Summary
Auxotrophic mutants genetically blocked at different steps of the thiamine pathway dramatically demonstrate the biochemical mechanism of hybrid vigor due to simple and perfect dominance at two unlinked loci. Heteroallelic hybrids of mutants requiring the pyrimidine moiety of thiamine display allelic complementation and thus furnish clear biochemical and genetic evidence for the superdominance hypothesis. Hybrids of low- and high-temperature-requiring leaky mutants demonstrate that heterozygosity at a single gene locus may confer developmental homeostasis on the heteroallelic combinations superior to that of the homoallelic parents. The results of this study on the autogamous plant, Arabidopsis, and of recent reports on the outbreeding species, Drosophila, render untenable the generalization that high versus low temperature dependent heterosis is determined by the breeding system.
Zusammenfassung
Auxotrophe Arabidopsis-Mutanten, bei denen verschiedene Schritte der Thiaminsynthese genetisch blockiert sind, lassen deutlich den biochemischen Mechanismus der Heterosis erkennen, der auf einfacher und völliger Dominanz in zwei ungekoppelten Loci beruht. Heteroallele Hybriden von Mutanten, die den Pyrimidinanteil des Thiamins benötigen, zeigen allele Komplementation und liefern damit den klaren biochemischen und genetischen Beweis für die Superdominanz-Hypothese. Hybriden von leaky-Mutanten, die einen niedrigen bzw. hohen Temperaturbedarf haben, zeigen, daß Heterozygotie in einem einzelnen Genlocus den heteroallelen Kombinationen eine Entwicklungshomeostasie verleihen kann, die größer als die der homoallelen Eltern ist. Die Ergebnisse unserer Untersuchungen an der autogamen Pflanze Arabidopsis und neuere Ergebnisse bei Drosophila lassen die Verallgemeinerung, daß die Art der Temperaturabhängigkeit der Heterosis durch das Zuchtsystem bestimmt wird, nicht zu.
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Literature
Allard, R. W.: Principles of Plant Breeding. New York-London: John Wiley & Sons, Inc. 1960.
Fan, D. P., M. J. Schlesinger, A. Torriani, K. J. Barrett, and C. Levinthal: Isolation and characterization of complementation products of Escherichia coli alkaline phosphatase. J. mol. Biol. 15, 32–48 (1966).
Fincham, J. R. S.: Genetic Complementation. New York-Amsterdam: W. A. Benjamin, Inc. 1966.
Garen, A., and S. Garen: Complementation in vivo between structural mutants of alkaline phosphatase from E. coli. J. mol. Biol. 7, 13–22 (1963).
Langridge, J.: A genetic and molecular basis for heterosis in Arabidopsis and Drosophila. Amer. Naturalist 96, 5–27 (1962).
Leechen, S., and L.M. Steinitz-Sears: The location of linkage groups in Arabidopsis thaliana. Canad. J. Genet. Cytol. 9, 381–384 (1967).
Lerner, I. M.: Genetic Homeostasis. Edinburgh-London: Oliver and Boyd 1954.
Lewis, D.: Gene environment interaction: the relationship between dominance, heterosis, pheno-typic stability and variability. Heredity 8, 333–336 (1954).
Lewis, D.: Gene interaction, environment and hybrid vigour. Proc. roy. Soc. B. 144, 178–185 (1955).
Li, S. L.: Genetics of thiamine metabolism in Arabidopsis. Doctoral Dissertation, University of Missourí (1968).
Moll, R. H., K. Kojima, and H. F. Robinson: Components of yield and overdominance in corn. Crop Science 2, 78–79 (1962).
Pontecorvo, G.: Gene structure and action in relation to heterosis. Proc. roy. Soc. B. 144, 171–177 (1955).
Rédei, G. P.: Single locus heterosis. Z. Vererb.-Lehre 93, 164 to 170 (1962).
Rédei, G. P.: Genetic blocks in the thiamine synthesis of the angiosperm Arabidopsis. Amer. J. Bot. 52, 834–841 (1965a).
Rédei, G. P.: Non-Mendelian megagametogenesis in Arabidopsis. Genetics 51, 857–872 (1965b).
Rédei, G., and S. L. Li: Effects of x-rays and ethyl methanesulfonate on the chlorophyll b locus in the soma and on the thiamine loci in the germline of Arabidopsis. Genetics 61 (2) in press (1969).
Reithel, F. J.: The dissociation and association of protein structures. Adv. Protein Chem. 18, 123–226 (1963).
Rothman, F., and R. Byrne: Fingerprint analysis of alkaline phosphatase of Escherichia coli K 12. J. mol. Biol. 6, 330–340 (1963).
Schlesinger, M. J., and C. Levinthal: Hybrid protein formation of E. coli alkaline phosphatase lead ingto in vitro complementation. J. mol. Biol. 7, 1–12 (1963).
Spiess, E. B.: Temperature-sensitivity and heterosis. Amer. Naturalist 101, 93–94 (1967).
Tomkins, G. M., K. L. Yielding, and J. Curran: Steroid hormone activation of L-alanine oxydation catalyzed by a subunit of crystalline glutamic dehydrogenase. Proc. natl. Acad. Sci.(U.S.) 47, 270–278 (1961).
Van Valen, L.: Heterosis and temperature. Amer. Naturalist 101, 92–93 (1967).
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Contribution from the Missouri Agricultural Experiment Station. Journal Series No. 5475 Approved by the Director.
This work was supported by U.S. Atomic Energy Commission Contract AT-(11-1)-16 and by National Science Foundation Grant GB 6577.
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Li, S.L., Rédei, G.P. Direct evidence for models of heterosis provided by mutants of Arabidopsis blocked in the thiamine pathway. Theoret. Appl. Genetics 39, 68–72 (1969). https://doi.org/10.1007/BF00307719
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DOI: https://doi.org/10.1007/BF00307719