SYNCHRONIZATION OF CELL CYCLE AND OCCURRENCE OF CHROMOSOME ABERRATIONS IN SUSPENSION CULTURE OF LIVERWORT WITH TRIFLURALIN

¹ Hokuriku National Agricultural Experiment Station, Joetsu 943-0193, Japan

² Japan science and Technology Corporation, Saitama 332-0012, Japan

³ National Institute Of Agrobiological Resources Tsukuba Science, Tsukuba 305-7439, Japan

⁴ Bio-oriented Technology Research Advancement Institution, Saitama 331-8537, Japan

⁵ Faculty of Engineering, Graduate School of Osaka University, Suita 565-0871, Japan

Dioecious liverwort, Marchantia polymorpha, has been used for studies on sex differentiation and its mechanisms, because it has eight autosomes with X or Y sex chromosome (female, n=8+X : male, n=8+Y) which is very samll. As the size of sex chromosomes are very small, it has been difficult to analyze them by cytological means. In cytological studies, it is also prerequisite to collect large number of chromosomes. Thus we examine the effect of the cell cycle inhibitors, such as hydroxyurea, colchicine and trifluralin using the suspension culture liverwort to accumulate the metaphase cells. In the first step, genome size of each cell lines were measured using flow cytometry, then a cell line with similar genome size with an intact plant was used for investigation. Significant improvement of metaphase index was obtained by trifluralin treatment. Proper concentration and treatment time of trifluralin was 1 uM, over 12 hours.Although trifluralin could improve metaphase index, chromosomes after the treatment were highly condensed comparing with controls, and moreover elevated generation of micronuclei was observed in the prolonged treatment.