Comparative Biological Effectiveness of the Gibberellins

NATUR E 1484 Comparative Biological Effectiveness of the Gibberellins SINCE the isola.tion1 of gibberellin A (later identified1 as a mixture of gibberellins Au A 9 and Aa), and more recently the discovery• of gibbere~ A,, numerous physiological responses have been mduced in plants' with the gibberellins. Takahashi et al.• reported that A 1, A 1 and A 8 all possessed str~ng physiological activities in stimulat~g the elongation of rice seedlings. Apart from this reference, the gibberellins have not been evaluated in ~erms of specific biological activities. The comparative effectiveness of gibberellins Au A,, A 8 and A. and the methyl esters of A 1 and A 3 in promoting vegetative extension, flowering of facultative long-day annuals and in fruit setting is now reported•. Beans (Pha8eol'U8 vulgaris, var. Blue Lake) w?re germinated in quartz sand, transferred to solution cultures and after 24 hr. 10 µI. of a 3 x 10--8 M solution' of a gibberellin or derivative was applied to the stem apex. Epicotyl elongation was dete~ined after 48 hr. Gibberellins Au A, and As, applied to the stem apex, resulted in significantly greater epicotyl extension than the methyl esters of A 1 and A 3 (Table 1). No significant differences we~e 8:pparent among the gibberellins. All produced s1gnificant~y longer epicotyls than the controls. By c~ntrast,. m unpublished studies (with B. K. Gaur), gibberellms A 1 and A 3 applied to one of the primary leaves of the bean produced significantly longer epicotyls t!tan A,. This has suggested a limitation in absorptiontransport of gibberellin A,. Table 1. C0MPARATIVII BI0LOGI0AL ACTIVITY 011 GIBBEJ\ELLINS AND METHYL ESTBR DERIVATIVIIS Compound Control 3-Indoleacetlc acid paN-Chlorophen oxyacetlc acid Glbberellln .A, Methyl ester of glbberellln .A 1 Glbberellln .A, Glbberellin .A, Methyl ester of glbberellln .A, Least differences necessary for algnlllcance at 6 per cent 1 per cent Epicotyl Flowering in lettuce Stimulation extension of parth~noin the carpym Time to bean (per- Seedvisible tomatoes centage of stalk (percentage flower control) heights prlmordia of non-pol(cm.) (days) linated control) 100 40·5 164·9 296* 216 49·8 145·3 320 208 147 253 267 36·4 36·1 54·8 157 ·7 157·3 139 ·3 160 204 228 127 38·8 154·1 140 260 - - May 24, 1958 voL. 1e1 following treatment with A 1 or A 3 , whereas bolting followed heading on plants treated with A 1, the methyl esters of A 1 and A•• and the controls. Similar effects on acceleration of flowering and seedstalk heights were observed with dill. Comparative fruit-setting activities, in the absence of pollination, were determin~d . with t?e tom~to (Lycopersicon esculentum, var. Michigan-Oh io Hybrid). Three flower buds from the first cluster were emasculated approximatel y 24 hr. before anthesis. 10 µI. of a 3 x 10- 8 M solution of the gibberellins, methyl esters of A 1 and A 8 , indoleacetic acid or para-chlorophenoxyaceti c acid were then ap:r;ilied to the ov?-ry, and its diameter measured after six days. Solutions of gibberellins Au A 2 and A 8 and indoleacetic ~id were equally effective in stimulating growth of ovaries, but less so than p-chlorophen oxyacetic acid at 3 X 10-3 M concentration . At a lower concentration (3 x 10-- 6 M), however, A 1, A 1 and As were as effec~ive as p-chlorophen oxyacetic acid and more so than mdoleacetic acid. As in other responses the methyl esters of A 1 and A 8 were less active than their free acids. Preliminary studies have indicated that gibb~rellin A, was equal in activity to A 1 for promotion ?f epicotyl extension of the bean and parthenocarp y m tomatoes. It was, however, less effective in stimulating stem elongation and flowering in le~tuce ~nd ~II. A consideration of the comparative b1ological activities of the gibberellins relative to epicotyl extension in beans, stem elongation and flowering in lettuce and dill, and parthenocarp ic fruit growth in tomatoes has established the following order of activity: A,> A 1 ~A,> A 2 > methylesterA 1 ~ methyl ester A•· We thank Dr. Y. Swniki, University of Tokyo, for gibberellins A 1 , A 2 and A, and Dr. J. F. Grove, Imperial Chemical Industries, Ltd., for A 1 and the methyl esters. These studies were supported in part by grants from Chas. Pfizer and Co., Inc., and Merck and Co., Inc. M. J. BUKOVAC s. H. WI'l'TWER Department of Horticulture, Michigan State University, East Lansing, Michigan. March 19. Yabuta T., and Sumlkl, Y., J. Agric. Ohem. Soc. Japan, 14, 1526 (11138). • Takahashi, N., Kitamura, H., Kawarada, A., Seta, Y., Takai, M., Tamura, S., and Sumiki, Y., Bull . .Agric. Ohem. Soc. Japan, 19 , 1 32 42 7·9 10·4 • Pollinated control. 6 ·7 8·8 47 64 I The effects of the gibberellins and derivatives on flowering were determined with lettuce (Lactuca sativa, var. Great Lakes) and dill (Anethum graveolena) grown in pot cultures and treated ini:tially at. the 6-7 leaf stage with 10 µl. of the solution described above. Treatments were repeated after two and four weeks. All plants were grown at a night temperature of 18° C. and at the prevailing winter photoperiod (9-11 hr.). The time required for flower primordia to appear in lettuce W?5 significantly reduced a~d seedstalk heights were mcreased by treatD?ent with gibberellins A 1 and A 8 • Plants treated with A, or the methyl esters of A 1 and As flowered slightly earlier than controls, but seedstalk elongation was not affected. Furthermore , no heads formed on plants 3 ~u~. . Takahashi, N., Seta, Y.i Kitamura, H., and Sumlki, Y., Bull . .Agne. Ohern. Soc. Japan, 2 , 396 (11157). • Stowe, B. B., and Yamaki, T., "Ann. Rev. Plant Physiol.", 8, 181 (1957). , Journal Article No. 2231 from the Michigan Agricultural Experimeni Station. Effects of Alkoxyglyc erols and especially Selachyl Alcohol on the Bone Marrow in connexion with Irradiation Treatment and in Leuk2mia Therapy IN connexion with irradiation treatment it has been shown that alkoxyglycer ols to a certain extent prevent and cure leuko- and thrombo-cyto prenia 1 • It was found that the effect was related to the amount of alkoxyglycero ls administered per os. Above a certain dosage there is less effect. © 1958 Nature Publishing Group  (...truncated)