Karyological studies of Iranian <i>Allium</i> (Amaryllidaceae) species with a focus on sect. <i>Acanthoprason</i>. 2. Meiotic chromosomes

Meiosis in pollen mother cells (PMCs) was studied of 23 Iranian <i>Allium</i> species (33 accessions, 105 individuals) that belong to two subgenera and six sections. Materials of 13 species were sampled from (near) type locations. Gametic chromosome numbers, chromosome configurations at metaphase I, chiasma frequency, as well as type and percentages of abnormalities were recognized. The basic chromosome number for all taxa investigated was <i>x</i> = 8. Most taxa were diploid and showed eight bivalents or in rare cases two or four pairs of univalents, but in <i>A. subakaka</i>, <i>A. ubipetrense</i> and <i>A. zagricum</i> tetravalents also occurred. Meiosis in less than 10% of PMCs of diploid accessions was disturbed displaying lagging chromosomes, chromatid bridges, micronuclei, or unbalanced chromosome segregations, but very rarely more than one kind of irregularities were found within one dividing cell. One to three B chromosomes were found in 11 accessions, and were recognized for the first time in <i>A. alamutense</i>, <i>A. elburzense</i> and <i>A. iranshahrii</i>. Our data showed no correlation between the occurrence of B chromosomes and the chiasma frequency, and also no noticeable effect of habitat factors on meiotic chromosome behavior. The studied accessions of <i>A. atroviolaceum</i> and <i>A. sabalense</i> were tetraploid (<i>n</i> = 16) showing irregular meiosis in 20–69% of the PMCs which is regarded as sign of autopolyploidy. Since only two out of 31 investigated accessions belonging to subg. <i>Melanocrommyum</i> were tetraploid, we may suggest a trivial role of polyploidy in the evolution of this subgenus.

本研究针对隶属于2个亚属、6个组的23种伊朗葱属（Allium）植物（共33份种质资源、105个个体）的花粉母细胞（pollen mother cells, PMCs）减数分裂过程展开了系统研究。其中13个物种的实验材料采自（近）模式产地。研究记录了如下核心数据：配子染色体数、减数分裂中期I的染色体构型、交叉频率，以及染色体异常的类型与占比。所有受试类群的基础染色体数均为x=8。多数类群为二倍体，通常表现为8个二价体，仅极少数个体出现2或4对单价体；但在阿克卡葱（A. subakaka）、乌比彼得伦葱（A. ubipetrense）与扎格里葱（A. zagricum）中，还观测到了四价体的存在。二倍体种质中，不足10%的花粉母细胞的减数分裂过程受到干扰，具体表现为染色体滞后、染色质桥、微核形成或染色体分离失衡，但单个分裂细胞内同时出现多种异常的情况极为罕见。研究团队在11份种质中发现了1至3条B染色体，其中在阿拉穆特葱（A. alamutense）、厄尔布尔士葱（A. elburzense）与伊朗沙赫里葱（A. iranshahrii）中，B染色体的存在为首次报道。本研究数据表明，B染色体的出现频率与交叉频率之间不存在相关性，生境因子对减数分裂染色体行为也无显著影响。紫花葱（A. atroviolaceum）与萨巴莱葱（A. sabalense）的受试种质为四倍体（n=16），其20%~69%的花粉母细胞存在减数分裂异常，这一特征被视为同源多倍体的典型标志。由于隶属于黑色葱亚属（subg. Melanocrommyum）的31份受试种质中仅2份为四倍体，我们推测多倍化在该亚属的演化过程中仅发挥了极为有限的作用。