Plant Molecular Biology 33: 667–678, 1997.
1997 Kluwer Academic Publishers. Printed in Belgium.
A novel glycine-rich/hydrophobic 16 kDa polypeptide gene from tobacco:
similarity to proline-rich protein genes and its wound-inducible and
developmentally regulated expression
, Hiroyasu Ebinuma
and Hiroetsu Wabiko
Biotechnology Institute, Akita Prefectural College of Agriculture, 2-2, Minami, Ohgata, Akita 010-04, Japan
author for correspondence);
Nippon Paper Industries, 5-21-1-Oji, Kita-ku, Tokyo 114, Japan
Received 26 August 1996; accepted in revised form 14 November 1996
Keywords: tobacco tumor, glycine-rich/hydrophobicprotein, wound-inducibleexpression, shoot- and root-speciﬁc
We have isolated a cDNA clone, NT16, encoding a novel glycine-rich/hydrophobic protein from tobacco crown
gall tumor tissues, which was induced by the T-DNA genes of Agrobacterium tumefaciens. The accumulation of
NT16 transcripts was high in unorganized callus as well as in shoot-forming calli. In normal tobacco plants, the
transcript levels were high in roots, and low in stems, whereas virtually no transcript accumulation was found
in ﬂowers or leaves. In leaves, however, NT16 transcript accumulation was induced by mechanical wounding.
These results show that NT16 expression is developmentally regulated and induced by wound-stress conditions.
Sequence analysis suggests that NT16 encodes a putative 16 kDa polypeptide that is apparently composed of 3
structural domains: two hydrophobic regions separated by a glycine-rich region. The NT16 polypeptide displays
similarity to a number of proteins in its hydrophobic domains, but is unique in its glycine-rich domain which,
in the corresponding domains of the homologous proteins, are mostly proline-rich. Since both glycine-rich and
proline-richproteinsare generally reported to be mostly cell wall proteins, the NT16 gene may be involvedin shoot
and root formation and in wound-healing process by modifying cell wall composition.
Crown gall is a neoplastic tumorous plant tissue
induced by infection with the soil bacterium Agrobac-
terium tumefaciens. Upon infection, a part (T-DNA) of
the tumor-inducingplasmid (Ti-plasmid), harbored by
the bacterium, is transferred to the plant cell [7, 8, 41].
Expression of the genes encoding proteins required
for synthesis of the plant growth substances, cytokinin
(gene 4) and auxin (both gene 1 and gene 2), and the
genes which modulate the action of these phytohor-
mones, such as gene 5 and gene 6b, is responsible
for the induction and maintenance of the tumorous
tissues [1, 20, 26, 40]. Introduction of these genes,
The nucleotide sequence datareported will appear in the DDBJ,
EMBL and GenBank Nucleotide Sequence Databases under the
accession numbers D86629 (NT16 in pEY38) and D86721(pEY11).
of expression, into plant cells in an experimentally
controlled manner, results in distinct tissue morpho-
logy. For instance, in tobacco plants, A. tumefaciens
strains defective in the cytokinin gene cause a rooty
phenotype, whereas those deﬁcient in the auxin genes
cytokinin and auxin genes together result in unorgan-
ized calli. In addition, the 6b gene, itself an oncogene
, induces tumors on plants in both a bacterial and
host-plant dependent manner. The 6b gene from the
strain, A. tumefaciens AKE10 (AK-6b gene), induces
shoot-forming tobacco callus on hormone-free medi-
um by promotingboth auxin andcytokininaction .
To understand molecular mechanisms underlying
development of a variety of the tumorous tissues, one
approach is to identify genes preferentially expressed
in association with tumorformation. Fujita et al. repor-
ted the systematic isolation of genes possibly involved