Ingham L D, Hanna W W, Baier J W, Hannah L C
Horticultural Sciences, University of Florida, Gainesville 32611.
Mol Gen Genet. 1993 Apr;238(3):350-6. doi: 10.1007/BF00291993.
In an attempt to identify relationships among genomes of the allotetraploid Pennisetum purpureum Schumach and closely related Pennisetum species with which it can be successfully hybridized, repetitive DNA sequences were examined. Digestion with KpnI revealed two highly repetitive fragments of 140 bp and 160 bp. The possibility that these sequences could be used as genome markers was investigated. Average sequences were determined for the 140 bp and 160 bp KpnI families from P. purpureum and P. squamulatum Fresen. Average sequences (based upon four or five repeats) were determined for the P. glaucum (L.) R. Br. 140 bp KpnI family and the diploid P. hohenackeri Hochst. ex Steud. 160 bp KpnI family. The average sequences of the 160 bp KpnI families in P. purpureum and P. squamulatum differ by only nine bases. The 140 bp KpnI families of the three related species, P. purpureum, P. squamulantum, and P. glaucum are nearly identical, and thus likely represent a recent divergence from a common progenitor or a common genome. Each repetitive sequence may contain internal duplications, which probably diverged following amplification of the original sequence. The 140 bp KpnI repeat probably evolved from the 160 bp KpnI repeat since the missing 18 bp segment is part of the internal duplication that is otherwise conserved in the subrepeats. Tandemly arrayed repetitive sequences in plants are likely to be composed of subrepeats which have been duplicated and amplified.
为了确定异源四倍体象草（Pennisetum purpureum Schumach）与能够成功与其杂交的近缘狼尾草属物种的基因组之间的关系，对重复DNA序列进行了研究。用KpnI酶切显示出两个高度重复的片段，大小分别为140 bp和160 bp。研究了这些序列用作基因组标记的可能性。测定了象草和鳞穗狼尾草（P. squamulatum Fresen）140 bp和160 bp KpnI家族的平均序列。测定了黍（P. glaucum (L.) R. Br.）140 bp KpnI家族和二倍体霍氏狼尾草（P. hohenackeri Hochst. ex Steud.）160 bp KpnI家族的平均序列（基于四到五个重复）。象草和鳞穗狼尾草160 bp KpnI家族的平均序列仅相差9个碱基。象草、鳞穗狼尾草和黍这三个相关物种的140 bp KpnI家族几乎相同，因此可能代表了最近从一个共同祖先或一个共同基因组中分化出来的。每个重复序列可能包含内部重复，这些内部重复可能在原始序列扩增后发生了分化。140 bp KpnI重复序列可能是从160 bp KpnI重复序列进化而来的，因为缺失的18 bp片段是内部重复的一部分，而内部重复在亚重复中其他部分是保守的。植物中串联排列的重复序列可能由已复制和扩增的亚重复组成。
