Hranueli D, Pigac J, Smokvina T, Alacević M
J Gen Microbiol. 1983 May;129(5):1415-22. doi: 10.1099/00221287-129-5-1415.
The development of a protoplast fusion technique for oxytetracycline-producing Streptomyces rimosus strains, and its evaluation for the application for a breeding programme, has been described. Treatment of S. rimosus protoplasts with 40% (w/v) PEG 1550 for 30 min gave optimal numbers of recombinants ranging from 1 to 10% of the total progeny. Therefore, by comparison with conjugation, protoplast fusion increased the frequency of recombination by two to three orders of magnitude. The proportion of multiple crossover classes amongst recombinants was higher, by a factor of ten, after protoplast fusion (13.3%) than after conjugation (1.5%). Participation of less frequent complementary genotype doubled from 9.0% in conjugation to 17.9% in protoplast fusion. Overall, this suggested that the opportunities for crossing over in a fusion of S. rimosus protoplasts were spatially and/or temporally extended leading to a loosening of linkage with a near-random assortment of genotypes in a cross. However, by minimizing the multiple crossover classes and calculating allele frequency gradients, it was shown that the protoplast fusion technique allows arrangement of genetic markers on the S. rimosus chromosome. These are ideal characteristics for the recombination of divergent lines in a strain improvement programme.
本文描述了一种用于生产土霉素的龟裂链霉菌菌株的原生质体融合技术的开发及其在育种计划中的应用评估。用40%（w/v）的聚乙二醇1550处理龟裂链霉菌原生质体30分钟，可获得最佳数量的重组体，其数量占总后代的1%至10%。因此，与接合相比，原生质体融合使重组频率提高了两到三个数量级。原生质体融合后（13.3%），重组体中多次交换类型的比例比接合后（1.5%）高十倍。较少出现的互补基因型的参与度从接合时的9.0%增加到原生质体融合时的17.9%。总体而言，这表明龟裂链霉菌原生质体融合过程中发生交换的机会在空间和/或时间上得到了扩展，导致杂交中基因型的连锁关系松弛，基因型近乎随机分配。然而，通过最小化多次交换类型并计算等位基因频率梯度，结果表明原生质体融合技术能够在龟裂链霉菌染色体上排列遗传标记。这些是菌株改良计划中不同品系重组的理想特性。
