Em gene expression during somatic embryogenesis in the monocot Triticum aestivum L

We have used in vitro cultures initiated from immature zygotic embryos of the monocot Triticum aestivum, variety Chinese Spring, to investigate some features of the transcriptional regulation of the Em gene. A 210-bp cDNA fragment internal to the coding region of the Em gene was amplified by PCR, cloned and used as a probe in northern analyses. Em gene expression was found to be associated with cultures displaying an embryogenic potential and, more precisely, with the presence of somatic embryos. The time-course of Em gene expression was thereafter monitored, by PCR and northern analysis, from the initiation of cultures until the appearance of embryogenic structures and was shown to be temporally regulated during the somatic embryogenesis process. Finally, the Fm protein was observed in both somatic embryos and embryogenic cultures whereas it was not detected in non-embryogenic cultures. Our results, obtained from a monocot, ask the question of whether Em gene expression could be used as a universal late marker of somatic embryogenesis.