Plant & Animal Genome V Conference
Town & Country Hotel, San Diego, CA, January 12-16, 1997.
PAG-V: S17 - ORGANIZATION, EVOLUTION AND FUNCTION OF GRASS GENOMES: MICROSYNTENY AND ITS
MANY EXCEPTIONS
S17
ORGANIZATION, EVOLUTION AND FUNCTION OF GRASS GENOMES: MICROSYNTENY AND ITS MANY EXCEPTIONS
BENNETZEN, JEFF
496. Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392 USA
Grass genomes differ tremendously in nuclear DNA content, chromosome number, and repetitive DNA content, but are signficantly
conserved in both gene content and gene order. However, the basic patterns of sequence organization, and their relationship to genome
function, are only vaguely understood in plants with large genomes. We have initiated studies of the organization of homologous regions of the
maize, sorghum and rice genomes. Our results have indicated that gene content, order and orientation are largely conserved in comparable
regions of these grass genomes, but that genic duplication and segmental deletion/insertion occur at detectable frequencies. Moreover, the
physical distance between genes is highly variable between species. As expected, the larger maize genome usually has greater distances
between genes than do the smaller rice and sorghum genomes. Interestingly, the nature of the DNA between the genes we have investigated
shows species-specific differences as well. The DNA between maize genes tends to be composed primarily of blocks of nested retroelement
insertions, while the sequences between rice and sorghum genes have few detected features. Evidence regarding the differences in origins and
evolution of these three grass genomes will be presented, as will information regarding the relationship of the different structures obtained to
genome folding and function.