Primary cassava somatic embryos were induced on a medium without CaCl(2), however, no or only a few secondary somatic embryos were formed from them. With 15 mM CaCl(2) in the medium for induction of cassava primary embryos, more secondary somatic embryos were produced from them, and they were much effective in maintaining their embryogenic capacity than the controls of embryos which were induce...

Neem is a highly heterozygous and commercially important perennial plant. Conventionally, it is propagated by seeds which loose viability within two weeks. Strictly cross pollinating nature of the plant causes serious barrier to the genetic improvement by conventional methods. Alternative methods of tree improvement such as somatic hybridization, mutagenesis and genetic transformation require a...

Background Hybrid yellow-poplar was a man-made cross between Liriodendron tulipifera Linn.× L. chinense(Hemsl.) Sarg.. Heterosis was strong both on growth and adaptation, no matter what, the crosses or the reciprocals. During the last 12 years, somatic embryogenesis systems were successfully established in our lab, in order to meet the needs of planting materials for expanding plantations in So...

Background Embryogenesis in Gymnosperms presents unique characteristics when compared to Angiosperm embryogenesis. However, little is known about the molecular regulation of embryo development in Gymnosperms because most studies have been conducted in Angiosperm model species. Due to the economic relevance of some forest species included in this group of plants, namely pines, efforts have been ...

The early embryo is formed by the fusion of two germ cells that must generate not only all of the nonreproductive somatic cell types of its body but also the germ cells for the next generation. Therefore, embryo cells face a crucial decision: whether to develop as germ or soma. How is this fundamental decision made and germ cell fate maintained during development? Studies in the nematode worm C...

Asymmetric segregation of maternally-encoded proteins is essential to cell fate determination during early cell divisions of the Caenorhabditis elegans (C. elegans) embryo, but little is known about the patterning of maternal transcripts inside somatic lineages. In the first Chapter of this thesis, by detecting individual mRNA molecules in situ, we measured the densities of the two maternal mRN...

With fertilization, the paternal and maternal contributions to the zygote are not equal. The oocyte and spermatozoon are equipped with complementary arsenals of cellular structures and molecules necessary for the creation of a developmentally competent embryo. We show that the nucleolus is exclusively of maternal origin. The maternal nucleolus is not necessary for oocyte maturation; however, it...

In many organisms, the transition from oocyte to embryo occurs in the absence of mRNA transcription. Therefore, early developmental programs rely on maternal mRNAs and proteins that are synthesized during oogenesis. The regulated translation of maternal RNAs is essential for the proper deployment of regulatory factors during early embryogenesis. Recent studies suggest that the degradation of ma...