Leino M, Thyselius S, Landgren M, Glimelius K
Department of Plant Biology and Forest Genetics, Swedish University for Agricultural Sciences, Box 7080, 750 07 Uppsala, Sweden.
Theor Appl Genet. 2004 Jul;109(2):272-9. doi: 10.1007/s00122-004-1644-6. Epub 2004 Apr 8.
Somatic Brassica napus (+) Arabidopsis thaliana hybrids with a cytoplasmic male sterility (CMS)-inducing cytoplasm were screened for fertility-restored plants. One line was selected and recurrently backcrossed with the maintainer line, B. napus, resulting in fertile/sterile segregating populations. Restriction fragment length polymorphism mapping showed the co-segregation of A. thaliana chromosome (chr) III markers with the fertility trait. As it was not possible to stabilise the fertility trait via selfings, a dihaploidisation strategy was assessed. Ninety haploid plants were regenerated and analysed with numerous simple sequence length polymorphism (SSLP) markers. Markers covering both arms of A. thaliana chr III were present in two plants, whereas no A. thaliana DNA could be detected in the other plants. Following colchicine-induced chromosome doubling only these two plants with A. thaliana DNA produced fertile offspring. In one of the two lines, however, the A. thaliana-specific DNA markers and fertility were lost in subsequent generations. The other line remained fertile after repeated selfings. Using genomic in situ hybridisation (GISH) we were able to demonstrate that this latter line possessed a disomic addition of the A. thaliana chromosome. The restored line was comparable to the maintainer line with respect to flower morphology, but the petals and stamens were slightly reduced in size. The homeotic conversion of stamens to pistil-like structures, which is typical for the CMS line, was reversed, and stamens with a normal appearance with viable pollen appeared. Flowering time was as in the CMS line-in both lines it was delayed in comparison to the maintainer line. The introgressed chromosome also contributes to several pleiotropic effects, such as reduced leaf crinkling and shorter stems. The ability to restore fertility through the introgression of nuclear genes from the main cytoplasmic donor species indicates that the CMS trait in this system mainly is due to B. napus/ A. thaliana alloplasmic incompatibility and not mitochondrial DNA rearrangements. Further exploitation of the material is discussed.
筛选具有细胞质雄性不育（CMS）诱导细胞质的甘蓝型油菜（+）拟南芥体细胞杂种，以获得育性恢复植株。选择了一个株系，并与保持系甘蓝型油菜反复回交，产生了可育/不育分离群体。限制性片段长度多态性图谱显示拟南芥Ⅲ号染色体（chr）标记与育性性状共分离。由于无法通过自交稳定育性性状，因此评估了双单倍体化策略。再生了90株单倍体植株，并用大量简单序列长度多态性（SSLP）标记进行分析。覆盖拟南芥Ⅲ号染色体双臂的标记存在于两株植物中，而在其他植物中未检测到拟南芥DNA。秋水仙素诱导染色体加倍后，只有这两株含有拟南芥DNA的植物产生了可育后代。然而，在这两个株系中的一个中，拟南芥特异性DNA标记和育性在后代中丢失。另一个株系在反复自交后仍保持可育。使用基因组原位杂交（GISH），我们能够证明后一个株系具有拟南芥染色体的双体附加。恢复育性的株系在花形态方面与保持系相当，但花瓣和雄蕊大小略有减小。CMS株系典型的雄蕊向雌蕊状结构的同源异型转化被逆转，出现了外观正常且有活力花粉的雄蕊。开花时间与CMS株系相同——与保持系相比，两个株系的开花时间都延迟了。导入的染色体还导致了一些多效性效应，如叶片皱缩减少和茎变短。通过导入主要细胞质供体物种的核基因来恢复育性的能力表明，该系统中的CMS性状主要是由于甘蓝型油菜/拟南芥异质不亲和性，而不是线粒体DNA重排。讨论了对该材料的进一步利用。
