The heterochronic maize mutant Corngrass1 results from overexpression of a tandem microRNA

• Published in: Nature genetics Vol. 39; no. 4; pp. 544 - 549
• Main Authors: Cigan, A Mark, Saeteurn, Koy, Hake, Sarah, Chuck, George
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01-04-2007
• Subjects: Base Sequence; Biological and medical sciences; Cloning; Cloning, Molecular; Corn; Domestication; Evolution, Molecular; Fundamental and applied biological sciences. Psychology; Gene expression; Gene mutations; Genetic aspects; Genetics of eukaryotes. Biological and molecular evolution; Grasses; Identification and classification; MicroRNAs - genetics; Molecular Sequence Data; Mutants; Mutation; Phenotype; Physiological aspects; Plant Proteins - genetics; Plants, Genetically Modified; Repetitive Sequences, Nucleic Acid; Retention; Ribonucleic acid; RNA; Sequence Homology, Nucleic Acid; Zea mays; Zea mays - genetics; United States; Monocotyledones; Zea mays; RNA interference; Gramineae; Angiospermae; Micro RNA; Gene overexpression; Spermatophyta; Mutation
• ISSN: 1061-4036; 1546-1718
• DOI: 10.1038/ng2001

Retention of juvenile traits in the adult reproductive phase characterizes a process known as neoteny, and speculation exists over whether it has contributed to the evolution of new species. The dominant Corngrass1 (Cg1) mutant of maize is a neotenic mutation that results in phenotypes that may be present in the grass-like ancestors of maize. We cloned Cg1 and found that it encodes two tandem miR156 genes that are overexpressed in the meristem and lateral organs. Furthermore, a target of Cg1 is teosinte glume architecture1 (tga1), a gene known to have had a role in the domestication of maize from teosinte. Cg1 mutant plants overexpressing miR156 have lower levels of mir172, a microRNA that targets genes controlling juvenile development. By altering the relative levels of both microRNAs, it is possible to either prolong or shorten juvenile development in maize, thus providing a mechanism for how species-level heterochronic changes can occur in nature.