The impact of Thiourea on Tea (Camellia sinensis) callus proliferation and secondary metabolites content

In the present experiment, the in vitro callus production from tea leaf explants was induced on three different basal media. Then, the efficiency of tea callus proliferation was enhanced through application of thiourea to the proliferation medium. Furthermore, the caffeine and Epigallocatechin Gallate content of the callus and leaf tissues were estimated through HPLC method. The calli mass volume in WPM (woody plant medium) supplemented with thiourea (either 0.1 or 1.0 mM) was significantly higher than other basal media. The callus tissue collected from media enriched with thiourea had significantly more caffeine content but the level of Epigallocatechin Gallate was not statistically affected by thiourea treatments. The amount of these two compounds was also estimated in young and old leaves of the tea mother plants and it was found that the callus tissue had little amount of caffeine and Epigallocatechin Gallate as compared to maternal tissues. It is concluded that, in species with low rate callus proliferation, addition of thiourea to the medium may be followed as an effective and low cost option for callus proliferation improvement.