A TGMS-linked nuclear DNA marker as originated from the mitochondrial genome in rice ( L.)

A nuclear RAPD marker, OPF18 2600 , was linked to a thermosensitive genetic male sterility (TGMS) gene ( tms3 ) in a rice mutant line IR32364TGMS. Segregation analysis in two mapping populations and reciprocal cross analysis involving different genotypes indicated, however, that this marker was maternally inherited. The RAPD marker was then cloned as pF18 and partially sequenced from both ends of the insert. Sequence analysis showed that pF18 was homologous to mitochondrial genes, cob2 and nad1 . Evidence was provided that the cob2 DNA segment near pF18 was genetically linked to tms3 . Thus pF18 could be the result of integration of a piece of mitochondrial DNA segment into the nuclear genome. The transferred DNA segment included at the least cob2 , a portion of nad1 , and intergenic sequences. The presence of intron and intergenic sequences in the transferred DNA fragment indicated that DNA was the transfer intermediate. The relationship between the transferred DNA and tms3 is discussed.