陆地棉与澳洲2个野生棉杂种细胞学研究

Cytological Studies of Hybrids Between G.hirsutum and Two WildCotton Species from Australia

本文首次报道了陆地棉×南岱华棉杂种Ｆ１的细胞学研究结果，并与陆地棉Ｘ斯特提棉的杂种进行了对比分析。供分析的细胞数均在７００个以上，中期Ⅰ染色体构型种类占总ＰＭＣ的百分率（构型率）均在７％以下，陆地棉与斯特提棉和南岱华棉杂种Ｆ１的染色体平均构型分别为２１．９７Ⅰ＋７，９７Ⅱ＋０．３５Ⅲ＋０．０１Ⅳ和２０．６２Ⅰ＋８．３７Ⅱ＋０．５２Ⅲ＋０．０２Ⅳ，单一细胞环状二价体、染色体桥和二价体交叉率分别是０．５３与０．４８、７．４４与７．８９和１．０７及１．０６。在２个杂种中均观察到八价体，但为数极少。中期Ⅰ时期二价体和多价体集中于细胞赤道面上，而单价体分散在周围。后期Ⅰ及以后，单价体分布完全随机，形成多个染色体块或片段。四分体形成时期，小孢子数目和大小及形状变异均较大。主要表现在小孢子不是规则的团体，体积大小相差可达２～４倍，单一ＰＭＣ中的数目从ｌ至１３，但其四分体占多数，均在６０％以上。且微核变幅较大，０～６个。经过比较分析，说明两个棉种亲缘关系很近，与陆地棉的种间关系差异也不大。

Chromosome behavior of pollen mather cells(PMC)in hybrid between G.hirsutumL.[(AD)1,2n = 4x=52]and G.sturtianum var. Nandewarense(Derera)Fryxell(C1一n , 2n=2x= 26)was reported firstly,and comparisons were made between the hybrid and the com-bination with G. sturtianum willis(C1,2n=2x=26) based on more than 700 PMC, Means ofchromosome configurations at metaphase I for(AD)1C1 and(AD)1C1-n were 21.97 Ⅰ +7.97Ⅱ+0.35Ⅲ+ 0.01Ⅳ and 20.62 Ⅰ+ 8.37Ⅱ+0.52Ⅲ+ 0.02Ⅳ, respectively. And therewere 7.44 chromosome bridges in(AD)1C1 per cell ,and 7.89 in(AD)1C1-n. Octovalents inthe two combinations appeared, but very few. Size and number of microspores in the hybridsdiffered largely from each other,with only l at least and even 13 at most in one PMC, butPMC,of tetrad formation totalled the most among all microspore formations. The results indi-cated that the two species from Australia were closely related,and there was also little differ-ence bet ween their hybrids with G. hirsutum.