Replication of DNA during barley endosperm development

The incorporation of [6-H-3]-thymidine into DNA of developing barley end sperm was examined by autoradiography of cross sections of seeds and DNA analysis. The majority of nuclear divisions took place in the very young endosperm, but as late as 25 days after anthesis there was evidence for DNA replication. The DNA content of the endosperm increases during development and in response to nitrogen application in parallel to the storage protein synthesis profile. The hordein genes were hypersensitive to DNase I treatment throughout development.