Agriculture Reference
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Fig. 1.5
Schematic representation of Agropine type Ri plasmid of
A. rhizogenes
The most common
A. rhizogenes
strains which represented by Ri plasmids are
agropine-type: pRiA4, pRi1855, pRiHRI, pRi15834, and pRiLBA9402, manno-
pine-type: pRi8196, cucumopine type: pRi2659 and mikimopine-type pRi1724. Al-
though mikimopine and cucumopine are stereo-isomers, there is no homology be-
tween opine biosynthetic genes on the nucleotide level (Filetici et al.
1987
; Davioud
et al.
1988
; Gartland
1995
; Ouartsi et al.
2004
; Veena and Taylor
2007
) (Fig.
1.4
).
Among the different known strains of
A. rhizogenes
, K47, K599 and HRI are
hyper-virulent types known to be capable of infecting a broad range of plant hosts.
More research on the virulence factors of these strains needs to be done for under-
standing of whether they are located on the chromosome(s), plasmid(s) or both
(Petit et al.
1983
; Isogai et al.
1988
; Porter
1991
; Suzuki et al.
2001
). Also, there
are differences between
A. rhizogenes
strains in terms of polarity of infection of
the plant tissue. For example, root growth can be induced by some strains of
A.
rhizogenes
only on the apical surfaces of carrot root discs and yield no detectable
outgrowth on the basal surfaces, whereas root proliferation can be induced by oth-
ers both inoculation of apical and basal surfaces (Cardarelli et al.
1985
; Ryder et al.
1985
; Capone et al.
1989
; Limami et al.
1998
). Based on these findings, various
A.
rhizogenes
strains were further classified as polar and non-polar types. Agropine
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