Four-step protocol was established for the in vitro regeneration of Citrus sinensis cv. Tarocco somatic embryos that were morphologically similar to small somatic embryos in vivo. The regeneration procedure comprises a mechanical destruction of embryogenic culture to obtain proembryogenic cell masses (PEMs) (step 1) followed by culturing on three different media (steps 2-4). The approach developed allows in vitro simulating somatic embryogenesis by dividing this process into three partially independent steps: PEM → globular somatic embryo → heart-shaped somatic embryo → somatic embryo with developed cotyledons. The highest frequency of morphogenetic stage transition was 64, 40, and 26%, respectively. It was shown that the first step (PEM → globular embryo) was associated with the formation of heterogeneous population of spherical bodies 50-500 μm in diameter, among which about 40% were somatic embryos at globular stage. The scheme is offered of alternative pathways for the development of spherical bodies in vitro, and interrelations between their sizes and ability to direct morphogenesis are discussed. © MAIK "Nauka/Interperiodica", 2006.

Export Date: 26 August 2010Source: Scopus