Pollination with heavily irradiated pollen in Nicotiana: Induced parthenogenesis and embryological study

Nicotiana crosses were pollinated in situ and in vitro with heavily irradia ted pollen (500, 700, 1000 Gy) to induce parthenogenesis and to study the d evelopment of embryo and endosperm. Haploids were obtained after in situ po llination only; however, parthenogenetic proembryos occurred also after in vitro pollination. It was demonstrated that ovule culture following pollina tion offers a better chance to produce haploids than undisturbed pollinatio n does. Pollination with irradiated pollen (PwIP) strongly decreased the nu mber of endosperm cells and the size of embryo sacs, and it affected the de velopment of embryos; no significant differences between applied irradiatio n doses were found. Ovules with endosperm only, embryo only, and with both embryo and endosperm were observed. The most frequent were the ovules with endosperm only, the rarest with embryo only. A small amount of storage prod ucts occurred in the endosperm cells. The diploid chromosome number counted in the endosperm produced after PwIP points to their origin without fertil ization. An interesting phenomenon observed after PwIP was vigorous growth of endothelium.