Putrescine and silver nitrate influences shoot multiplication, in vitro flowering and endogenous titers of polyamines in Cichorium intybus L. cv. Lucknow local

The influence of putrescine (Put) and AgNO3 on shoot multiplication, in vit ro flowering and endogenous titers of polyamines in Cichorium intybus L, cv . Lucknow local was investigated. Exogenous administration of Put at a conc entration of 40 mM resulted in maximum tissue response in terms of shoot nu mbers (34.6 +/- 2.61) and shoot lengths (7.6 +/- 0.57 cm) on MS media suppl emented with 2-iP (2.0 mg L-1) and GA(3) (0.5 mg L-1) as observed on the 35 (th) day. Exogenous application of 40 muM AgNO3 resulted in maximum shoot n umber (36.8 +/- 2.63) and shoot lengths (7.9 +/- 0.76 cm) on day 35 on the same media. Endogenous titers of conjugated spermidine decreased sharply fr om day 7-21, whereas endogenous conjugated spermine levels peaked on day 28 (1265 +/- 94.9 nmoles g(-1) FW), after treatment with 40 mM Put. Whereas, AgNO3 (40 muM) fed samples resulted in higher titers of endogenous conjugat ed spermine (1405 +/- 105.6 nmoles g(-1) FW, 3.62 fold over control) on day 14. All other treatments showed decreasing endogenous levels during the wh ole culture period. Both Put (40 mM) and AgNO3 (40 muM) resulted in floral initiation and floral development on day 28 and 14 (3.76 +/- 0.16, 4.2 +/- 0.21 flowers per shoot apices), respectively. To investigate the role of Pu t (40 mM) and AgNO3 (40 muM) on morphogenetic response and endogenous conju gated polyamine titers in shoots of chicory, polyamine inhibitors (DFMA and DFMO) were used. The morphogenetic response and the endogenous conjugated pool of polyamines were diminished in DFMA and DFMO treatments, but could b e restored by addition of Put (40 mM) and AgNO3 (40 muM). Under exogenous P ut feeding, ethylene production was reduced in shoot cultures of chicory. T his study shows for the first time the influence of polyamines on multiple shoot initiation from axillary buds of C. intybus L. cv. Lucknow local and also indicates the promotive effect of Put and AgNO3 on autoregulation of p olyamine biosynthesis, thereby regulating in vitro flowering, the endogenou s pool of polyamines and shoot multiplication.