Studies on chromosome elimination mechanism in hybrid embryos by super-wide crosses (II)

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In previous study, we observed that the centromere of maize chromosomes in hybrid embryos between wheat and maize does not interact with spindle fibers, and that thus the maize chromosomes are eliminated in the first zygotic division. In this study we first tried to reveal the centromere binding proteins in maize centromere in the embryos by immuno-staining method. We first developed the method to observe phosphorylate histone H3 in mitosis of root tip cells. The signals were observed by fluorescent microscope with deconvolution system. This method did not work for the first zygotic cells, however, in the period of this study. Next, we made hybrids between oat and maize. We could recognize maize chromosomes by FISH in the hybrids. The maize chromosomes in oat carried normal centromere proteins. In the cross between wheat and pearl millet, the millet's chromosomes were gradually eliminated. The frequency of millet chromosomes remained in the embryos was significantly affected by the genetic background of wheat. Structural abnormality was observed both in the millet and wheat chromosomes. We tried to induce translocation between the chromosomes of wheat and maize or millet. However, wheat plants carrying a part of maize or milled did not appeared.