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Science 2 September 1988:
Vol. 241. no. 4870, pp. 1216 - 1218
DOI: 10.1126/science.241.4870.1216
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Articles

Gibberellins: A Phytohormonal Basis for Heterosis in Maize

STEWART B. ROOD 1, RICHARD I. BUZZELL 2, LEWIS N. MANDER 3, DAVID PEARCE 4, and RICHARD P. PHARIS 4

1 Department of Biological Sciences, University of Lethbridge, Alberta, T1K 3M4, Canada.
2 Agriculture Canada Research Station, Harrow, Ontario, NOR 1G0.
3 Research School of Chemistry, Australian National University, Canberra, A.C.T. 2600, Australia.
4 Department of Biological Sciences, University of Calgary, Alberta, T2N 1N4.

Four commercially important maize parental inbreds and their 12 F1 hybrids were studied to investigate the role of the phytohormone gibberellin (GA) in the regulation of heterosis (hybrid vigor). All hybrids grew faster than any inbred. In contrast, all inbreds showed a greater promotion of shoot growth after the exogenous application of GA3. Concentrations of endogenous GA1, the biological effector for shoot growth in maize, and GA19, a precursor of GA1, were measured in apical meristematic shoot cylinders for three of the inbreds and their hybrids by gas chromatography—mass spectrometry with selected ion monitoring; deuterated GAs were used as quantitative internal standards. In 34 of 36 comparisons, hybrids contained higher concentrations of endogenous GAs than their parental inbreds. Preferential growth acceleration of the inbreds by exogenous GA3 indicates that a deficiency of endogenous GA limits the growth of the inbreds and is thus a cause of inbreeding depression. Conversely, the increased endogenous concentration of GA in the hybrids could provide a phytohormonal basis for heterosis for shoot growth.

Submitted on February 23, 1988
Accepted on June 15, 1988


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
A Genetic Test of Bioactive Gibberellins as Regulators of Heterosis in Maize.
D. L. Auger, E. M. Peters, and J. A. Birchler (2005)
J. Hered. 96, 614-617
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Science. ISSN 0036-8075 (print), 1095-9203 (online)