大麦平衡三级三体的细胞遗传研究

CYTOGENETIC STUDIES ON BALANCED TERTIARY TRISOMICS IN BARLEY

本文以大麦平衡三级三体1-7c ac2 为材料,对其根尖细胞染色体进行测定,得出该材料中的额外染色体为中间着丝点染色体,其臂比为1.00.相对长度为第1染色体的1.09,外观形态可明显区别于其它染色体。在花粉母细胞减数分裂过程中观察发现:1.额外染色体和与之有部分同源关系的2对正常染色体之间的联会形式有7种,其中以6Ⅱ+1Ⅲ的联会形式最普遍,高达61.0％。这与该染色体相对长度较长有关。 2.后期Ⅰ染色体的分离以7:8的分离比例为主,占86.3％。虽然观察到各种落后染色体和染色体桥、断片等异常现象,但正常分离的细胞仍占多数,因而三体植株育性较好,适用于生产杂交种。

The balanced tertiary trisomic l-7c ac_2 of barley was used to test the cell chromosomes of its root tip. The results showed that the extra-chromosome was a metacentric one with an arm ratio of 1.00 and relative length of 1.09 to the first chromosome. It differs from the other chromosomes in morphological characters. During the meiosis of pollen mother cells, 7 synaptic forms existed between extra-chromosome and its two pairing homoeologous chromosomes. Among them the synaptic form of 6Ⅱ+1Ⅲ was the most common (61.0%) .The 7 : 8 chromosome disjunction predominated in anaphase I of the meiosis, covering 86.3% of the total. Although various sorts of abnormal phenomena such as lagging, bridge and fragments of chromosomes were observed, but the normal disjunction cells were superior. Therefore, trisomic plants, with a better fertility, fit the production of hybrid seeds.