ARS | Publication request: PREDICTING SUCCESS OF INDICA/JAPONICA CROSSES IN RICE, BASED ON A PCR MARKER FOR THE S-5**N ALLELE AT A HYBRID-STERILITY LOCUS

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 17, 1997
Publication Date: N/A

Interpretive Summary: The two subspecies of rice, indica and japonica, are difficult to cross and important traits cannot be easily transferred between them. This crossing barrier is due to a genetic factor that causes sterility in the progeny. However, an intermediate form of rice, javanica, contains a gene that allows it to make fertile crosses with both indica and japonica. Because this gene, S-5, is difficult to follow through crosses, we have developed and tested an easily followed molecular marker for the gene. Now plant breeders can easily incorporate S-5 into their indica and japonica breeding lines and transfer important traits between the subspecies.

Technical Abstract: Exploitation of crosses between the japonica and indica subspecies of rice (Oryza sativa L.) is hindered by hybrid sterility. However, germplasm containing the S-5**n wide compatibility allele, derived from tropical japonica (javanica), can be used as an intermediate in the transfer of traits. A PCR-based DNA marker, STS213, was used to identify the fraction of an F sub 3 population, segregating for S-5**n and the japonica allele S-5j, that was most likely to yield fertile progeny from crosses with indica rice. Plants carrying the STS213 allele associated with wide compatibility, had significantly higher fertility than plants containing the japonica allele. The ability to detect seedlings baring S-5**n, the wide-compatibility allele, will facilitate the introgression of this allele into temperate japonica cultivars while eliminating the need to test cross, self and score for fertility a majority of the individuals during introgression.