microRNA172 down-regulates glossy15 to promote vegetative phase change in maize.

Shoot development in many higher plant species is characterized by phase change, where meristems and organs transition from one set of identities to another. The transition from a juvenile to adult leaf identity in maize is regulated by the APETALA2-like gene glossy15 (gl15). We demonstrate here that increasing gl15 activity in transgenic maize not only increases the number of leaves expressing juvenile traits, but also delays the onset of reproductive development, indicating that gl15 plays a primary role in the maintenance of the juvenile phase. We also show that the accumulation of a maize microRNA homologous to miR172 increases during shoot development and mediates gl15 mRNA degradation. These data indicate that vegetative phase change in maize is regulated by the opposing actions of gl15 and miR172, with gl15 maintaining the juvenile phase and miR172 promoting the transition to the adult phase by down-regulation of gl15. Our results also suggest that the balance of activities between APETALA2-like genes and miR172 may be a general mechanism for regulating vegetative phase change in higher plants.

[1]  R. Poethig,et al.  HASTY: a gene that regulates the timing of shoot maturation in Arabidopsis thaliana. , 1998, Development.

[2]  Javier F. Palatnik,et al.  Specific effects of microRNAs on the plant transcriptome. , 2005, Developmental cell.

[3]  J. Langdale,et al.  The rough sheath2 gene negatively regulates homeobox gene expression during maize leaf development. , 1998, Development.

[4]  S. Moose,et al.  Glossy15 Controls the Epidermal Juvenile-to-Adult Phase Transition in Maize. , 1994, The Plant cell.

[5]  B. Reinhart,et al.  Prediction of Plant MicroRNA Targets , 2002, Cell.

[6]  T. Berardini,et al.  HASTY, the Arabidopsis ortholog of exportin 5/MSN5, regulates phase change and morphogenesis , 2003, Development.

[7]  A. Allsopp.  Heteroblastic development in vascular plants. , 1967, Advances in morphogenesis.

[8]  R. Poethig,et al.  Heterochronic effects of glossy15 mutations on epidermal cell identity in maize. , 1994, Development.

[9]  Richard C. Moore,et al.  The early stages of duplicate gene evolution , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[10]  M. Fromm,et al.  Field evaluation of european corn borer control in progeny of 173 transgenic corn events expressing an insecticidal protein from Bacillus thuringiensis , 1995 .

[11]  Xuemei Chen,et al.  A MicroRNA as a Translational Repressor of APETALA2 in Arabidopsis Flower Development , 2004, Science.

[12]  R. Poethig.  Heterochronic mutations affecting shoot development in maize. , 1988, Genetics.

[13]  Peter Hajdukiewicz,et al.  The small, versatilepPZP family ofAgrobacterium binary vectors for plant transformation , 1994, Plant Molecular Biology.

[14]  Subhamoy Pal,et al.  Guts and glory: balancing microbes and the immune response. , 2005, Developmental cell.

[15]  H. Goodman,et al.  Uridine Addition After MicroRNA-Directed Cleavage , 2004, Science.

[16]  Michelle T. Juarez,et al.  microRNA-mediated repression of rolled leaf1 specifies maize leaf polarity , 2004, Nature.

[17]  R. Poethig,et al.  Gibberellins Promote Vegetative Phase Change and Reproductive Maturity in Maize , 1995, Plant physiology.

[18]  R. Poethig,et al.  The early phase change Gene in Maize Article, publication date, and citation information can be found at www.plantcell.org/cgi/doi/10.1105/tpc.010406. , 2002, The Plant Cell Online.

[19]  R. Poethig,et al.  Shoot development in plants: time for a change. , 1995, Trends in genetics : TIG.

[20]  J. Widholm,et al.  Type I callus as a bombardment target for generating fertile transgenic maize (Zea mays L.) , 1995, Planta.

[21]  R. Poethig,et al.  Phase identity of the maize leaf is determined after leaf initiation. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[22]  S. Moose,et al.  Glossy15, an APETALA2-like gene from maize that regulates leaf epidermal cell identity. , 1996, Genes & development.

[23]  R. Poethig,et al.  Phase Change and the Regulation of Developmental Timing in Plants , 2003, Science.

[24]  Patrick Achard,et al.  Modulation of floral development by a gibberellin-regulated microRNA , 2004, Development.

[25]  S. Hake,et al.  The control of maize spikelet meristem fate by the APETALA2-like gene indeterminate spikelet1. , 1998, Genes & Development.

[26]  Hajime Sakai,et al.  Regulation of Flowering Time and Floral Organ Identity by a MicroRNA and Its APETALA2-Like Target Genes Article, publication date, and citation information can be found at www.plantcell.org/cgi/doi/10.1105/tpc.016238. , 2003, The Plant Cell Online.

[27]  R. Poethig,et al.  The viviparous8 mutation delays vegetative phase change and accelerates the rate of seedling growth in maize , 1997 .

[28]  R. Kerstetter,et al.  The specification of leaf identity during shoot development. , 1998, Annual review of cell and developmental biology.

[29]  Gene E Robinson,et al.  Pheromone-mediated gene expression in the honey bee brain , 2003, Proceedings of the National Academy of Sciences of the United States of America.