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各国棉花育种工作都在开展野生二倍体棉种的利用问题。试验用二倍体亚洲棉G。arboreum 2n(2x)=26,染色体组A_2,与野生比克氏棉G. bickii, 2n(2x)=26,染色体组G杂交,获得异源二倍体杂种。因二者亲缘关系最远,杂种高度不育。对A_2×GF_1PMC减数分裂观察,M_2染色体大都不配对,二价体变幅1—6对,并出现三价体,染色体构型为1.64Ⅰ+4.0Ⅱ+0.4Ⅲ。平均交叉频率为1.07个。由于四分体发育不正常,形成畸形败育花粉,导致杂种F_1高度不育。对A_2×G F_1进行染色体加倍,合成异源四倍体,观察F_2PMC减数分裂时,染色体数为52条。MI,大都配对,交叉频率为1.83,大多数为环状二价体。染色体构型为:2.75Ⅰ+24.5Ⅱ+0.25Ⅲ。其中完全配对成26个二价体的细胞数占30％。后期Ⅰ,染色体平均分配,两级各有26条,形成正常的四分体,花粉生活力达89％杂种植株育性恢复,每株结铃平均为33个,每铃种子平均9.1粒,为人工合成异源四倍体新种质
Cotton breeding in various countries are carrying out the use of wild diploid cotton species. Test with diploid cotton Asia G. arboreum 2n (2x) = 26, chromosome group A_2, crossed with G. bickii, 2n (2x) = 26, Genome G, and allotetraploid hybrids were obtained. Because the two are the most distant relatives, the hybrid is highly infertile. For the meiosis of A_2 × GF_1PMC, most of the M_2 chromosomes did not pair with each other. The bivalents varied by 1-6 pairs with the appearance of trivalent chromosomal structures of 1.64Ⅰ + 4.0Ⅱ + 0.4Ⅲ. The average crossover frequency is 1.07. Due to abnormal tetrad development, the formation of abnormal abortion pollen, resulting hybrid F1 highly sterile. Chromosomal doubling was performed on A_2 × G F_1 to synthesize allotetraploid. When meiotic division of F_2PMC was observed, the number of chromosomes was 52. MI, most of the matching, the crossover frequency of 1.83, the majority of circular bivalent. Chromosome configuration: 2.75 Ⅰ +24.5 Ⅱ +0.25 Ⅲ. The number of fully paired 26 bivalent cells accounted for 30%. In late stage I, the chromosomes were evenly distributed, with 26 in each stage, forming a normal tetrad. The pollen viability reached 89%. The fertility of the hybrid plants was restored. The average boll number per plant was 33 and the average number of seeds per bell was 9.1, which was Synthetic Heterotetraploid New Germplasm