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| In plant distant crosses, non-classical hybrids with unexpected chromosome complements, chromosome elimination and genetic introgression have been documented. Herein hybrid plants were obtained with embryo rescue from intergeneric crosses between Brassica rapa, B. rapa var. chinensis and another crucifer, Orychophragmus violaceus, and mainly displayed a female B. rapa phenotype but also certain O. violaceus or novel characteristics. Variable numbers of chromosomes appeared in somatic cells in the roots of plantlets on medium and ovaries and pollen mother cells (PMCs) and higher cell numbers were recorded in the roots. GISH observations revealed the majority of ovary cells and PMCs to twenty chromosomes of B. rapa with or without individual O. violaceus chromosomes or fragments added or introgressed. AFLP analysis revealed that fragments deleted for B. rapa was much more frequent than novel and O. violaceus fragments and about 50% of them were the same in more than half of F1 plants, and the number of O. violaceus fragments positively correlated with its traits expressed in hybrids. The mechanisms behind the results were the genome doubling and successive elimination of the O. violaceus chromosomes accompanied by the fragment recombination and introgression, producing B. rapa-type plants with modified genetic constitutions and phenotypes. |
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| Keywords:Brassica rapa, Orychophragmus violaceus, Intergeneric hybrids, Genomic in situ hybridization (GISH), Amplified fragments length polymorphism (AFLP), Genome doubling, Chromosome elimination, Introgress |
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