Rezaei Masoumeh, Arzani Ahmad, Sayed-Tabatabaei Badraldin Ebrahim
Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan 84156 83111, Iran.
J Genet. 2010 Dec;89(4):401-7. doi: 10.1007/s12041-010-0058-2.
Meiotic restitution is considered to be a common mechanism of polyploidization in plants and hence is one of the most important processes in plant speciation. Meiotic behaviour of plant chromosomes is influenced by both genetic and environmental factors. In this study, the meiotic behaviour of cereal crops was investigated, which includes tetraploid wheat genotypes (with and without the meiotic restitution trait) and their derivates (synthetic hexaploid wheats and a doubled haploid (DH) line), grown at two planting dates in the field. In addition, two local landraces of emmer wheat (Triticum turgidum ssp. dicoccum), one wheat cultivar (Chinese spring), one DH triticale cultivar (Eleanor) and one rye accession were included. Immature spikes of mid-autumn and end-winter sowing plants were collected in April and May 2008, respectively, fixed in Carnoy's solution and stained with hematoxylin. Pollen mother cells (PMCs) from anthers at different stages of meiotic process were analysed for their chromosomal behaviour and irregularities. Meiotic aberrations such as laggards, chromosome bridges, micronuclei, abnormal cytokines, chromatin pulling and meiotic restitution were observed and the studied genotypes were accordingly ranked as follows: triticale > synthetic hexaploid wheats > tetraploid wheats possessing meiotic restitution > tetraploid wheats lacking meiotic restitution > rye. The results indicated that the samples that had been planted in the autumn, thus experiencing an optimum temperature level at the flowering stage, exhibited less meiotic irregularities than winter planting samples that encountered heat stress at the flowering period.
减数分裂染色体数目恢复被认为是植物多倍体化的一种常见机制，因此是植物物种形成中最重要的过程之一。植物染色体的减数分裂行为受遗传和环境因素的影响。在本研究中，对谷类作物的减数分裂行为进行了调查，其中包括四倍体小麦基因型（具有和不具有减数分裂染色体数目恢复性状）及其衍生物（人工合成六倍体小麦和双单倍体（DH）系），这些材料在田间两个播种期种植。此外，还纳入了两个地方二粒小麦（Triticum turgidum ssp. dicoccum）农家品种、一个小麦品种（中国春）、一个DH小黑麦品种（埃莉诺）和一份黑麦材料。分别于2008年4月和5月采集中秋和冬末播种植株的未成熟穗，固定于卡诺氏固定液中，并用苏木精染色。对减数分裂不同阶段花药中的花粉母细胞（PMC）进行染色体行为和异常分析。观察到减数分裂异常现象，如落后染色体、染色体桥、微核、异常细胞分裂、染色质牵拉和减数分裂染色体数目恢复，并据此对所研究的基因型进行如下排序：小黑麦>人工合成六倍体小麦>具有减数分裂染色体数目恢复的四倍体小麦>缺乏减数分裂染色体数目恢复的四倍体小麦>黑麦。结果表明，秋季播种的样本在开花期经历了最适宜的温度水平，其减数分裂异常现象比在开花期遭遇热胁迫的冬季播种样本少。
