Arabidopsis thaliana chromosome III restores fertility in a cytoplasmic male-sterile Brassica napus line with A. thaliana mitochondrial DNA

Abstract

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.

A Novel Cytoplasmic Male Sterility in Brassica napus (inap CMS) with Carpelloid Stamens via Protoplast Fusion with Chinese Woad

“…This further testified that the fertility restoration gene(s) of alloplasmic CMS lines generally existed in nuclear genome of cytoplasm donor species. The restoration gene of a B. napus CMS line with rearranged A. thaliana mtDNA was located on chromosome III of A. thaliana (Leino et al, 2004). The restorer line for Nsa CMS of B. napus developed by the somatic hybridization with Sinapis arvensis was one disomic addition line with the restoration gene on the alien chromosome (Wei et al, 2010).…”

Intergeneric somatic hybridization and its application to crop genetic improvement

“…Similarly, the cybrids between tobacco and Hyoscyamus niger showed late germination of seeds, dramatic decrease in chlorophyll in vivo and pigment deficiency in cotyledons in vitro owing to nucleo-cytoplasmic incompatibilities (Zubko et al, 2001). In addition, alloplasmic incompatibility between nucleus and mitochondria was reported to be responsible for CMS in somatic hybrids between A. thaliana and B. napus and their progenies (Leino et al, 2004).…”

“…Besides, CMS present in some species with reproductive defects cannot be transferred by traditional way. To date successful CMS transfer via protoplast fusion has been accomplished in several combinations, such as sunflower and chicory (Rambaud et al, 1993;Varotto et al, 2001), A. thaliana and B. napus (Forsberg et al, 1998a;Leino et al, 2003Leino et al, , 2004, R. sativus and B. oleracea (Kameya et al, 1989;Kanno et al, 1997), tobacco and Petunia hybrida (Dragoeva et al, 1999), B. juncea + Moricandia arvensis . In addition intergeneric transfer of CMS has been accomplished between R. sativus and B. napus via cytoplast-protoplast fusion (Sakai and Imamura, 1990).…”

Cytoplasmic male sterility in Brassicaceae crops

“…A recombined mitochondrial genome was found in B. napus CMS lines derived from somatic hybridization with A. thaliana (Carlsson et al 2007, Leino et al 2003, 2004, Teixeira et al 2005). The association of fertility restoration with markers on chromosome 3 of A. thaliana suggested that the male sterility genes are also derived from A. thaliana (Leino et al 2004). …”