Carputo D
DISSPA - Department of Soil, Plant and Environmental Sciences, University of Naples Federico II, Via Università 100, 80055 Portici, Italy.
Theor Appl Genet. 2003 Mar;106(5):883-8. doi: 10.1007/s00122-002-1165-0. Epub 2003 Jan 28.
Cytology and breeding behavior of Solanum commersonii - S. tuberosum hybrids derived from 3 x x 4 x crosses was examined. The chromosome number of hybrids ranged from hypo-pentaploid (2 n=5 x - 8=52), to hyper-pentaploid (2 n=5 x + 7=67), with the euploid pentaploid 2 n=5 x=60 class predominant. The high variability in chromosome number of the 3 x x 4 x hybrids was attributed to the fact that meiotic restitution during megasporogenesis of the 3 x female may have involved poles with various chromosome numbers, resulting in 2 n eggs with 24-48 chromosomes. Microsporogenesis analyses provided evidence that chromosome pairing between S. commersonii and S. tuberosum genomes occurred. In addition, chromosome distribution at anaphase I and anaphase II revealed an average chromosome number of 29.5 and 29.1 per pole, respectively. To further study the extent of transmission of extra genome chromosomes from pentaploids, 5 x x 4 x and 4 x x 5 x crosses were performed, and the chromosome number of resulting progeny was determined. Ploidy ranged from 2 n=4 x=48 to 2 n=5 x=60 following 5 x x 4 x crosses, and from 2 n=4 x + 1=49 to 2 n=5 x=60 following 4 x x 5 x crosses. These results provided indirect evidence that the pentaploid hybrids produced viable aneuploid gametes with a chromosome number ranging from 24 to 36. They also demonstrated that gametes with large numbers of extra chromosomes can be functional, resulting in sporophytes between the 4 x and 5 x ploidy level. Fertility parameters of crosses involving various (aneuploid) pentaploid genotypes were not influenced by chromosome number, suggesting a buffering effect of polyploidy on aneuploidy. The possibility of successfully using (aneuploid) pentaploid genotypes for further breeding efforts is discussed.
对由3x×4x杂交产生的野生马铃薯 - 马铃薯杂种的细胞学和育种行为进行了研究。杂种的染色体数范围从亚五倍体（2n = 5x - 8 = 52）到超五倍体（2n = 5x + 7 = 67），整倍体五倍体2n = 5x = 60类占主导。3x×4x杂种染色体数的高变异性归因于以下事实：3x雌性大孢子发生过程中的减数分裂恢复可能涉及具有不同染色体数目的极，从而产生具有24 - 48条染色体的2n卵子。小孢子发生分析提供了证据，表明野生马铃薯和马铃薯基因组之间发生了染色体配对。此外，后期I和后期II的染色体分布显示，每个极的平均染色体数分别为29.5和29.1。为了进一步研究额外基因组染色体从五倍体的传递程度，进行了5x×4x和4x×5x杂交，并确定了所得后代的染色体数。5x×4x杂交后，倍性范围从2n = 4x = 48到2n = 5x = 60，4x×5x杂交后，倍性范围从2n = 4x + 1 = 49到2n = 5x = 60。这些结果提供了间接证据，表明五倍体杂种产生了染色体数范围从24到36的可行非整倍体配子。它们还表明，具有大量额外染色体的配子可以发挥功能，从而产生4x和5x倍性水平之间的孢子体。涉及各种（非整倍体）五倍体基因型的杂交的育性参数不受染色体数的影响，这表明多倍体对非整倍体具有缓冲作用。讨论了成功使用（非整倍体）五倍体基因型进行进一步育种的可能性。
