ABSTRACT
Polyploidy has played an important role in the evolution of grass family Gramineae. This chapter deals with the structure, organization, chromosomal location, divergence, and evolution of repeated DNA sequences in cereals. Extensive accounts of the origin and evolution of specific cereal crops are available J. R. Harlan et al. The haploid DNA content varies considerably among the cereals. The number of reverse repeats in a genome is related to the DNA content. In spite of the presence of an unusually large amount of repeated DNA sequences in the monocots, no satellite DNA fraction has been found. The proportion of repeated DNA in eight rice species varied from 56 to 66%. Repeated DNA in pearl millet varies from 54 to 69%. The polyploid cereals have a higher DNA content compared to the diploids; however, the DNA content in finger millet and hexaploid oats is lower in comparison to many diploid cereals.
