Identification of Allopolyploids of Chinese Cabbage (Brassica campestris L.ssp. pekinensis(Lour.) Olsson) and Cabbage (B. oleracea var. capitata L.) | 大白菜与结球甘蓝种间异源多倍体的鉴定

Chino. 利用异源多倍体作为桥梁材料是克服远缘杂交障碍，创制新种质和进行品种改良的一种重要途径。本研究对已获得的大白菜(Brassica campestris L. ssp. pekinensis (Lour.) Olsson)与结球甘蓝(Brassica oleracea var. capitata L.)种间异源四倍体和异源三倍体，利用形态学、解剖学、分子标记及细胞学等方法进行比较鉴定。研究表明，多倍体在植株形态、花器官和气孔大小等方面均表现出巨大性和超亲优势，其中四倍体比三倍体表现普遍更明显。多倍体的气孔密度显著的低于双亲。多倍体花粉生活力比双亲降低，四倍体花粉活力为81.56%，三倍体的花粉活力仅有18.78%。多倍体自交结实性明显低于双亲，四倍体自交结实率仅为0.28%；四倍体作为母本与大白菜杂交结籽率比其反交要高，是反交的2.11倍，以三倍体为母本或父本时与大白菜杂交，结实均非常低，且三倍体自交未获得种子。相关序列扩增多态性(SRAP)标记结果表明，多倍体中包含了双亲的遗传信息，但分子标记并不能区分四倍体与三倍体。细胞学观察显示，四倍体的染色体数目为2n=4x=38，三倍体的染色体数目为2n=3x=29。大白菜-结球甘蓝异源多倍体的鉴定为进一步大白菜品种改良和新种质的创制提供了基础资料。

Inglés. Allopolyploid can be used as a bridge to overcome distant hybridization barriers and a promising approach to improve varieties. In this study, allotriploid and allotetraploid hybrids between Chinese cabbage(Brassica campestris L.ssp.pekinensis(Lour.) Olsson) and cabbage (B. oleracea var. capitata L.) were identified by morphological, anatomical and cytological observation and molecular markers analysis. Results showed that polyploidy plants showed obvious heterosis in plant types, floral organ and stomata sizes and allotetraploid heterosis was more obvious than that of allotriploid generally. The pollen viability and stomata density of polyploids were lower than that of both parents and pollen viability of allotriploid was the lowest of 18.78%, whereas it reached 81.56% in allotetraploid. The seed setting rates in the selfing of allopolyploids were lower than that of both parents, which in selfing of allotetraploid was 0.28%. The seeds setting rate was higher in crossing allotetraploid with Chinese cabbage than that in their inverse cross combinations, which increased by 2.11 times. The seed setting rate of reciprocal crosses between allotriploid and Chinese cabbage was very low, and no seed was obtained in the selfing of allotriploid. The SRAP assay further confirmed that polyploids included the genetic information of their parents and were the true hybrid, while it was hard to distinguish allotriploid from allotetraploid by SRAP. Cytological identification revealed that the allotetraploid had putative chromosomes (2n=4x=38) and the allotriploid had putative chromosom(2n=3x=29). The obtaining and identification of allopolyploids provide a foundation for the improvement of Chinese cabbage cultivars in the near future.