Production and characterization of a complete set of individual chromosome additions from Oryza officinalis to Oryza sativa using RFLP and GISH analyses.

Monosomic alien addition lines (MAALs) are valuable materials for comparative analyses of two distinct genomes, for elucidating introgression mechanisms, and for dissecting genes controlling complex traits. In the study reported here, MAALs of rice containing the complete genome of Oryza sativa and individual chromosomes of Oryza officinalis were produced. Interspecific hybridizations were made between O. sativa L. ssp. Japonica (CV, Hejiang 19, 2 n = 24, AA) and O. officinalis (Acc. HY018, 2 n = 24, CC). Two backcrosses were made to the cultivated rice to obtain BC2F1 plants. Through RFLP and GISH analyses, 25 MAALs (2 n = 25, AA + 1C) were identified and divided into 12 syntenic groups, designated MAALs 1-12. MAALs 1, 2, 3, 5, 7 and 10 were each represented by one plant, MAALs 8, 11 and 12 by two plants, MAALs 6 and 9 by four plants, and MAAL 4 by five plants. An ideogram of the C-genome of O. officinalis was constructed, based on GISH analysis of the interspecific hybrid and the MAALs. Comparative RFLP maps showed strong syntenic associations between the A-genomes and C-genomes. Chromosomal arrangements such as translocations and duplications were detected in different alien chromosomes of the MAALs. The complete set of O. officinalis MAALs generated here provides a novel manipulation platform for exploiting and utilizing the O. officinalis genome and carrying out genetic studies.