In an article entitled, “Genetic analysis of hybrid seed formation ability of Brassica rapa in intergeneric crossings with Raphanus sativus,” published in the December issue of Theoretical And Applied Genetics, Nishio and four other authors, have presented the results of the crosses, Raphanus sativus x Brassica rapa (=rape). They reported that a Brassica rapa line derived from turnip cultivar ‘Shogoin-kabu’ produces a large number of hybrid seeds when it is used as a maternal parent. However, the development of embryos in this cross combination was slower than those in intraspecific crosses. These researchers further observed that hybrid seeds fail to develop when Chinese Cabbage cultivar ‘Chiifu’was used as the female parent.
At the next stage of their investigation these authors studied quantitative trait loci (QTLs) conditioning the hybrid seed formation. Using two different F2populations derived from the F1 hybrids, the authors analyzed the intergeneric progeny. They detected three significant QTLs . Among them, two QTLs were traced to linkage group A10 and the other in linkage group A01, both in the F2populations. These two QTLs had opposing effects on determining the number of hybrid seeds. Epistatic interaction between these two QTLs was also detected.