Influence of exogenous hormones on growth and secondary metabolite production in hairy root cultures of Cichorium intybus L. cv. Lucknow Local

The effect of exogenously fed hormones on hairy root cultures of Cichorium intybus L. cv. Lucknow Local was studied. It was seen that auxin in the pre sence of low levels of kinetin induces rapid disorganization in hairy root cultures of C. intybus, ultimately to form suspension cultures, and this pr ocess was associated with the decrease in coumarin content in the cells. Of various treatments, it was observed that with an increase in the auxin: cy tokinin ratio, the biomass decreased with the increase in disorganization i ndex during the culture period of 28 d. The disorganization index was less when the inoculum size was enhanced to 10-fold. The total endogenous indole -3-acetic acid titers and indole-3-acetic acid oxidase activity also decrea sed with an increase in disorganization index, and was independent of initi al inoculum. size, with only a magnitude difference. The total coumarin con tent strictly correlated with growth in all the treatments. In contrast, ex ogenously supplied gibberellic acid at the 0.5 mg l(-1) level enhanced grow th, coumarin content, and branching patterns over the control and other tre atments on day 28. The exogenously fed growth regulators had an effect on g rowth, auxin and coumarin biosyntheses, wherein transformed roots treated w ith increasing concentration of auxin to cytokinin ratios lost their abilit y for coumarin biosynthesis. The behavior of hairy roots from an Indian cul tivar of chicory upon growth regulator treatment is discussed in terms of g rowth, coumarin and auxin biosyntheses.