Originally published as Genetics Published Articles Ahead of Print on April 3, 2007.
Genetics, Vol. 176, 283-294, May 2007, Copyright © 2007
doi:10.1534/genetics.107.071746
Divergent Regulatory OsMADS2 Functions Control Size, Shape and Differentiation of the Highly Derived Rice Floret Second-Whorl Organ
Shri Ram Yadav1,
Kalika Prasad1,2 and
Usha Vijayraghavan3
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
3 Corresponding author: Department of Microbiology and Cell Biology, Indian Institute of Science, C. V. Raman Rd., Bangalore 560012, India.
E-mail: uvr{at}mcbl.iisc.ernet.in
Functional diversification of duplicated genes can contribute to the emergence of new organ morphologies. Model eudicot plants like Arabidopsis thaliana and Antirrhinum majus have a single PI/GLO gene that together with AP3/DEF regulate petal and stamen formation. Lodicules of grass flowers are morphologically distinct reduced organs occupying the position of petals in other flowers. They serve a distinct function in partial and transient flower opening to allow stamen emergence and cross-pollination. Grasses have duplicated PI/GLO-like genes and in rice (Oryza sativa) one these genes, OsMADS2, controls lodicule formation without affecting stamen development. In this study, we investigate the mechanistic roles played by OsMADS2. We ascribe a function for OsMADS2 in controlling cell division and differentiation along the proximaldistal axis. OsMADS2 is required to trigger parenchymatous and lodicule-specific vascular development while maintaining a small organ size. Our data implicate the developmentally late spatially restricted accumulation of OsMADS2 transcripts in the differentiating lodicule to control growth of these regions. The global architecture of transcripts regulated by OsMADS2 gives insights into the regulation of cell division and vascular differentiation that together can form this highly modified grass organ with important functions in floret opening and stamen emergence independent of the paralogous gene OsMADS4.
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Copyright © 2007 by the Genetics Society of America.