Reference "OsMADS1, a rice MADS-box factor, controls differentiation of specific cell types in the lemma and palea and is an early-acting regulator of inner floral organs"

Reference ID

11391

Title

OsMADS1, a rice MADS-box factor, controls differentiation of specific cell types in the lemma and palea and is an early-acting regulator of inner floral organs

Source

The Plant journal : for cell and molecular biology, 2005, vol. 43, pp. 915-928

Authors (3)

Prasad-K	Parameswaran-S
Vijayraghavan-U

Abstract

Grass flowers are highly derived compared to their eudicot counterparts. To
delineate OsMADS1 functions in rice floret organ development we have examined
its evolution and the consequences of its knockdown or overexpression. Molecular
phylogeny suggests the co-evolution of OsMADS1 with grass family
diversification. OsMADS1 knockdown perturbs the differentiation of specific cell
types in the lemma and palea, creating glume-like features, with severe
derangements in lemma differentiation. Conversely, ectopic OsMADS1 expression
suffices to direct lemma-like differentiation in the glume. Strikingly, in many
OsMADS1 knockdown florets glume-like organs occupy all the inner whorls. Such
effects in the second and third whorl are unexplained, as wild-type florets do
not express OsMADS1 in these primordia and because transcripts for rice B and C
organ-identity genes are unaffected by OsMADS1 knockdown. Through a screen for
OsMADS1 targets we identify a flower-specific Nt-gh3 type gene, OsMGH3, as a
downstream gene. The delayed transcription activation of OsMGH3 by dexamethasone-
inducible OsMADS1 suggests indirect activation. The OsMGH3 floret expression
profile suggests a novel role for OsMADS1 as an early-acting regulator of second
and third whorl organ fate. We thus demonstrate the differential contribution of
OsMADS1 for lemma versus palea development and provide evidence for its
regulatory function in patterning inner whorl organs.