Grass genomes

Jeffrey L. Bennetzen, Phillip Sanmiguel, Mingsheng Chen, Alexander Tikhonov, Michael Francki, Zoya Avramova

Research output: Contribution to journalArticlepeer-review

128 Scopus citations


For the most part, studies of grass genome structure have been limited to the generation of whole-genome genetic maps or the fine structure and sequence analysis of single genes or gene clusters. We have investigated large contiguous segments of the genomes of maize, sorghum, and rice, primarily focusing on intergenic spaces. Our data indicate that much (>50%) of the maize genome is composed of interspersed repetitive DNAs, primarily nested retrotransposons that insert between genes. These retroelements are less abundant in smaller genome plants, including rice and sorghum. Although 5- to 200-kb blocks of methylated, presumably heterochromatic, retrotransposons flank most maize genes, rice and sorghum genes are often adjacent. Similar genes are commonly found in the same relative chromosomal locations and orientations in each of these three species, although there are numerous exceptions to this collinearity (i.e., rearrangements) that can be detected at the levels of both the recombinational map and cloned DNA. Evolutionarily conserved sequences are largely confined to genes and their regulatory elements. Our results indicate that a knowledge of grass genome structure will be a useful tool for gene discovery and isolation, but the general rules and biological significance of grass genome organization remain to he determined. Moreover, the nature and frequency of exceptions to the general patterns of grass genome structure and collinearity are still largely unknown and will require extensive further investigation.

Original languageEnglish (US)
Pages (from-to)1975-1978
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number5
StatePublished - Mar 3 1998
Externally publishedYes


  • Chromosomal evolution
  • Gene discovery
  • Genetic maps
  • Genome rearrangement
  • Microcollinearity

ASJC Scopus subject areas

  • General

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