|Coe Jr, Edward|
Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2004
Publication Date: 1/15/2005
Citation: Auger, D.L., Gray, A.D., Ream, T.S., Kato, A., Coe Jr, E.H., Birchler, J.A. 2005. Non-additive gene expression in diploid and triploid hybrids of maize. Genetics. 169(1):389-397.
Interpretive Summary: Hybrids are produced for a number of crops, most notably maize. Because of hybrid vigor that results when selected strains (inbred lines) are crossed with others, the productiveness of the hybrids is of great significance and high value in production. The molecular and biochemical basis of hybrid vigor is not understood, and these experiments are directed to its mechanism. The knowledge gained from these studies will be important to plant scientists, including plant breeders, as they work to increase capacity for breeding hybrids that are further improved in productivity and efficiency, using the gains in understanding the mechanisms of hybrid vigor.
Technical Abstract: The molecular basis of hybrid vigor (heterosis) has remained unknown despite the importance of this phenomenon in evolution and in practical breeding programs. In order to formulate a molecular basis of heterosis, an understanding of gene expression in inbred and hybrid states is needed. In this study, we examined in maize (Zea mays L.) the amount of various transcripts in hybrid and inbred individuals (B73 and Mo17) to determine whether the quantities of specific messenger RNAs were additive or non-additive in the hybrids. Further, we examined the levels of the same transcripts in hybrid triploid individuals that had received unequal genomic contributions, one haploid genome from one parent and two from the other. If allelic expression were merely the additive value in hybrids from the two parents, the midparent values would be observed. Our study revealed that a substantial number of genes do not exhibit the midparent value of expression in hybrids. Instead, transcript levels in the diploid hybrids correlate negatively with transcript levels in the diploid inbreds. Although transcript levels were clearly non-additive, transcript levels in triploid hybrids were affected by genomic dosage.