EMBRYOLOGICAL PROCESSES DURING THE SEED FORMATION IN TWO TRIPLOID SPECIES OF Taraxacum

Abstract. The present paper reports on our observations on embryological processes occurring in the ovules of triploids: Taraxacum belorussicum (sect. Palustria) and T. atricapillum (sect. Borea). The reproduction of these dandelions comprises meiotic diplospory, parthenogenesis and autonomous endosperm development. Mature seeds contain viable embryos that provide regular seedlings. At present the importance of cytological and embryological studies of apomicts is specially emphasized because Taraxacum is one of the model genus for investigations of apomixis. It forms a polyploid complex within which there is a close relationship between the mode of reproduction and the ploidy level: diploids reproduce sexually, whereas polyploids are apomicts. Apomixis is of a great interest in plant breeding because it allows clonal seed production but asexual seeds formation by apomixis is not found in any crop plants. Unfortunately, to date any attempts at introducing of apomixis into crop species have failed. It is worth mentioning that dandelions are valuable honey plants and numerous species of Taraxacum are also used in modern herbal medicine