Synergistic effect of auxins and polyamines in hairy roots of Cichorium intybus L. during growth, coumarin production and morphogenesis.

Hairy roots of Cichorium intybus obtained by infecting with
different Agrobacterium rhizogenes strains (LMG-150 and
A20/83) were studied for total endogenous indole-3-acetic
acid (IAA) levels and indole-3-acetic acid oxidase (IAAO) activity.
The roots initiated by LMG- 150 showed higher endogenous
IAA levels as well as IAAO activity as compared to the
roots from A20/83. Coumarin production in roots obtained by
both of these strains strictly correlated with growth, with
higher content in the roots obtained by LMG- 150. Moreover
roots from LMG-150 showed increased growth index, length
of primary roots and number of secondary and tertiary roots.
The roots derived from LMG- 150 were studied for total endogenous
IAA and IAAO activity under the exogenous administration
of polyamines and fungal elicitors. The treatment with
putrescine (Put) at 1.5 mM level showed maximum endogenous
IAA levels and IAAO activity as compared to the control
and other polyamine administration, it also supported faster
growth in terms of biomass accumulation, and total coumarin
production. Of the various treatments, mycelial extract (ME)
and culture media filtrate (CM F) of Pythium aphanidermatum
and Phytopthoraparasitica vat. nicotiana, the treatment with 1
% CMF of P. parasitica var. nicotiana, resulted in maximum
IAA levels and IAAO activity, which was supported by maximum
biomass, coumarin production as compared to the control
and other elicitor treatments. Two different regenerants of
chicory obtained through A. rhizogenes LMG-150 designated
as T-I and T-II, were studied for total endogenous IAA levels
and IAAO activity. T-II showed higher titers of IAA with
higher activity of IAAO as compared to T-I. Endogenous titer
of IAA and IAAO activity was found to be maximum in transformed
roots as compared to T-l, T-II, normal roots and normal
plants. Our work showed a variation in endogenous auxin levels
in these transformed plants. There exists a synergistic effect
of endogenous IAA titers and polyamines in regulating root
morphogenesis. Fungal elicitors influenced growth and
coumarin production and an elicitor preparation of 1% CMF of
P. parasitica var. nicotiana gave spontaneous regeneration of
shoots. The implications of these results are discussed.