Abstract：One chromosome with the character of chromosome 4Ag was microdissected from the root tip cell of blue-grained wheat (Triticum aestivum L.(2n=6x=42)×Thinopyrum ponticum Liu & Wang (2n=10x=70)) at mitotic metaphase using glass needle. Then the cell was analyzed by the fluorescent in situ hybridization (FISH). The result showed that the single chromosome left in the cell and the microdissected chromosome were chromosome 4Ag. The isolated chromosome was amplified in vitro by Sau3A linker adaptor-mediated PCR，and from 200 bp to 2 000 bp, especially from 250 bp to 750 bp smear DNA fragments were obtained．Southern hybridization result indicated that DNA from the single chromosome has been successfully amplified. FISH showed that the in vitro amplified fragments of microdissected chromosome were from 4Ag chromosome of the blue-grained wheat．This study broaden the scope of chromosomal mircodissection and provide a useful way to construct specific library and replicate some important genes from a single chromosome．
