铺地黍染色体制片优化及核型分析

以铺地黍(Panicum repens)根尖为材料,比较不同的预处理、固定、前低渗、解离条件对染色体制片效果的影响,并进行核型分析.结果表明,铺地黍染色体制片的优化条件分别为:冰水混合物、4℃条件预处理22 h,卡诺氏固定液Ⅰ、4℃条件固定24 h,0.075 mol·L-1 KCl溶液在25℃条件前低渗15～20 min,1％果胶酶和2％纤维素酶混合酶液于25℃条件酶解3 h.铺地黍核型公式为2n=2x=40=34m+6sm,未发现有随体;染色体绝对长度范围为10.87～19.21μm,属于大型染色体;染色体相对长度组成为2n=40=2L+16M2+22M1;最长与最短染色体长度比值为1.77,臂比值范围为1.04～2.08;核型不对称系数为58.99％,核型类型属于2A型,其在进化类型上可能属于原始类型,为铺地黍的起源、演化及遗传育种提供了一定的理论依据和技术基础.

Optimization of chromosome preparation and karyotype analysis of Panicum repens

In order to explore the optimal approach for analyzing the root tips of Panicum repens, we compared different pre-treatment, fixation, prehypotension, and dissociation conditions during chromosome preparation. The results demonstrated that the optimal pre-treatment was a mixture of ice and water at 4 ℃ for 22 h, the optimal fixation was Cano′s fixed liquid Ⅰ at 4 ℃ for 24 h, the optimal pre-hypotension was 0.075 mol·L?1 KCl at 25 ℃ for 15～20 min, and the optimal dissociation was a mixture of 1% pectinase and 2% cellulase at 25 ℃ for 3 h. The karyotype analysis revealed the formula for P. repens to be 2n = 2x = 40 = 34m + 6sm. Furthermore, no satellite was observed. The absolute chromosome length ranged from 10.87 to 19.21 μm, which indicates P. repens contains a single large chromosome. The relative chromosome length composition was 2n = 40 = 2L + 16M2 + 22M1. The ratio of longest to shortest chromosome length was 1.77, and the arm ratio ranged from 1.04 to 2.08. The karyotype asymmetry coefficient was 58.99%, and the karyotype beingwas 2A, which may be an evolutionarily primitive type, providing a certain theoretical and technical basis for the origin, evolution, inheritance, and breeding of P. repens.