Genetic Definition and Sequence Analysis of Arabidopsis Centromeres

Abstract

High-precision genetic mapping was used to define the regions that contain centromere functions on each natural chromosome in Arabidopsis thaliana. These regions exhibited dramatic recombinational repression and contained complex DNA surrounding large arrays of 180-base pair repeats. Unexpectedly, the DNA within the centromeres was not merely structural but also encoded several expressed genes. The regions flanking the centromeres were densely populated by repetitive elements yet experienced normal levels of recombination. The genetically defined centromeres were well conserved among Arabidopsis ecotypes but displayed limited sequence homology between different chromosomes, excluding repetitive DNA. This investigation provides a platform for dissecting the role of individual sequences in centromeres in higher eukaryotes.

Sequence and analysis of chromosome 2 of the plant Arabidopsis thaliana

“…Two BACs (T5M2 and T5E7) within the genetically de®ned centromere 26 were found to contain long stretches of sequence with very high similarity to the Arabidopsis C24 mitochondrial genome (69 kb on T5M2, and 74 kb on T5E7) joined directly to nuclear sequence. Two overlapping BACs provided an additional 122 kb of purely mitochondrial sequence to close the gap, suggesting that the total size of the organellar DNA insertion is about 270 kb.…”

“…This accumulation of retroelements and other transposons may be due to either preferential insertion into the regions¯anking the centromere or their elimination from the rest of the genome at a higher rate 26 . In addition, representatives of previously described intermediate repeats as well as some new repeats were identi®ed (Fig.…”

The role of repetitive DNA in structure and evolution of sex chromosomes in plants

“…Centromeres are regions with lower recombination frequency (Beadle, 1932;Clarke and Carbon, 1980) and often exhibit interspersion of satellite sequences and TEs, as in cereals (Zhong et al, 2002), Arabidopsis (Copenhaver et al, 1999), insects (Sun et al, 2003) and fungi (Cambareri et al, 1998). There are indications of the evolutionary link between the centromere structure and TE's activity: centromeric satellite repeats may arise from DNA transposons (Kapitonov and Jurka, 1999).…”

Recent advances in plant centromere biology

“…In higher plants, the centromeres were mainly composed of tandem repeats and retrotransposons, which are interspersed (Figure 1). Through genetic analysis and sequencing, a 180-base pair repeat sequence was found to be the main component in Arabidopsis centromeres [12]. This was confirmed by ChIP using antibody against the Arabidopsis centromeric histone CENH3 (called HTR12 in Arabidopsis) [13].…”