Embryological studies on ovules of Melandrium album pollinated in vitro with Lychnis coronaria pollen grains

Placentae of Melandrium album excised from ovaries of unopened flowers were pollinated in vitro with pollen grains of Lychnis coronaria. Pollen grains germinated, and pollen tubes were found entering the micropyles 18 h after pollination. Double fertilization occurred. Immature and mature hybrid embryos at different stages of development were analyzed up to the third week of culture. Twenty-five days after culture, cotyledonary embryos were isolated from ovules and transferred to MS medium supplemented with 0.5, 1 or 2 mg l-1 indole-3-acetic acid (IAA). About 85% of the 115 inoculated embryos died shortly after transfer to medium, due to atrophy of the root and one cotyledon. Eighteen embryos survived; of these, 16 well-formed seedlings with root system were transferred to soil. The hybrid plants grew normally, and their hybridity was confirmed by morphological study. Female and male organs of the intergeneric hybrid were completely sterile.