Broun P, Tanksley S D
Department of Plant Breeding and Biometry, Cornell University, Ithaca, NY 14853.
Plant Mol Biol. 1993 Oct;23(2):231-42. doi: 10.1007/BF00029000.
A tomato lambda genomic library was screened with the human minisatellites 33.6 and 33.15. Similar tomato sequences are estimated to occur on average every 4000 kb. In thirteen hybridizing clones characterized, the size of minisatellite arrays varied between 100 bp and 3 kb. The structure of the repetitive elements is complex as the human core sequence is interspersed with other elements. In three cases, sequences similar to the human minisatellites were part of a higher-order tandem repeat. The chromosomal position of these sequences was established by ascertaining linkage to previously mapped RFLP markers. In contrast to the human genome, no clustering of minisatellite loci was observed in tomato. The fingerprints generated by hybridizing tomato minisatellites to genomic DNA of a set of cultivars were, in two cases, more variable than those obtained with 33.6 or 33.15. Two of the characterized probes detected 4-8 alleles of a single locus, which displayed 10-15 times more polymorphism than random RFLP clones. Some minisatellites contain di- and tri-nucleotide microsatellite repeated motifs which may account for the high level of polymorphism detected with these clones.
用人源小卫星33.6和33.15筛选了一个番茄λ基因组文库。估计相似的番茄序列平均每4000 kb出现一次。在对13个杂交克隆进行表征时，小卫星阵列的大小在100 bp到3 kb之间变化。由于人源核心序列与其他元件相间排列，重复元件的结构很复杂。在3个案例中，与人源小卫星相似的序列是高阶串联重复序列的一部分。通过确定与先前定位的RFLP标记的连锁关系，确定了这些序列的染色体位置。与人类基因组不同，在番茄中未观察到小卫星位点的聚类现象。在两个案例中，用番茄小卫星与一组品种的基因组DNA杂交产生的指纹图谱比用33.6或33.15获得的指纹图谱更具变异性。两个已表征的探针检测到单个位点的4 - 8个等位基因，其多态性比随机RFLP克隆高10 - 15倍。一些小卫星包含二核苷酸和三核苷酸微卫星重复基序，这可能是这些克隆检测到高多态性水平的原因。
