Cloning and mapping of chromosome-specific DNA markers in crops

从中间偃麦草(Agropyron interdium，2n=42，E1E1E2E2XX)中克隆的重复DNA序列，通过Southern和原位杂交鉴定了小麦基因组中的中间偃麦草染色体。克隆pTA100与EcoO109消化确定的350bp串联重复家族杂交。克隆pTA100与黑麦EcoO109I-380bp串联重复家族(Tomita等人，1993)具有同源性，后者属于350bp家族或黑麦(Bedbrook等人，1980，Appels等，1986)。经EcoO109酶切后，克隆pTA28与6800bp、6200bp、3600bp和1850bp四个重复片段杂交。以pTA100为探针的CS(2n=56)与CS(2n…)之间的两倍体AGCS(2n=56，AABBDDEE)在基因组Southern和染色体原位分析中均未显示杂交信号More=42，AABBDD)和AGROGATIMA(2n=14，EE)。这一发现表明，pTA100家族在E基因组中缺失。但是，克隆pTA100与中间银杏的10对染色体的末端区域杂交。这些结果表明，至少有3对染色体属于E_1或E_2染色体组，这些染色体上的杂交区片段可能来源于X染色体。在附加系A、B、C和D中观察到350bp的串联带，其余3个附加系未观察到杂交。此外，在染色体原位分析的基础上，克隆pTA100分别杂交到添加染色体A的短臂末端、添加染色体B的长臂以及添加染色体C和D的双臂上，由于添加染色体C和D的臂比例不同，可以通过克隆pTA100的ISH位点将这4条添加染色体区分开来。显示克隆pTA100的ISH位点和微弱C-带的A、B、D三条附加染色体可能来源于中间银杏的X染色体。较少

Repeated DNA sequences cloned from Agropyron intermedium (2n=42, E1E1E2E2XX) enabled to identify the Ag.intermedium chromosomes in the common wheat genome by Southern and in situ hybridization.Two repetitive DNA clones not hybridized to the total genomic DNA of Triticum aestivum cv.Chinese Spring (CS) were screened from the MboI-digested genomic DNA library of Ag.intermedium. The clone pTA100 hybridized to the 350bp tandem repeated family defined by digestion with EcoO109I.The clone pTA100 showed homology with the EcoO109I-380 bp tandem repeated family of rye (TOMITA et al.1993) which belonged to the 350 bp family or rye (BEDBROOK et al.1980, APPELS et al.1986) . the clone pTA28 hybridized to four kinds of repeated fragments, 6800 bp, 6200 bp, 3600 bp and 1850 bp defined by digestion with EcoO109I.The clone pTA100 used as a probe did not exhibit hybridization signals based on both genomic Southern and chromosomal in situ analysis for the amphiploid AgCS (2n=56, AABBDDEE) between CS (2n … More =42, AABBDD) and Ag.elongatum (2n=14, EE) . This finding indicated that the pTA100 family was absent in the E genome. However, the clone pTA100 hybridized to the terminal regions of the ten pairs of chromosomes in Ag.intermedium. These results indicated that at least three pairs of chromosomes belonged to the E1 or E2 genomes and the segments of the hybrid region in these chromosomes must have originated from the X genome.The clone pTA100 was used as a probe for Southern hybridization to seven kinds of Wheat-Ag.intermedium chromosome addition lines. The 350bp tandem patterns were observed in the addition lines A,B,C and D,while no hybridization was observed in the remaining three addition lines. Moreover, based on chromosomal in situ analysis the clone pTA100 hybridized to each terminal region of the short arm of added chromosome A,the long arm of added chromosome B and both arms of added chromosomes C and D.As the added chromosomes C and D differed in their arm rotios, it was possible to distinguish these four added chromosomes from each other by the ISH site of the clone pTA100. The three kinds of added chromosomes A,B and D showing the ISH site of the clone pTA100 and faint C-bands may have originated from the X genome of Ag.intermedium. Less