Visualization of diffuse centromeres with centromere-specific histone H3 in the holocentric plant Luzula nivea

Although holocentric species are scattered throughout the plant and animal kingdoms, only holocentric chromosomes of the nematode worm Caenorhabditis elegans have been analyzed with centromeric protein markers. In an effort to determine the holocentric structure in plants, we investigated the snowy woodrush Luzula nivea. From the young roots, a cDNA encoding a putative centromere-specific histone H3 (LnCENH3) was successfully isolated based on sequence similarity among plant CENH3s. The deduced amino acid sequence was then used to raise an anti-LnCENH3 antibody. Immunostaining clearly revealed the diffuse centromere-like structure that appears in the linear shape at prophase to telophase. Furthermore, it was shown that the amount of LnCENH3 decreased significantly at interphase. The polar side positioning on each chromatid at metaphase to anaphase also confirmed that LnCENH3 represents one of the centromere-specific proteins in L. nivea. These data from L. nivea are compared with those from C. elegans, and common features of holocentric chromosomes are discussed.