Flowers Into Shoots: Photo and Hormonal Control of a Meristem Identity Switch in Arabidopsis (Gibberellins͞phytochrome͞floral Reversion)
Proc. Natl. Acad. Sci. USA Vol. 93, pp. 13831–13836, November 1996 Developmental Biology Flowers into shoots: Photo and hormonal control of a meristem identity switch in Arabidopsis (gibberellinsyphytochromeyfloral reversion) JACK K. OKAMURO*, BART G. W. DEN BOER†,CYNTHIA LOTYS-PRASS,WAYNE SZETO, AND K. DIANE JOFUKU Department of Biology, University of California, Santa Cruz, CA 95064 Communicated by Bernard O. Phinney, University of California, Los Angeles, CA, September 10, 1996 (received for review February 1, 1996) ABSTRACT Little is known about the signals that govern MOUS (AG) (3, 15, 17, 21–23). The LFY gene encodes a novel the network of meristem and organ identity genes that control polypeptide that is reported to have DNA binding activity in flower development. In Arabidopsis, we can induce a hetero- vitro (20). AG encodes a protein that belongs to the evolu- chronic switch from flower to shoot development, a process tionarily conserved MADS domain family of eukaryotic tran- known as floral meristem reversion, by manipulating photo- scription factors (24, 25). However, little is known about how period in the floral homeotic mutant agamous and in plants these proteins govern meristem identity at the cellular and heterozygous for the meristem identity gene leafy. The trans- molecular levels. Previous studies suggest that the mainte- formation from flower to shoot meristem is suppressed by hy1, nance of flower meristem identity in lfy and in ag mutants is a mutation blocking phytochrome activity, by spindly, a mu- controlled by photoperiod and by one class of plant growth tation that activates basal gibberellin signal transduction in regulators, the gibberellins (12, 15, 21).
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