The wild species Oryza glumaepatula Steud. is distributed in South and Central America, and long awn is one of its typical characters as well as other wild rice species. We have developed O. glumaepatula (IRGC Acc. No. 105668) introgression lines (glumILs) in the background of O. sativa cv. Taichung 65 (Sobrizal et al. 1999) to rationally utilize the genetic variation hidden in wild germplasm. We have previously reported two genes for forming long awn, An7 and An8, located on chromosomes 5 and 4 in Oryza meridionalis Ng (Kurakazu et al. 2001). Here we report the new allele of these two loci found using glumILs.

Some glumILs showed typical awn character. Therefore, we used two BC₄F₂ populations in which the awnness segregated and chromosomal segments corresponding to An8 and An7 were retained. SSR markers (McCouch et al. 2002) were used for the linkage mapping.

In one population consisting of 74 plants, awnness was segregated into 61 awned and 13 awnless. Linkage analysis revealed that the gene controlling the awnness was located between the two SSR markers, RM261 and RM1359 on chromosome 4, with map distances of 12.2 and 7.1 cM, respectively. This map position was identical to that of An8 previously identified as O. meridionalis allele. Thus, we concluded that this gene (An8-glum) was new allele of An8. In the other population, awn character was segregated into 66 awned and 5 awnless plants. Although this segregation ratio was distorted from the expected 3 : 1 ratio, this gene could be mapped between RM3419 and RM289 on chromosome 5 as a single dominant gene. In the same way as An8, we considered that this gene (An7-glum) was allelic to An7 from O. meridionalis. Awnness caused by An8 and An7 were comparable to each other (Fig. 2). These results suggested that An8 and An7 are widely distributed in wild rice species.

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