The Heterochronic Maize Mutant Corngrass1 Results From Overexpression of a Tandem microRNA

Nat Genet. 2007 Apr;39(4):544-9. doi: 10.1038/ng2001. Epub 2007 Mar 18.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Base Sequence
  • Cloning, Molecular
  • Evolution, Molecular
  • MicroRNAs / genetics*
  • Molecular Sequence Data
  • Phenotype
  • Plant Proteins / genetics*
  • Plants, Genetically Modified
  • Repetitive Sequences, Nucleic Acid*
  • Sequence Homology, Nucleic Acid
  • Zea mays / genetics*

Substances

  • MicroRNAs
  • Plant Proteins