A PCR marker system for monitoring the frequencies of normal and sterility-inducing cytoplasm types in German chive varieties

Random amplified polymorphic DNAs and atp9‐related sequences were amplified in cytoplasmic male sterile (CMS) and maintainer lines drawn from a backcross programme to represent all five known cytoplasm types in chives. From these PCR amplifications, markers associated with CMS‐inducing cytoplasm types, (S1) and (S₂), and for two of the three known normal cytoplasm types, (N₂) and (N₃), were developed. These newly developed PCR markers were used to determine the cytoplasm types in 126 plants representing 12 German chive varieties. The dependability of these PCR markers was confirmed by analysis with previously described and marker‐trait linked restriction fragment length polymorphisms. Two to five cytoplasm types were found in each of the 12 German chive varieties investigated. While the (S1) cytoplasm occurred, on average, at a frequency of 5% and the (S₂) cytoplasm at 12%, the three normal cytoplasms (N1), (N₂) and (N₃) were present at 30, 29 and 24%, respectively. Thus, the prospects of finding maintainers for both CMS systems are relatively high in this population, if the frequency of non‐restoring alleles for the nuclear genes involved is also high enough.