Red rice is a major weed in rice production in the southern United States. Red rice and rice intercross because they are the same species. Our objectives were to determine the genetic diversity represented by accessions of red rice and to identify DNA markers that might be useful in identifying hybrids between red and cultivated rice. Red rice accessions were collected from Arkansas and other rice-producing states. Seventy-nine red rice accessions, 10 known or putative hybrid derivatives of red rice and cultivated rice (RC hybrids), and seven rice cultivars were analyzed using microsatellite DNA markers developed for cultivated rice. Microsatellite markers differentiated awned and awnless red rice accessions, six of the seven rice cultivars, and all 10 RC hybrids tested. Thus, these markers were useful in identifying red rice types and RC hybrids.

Nomenclature: Red rice, Oryza sativa L. ORYSA; rice, Oryza sativa L.