Khazanehdari K A, Jones G H, Ford-Lloyd B V
School of Biological Sciences, University of Birmingham, UK.
Chromosome Res. 1995 Nov;3(7):433-9. doi: 10.1007/BF00713894.
Meiotic chromosome pairing of the tetraploid species Allium porrum, the cultivated leek, was analysed by electron microscopy of 83 surface-spread nuclei in the late zygotene to early diplotene interval of prophase I, from four different varieties. Prophase I quadrivalent frequency, at 71%, marginally but significantly exceeds the two-thirds expected on a simple random end-pairing model, suggesting that more than two autonomous pairing sites occur, in some tetrasomes at least. This pattern of synaptic behaviour is consistent with an autotetraploid status, but comparison with other tetraploids, including other Allium species, indicates that Allium porrum may be a weak segmental allopolyploid displaying limited preferential homologous pairing. The incidence of pairing partner switches (PPSs) in prophase I quadrivalents is relatively low; 90% of all analysed quadrivalents had only one or two PPSs. The positional distribution of PPSs along quadrivalents was distinctly uneven with peaks in mid-chromosome arms and reduced frequencies around centromeres and near the ends. The four different varieties of leek analysed were remarkably similar in their meiotic behaviour despite their diverse breeding history, but individual plants within varieties displayed substantial variation in quadrivalent and PPS frequencies.
通过电子显微镜对四个不同品种的83个处于减数分裂前期I偶线期晚期至双线期早期的表面铺展细胞核进行分析，研究了四倍体物种韭葱（栽培韭菜）的减数分裂染色体配对情况。前期I四价体频率为71%，略高于但显著超过简单随机末端配对模型预期的三分之二，这表明至少在一些四体中存在两个以上的自主配对位点。这种联会行为模式与同源四倍体状态一致，但与其他四倍体（包括其他葱属物种）相比，表明韭葱可能是一个弱片段异源多倍体，表现出有限度的优先同源配对。前期I四价体中配对伙伴交换（PPS）的发生率相对较低；所有分析的四价体中有90%只有一个或两个PPS。PPS沿四价体的位置分布明显不均匀，在染色体臂中部出现峰值，着丝粒周围和末端附近频率降低。尽管所分析的四个不同品种的韭菜育种历史不同，但其减数分裂行为非常相似，但品种内的单株在四价体和PPS频率上表现出很大差异。
