中华蚊母树染色体制片及核型分析

Chromosome Preparation and Karyotype Analysis of Distylium chinense(Fr.) Diels

以中华蚊母树根尖为材料,采用常规压片法制片,比较材料的不同采集时间、预处理方法、固定剂、解离方法、解离时间及染色方法对中华蚊母树根尖染色体制片的影响.结果表明最佳的制片技术为：取材时间为上午9：00-11：00或下午13：00-15：00,以饱和对二氯苯预处理3 h,用1 mol.L^-1盐酸60℃下解离8 min,卡诺固定剂固定,以改良石碳酸品红染色10 min.以该最佳制片方案对中华蚊母树进行体细胞染色体核型分析,首次揭示了中国特有植物———中华蚊母树体细胞染色体数目为2n=2x=24,染色体基数x=12,染色体核型公式为2n=2x=24=12m（2SAT）＋10sm＋2st,主要由中部和近中部着丝点染色体组成;染色体相对长度组成为2n=24=2L＋8M2＋12M1＋2S,核型不对称指数为64.29%,属于2A型.结果显示中华蚊母树核型对称程度较高,在进化中属于比较原始的类型.

In present study,we compared that the different methods about sampling time,the pretreatments,fixatives,dissociations time and dyeing in chromosome preparation of Distylium chinense（Fr.） Diels,an endemic tree species in China,on the root tips.The results showed that the best experimental protocol for karyotype analysis of D.chinense was the better sampling time at 9：00~11：00 a.m.and 13：00~15：00 p.m.,the better pretreatment with saturated p-dichlorobenzene for 3 h,the better dissociation way with 1 mol·L-1 HCl at 60℃ for 8 min,and dyeing time for 10 min with modified carbolic acid-magenta.Consequently,chromosome numbers and karyotype of D.chinense was reported for the first time with the best experimental protocol for karyotype analysis.The somatic cell chromosome number of D.chinense at metaphase is 2n=2x=24,the basic chromosome number is x=12.Karyotype formulae is 2n=24=12m（2SAT）＋10sm＋2st,mainly consisting of metacentric and submetacentric chromosomes.Chromosome composition of relative length is 2n=24=2L＋8M2＋12M1＋2S,its index of As.k% is 64.29%,and the karyotype asymmetry belongs to ＂2A＂ type.These results revealed karyotype of D.chinense is symmetrical to a higher degree,indicating that D.chinense belongs to a relatively primitive type and relatively old or the original plant in evolutionary processes.