Int. J. Dev. Biol. 55: 657 - 664 (2011)

https://doi.org/10.1387/ijdb.113340er

Vol 55, Issue 6

Reproductive Meristem22 is a unique marker for the early stages of stamen development

Developmental Expression Pattern | Published: 24 August 2011

Elisson Romanel¹, Pradeep Das², Richard M. Amasino³, Jan Traas², Elliot Meyerowitz⁴ and Marcio Alves-Ferreira*^,1

¹Laboratório de Genética Molecular Vegetal (LGMV), Departamento de Genética, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil, ²Laboratoire RDP, Ecole Normale Supérieure de Lyon (ENS), Université de Lyon, Lyon, France, ³Department of Biochemistry, University of Wisconsin, Madison, WI, USA and ⁴Division of Biology, 156-29, California Institute of Technology, Pasadena, California, USA

Abstract

Stamens undergo a very elaborate development program that gives rise not only to many specific tissue types, but also to the male gametes. The specification of stamen identity is coordinated by a group of homeotic genes such as APETALA3 (AP3) and PISTILLATA (PI), AGAMOUS (AG) and SEPALLATA (SEP1-4) genes. Genome-wide transcriptomic comparisons between floral buds of wild-type and ap3 mutants led to the identification of the REM22 gene, which is expressed in the early stages of stamen development. This gene is member of the plant-specific B3 DNA-binding superfamily. In this work, we dissect the spatio-temporal expression pattern of REM22 during the early stages of stamen development. To this end, both in situ hybridization analyses as well as in vivo fluorescence strategies were employed. At stage 4 of flower development, REM22 is expressed exclusively in those undifferentiated cells of the floral meristem that will give rise to the stamen primordia. At stage 5, REM22 expression is restricted to the epidermal and the subepidermal layers of anther primordia. Later, this expression is confined to the middle layer and the differentiating tapetal cells. After stage 10 when all the tissues of the anther have differentiated, REM22 expression is no longer detectable. Furthermore, we examined the pREM22::GUS-GFP marker line in an inducible system where the ectopic AG function is used to promote microsporogenesis. The data support the idea that REM22 expression is a useful marker to study the early stages of stamen development.

Keywords

male sporogenesis, B3 domain, reproductive meristem, stamen development, REM22 function