Identification of genes expressed during early Arabidopsis carpel development by mRNA differential display: characterisation of ATCEL2, a novel endo-1,4-beta-D-glucanase gene

The floral homeotic gene AGAMOUS (AG) imparts carpel identity on the fourth whorl of floral organs in wild-type Arabidopsis flowers. Less is known abo ut the genes that regulate carpel patterning and differentiation. To identi fy candidate regulators, we screened for genes expressed in developing carp els. Since Arabidopsis carpels are difficult to isolate, we used whole infl orescence apices of two floral homeotic mutants (pi and pi ag) and mRNA dif ferential display, to identify carpel transcripts. Two of the resulting cDN A clones were shown to be expressed predominantly in flowers. They encoded AGL11, a MADS box transcription factor known to be expressed in the carpel and ovules, and a novel Arabidopsis endo-1,4-beta-D-glucanase (ATCEL2). In situ hybridisation localised the ATCEL2 transcript to the developing septum and ovule primordia of young carpels.