Reference "SUPERWOMAN1 and DROOPING LEAF genes control floral organ identity in rice"

Reference ID

7993

Title

SUPERWOMAN1 and DROOPING LEAF genes control floral organ identity in rice

Source

Development (Cambridge, England), 2003, vol. 130, pp. 705-718

Authors (7)

Nagasawa-N	Miyoshi-M
Sano-Y	Satoh-H
Hirano-H	Sakai-H
Nagato-Y

Abstract

We analyzed recessive mutants of two homeotic genes in rice, SUPERWOMAN1 (SPW1)
and DROOPING LEAF (DL). The homeotic mutation spw1 transforms stamens and
lodicules into carpels and palea-like organs, respectively. Two spw1 alleles,
spw1-1 and spw1-2, show the same floral phenotype and did not affect vegetative
development. We show that SPW1 is a rice APETALA3 homolog, OsMADS16. In
contrast, two strong alleles of the dl locus, drooping leaf-superman1 (dl-sup1)
and drooping leaf-superman2 (dl-sup2), cause the complete transformation of the
gynoecium into stamens. In these strong mutants, many ectopic stamens are formed
in the region where the gynoecium is produced in the wild-type flower and they
are arranged in a non-whorled, alternate pattern. The intermediate allele dl-1
(T65), results in an increase in the number of stamens and stigmas, and carpels
occasionally show staminoid characteristics. In the weakest mutant, dl-2, most
of the flowers are normal. All four dl alleles cause midrib-less drooping
leaves. The flower of the double mutant, spw1 dl-sup, produces incompletely
differentiated organs indefinitely after palea-like organs are produced in the
position where lodicules are formed in the wild-type flower. These incompletely
differentiated organs are neither stamens nor carpels, but have partial floral
identity. Based on genetic and molecular results, we postulate a model of stamen
and carpel specification in rice, with DL as a novel gene controlling carpel
identity and acting mutually and antagonistically to the class B gene, SPW1.