甘蓝型油菜与Brassica maurorum的异源六倍体后代及BC2细胞学分析

将甘蓝型油菜品种中油821（2n=38, AACC）与芸薹属野生资源Brassica maurorum（2n=16, MM）的三倍体杂种进行染色体加倍，得到异源六倍体（2n=54, AACCMM）。该多倍体雄性高度不育，雌性育性极低。在其花粉母细胞的减数分裂终变期，染色体平均配对构型为1.17Ⅰ+20.71Ⅱ+0.56Ⅲ+2.25Ⅳ+0.08Ⅴ+0.06Ⅵ。用甘蓝型油菜与该多倍体连续回交2次，均需借助幼胚培养才得到后代植株，BC1、BC2植株均雄性不育，雌性育性很低。BC2植株的形态特征接近甘蓝型油菜，但各植株形态有明显差异。基因组原位杂交分析表明，BC2植株含有2~5条M基因组的染色体，甘蓝型油菜染色体多配对形成二价体，附加的染色体多以单价体形式存在，或与甘蓝型油菜染色体发生联会配对。

Cytology of Brassica allohexaploids and BC2 progenies from B.napus and B.Maurorum

Allohexaploids(2n=54,AACCMM) plants from Brassica napus cv.Zhongyou 821(2n=38,AACC) and wild species B.maurorum(2n=16,MM) were produced by hybrids chromosome doubling.The polyploids were totally male sterile and extremely low female fertile.In polyploids pollen mother cells at diakinesis,the mean chromosome pairing configuration was 1.17Ⅰ+20.71Ⅱ+0.56Ⅲ+2.25Ⅳ+0.08Ⅴ+0.06Ⅵ.BC1 and BC2 from polyploids and Zhongyou 821 were only obtained by embryo rescue,and they were both male sterile and low fertility for female.The BC2 plants were morphologically diverse but similar to B.napus.Genomic in situ hybridization(GISH) analysis showed that BC2 plants remained 2~5 M-genome chromosomes from B.maurorum,and chromosomes from B.napus mainly formed bivalents.In BC2 populations,the additional chromosomes frequently appeared as univalents or paired with B.napus chromosomes.