their growth rate (cf. Braun and Stonier, 1958).
This is supposed to result from a transport of auxin-type growth substances from the site of the vigorously growing tumor to tissues situated
basally to it.
It is also possible to increase the growth of slow tumors by applying
synthetic growth substances. The studies by Braun and others (cf. e.g.,
Braun, 1962) have led to the conclusion that the nonvirulent and
moderately virulent bacteria are able to cause the primary transformation of the cells but are not able to induce an elevated level of auxin production in them. By using tissue cultures, Braun and his associates have
demonstrated that the transformation is a prolonged process during
which a series of biosynthetic systems become activated leading to more
and more autonomous tumor cells (Braun and Wood, 1961; Wood and
Braun, 1961). Apparently, the elevated auxin production is one of the
characteristics the cells acquire at later stages of the tumor transformation.
V. Wound and Crown Gall Tissue
A. Anatomical Aspects
1. Wound
Reaction
The anatomical reaction of plant cells to the stimulus caused by
wounding is dependent on several factors. First, the most important of
these is the plant species. The reaction is fairly strong in most dicots as
well as in a number of conifers, whereas the monocots often react weakly
or, in the anatomical sense, not at all. Work done in the laboratory of
Kupila-Ahvenniemi (unpublished) shows that in the stem tissue of the
tulip a small number of cell divisions is induced after wounding with a
needle, but they appear relatively late. Second, the wound reaction depends on the age of the tissue. The meristematic tissue of both the root
and the stem tip is very reactive and, if the damage is not too drastic,
can often completely regenerate the normal pattern. The earlier studies
GALL
55
vitro, e.g., the number of new buds as well as the color of the tissue, is
largely dependent on light conditions.
Tumors have also the ability to affect each other. When slowly growing tumors are produced by a moderately virulent bacterial strain or by
a short treatment with a virulent strain, a more vigorously growing
tumor nearby increases their growth rate (cf. Braun and Stonier, 1958).
This is supposed to result from a transport of auxin-type growth substances from the site of the vigorously growing tumor to tissues situated
basally to it.
It is also possible to increase the growth of slow tumors by applying
synthetic growth substances. The studies by Braun and others (cf. e.g.,
Braun, 1962) have led to the conclusion that the nonvirulent and
moderately virulent bacteria are able to cause the primary transformation of the cells but are not able to induce an elevated level of auxin production in them. By using tissue cultures, Braun and his associates have
demonstrated that the transformation is a prolonged process during
which a series of biosynthetic systems become activated leading to more
and more autonomous tumor cells (Braun and Wood, 1961; Wood and
Braun, 1961). Apparently, the elevated auxin production is one of the
characteristics the cells acquire at later stages of the tumor transformation.
V. Wound and Crown Gall Tissue
A. Anatomical Aspects
1. Wound
Reaction
The anatomical reaction of plant cells to the stimulus caused by
wounding is dependent on several factors. First, the most important of
these is the plant species. The reaction is fairly strong in most dicots as
well as in a number of conifers, whereas the monocots often react weakly
or, in the anatomical sense, not at all. Work done in the laboratory of
Kupila-Ahvenniemi (unpublished) shows that in the stem tissue of the
tulip a small number of cell divisions is induced after wounding with a
needle, but they appear relatively late. Second, the wound reaction depends on the age of the tissue. The meristematic tissue of both the root
and the stem tip is very reactive and, if the damage is not too drastic,
can often completely regenerate the normal pattern. The earlier studies