Establishment and characterization of Brassica juncea–Orychophragmus violaceus additions, substitutions and introgressions

Intergeneric hybridizations between cultivated Brassica species and Orychophragmus violaceus have been shown to be an efficient approach to produce Brassica aneuploids. Herein B. juncea–O. violaceus additions, substitutions and introgressions were obtained among progenies of partial hybrids after B. juncea (2n = 36) was pollinated by O. violaceus (2n = 24) and they expressed some traits from O. violaceus or novel for two parents. The single O. violaceus chromosome which was added to or substituted into the B. juncea chromosome complement was distinguishable most easily in pollen mother cells at anaphase I (AI) from its darker staining and more condensed form. The one pair of the O. violaceus chromosome in the substitutions paired and segregated regularly with others from B. juncea, and the single one formed one bivalent with one B. juncea chromosome and showed normal segregation and was more darkly stained in some AI group. Stable introgressions with 2n = 36 gave amplified fragment-length polymorphism (AFLP) profiles mainly similar to those of the female B. juncea parent, but fragments specific for O. violaceus could be found in every plants together with those deleted in B. juncea and novel bands for two parents. The mechanisms behind these unusual results are discussed.