Jin Weiwei, Melo Juliana R, Nagaki Kiyotaka, Talbert Paul B, Henikoff Steven, Dawe R Kelly, Jiang Jiming
Department of Horticulture, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Plant Cell. 2004 Mar;16(3):571-81. doi: 10.1105/tpc.018937. Epub 2004 Feb 18.
Centromeric DNA sequences in multicellular eukaryotes are often highly repetitive and are not unique to a specific centromere or to centromeres at all. Thus, it is a major challenge to study the fine structure of individual plant centromeres. We used a DNA fiber-fluorescence in situ hybridization approach to study individual maize (Zea mays) centromeres using oat (Avena sativa)-maize chromosome addition lines. The maize centromere-specific satellite repeat CentC in the addition lines allowed us to delineate the size and organization of centromeric DNA of individual maize chromosomes. We demonstrate that the cores of maize centromeres contain mainly CentC arrays and clusters of a centromere-specific retrotransposon, CRM. CentC and CRM sequences are highly intermingled. The amount of CentC/CRM sequence varies from approximately 300 to >2800 kb among different centromeres. The association of CentC and CRM with centromeric histone H3 (CENH3) was visualized by a sequential detection procedure on stretched centromeres. The analysis revealed that CENH3 is always associated with CentC and CRM but that not all CentC or CRM sequences are associated with CENH3. We further demonstrate that in the chromosomal addition lines in which two CenH3 genes were present, one from oat and one from maize, the oat CENH3 was consistently incorporated by the maize centromeres.
多细胞真核生物中的着丝粒DNA序列通常高度重复，并非特定着丝粒或所有着丝粒所特有。因此，研究单个植物着丝粒的精细结构是一项重大挑战。我们使用DNA纤维荧光原位杂交方法，利用燕麦（ Avena sativa ）-玉米染色体附加系研究单个玉米（ Zea mays ）着丝粒。附加系中玉米着丝粒特异性卫星重复序列CentC使我们能够描绘单个玉米染色体着丝粒DNA的大小和组织。我们证明，玉米着丝粒的核心主要包含CentC阵列和着丝粒特异性逆转座子CRM的簇。CentC和CRM序列高度交织。不同着丝粒之间CentC/CRM序列的数量从大约300 kb到>2800 kb不等。通过对拉伸着丝粒的顺序检测程序，可视化了CentC和CRM与着丝粒组蛋白H3（CENH3）的关联。分析表明，CENH3总是与CentC和CRM相关联，但并非所有CentC或CRM序列都与CENH3相关联。我们进一步证明，在存在两个CenH3基因的染色体附加系中，一个来自燕麦，一个来自玉米，燕麦CENH3始终被玉米着丝粒整合。
