Submitted to: Nature Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2007
Publication Date: 4/1/2007
Citation: Chuck, G.S., Cigan, M.A., Saetrun, K., Hake, S.C. 2007. The heterochronic maize mutant Corngrass1 results from overexpression of a tandem microRNA. Nature Genetics. 39(4)544-549. Interpretive Summary: 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.
Technical Abstract: We cloned Cg1 and found that it encodes two tandem miR156 genes that are over expressed in the meristem and lateral organs. Furthermore, a target of Cg1 is teosinte glume architecture11, a gene known to have played a role in the domestication of maize from teosinte. Cg1 mutant plants overexpressing miR156 have lowered levels of mir172, a microRNA that targets genes controlling juvenile development2. 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.