Badaeva E D
Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991 Russia.
Genetika. 2002 Jun;38(6):799-811.
Four tetraploid (Aegilops ovata, Ae. biuncialis, Ae. columnaris, and Ae. triaristata) and one hexaploid (Ae. recta) species of the U-genome cluster were studied using C-banding technique. All species displayed broad C-banding polymorphism and high frequency of chromosomal rearrangements. Chromosomal rearrangements were represented by paracentric inversions and intragenomic and intergenomic translocations. We found that the processes of intraspecific divergence of Ae. ovata, Ae. biuncialis, and Ae. columnaris were probably associated with introgression of genetic material from other species. The results obtained confirmed that tetraploid species Ae. ovata and Ae. biuncialis occurred as a result of hybridization of a diploid Ae. umbellulata with Ae. comosa and Ae. heldreichii, respectively. The dissimilarity of the C-banding patterns of several chromosomes of these tetraploid species and their ancestral diploid forms indicated that chromosomal aberrations might have taken place during their speciation. Significant differences of karyotype structure, total amount and distribution of C-heterochromatin found between Ae. columnaris and Ae. triaristata, on the one hand, and Ae. ovata and Ae. biuncialis, on the other, evidenced in favor of different origin of these groups of species. In turn, similarity of the C-banding patterns of Ae. columnaris and Ae. triaristata chromosomes suggested that they were derived from a common ancestor. A diploid species Ae. umbellulata was the U-genome donor of Ae. columnaris and Ae. triaristata; however, the donor of the second genome of these species was not determined. We assumed that these tetraploid species occurred as a result of introgressive hybridization. Similarity of the C-banding patterns of chromosomes of Ae. recta and its parental species Ae. triaristata and Ae. uniaristata indicated that the formation of the hexaploid form was not associated with large modifications of the parental genomes.
利用C带技术对U基因组簇的4个四倍体物种（卵形山羊草、偏凸山羊草、柱穗山羊草和三芒山羊草）和1个六倍体物种（直芒山羊草）进行了研究。所有物种均表现出广泛的C带多态性和高频率的染色体重排。染色体重排表现为臂内倒位以及基因组内和基因组间的易位。我们发现，卵形山羊草、偏凸山羊草和柱穗山羊草的种内分化过程可能与其他物种遗传物质的渗入有关。所得结果证实，四倍体物种卵形山羊草和偏凸山羊草分别是由二倍体伞形山羊草与科莫萨山羊草和赫尔德赖希山羊草杂交产生的。这些四倍体物种的几条染色体与其祖先二倍体形式的C带模式不同，表明在它们的物种形成过程中可能发生了染色体畸变。一方面，柱穗山羊草和三芒山羊草之间，另一方面，卵形山羊草和偏凸山羊草之间，核型结构、C异染色质总量和分布存在显著差异，证明这些物种组的起源不同。反过来，柱穗山羊草和三芒山羊草染色体的C带模式相似，表明它们来自共同的祖先。二倍体物种伞形山羊草是柱穗山羊草和三芒山羊草的U基因组供体；然而，这些物种第二个基因组的供体尚未确定。我们推测这些四倍体物种是渐渗杂交的结果。直芒山羊草及其亲本物种三芒山羊草和单芒山羊草染色体的C带模式相似，表明六倍体形式的形成与亲本基因组的大量修饰无关。
