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United States Department of Agriculture

Agricultural Research Service

Research Project: Genomic and Genetic Analysis of the Cereal Circadian System and Crop Production Title: The circadian clock-associated gene zea mays gigantea1 affects maize developmental transitions

Authors
item Bendix, Claire -
item Stanley, Desiree -
item Mendoza, Juan-Miguel
item Meeley, Robert -
item Harmon, Frank

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 2013
Publication Date: June 4, 2013
Citation: Bendix, C., Stanley, D., Mendoza, J.H., Meeley, R., Harmon, F.G. 2013. The circadian clock-associated gene zea mays gigantea1 affects maize developmental transitions. Plant Cell and Environment. 36(7):1379–1390.

Interpretive Summary: The circadian clock is an internal timing mechanism that allows plants to make developmental decisions in accordance with environmental conditions. Genes that makeup the circadian clock in maize are not well defined. Gigantea (gi) genes are conserved across flowering plants. In model plants, gi is proven as a gene that is critical to circadian clock function, as well as direct involvement in regulation of developmental transitions like flowering and vegetative phase change. For this reason, mutants in the maize gene gigantea1 (gi1) were studied with respect to their effect on these developmental processes. Mutants in gi1 were found flower sooner than non-mutant plants. Part of the mechanism behind the change in flowering of gi1 mutants was changed expression of other genes that regulate maize flowering. This study shows that gi1 participates in a pathway that represses flowering. gi1 mutants also underwent earlier vegetative phase change and grew taller than normal plants. Thus, gi1 also contributed to the regulatory pathways that govern these aspects of maize development and growth. Direct study of maize mutants as described here is necessary to understand the role of circadian clock regulation in important developmental events like flowering time.

Technical Abstract: The circadian clock is the internal timing mechanism that allows plants to make developmental decisions in accordance with environmental conditions. The genes of the maize circadian clock are not well defined. Gigantea (gi) genes are conserved across flowering plants, including maize. In model plants, gi is proven as a gene that is critical to circadian clock function and has direct involvement in regulation of developmental transitions like flowering and vegetative phase change. To better understand the circadian clock in maize and its regulatory pathways, mutants of the gigantea1 (gi1) gene were evaluated for their effect on these developmental processes. Mutants in gi1 were found to flower sooner than non-mutant plants, which was more apparent in long day photoperiods. Part of the mechanism behind the hastening of flowering in gi1 mutants was the upregulation of expression for the floral regulators zcn8, a gene for an FT-like floral activator, and conz1, a CONSTANS-like gene. Therefore, gi1 participates in a pathway that suppresses flowering in long day conditions. gi1 mutants also underwent earlier vegetative phase change and grew taller than normal plants. Thus, gi1 participates in multiple regulatory pathways that govern maize development and growth, where it generally has a repressive function.

Last Modified: 10/25/2014
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