Abstract
Red light (R) and gibberellins (GA) each induce a water potential decrease in the axes of lettuce (Lactuca sativa L.) embryos resulting in germination of intact “seeds” (achenes) or an increase in growth of the axes of isolated embryos. The fruit coat and endosperm are a substantial barrier to the penetration of exogeneous GA. Isolated embryos take up 35 times as much [3H]GA1 as the embryos of intact seeds and respond to less than 1·10-10 M GA3 or GA4+7. We calculated that only 1·10-8 M of either GA3 or GA4+7 would result in 50% germination if the GA were able freely to penetrate the fruit coat. Exogenous GA3 or GA4+7, at concentrations insufficient to cause germination, result in an apparent synergistic promotion of germination when suboptimal R is applied. Yet suboptimal concentrations of exogenous GA3 or GA4+7 and suboptimal R result in only additive increases in the growth response in axes of isolated embryos. Dose-response curves demonstrate quantitative increases in the growth response of the isolated axes after R or GA treatments insufficient to induce germination in intact seeds, indicating that a threshold potential must be achieved by the embryonic axes before germination can occur.
Similar content being viewed by others
Abbreviations
- FR:
-
far=red light
- GA:
-
gibberellin
- PEG:
-
poly-ethylene glycol 4000
- Pfr :
-
far-red-absorbing phytochrome
- R:
-
red light
References
Bewley, J.D., Negbi, M., Black, M. (1968) Immediate phytochrome action in lettuce seeds and its interaction withgibberellins and other germination promoters. Planta 78, 351–357
Black, M. (1969) Light-controlled germination in seeds. Symp. soc. Exp. Biol. 23, 193–217
Blumenthal-Goldschmidt, S., Lang, A. (1960) The presence of gibberellin-like substances in mature lettuce seed. Nature (London) 186, 815–816
Brian, P.W. (1958) Role of gibberellin-like hormones in regulation of plant growth and flowering. Nature (London) 181, 1122–1123
Carpita, N.C., Ross, C.W., Nabors, M.W. (1979a) The influence of plant growth regulators on the growth of the embryonic axes of red- and far-red-treated lettuce seeds. Planta 145, 511–516
Carpita, N.C., Ross, C.W., Nabors, M.W., Petretic, N.L. (1979b) The growth physics and water relations of red-light-induced germination in lettuce seeds. III. Changes in the osmotic and pressure potential in theembryonic axes of red- and far-red-treated seeds. Planta 144, 217–224
Carpita, N.C., Nabors, M.W., Ross, C.W., Petretic, N.L. (1979c) The growth physics and water relations of red-light-induced germination in lettuce seeds. IV. Biochemical changes in the embryonic axes of red- and far-red-treated seeds. Planta 144, 225–233
Cooke, R.J., Saunders, P.F. (1975) Phytochrome mediated changes in extractable gibberellin activity in a cell-free system from etiolated wheat leaves. Planta 123, 299–302
Evans, A., Smith, H. (1976) Localization of phytochrome in etioplasts and its regulation in vitro of gibberellins. Proc. Natl. Acad. Sci. USA 73, 138–142
Ikuma, H., Thimann, K.V. (1960) Action of gibberellic acid in lettuce seed germination. Plant Physiol. 35, 557–566
Köhler, D. (1966) Veranderungen des Gibberellingehaltes von Salatsamen nach Belichtung. Planta 70, 42–45
Nabors, M.W., Lang, A. (1971) The growth physics and water relations of red-light-induced germination in lettuce seeds. I. Embryos germinating in osmoticum. Planta 101, 1–25
Reid, D.M., Clements, J.B., Carr, D.J. (1968) Red light initiation of gibberellin synthesis in leaves. Nature (London) 217, 580–582
Reid, D.M., Tuing, M.S., Durley, R.C., Railton, I.D. (1972) Red-light-enhanced conversion of tritiated gibberellin A9 into other gibberellin-like substances in homogenates of etiolated barley leaves. Planta 108, 67–75
Scheibe, J., Lang, A. (1965) Lettuce seed germination: evidence for a reversible light-induced increase in growth potential and for phytochrome mediation of the low temperature effect. Plant Physiol. 40, 485–492
Speer, H.L. (1974) Some aspects of the function of the endosperm during the germination of lettuce seed. Can. J. Bot. 52, 1117–1121
Wareing, P.F., Von Staden, J., Webb, D.P. (1973) Endogenous hormones in control of seed dormancy. In: Seed ecology, pp. 145–155, Heydecker, W., ed. Pennsylvania State Univ. Press, University Park, Md., USA
Author information
Authors and Affiliations
Additional information
III.=Carpita et al. 1979b; IV.=Carpita et al. 1979c
Rights and permissions
About this article
Cite this article
Carpita, N.C., Nabors, M.W. Growth physics and water relations of red-light-induced germination in lettuce seeds. Planta 152, 131–136 (1981). https://doi.org/10.1007/BF00391184
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00391184