甘蓝型油菜与诸葛菜属间五倍体后代非整倍体的细胞遗传学研究(英文)

Analysis of cytogenetics for the aneuploids in pentaploid progenies from intergeneric cross between Brassica napus and Orychophragmus violaceus

甘蓝型油菜与诸葛菜属间五倍体后代的细胞学观察结果表明 ,非整倍体中体细胞或花粉母细胞 (PMCs)出现 4 7、4 4和 4 1条染色体的频率均高于其他类型的细胞 .除了 2 n=38的植株外 ,其余均为混倍体 .在 2 n>38的花粉母细胞中 ,附加的异源染色体经常落后于后期核外而呈现染色体消除现象 .在减数分裂的第一次分裂时期 ,多数 PMCs趋向于均衡分离 .另外也观察到后期 细胞一极出现 17或 18条染色体的特殊分离方式 .对 PMC后期 细胞核以及雌雄配子的组成及比例的研究也发现 ,在 2 n=4 4和 4 1的植株中存在染色体的消减现象 ,雄配子染色体消减的速率快于其余两种情况 .而且低染色体数目配子 (n=2 2～ 19)具有更高频率传递给后代 .根尖的体细胞中存在染色体消除现象 .

Cytological observation on progenies of intergeneric pentaploids between Brassica napus and Orychophragmus violaceus was conducted and the results indicated that frequency of cells with 47, 44 and 41 chromosomes in somatic cells or pollen mother cells (PMCs) was higher than that with other chromosome number in aneuploids among the aneuploid progenies Except for the plants with 38 chromosomes, they were mixoploid with extra chromosomes derived most likely from O violaceus Chromosome elimination, due to exclusion from telophase nuclei and sebsequent digestion of the extra chromosomes, occurred in all PMCs (2n>38) Some modes of segregation that were apt to cause symmetrical distribution of chromosome in PMCs at the metaphase I (MI) stage Moreover, several special segregation modes were discovered in PMCs which led to aggregation of 18 or 17 chromosomes at this stage In each of three parts (anaphase I (AI) stage of PMCs, female gametes and male gametes), chromosome number was lowered in plants with 44 or 41 chromosomes according to gamete constitutes and frequency Among these three parts, the ratio of male gametes with decreased chromosome number was larger than both of others Gametes with lower chromosome numbers (n=2219) were more easily transferred to offsprings Somatic chromosome diminution was observed in root tips of seedling according to their somatic constituent