Tulipaline and tuliposide in cultured explants of tulip bulb scales

Abstract

We developed a method for rapid and reliable determination of tulipaline A (α-methylene-γ-butyrolactone) and tuliposide A. In this process we identified two isomers of the tuliposide A which are spontaneously interconverted into each other. In bulb scales of tulip ( Tulipa gesneriana) cv. Apeldoorn, relatively large amounts of free tulipaline A were found to be present in the scale tissue and a small amount of tuliposide A. In young developing shoots, the situation was reversed: tuliposide is the main component but the concentration is much lower. During the tissue culture period (10 weeks) an increase was found of both tulipaline A and tuliposide A. In bulb scale explants this temporary increase amounted to ca. 1300% in non-regenerating and ca. 550% in regenerating explants, when compared to the start level. It was followed by a decrease of ca. 700% in non-regenerating and ca. 250% in regenerating explants, when compared to the peak level. The higher increase in non-regenerating bulbs suggests a role for tulipaline A in the response of bulb scales to incubation in vitro.