| Summary: | 碩士 === 國立中興大學 === 農藝學系所 === 102 === For isolating a large number of maize B-chromosome specific molecular markers, we used the B-chromosome specific sequence, CL-repeat which are widely distributed on the B-chromosome, and referred to the IRRE (iris retroelement) retrotransposon display technique to establish the CL-repeat display technique of maize B-chromosome. A total of 26 B-chromosome specific markers were obtained and mapped by five B-10L translocations. Additonal 13 B-10L translocations with breakpoints on the distal heterochromatic region were used to verify breakpoints of these translocations and to finely map each CL-repeat display marker. All of the 26 markers were cloned and sequenced. On the basis of sequence characteristics, those sequence could be divide into four categories: markers with CL-repeat sequence, markers with B-centromere sequence, markers with CL-repeat and B-centromere sequences, and markers with unknown sequence. Subsequently, one marker with B-centromere sequence, two markers with CL-repeat and B-centromere sequences, and two markers with unknown sequence were selected to convert into SCAR (sequence characterized amplified region) markers, and mapped by B-10L translocations. Among these five markers, the 3i-08-SCAR marker with B-centromere sequence were mapped to unexpected regions. Those unexpected SCAR markers were cloned and sequenced from different regions, and used to constructed an unrooted evolution tree for exploring the differentiation of maize B-centromere sequences between the B-centromere and the distal heterochromatin region. Furthermore, we used restriction enzyme HindIII to perform the CL-repeat display technique and hoped to get more different B-chromosome specific CL-repeat display markers.
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