A CHROMO BOX GENE FROM CARROT (DAUCUS-CAROTA L.) - ITS CDNA STRUCTUREAND EXPRESSION DURING SOMATIC AND ZYGOTIC EMBRYOGENESIS

A cDNA clone, designated DcDB1, was isolated from a cDNA library prepa red from embryogenic cell clusters of carrot (Daucus carota L.) and ch aracterized. The cDNA (1416 bp) encoded for a protein of 392 amino aci d residues that contained a conserved chrome domain. The chrome domain is a 37 aa region found in both the Polycomo gene product, which is a repressor of homeotic genes, and a heterochromatin protein 1 of Droso phila. This domain is postulated to function in the binding of protein s to chromatin. Genomic blot hybridization experiments suggested that the number of DcCB1 genes in the carrot genome is low. The level of Dc CB1 mRNAs was high in somatic embryos at globular and heart-shaped sta ges but low in torpedo-shaped somatic embryos. The level of DcCB1 tran scripts decreased during the formation of seeds. The existence of both homeo and chrome box genes in plants suggests that regulatory mechani sms of developmental genes in plants may resemble those in Drosophila. (C) 1998 Elsevier Science B.V. All rights reserved.