大白菜与甘蓝种间BC_1的减数分裂观测及其性状鉴定

Meiosis Observation and Behaviour Evaluation of Interspecific BC_1 Derived from Chinese Cabbage and Cabbage

以回交父本二倍体大白菜(代号为85-1,2n=20)为对照,对异源三倍体(AAC)与二倍体大白菜(AA)回交的BC1(代号为a2,2n=22)进行花粉孢母细胞减数分裂观察,并对其生殖时期田间性状和花粉特性进行了观测。结果表明:花粉孢母细胞减数分裂复杂,终变期观察到8Ⅱ+2Ⅲ、10Ⅱ+2Ⅰ、9Ⅱ+1Ⅲ+1Ⅰ等多种联会方式;中期I、II出现单个或多个游离染色体;后期I、II出现落后染色体或丢失染色体的频率很高,导致多种方式的分离,出现了较少的、利用价值较高的11条染色体的配子。此外,田间观察证明,与85-1相比较,a2生长势弱,花粉量和生活力均较低,叶片、花和花蕾都较小,抽薹和开花较早。上述结果为大白菜杂交育种的后代种植群体设置和调节花期提供了理论依据。

The pollen mother cells（PMC） meiosis of BC 1 derived from allotriploid（AAC） and diploid Chinese cabbage（AA） were studied,and both farm characteristics and pollen character of BC 1 were evaluated at reproductive stage,using diploid Chinese cabbage（codenamed 85-1,2n=20） as a control.The results showed that the chromosome division during PMC meiosis appeared complicated.Multi-synapsis types（8Ⅱ＋2Ⅲ,10Ⅱ＋2Ⅰ,9Ⅱ＋1 Ⅲ＋1Ⅰ） were observed at diakinesis stage.Single or a few isolated free chromosomes were funded during metaphaseⅠandⅡ.The frequency of chromosome lagging or losing was very high during anaphaseⅠandⅡ.The results mentioned above may be the main reasons which caused a variety of ways of chromosomes separation.There were a few valuable gametes with 11 chromosomes appeared.In addition,field observation showed that both the growth vigor and pollen quantity or viability of a2 were weaker or lower than that of 85-1.A2 had smaller leaves,flowers and flower buds,and had earlier bolting and flowering trait,comparing with 85-1.All the results mentioned above provided a theoretical basis for progeny planting population setting up and regulating flowering date in cross-breeding of Chinese cabbage.