叶用甜菜染色体制片条件优化及核型分析

摘要

In the present study, the green⁃stalk leaf beet cultivar was used as plant material, chromosome staining factors including dissociation duration, pretreatment and sampling time point were optimized, and karyotype charac⁃teristics were also investigated. The results showed that the best chromosome staining and cytoplasm transparency as well as the highest contrast were observed at 12 min dissociation;The best contraction, shape and dispersion of chro⁃mosomes were found at 9 h pretreatment with 0�002 mol·L-1 8⁃hydroxyquinoline;The percentage of the mitotic cells and metaphase cells reached maximum when sampled at 9:00 A. M. . Leaf beet had a total of 18 chromosomes. The karyotype formula was 2n=2x=18=16m+2sm (2SAT), the ratio of chromosome length (L/S) was 1�52, and the constitution of the relative length was 8M2 +10M1 . The relative lengths ranged from 8�75% to 13�29%, the centro⁃meric index ranged from 36�67% to 47�04%, and arm ratio ranked from 1�13 to 1�73. Moreover, the second pair of chromosomes, which own two satellites ( SAT) , was submetacentric chromosomes ( sm) , while other eight pairs of them were metacentric chromosomes ( m) . Karyotype asymmetry index ( As. K) was 58�50%, and karyotype charac⁃teristics fell into type 1A according to Stebbins classification criteria. Meanwhile, the obtained results were compared with those from the already reported sugar beet so as to reveal the karyotype differences between the two, and the sig⁃nificant differences were found on karyotype formula, karyotype characteristics, satellites and As. K. In conclusion, the results revealed the karyotype characteristic of leaf beet, and provided a theoretical basis for karyotype compari⁃son among different types of leaf beet.%以叶用甜菜绿梗品种为材料，对影响染色体制片效果的解离时间、预处理时间和取材时间等条件进行优化，并进行核型分析。结果表明，1 mol·L－1 HCl 60℃解离12 min，染色体着色良好而且细胞质透明，对比度高；0�002 mol·L－18⁃羟基喹啉预处理9 h染色体收缩性最好，形态最佳，分散性好；上午9：00取材，分裂相细胞和中期分裂相细胞最多。叶用甜菜的染色体数目为2n＝2x＝18，核型公式为2n＝2x＝18＝16m＋2sm （2SAT），染色体长度比为1�52，染色体相对长度组成为8M2＋10M1，染色体相对长度变化范围为8�75％～13�29％，着丝粒指数变化范围为36�67％～47�04％，臂比值变化范围为1�13～1�73，其中，第2对染色体为近中部着丝粒染色体（ sm），且具有随体，其余均为中部着丝粒染色体（ m），核型不对称系数为58�50％，核型分类标准属1A型。同时，该研究还比较了叶用甜菜与已报道的糖用甜菜的核型结果，发现两者在核型公式、核型分类、随体和核型不对称系数等方面存在明显差异。研究结果从细胞遗传学角度揭示叶用甜菜的核型特征，为今后进行不同类型叶用甜菜的核型比较提供理论依据。