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1: Nat Genet. 2007 Apr;39(4):544-9. Epub 2007 Mar 18.
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The heterochronic maize mutant Corngrass1 results from overexpression of a tandem microRNA.

Chuck G, Cigan AM, Saeteurn K, Hake S.

Plant Gene Expression Center, 800 Buchanan St., Albany, California 94710, USA. gchuck@nature.berkeley.edu

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.

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PMID: 17369828 [PubMed - indexed for MEDLINE]