Distribution of deletion type in cpDNA of cultivated and wild rice

The ORF100 region within Pst-12 fragment of chloroplast DNA (cpDNA) in rice (Oryza sativa) were amplified by polymerase chain reaction in 137 cultivars and 117 strains of wild rice from various countries. Two cpDNA types, with and without a deletion at the region, were found. In O. sativa, 63 and 74 cultivars had the deletion and the non-deletion cpDNAs, respectively. It corresponded to indica and japonica classified by morphological and physiological characters. Plant groups of 45 strains having the deletion and 72 strains with the non-deletion in spDNA were found in wild rice. Wild species that distantly related to O. sativa had mostly cpDNAs without the deletion. The deletion is likely to have differentiated in O. rufipogon. Annual types of O. rufipogon tend to have the deletion, while perennial types tend to loose it. The results of this study supported a view that the indica and japonica types were differentiated in wild species before domestication.