Segregation Distortion Observed in the Progeny of Crosses Between and . Caused by Abortion During Seed Development.

Wild rice relatives having the same AA genome as domesticated rice () comprise the primary gene pool for rice genetic improvement. Among them, and are found in the northern part of Australia. Three Australian wild rice strains, Jpn1 (), Jpn2, and W1297 (), and one cultivated rice cultivar Taichung 65 (T65) were used in this study. A recurrent backcrossing strategy was adopted to produce chromosomal segment substitution lines (CSSLs) carrying chromosomal segments from wild relatives and used for trait evaluation and genetic analysis. The segregation of the DNA marker RM136 locus on chromosome 6 was found to be highly distorted, and a recessive lethal gene causing abortion at the seed developmental stage was shown to be located between two DNA markers, KGC6_10.09 and KGC6_22.19 on chromosome 6 of W1297. We name this gene as (gene symbol: ). . is thought to share the functional dominant allele (s for ), and is thought to share the recessive abortive allele - (m for ). Though carrying the - allele, the accessions can self-fertilize and bear seeds. We speculate that the gene may have been duplicated before the divergence between and the other AA genome species, and that has lost the function of the gene and has kept the function of another putative gene named .