ARS | Publication request: A PCR-BASED POLYMORPHISM DETECTING MIXTURES OF MALE-FERTILE AND MALE STERILE CYTOPLASMIC ONION IN HYBRID-SEED LOTS

Submitted to: International Symposium on the Edible Alliaceae
Publication Type: Abstract Only
Publication Acceptance Date: January 30, 2001
Publication Date: N/A

Technical Abstract: S cytoplasm of onion is likely an alien cytoplasm introduced in antiquity into onion populations. We previously showed that size differences in an intergenic spacer in the chloroplast DNA distinguish N and S cytoplasms of onion. We cloned and sequenced this intergenic spacer from N and S cytoplasms of onion, as well as related species in Allium section Cepa to identify the nature of previously described restriction fragment length polymorphisms and to develop a PCR-based marker revealing N-cytoplasmic contamination of S-cytoplasmic hybrid seed lots. As previously reported, this region is AT rich and size differences among related Allium species and among individuals within a species are likely due to replication slippage. Oligonucleotide primers specific to this region of the chloroplast DNA were designed to preferentially amplify a fragment only from N-cytoplasmic onion. This marker revealed the presence of N cytoplasm to a limit of 1 percent.