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United States Department of Agriculture

Agricultural Research Service

Title: Genetic analysis of central carbon metabolism unveils an amino acid substitution that alters maize NAD-dependent isocitrate dehydrogenase activity

Authors
item Zhang, Nengy -
item Gur, Amit -
item Gibbon, Yves -
item Sulpice, Ronan -
item Flint-Garcia, Sherry
item McMullen, Michael
item Stitt, Mark -
item Buckler, Edward

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 5, 2010
Publication Date: April 1, 2010
Citation: Zhang, N., Gur, A., Gibbon, Y., Sulpice, R., Flint Garcia, S.A., Mcmullen, M.D., Stitt, M., Buckler IV, E.S. 2010. Genetic analysis of central carbon metabolism unveils an amino acid substitution that alters maize NAD-dependent isocitrate dehydrogenase activity. PLoS One. 5(4):e9991.

Interpretive Summary: Central carbon metabolism (CCM) is a fundamental component of life. The participating genes and enzymes are thought to be structurally and functionally conserved across and within species and thus have not been obvious targets as candidates for crop improvement. We test this functional conservation in maize, the most diverse model crop species. First, we found heritable variation in enzyme activity for every enzyme tested. Using several genetic approaches we found heritable variation for every CCM gene tests, CCM genes are significantly associated with several whole-plant productivity traits, and natural variation at the NAD-dependent isocitrate-dehydrogenase (IDH) could be related to the single nucleotide level. Our results demonstrate the presence of considerable genetic diversity in CCM genes, which drives heritable phenotypic variation in enzyme activities and whole-plant phenotypes. The use of diverse germplasm to genetically dissect the variation in target enzyme activities in parallel with agronomic traits could be a powerful way to link metabolism and crop improvement. This approach can be complementary to transgenic approaches, which to date have had only limited success in improving crop performance, by manipulating central carbon metabolism.

Technical Abstract: Central carbon metabolism (CCM) is a fundamental component of life. The participating genes and enzymes are thought to be structurally and functionally conserved across and within species and thus have not been obvious targets as candidates for crop improvement. We test this functional conservation in maize, the most diverse model crop species. First, we found heritable variation in enzyme activity for every enzyme tested. Using association mapping of diverse maize genotypes, we then found that SNPs within CCM genes are significantly associated with several whole-plant productivity traits. One of these enzymes was the NAD-dependent isocitrate-dehydrogenase (IDH), in which we identified a novel amino-acid substitution in a phylogenetically conserved site which was strongly associated with changes in enzymatic activity. The proposed mechanism for the IDH activity variation includes additional components regulating protein level. Our results demonstrate the presence of considerable genetic diversity in CCM genes, which drives heritable phenotypic variation in enzyme activities and whole-plant phenotypes. The use of diverse germplasm to genetically dissect the variation in target enzyme activities in parallel with agronomic traits could be a powerful way to link metabolism and crop improvement. This approach can be complementary to transgenic approaches, which to date have had only limited success in improving crop performance, by manipulating central carbon metabolism.

Last Modified: 12/20/2014
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