SECONDARY TRISOMICS AND TELOTRISOMICS OF RICE - ORIGIN, CHARACTERIZATION, AND USE IN DETERMINING THE ORIENTATION OF CHROMOSOME MAP

Secondary trisomics and telotrisomics representing the 12 chromosomes of rice were isolated from the progenies of primary trisomics. A large population of each primary trisomic was grown. Plants showing variati on in gross morphology compared to the primary trisomics and disomic s ibs were selected and analyzed cytologically at diakinesis and pachyte ne. Secondary trisomics for both arms of chromosomes 1, 2, 6, 7 and 11 and for one arm of chromosomes 4, 5, 8, 9 and 12 were identified. Tel otrisomics for short arm of chromosomes 1, 8, 9 and 10 and for long ar ms of chromosomes 2, 3 and 5 were isolated. These secondary and telotr isomics were characterized morphologically and for breeding behavior. Secondary trisomics 2n + 1S . 1S, 2n + 1L . 1L, 2n + 2S . 2S, 2n + 2L . 2L, 2n + GS . GS, 2n + 6L . 6L and 2n + 7L . 7L are highly sterile, and 2n + 1L . 1L, 2n + 2L . 2L and 2n + 7L . 7L do not set any seed ev en upon backcrossing. Telotrisomics are fertile and vigorous. Genetic segregation of 43 marker genes was studied in the F-2 or backcross pro genies. On the basis of segregation data, these genes were delimited t o specific chromosome arms. Correct orientation of 10 linkage groups w as determined and centromere positions on nine linkage groups were app roximated. A revised linkage map of rice is presented.