ЭлБиб

PLANT GENETICTRANSFORMATION, CELL SELECTION AND SOMATIC HYBRIDIZATION

HORMONALIMBALANCEANDRHIZOGENESISINTHEGINSENGrolC

TRANSGENICCULTURES

V.P.Bulgakov, O.L.Belozerova ,M.V.Khodakovskaya, G.K.Chernodedand

Y.N.Zhuravlev

TheInstitute o fBiologyand SoilScience, FarEastBranch o fRussianAcademyo f

Sciences, Vladivostok, 690022Russia,

Biotech@ibss.marine.su

Plasmide construction containing the

rolC

gene isolated earlier (Estruch

et al., 1987) from the central part of the TL-DNA of

Agrobacterium rhizogenes

have been used to transform the cell culture (strain 1c) of Panax ginseng C.

A. Meyer. The

rolC

gene encodes for an enzyme able to release active

cytokinins from their glucoside conjugates (Estruch et al., 1991). To explain

"paradox of Estruch", namely, rhizogenesis in ro/C-expressing plant cell

cultures, the levels of endogenous cytokinins and IAA were measured in the

resulting transgenic tissues. The content of conjugated cytokinins in the

non-transformed 1c culture dramatically increased throughout culture period,

whereas the content of conjugated cytokinins in

rolC

-roots dropped markedly

within the first 25 days of cultivation and remained further at a constant level.

The levels of free cytokinins and IAA in transgenic roots were lower, compared

to the non-transformed culture 1c (5.8 times and 179 times, respectively).

These results provide evidence that root formation in rolC-tumors is likely to

be a result of reducing in cytokinin content. We have supposed that conversion

of native type of cytokinin methabolism to "accelerated" type, which is

determined by rapid degradation of cytokinins by side chain cleavage, occurs

in the 1c culture following the

rolC

gene integration.

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