Chen Hai-Feng, Wang Hua, Li Zai-Yun
National Key Lab of Crop Genetic Improvement, National Center of Crop Molecular Breeding Technology, National Center of Oil Crop Improvement (Wuhan), Huazhong Agricultural University, Wuhan 430070, China.
Plant Cell Rep. 2007 Oct;26(10):1791-800. doi: 10.1007/s00299-007-0392-x. Epub 2007 Jun 14.
Capsella bursa-pastoris (L.) Medic (2n = 4x = 32) is a natural double-low (erucic acid < 1%, glucosinolates < 30 micromol/g) germplasm and shows high degree of resistance to Sclerotinia sclerotiorum. Hybridizations were carried out between two Brassica species viz. B. rapa (2n = 20) and B. napus (2n = 38) as female and C. bursa-pastoris as male parent to introduce these desirable traits into cultivated Brassica species. Majority of F(1) plants resembled female parents in morphology and only a few expressed some characters of male parent, including the white petals. Based on cytological observation of somatic cells, the F(1) plants were classified into five types: two types from the cross with B. rapa, type I had 2n = 27-29; type II had 2n = 20; three types from the crosses with B. napus, type III was haploids with 2n = 19; type IV had 2n = 29; type V had 2n = 38. One to two chromosomes of C. bursa-pastoris were detected in pollen mother cells (PMCs) of type I plant by genomic in situ hybridization (GISH), together with chromosomal segments in ovary cells and PMCs of some F1 plants. Amplified fragment length polymorphism (AFLP) bands specific for the male parent, novel for two parents and absent bands in Brassica parents were generated in majority of F1 plants, even in Brassica-types and haploids, indicating the introgressions at various levels from C. bursa-pastoris and genomic alterations following hybridization. Some Brassica-type progeny plants had reduced contents of erucic acid and glucosinolates associated with improved resistance to S. sclerotiorum. The cytological and molecular mechanisms behind these results are discussed.
荠菜（Capsella bursa-pastoris (L.) Medic，2n = 4x = 32）是一种天然的双低（芥酸<1%，硫代葡萄糖苷<30微摩尔/克）种质，对核盘菌表现出高度抗性。在两个芸苔属物种之间进行了杂交，即分别以白菜型油菜（B. rapa，2n = 20）和甘蓝型油菜（B. napus，2n = 38）为母本，以荠菜为父本，将这些优良性状导入栽培的芸苔属物种中。大多数F1植株在形态上类似于母本，只有少数表现出父本的一些特征，包括白色花瓣。基于体细胞的细胞学观察，F1植株被分为五种类型：与白菜型油菜杂交产生的两种类型，I型有2n = 27 - 29条染色体；II型有2n = 20条染色体；与甘蓝型油菜杂交产生的三种类型，III型是单倍体，有2n = 19条染色体；IV型有2n = 29条染色体；V型有2n = 38条染色体。通过基因组原位杂交（GISH）在I型植株的花粉母细胞（PMC）中检测到一到两条荠菜的染色体，同时在一些F1植株的子房细胞和PMC中也检测到染色体片段。大多数F1植株，甚至是芸苔属类型和单倍体植株中，都产生了父本特有的扩增片段长度多态性（AFLP）条带、双亲都没有的新条带以及芸苔属亲本中不存在的条带，这表明来自荠菜的不同水平的基因渗入以及杂交后的基因组改变。一些芸苔属类型的后代植株芥酸和硫代葡萄糖苷含量降低，对核盘菌的抗性增强。本文讨论了这些结果背后的细胞学和分子机制。
