Activity of Gibberellin ‘D’ on the Germination of Photosensitive Lettuce Seeds

Abstract

RECENT discoveries in the gibberellin series have brought to light a large number of new compounds the activity of which varies widely in different tests¹. In particular, Hashimoto and Yamaki² with tobacco seeds, and Toole and Cathey³ with lettuce seeds, reported that GA₄ was much more active than GA₃, while Brian et al.¹ indicate that GA₄ and GA₇, which had about equal activity on lettuce seeds, were both more active than GA₃. However, the latter group stated that they were “not able to establish a simple relationship between dose and response” in their test. Borriss and Schmidt⁴ crystallized a gibberellin preparation from cultures of Gibberella fujikuroi which was 30 times as active as GA₃ on the germination of Diplotaxus seeds and up to 2,000 times more active than GA₃ on seeds of Lepidium ruderale. Later this preparation, first called gibberellin A₆ or ‘D’ (ref. 4), was found to be a mixture of GA₄ and GA₇.