不结球白菜根尖体细胞染色体制片及其二倍体和四倍体有丝分裂过程观察

摘要

以不结球白菜(Brassica campestris ssp.chinensis Makino)根尖为材料,对染色体制片过程中根长(小于0.5 cm、0.5 ～ 1.0 cm、1.0～2.0 cm及大于2.0 cm)、预处理方法、预处理剂种类(2 mmol·L-1 8-羟基喹啉、2 mmol·L-1 8-羟基喹啉与质量浓度0.2g·L-1秋水仙素等体积混合液、质量浓度0.2g·L-1秋水仙素、饱和对二氯苯、质量浓度20或40 mg·L-1放线菌酮、质量浓度40mg·L-1放线菌酮与2 mmol·L-1 8-羟基喹啉等体积混合液)及预处理时间(1.0～3.5 h)进行了比较和筛选；在此基础上,对二倍体和四倍体不结球白菜根尖体细胞有丝分裂过程进行观察.结果表明:根长度对分裂相的数量有显著影响；根长1.0～2.0 cm,分裂相相对较多,占细胞总数的64.75％.冰冻预处理22 ～ 23 h,能获得一定量的分裂相.采用不同的预处理剂及预处理时间,分裂相的数量及染色体形态有明显差异；用质量浓度40 mg·L-1放线菌酮溶液处理3.5h,分裂相数量最多,但易导致染色体加倍；用质量浓度20mg·L-1放线菌酮预处理3.5h,染色体长且着丝点及随体清晰,且分裂相较多,占细胞总数的53.65％.因而,根长度以1.0 ～2.0 cm为宜,适宜的预处理方法为用质量浓度20 mg·L-1放线菌酮浸泡2.0～3.0 h.二倍体及四倍体不结球白菜根尖体细胞有丝分裂过程基本相似,在有丝分裂的间期、前期、中期、后期和末期染色体的行为基本一致,但在四倍体的有丝分裂过程中会出现多价体、染色体桥、落后染色体、染色体异常分离及内源有丝分裂等异常现象.%Using root-tip of non-heading Chinese cabbage (Brassica campestris ssp. Chinensis Makino) as experimental material, root length (shorter than 0.5 cm, 0.5-1.0 cm, 1.0-2.0 cm and longer than 2.0 cm) , pretreatment method, pretreatment agent types (2 mmol · L-1 8-hydroxyquinoline, equivalent volume mixed solution of 2 mmol · L-1 8-hydroxyquinoline and 0. 2 g · L-1 colchicine, 0. 2 g · L-1 colchicine, saturated p-dichlorobenezene, 20 or 40 mg · L-1 cycloheximide, equivalent volume mixed solution of 40 mg · L-1 cycloheximide and 2 mmol · L-1 8-hydroxyquinoline) and pretreatment time (1.0 -3. 5 h) in chromosome preparation process were compared and selected. And on this basis, mitosis process of somatic cell in root-lip of diploid and tetraploid of non-heading Chinese cabbage was observed. The results show that root length obviously influences on number of split phase. And there are relatively more split phases in 1.0-2.0 cm root with an account for 64. 75% of total cell number. Some split phases can be obtained by frozen pretreating for 22-23 h. Using different pretreatment agents andtimes, number of split phase and chromosome morphology are obviously different. Pretreating for 3. 5 h with 40 mg · L-1 cycloheximide, number of split phase is the most but chromosome doubling is easy to be caused. And pretreating for 3. 5 h with 20 mg · L-1 cycloheximide, chromosomes are long with clear kinetochore and satellite, and number of split phase accounts for 53. 65% of total cell number. Therefore, suitable length of root is 1. 0-2. 0 cm, optimal pretreatment method is using 20 mg · L-1 cycloheximide soaking for 2. 0-3. 0 h. The mitosis process of somatic cell in root-tip of diploid and tetraploid of non-heading Chinese cabbage is generally similar, and their chromosome behavior is basically identical in interphase, prophase, metaphase, anaphase and telophase of mitosis. But there are some abnormal phenomena in mitosis process of tetraploid, such as, multivalent, chromosome bridge, lagging chromosome, chromosome abnormal segregation and endogenous mitosis.