Globular embryo-like structures and highly efficient thidiazuron-induced multiple shoot formation in saffron (Crocus sativus L.)

Saffron (Crocus sativus L.) is a monocotyledonous plant propagated via corms, but recently several alternative methods have been reported. To find the conditions suitable for saffron shoot formation from corms, the effect of different concentrations of the plant growth regulatory cytokinins N-6-benzyladenine (BA) and N-phenyl-1, 2,3-thidiazol-5-ylurea, commonly known as thidiazuron (TDZ), were compared. In all corm explants, an average of 39.5 +/- A 5.1 shoots per corm were induced by 4.54 mu M TDZ, whereas only 3.6-11.4% by BA. The outstanding result in the shoot formation stage is the generation of globular, translucent structures that are morphologically similar to globular embryos. To optimize the plant regeneration from the induced adventitious shoots obtained from the TDZ treatment, the shoots were transferred to MS and B5 media supplemented with different concentrations and combinations of NAA and BA. The highest rate of plant regeneration from developing shoots was observed in the B5 medium containing 2.22 mu M NAA and 2.68 mu M BA. With optimized hormonal conditions, an average of 19.55 +/- A 5.75 shoots and 3.18 +/- A 1.5 roots per explants were obtained. Based on this experiment, a simple, new and efficient protocol is presented to produce numerous plants from induced corm explants of saffron.