Agrobacterium rhizogenes-Mediated Transformation and Its Biotechnological Applications in Crops - Crop Improvement: New Approaches and Modern Techniques - page 13

Table 1.1 Oncogenes of A. rhizogenes , their encoded proteins, functions and phenotypic changes
in host pla nts

Gene Protein Function Phenotype

rol A Sequence motif

common in DNA-
binding proteins
Regulatory transcrip-
tion factor

Inhibits cell elongation via
diffusible factor
Decreases hormone
concentrations
Increase sensitivity to auxin
Modulating hormone physiol-
ogy of GA
Interfere polyamine
metabolism
Correlate with plasma mem-
brane H + ATPase activity

Stunted growth, dark green
wrinkled leaves with
an altered length to
width ratio, condensed
inflorescences, retarded
onset of flowering,
compact reduced number
of flowers

rol B Localizes to plasma

membrane

Alterations in the reception/
transduction of the auxin
signal
Stimulates new meristem
formation
Induce secondary metabolism

Fast growth, root meri-
stem neoformation,
high branching and
plagiotropism

rol C Phloem-specific

expression in the
root, low expres-
sion in the leaf,
and no expression
in the shoot tip

Reduces cell size
Reduces abscisic acid (ABA),
polyamine, and ethylene
levels
Formation of shoot meristems
Regulate sugar metabolism
and transport
Stimulate the production of
high levels of secondary
metabolites

Increased branching,
dwarfed plants with short
internodes, reduced epi-
dermal cell size in inter-
nodes, lanceolate leaves,
early flowering, reduced
flower size and reduced
pollen production

rol D Only expresses in

Agropine type
strains
Cytosolic protein
Exhibits poor tissue-
or organ-specific
expression

Incapable of inducing root
formation on its own
Provide defense response as
a result of environmental
stress

Increased flowering, reduced
rooting, elongating and
expanding tissues of each
organ but not on apical
meristem, callus growth
giving rise to initia-
tion of tumor resemble
formation

rol B TR

CX5R motif is absent
N-terminal part
contain 14 amino
acids

rol B homolog on TR-DNA
in the agropine type Ri
plasmid

Wrinkled leaves bent
strongly downward,
formed shoots at the base
of the stem and retarded
growth

ORF3n Modification of phe-
nolic enzymes and
involve secondary
metabolism and/
or the transport of
hormones

Negative regulator to the
dedifferentiation of tissues

Retarded flowering, less
dense inflorescences,
altered internode elonga-
tion and leaf morphology
and necrotic tips of upper
leaves, sepals and bracts
no sign of necrosis on the
basal leaves