| Several abnormal chromosome behaviors in plant wide crosses have been reported, such as pseudogamy, semigamy, chromosome doubling, chromosme elimination, unreduced gametes and spatial separation of parental gemomes, especially the separation of parental genomes during the mitotic and meiotic divisions of the hybrid cells was proposed in the intergeneric hybridizations between the cultivated Brassica species and Orychophragmus violaceus (L.) O. E. Schulz. (2n=24). In contiuaiton of these studies, the hybrids of O. violaceus with Brassica napus L. (2n=38, genomes AACC), B. juncea (L.) Czern & Coss. (2n=36, AABB) and B. carinata A. Braun (2n=34, BBCC) were obtained again and investigated by the methods of genomic in situ hybridization (GISH) and amplified fragment length polymorphisms (AFLP). The results were described as follows.1,In B. carinata (GO-7) × O. violaceus cross, F1 plants from 25 immature embryos were obtained following embryo rescue and were classified into three types according to their chromosome numbers in ovary cells and phenotypic characters. All the F1 plants with high fertility resembled closely to B. carinata in morphological attributes and were mixoploids with 2n chromosome numbers ranging from 17-35, however, 34 same as in B. carinata being the most frequent in ovary and pollen mother cells. GISH clearly identified 16 chromosomes of B. nigra in ovary cells and PMCs with 2n=34 and 35. However, no O. violaceus chromosome was detected, indicating the presence of intact B. carinata genome and elimination of entire O. violaceus genome. However, some AFLP bands specific for O. violaceus, deleted in B. carinata and novel for the two parents were detected in the leaves. Cells with fewer than 34 chromosomes had lost some B. oleracea chromosomes. F2 plants were predominantly liked B. carinata but some contained O. violaceus characters.2, B. napus × O. violaceus cross was repeated with embryo rescue. All F1 plants except one B. napus haploid (2n=19) were mixploids (2n=17-39 in ovaries) with 2n=31, 37, 38, 39 as the maximal chromosome numbers in individuals, but higher numbers appeared in pollen mother cells (PMCs) and only one chromosome and one chromosome segment of 0. violaceus were detected in low frequency in some PMCs and ovary cells (2n=37, 38, 39) by GISH analysis. These chromosome numbers and complements in these mixoploids were attributed to the chromosome additions, substitutions between the genomes from... |
