Short Communication Tissue-Specific Localization of mRNA for Carrot Homeobox Genes, CHBs, in Carrot Somatic Embryos

We examined spatial and temporal expression patterns of four carrot HD-Zip I homeobox genes in somatic em-bryos. The mRNAs for CHB3, CHB4 and CHB5 were ac-cumulated preferentially in the innermost cortical cell lay-ers of the embryo axis in the torpedo-shaped embryo. In contrast, the accumulation of CHB6 mRNA was restricted to procambial cells of the heart- and torpedo-shaped em-bryos. In the embryonic cotyledons and the hypocotyl of the seedlings, all of the mRNAs for the four genes were located in the vascular tissues. These findings indicate that different HD-Zip I homeobox genes may be involved in the differentiation of specific tissues during somatic embryo-genesis. Key word: Carrot — Homeobox gene — In situ hybridi-zation — Somatic embryogenesis — Tissue differentiation