Ontogeny of embryogenic aggregates in suspension culture of diploid watermelon [Citrullus lanatus (Thunb.)

Abstract Cell suspension culture from leaf-derived callus of diploid watermelon [Citrullus lanatus (Thunb.)] was established. The callus obtained on agar-gelled Murashige and Skoog (MS) medium containing 2.5 mgl-1 2,4-dichlorophenoxyacetic acid (2,4-D) was used for suspension culture. The growth of cell in the suspension culture was the highest in liquid MS medium containing same concentration (2.5 mgl-1) of 2,4-D as used for callus induction. Cells in suspension culture underwent division as result both free cells and cell aggregates were formed. In first 15 days, profuse number of early proembryogenic structures (two-, three- and four-celled) was observed while after more 15 days of culture, multi-celled proembryogenic structure was greater in suspension. The initial amount of cell in suspension culture was effective for cell proliferation and cell aggregation. As initial amount of cells, 4 ml sedimented cell volumes (SCV) could proliferate and aggregate at a highest level after 30 days of culture. Three typical phages (lag, exponential and stationary phases) in S-shaped growth curve were found in the batch culture. Among the cell growth phages, duration of exponential phage is important for the high production of cell and biosynthesis of cell compounds.