Synthesis of male sterile, triazine-resistant Brassica napus by somatic hybridization between cytoplasmic male sterile B. oleracea and atrazine-resistant B. campestris

Abstract

Fusion of leaf protoplasts from an inbred line of Brassica oleracea ssp. botrytis (cauliflower, n=9) carrying the Ogura (R1) male sterile cytoplasm with hypocotyl protoplasts of B. campestris ssp. oleifera (cv "Candle", n=10) carrying an atrazine-resistant (ATR) cytoplasm resulted in the production of synthetic B. napus (n=19). Thirty-four somatic hybrids were produced; they were characterized for morphology, phosphoglucose isomerase isoenzymes, ribosomal DNA hybridization patterns, chromosome numbers, and organelle composition. All somatic hybrids carried atrazine-resistant chloroplasts derived from B. campestris. The mitochondrial genomes in 19 hybrids were examined by restriction endonuclease and Southern blot analyses. Twelve of the 19 hybrids contained mitochondria showing novel DNA restriction patterns; of these 12 hybrids, 5 were male sterile and 7 were male fertile. The remaining hybrids contained mitochondrial DNA that was identical to that of the ATR parent and all were male fertile.

Patterns of mitochondrial DNA instability in Brassica campestris cultured cells

“…Our preliminary results indicate at least alterations mapping within a SalI fragment of 11.8 kb [see map in 33] as well as sequences flanking atp9, atp6, and cox1 regions (unpublished data). The susceptibility of the Ogura mitochondrial genome to structural changes following in vitro manipulations has also been reported by other groups employing different techniques [47,36,35,21].…”

“…Third, both in our evolutionary and in vitro studies we noted that most of the structural alterations of the Brassica mitochondrial genome occur at specific sites via recombination across short repeated elements. Although a number of studies have already demonstrated an increased plasticity of plant mtDNA in response to tissue culture manipulations [ 17,7,39,41,50,21,4] it is still uncertain as to whether these 'culture-induced' alterations occur systematically in all higher-plant species or whether they reflect particular culture conditions such as culture age [34] or the in vitro technique employed [23]. A study of in vitro mtDNA alterations of maize [7] has also shown that the occurrence of specific types of rearrangements (i.e.…”

“…inversion, deletion/insertion, transposition) in the organization of the mitochondrial genome may be observed [7, 34,62]. The instability of the mitochondrial genome has been investigated in somatic hybrids [ 15,38,60,41,21 ] as well as in vitro cultures of various plant systems [8,39,18,58,50,4]. An often cited example of culture-induced somaclonal variation associated with mtDNA is the reversion to fertility of different cytoplasmic malesterile types in maize [16,5,12,48].…”

Expression of self-incompatibility and fertility of Brassica napus L. resynthesized by interspecific somatic hybridization

“…Use of trade names does not imply endorsement of the products named nor criticism of similar ones omitted. and B. rapa (Schenck & R6bbelen, 1982;Sundberg & Glimelius, 1986;Robertson et al, 1987;Sundberg et al, 1987;Rosdn et al,, 1988;Jourdan et al, 1989;Yamashita et al, 1989). While sporophytic self-incompatibility (SI) is common within the diploid species and is often used in the commercial production of hybrid cultivars (Dickson & Wallace, 1986), most natural B. napus is self-compatible (SC), with some exceptions (Gemmell et al, 1989;Gowers, 1989).…”

“…While sporophytic self-incompatibility (SI) is common within the diploid species and is often used in the commercial production of hybrid cultivars (Dickson & Wallace, 1986), most natural B. napus is self-compatible (SC), with some exceptions (Gemmell et al, 1989;Gowers, 1989). Several previous studies in the somatic resynthesis of B. napus have emphasized cytoplasmic male sterility for use in commercial hybrid production in canola (Sundberg & Glimelius, 1986;Robertson et al, 1987;Sundberg et al, 1987;Ros6n et al, 1988;Jourdan et al, 1989), yet none have explored the interaction among S-alleles in somatic hybrids of the two closely-related diploid species.…”