Distribution and sequence analysis of the centromere-associated repetitive element CEN38 of Sorghum bicolor (Poaceae)

Fluorescence in situ hybridization (FISH) of a large-insert genomic clone, BAC 22B2, previously suggested that Sorghum bicolor (2n = 20) has the tetraploid architecture AbAbBbBb. Here, we report on BAC 22B2 subclone pCEN38 (1047-bp insert) as related to sorghum and sugarcane. Mitotic FISH of six different subclones of BAC 22B2 showed that pCEN38 produced the strongest specificity to the Absubgenome and signal occurred primarily near centromeres. Southern blots of pCEN38 to 21 crop plants revealed a narrow taxonomic distribution. Meiotic metaphase I FISH positioned pCEN38 sequences near active centromeres. Pachytene FISH revealed that the distributions are trimodal in several Bband possibly all sorghum chromosomes. DNA sequencing revealed that the pCEN38 fragment contains three tandemly repeated dimers (