Synthesis of Brassica oleracea/Brassica napus somatic hybrid plants with novel organeile DNA compositions

Abstract

Broccoli (Brassica oleracea L. italica) hypocotyl protoplasts were fused with mesophyll protoplasts of two B. napus lines, one carrying the Ogura (ogu) cms cytoplasm, and the other carrying a hybrid cytoplasm consisting of ogu mitochondria combined with triazine-tolerance-conferring chloroplasts from ctr cytoplasm. Two male-sterile somatic hybrids were recovered from the fusion of broccoli protoplasts with those of ogu/ctr cybrid B. napus. The ogu mtDNAs and ctr cpDNAs were not altered in these hybrids. Four male-sterile plants were recovered from the somatic hybridization of broccoli with ogu cms B. napus. Three of these possessed mitochondrial genomes that appeared to have resulted from recombination between the ogu and normal B. oleracea (ole) mtDNAs, while the fourth possessed an unrearranged ogu mtDNA. All four of these plants had B. oleracea cpDNA, and none displayed the seedling chlorosis associated with ogu chloroplasts. Most of the plants recovered from these fusions had the chromosome number expected of B. oleracea + B. napus hybrids (2n = 56). The novel cytoplasms may prove to be useful for the molecular analysis of Brassica cms and for the production of hybrid Brassica.

Genetic correlation of the orf224/atp6 gene region with Polima CMS in Brassica somatic hybrids

“…oleracea mitochondrial genome are also malefertile [6]. The male sterility of the somatic hybrids produced in the present experiments therefore apparently results from the transmittal of CMS-conferring factors from the pol mitochondrial genome.…”

“…We have generated somatic hybrids ofpol CM S B. napus and fertile broccoli (B. oleracea L. var. italica), using a previously described selection scheme for the elimination of unfused B. napus and B. oleracea protoplasts [6]. We recovered three sterile plants, designated OFP3, OFP5 and OFP16 from a single fusion experiment.…”

A stable cytoplasmic male‐sterile line of Brassica juncea carrying restructured organelle genomes from the somatic hybrid Trachystoma ballii+B. juncea

“…From the hybridization pattern of mitochondrial probes it was evident that the CMS line obtained from the somatic hybrid T. ballii + B.juncea carried a novel mitochondrial genome organization resulting from intergenomic mitochondrial DNA recombination. Mitochondrial recombination in parasexual hybrids is a common phenomenon and has been frequently documented (Kao et al 1992, Landgren and Glimelius 1994, Kirti et al 1995b. were involved in recombination, particularly the regions surrounding atpb and coxl.…”

Male Sterility

“…CMS has been obtained frequently using this approach, thanks to incompatible mitochondria/nucleus interactions resulting from the introduction of the nuclear genome of one species into an alien cytoplasm. Subsequently, similar experiments were performed on "Ogura" CMS in B. napus (Menczel et al 1987;Jarl and Bornman 1988;Jarl et al 1989) as well as in B. oleracea (Pelletier et al 1988(Pelletier et al , 1989Kao et al 1992;Walters et al 1992;Walters and Earle 1993) and in B. juncea (Kirti et al 1995a). A first practical example emerged when the male sterility inducing cytoplasm of radish (Ogura 1968) was introduced into B. oleracea, B. napus, B. rapa and B. juncea.…”