ENDOGENOUS GIBBERELLINS AND BOLTING IN CULTIVARS OF JAPANESE RADISH

Endogenous gibberellins (GAs) were identified and quantified by combined gas chromatography/mass spectrometry in four cultivars of Japanese radish (Raphanus sativus L. cvs. Sofutori-Miyashige, Wakayama, Hanashirazu-Hayafutori-Tokinashi and Wase-Shijunichi), which vary greatly in their cold requirement for bolting (or stem elongation) and flowering. In all of the cultivars, a series of GAs belonging to either the early-13-hydroxylation or early-non-hydroxylation pathway were identified, suggesting that the endogenous active GAs are GA₁ and GA₄. The concentration of GA₁ increased in the stem and decreased in the leaf during bolting in all the cultivars. Thus the mechanism by which endogenous GAs are involved in bolting and flowering may be common to various cultivars of R. sativus.