Comparison of Pollen Characteristics of Nakdongbyeo and Leaf folder (Cnaphalocrocis medinalis) Resistant Rice of Its Transgenic Line

Experiments were conducted in the green house and laboratory premises of Kyungpook National University from June to September, 2008 to compare flowering characteristics, pollen viability and germination rate of transgenic rice line(leaf-folder resistant rice) and non-transgenic rice cultivar, Nakdongbyeo. The study on flowering characteristics showed that non-transgenic cultivar, Nakdongbyeo had 2-3 days earlier flowering than that of transgenic line, however there was overlapping of 2-3 days in flowering between two genotypes. Moreover, flowering completed within 14 days irrespective of seeding and transplanting dates because of photoperiod and temperature sensitivity of rice genotypes. The reaction of pollen with 3- {4,5 dimethylthiazolyl-2 }-2,5-diphenyl monotetrazolium bromide(MTT) as a staining chemical immediately after pollen dehiscence showed pollen viability of 72% in Nakdongbeyo and 61% in transgenic rice line. The mean difference of pollen viability between non-transgenic cultivar and transgenic line was not significantly different by F-test indicating transformation did not affect pollen viability of the cultivar, Nakdongbyeo. Our preliminary experiment on pollen germination showed that Nakdongbyeo, had germination rate of 26, 16 and 14%, while that of transgenic line had 20, 13 and 12% on sucrose, boric acid and calcium nitrate media, respectively. Result of this study on flowering characteristics, pollen viability and germination has elucidated that transgenic line might not be different from that of non-transformed cultivar, Nakdongbyeo, for all those characteristics thereby indicating possibility of pollen-mediated gene flow to compatible cultivated and weedy species. However, further study on in vitro pollen germination rate of transgenic line would elucidate fully regarding potential threat on pollen-mediated gene flow.