Autonomous endosperm development in unpollinated ovaries of Brassica napus L. cv. Topas cultured in vitro

Autonomous endosperm (AE) was found in 39 (17.3%) of in vitro cultured unpollinated ovaries of Brassica napus L. cv. Topas, with average frequency 1.5 ovule with AE per ovary. AE was induced on MS medium and on MS + 2 mg/l BAP + 0.1 mg/l NAA , MS + 2 mg/l BAP + 2 mg/l 2,4-D, and in ovules exposed to 1 h auxin treatment (MS + 20 or 40 mg/l 2,4-D) and then transferred to hormone-free MS medium. The highest frequency of AE induction occurred after 1 h auxin treatment (34.5%). The structure and size of AE nuclei suggest their origin from secondary nucleus or polar nucleus/nuclei. The control experiment with unpollinated, bagged flower buds left on plants, revealed no AE induction in situ. Gynogenic embryos were not observed in the material studied.