Optimization of biotin and thiamine requirements for somatic embryogenesisof date palm (Phoenix dactylifera L.)

This study was conducted to examine the effect of biotin and thiamine conce ntrations on callus growth and somatic embryogenesis of date palm (Phoenix dactylifera L.). Embryogenic callus derived from offshoot tip explants. was cultured on hormone-free MS medium containing biotin at 0, 0.1, 1, or 2 mg l(-1) combined with thiamine at 0.1, 0.5, 2, or 5 mg l(-1). Embryogenic ca llus weight, number of resultant embryos, and embryo length were significan tly influenced by thiamine and biotin concentration. The optimum callus gro wth treatment consisted of 0.5 mg l(-1) thiamine and 2 mg l(-1) biotin. Thi s treatment also gave the highest number of embryos. Embryo elongation was greatest at 0.5 or 2 mg l(-1) thiamine combined with 1 mg l(-1) biotin. Emb ryos from all treatments germinated and regenerants exhibited normal growth in soil. This study provides an insight into the importance of optimizing various culture medium components to overcome in vitro recalcitrance of dat e palm.