[Hypoploid groups and their cytogenetic analysis in the progenies between Brassica napus and Orychophragmus...

Several groups of hypoploids were characterized in pentaploid (p) progenies of B. napus and O. violaceus. Cytological characterization of the P3 population revealed allosubstitution of one pair of B. napus chromosomes with O. violaceus chromosomes. This population had normal fertility and had three kinds of somatic cells with 36-38 chromosomes. Its somatic cells and pollen mother cells (PMC) mainly had 38 chromosomes. From a P4 population, three monosomic plants with 37 chromosomes were identified with differing morphology and fertility. One plant which grew vigorously was composed of various types of somatic cell and PMC, in which the cells with 37 chromosomes were observed mainly. The unpaired chromosome was small and with no negative effects on plant development. In the offsprings of the aneuploids (P3) with 41-44 chromosomes, there are four types of plants with 29-32 chromosomes. Except the plant with 29 chromosomes, others which appeared abnormal meiosis behavior and poor pollen fertility are mixoploid. The origin of these hypoploids and their prospects of application have been discussed.