建立定量DNA纤维作图（QDFM）技术，选择玉米遗传图连锁紧密不能分辨次序的五个基因群捎肣DFM技术确定每群内基因间的排列次序及其物理距离。QDFM较常规原位杂交的分辨率?0倍以上，而且可以测定衔接重复基因的拷贝数和基因间相距硷基对数。QDFM的应用将大筇岣呋蛭锢碜魍嫉木杆剑蚨曰蜃榈娜鲜兑步灾岣摺

In this study, we have mastered a new cytogenetic technique-extended DNA fiber in situ hybridization in plant. Using this technique, we have done the extended DNA fiber in situ hybridization with centromeres, telomeres, specific BAC clones, 5S and 45S rDNA in rice. The results showed that the DNA fiber obtained by us was close to theoretical value in size of the unit distance. We measured size and and copy numberof the tested DNA sequences based on the size of the unit distance and obtained more convinced results. We also verified relationship between the tested clones in some contigs, estimated fragments overlapping between clones in size as well as primarily observed length variations of the telomeres during different development stages in rice. It will offer conditions for verifying sequencing of rice genome and open a new approach for analyzing copy number of the multicopy genes as well as promote development of international cooperation in this field