Intertribal somatic hybrids between Brassica napus and Thlaspi perfoliatum with high content of the T. perfoliatum-specific nervonic acid

Abstract

Protoplast fusions were performed between hypocotyl protoplasts of Brassica napus and mesophyll protoplasts of Thlaspi perfoliatum. The two species are members of the Lepidieae and Brassiceae tribes, respectively, in the family of Brassicaceae. Seeds of T. perfoliatum are rich in the fatty acid C24∶1 (nervonic acid), an oil valuable for technical purposes. In the search for renewable oils to replace the mineral oils, plant breeders have been trying to develop oil crops with a high content of long-chain fatty acids. After fusion of B. napus protoplasts with non-irradiated as well as irradiated protoplasts of T. perfoliatum selection was carried out by flow cytometry and cell sorting. Of the shoots regenerated from different calli 27 were verified as hybrids or partial hybrids using the isoenzyme phosphoglucose isomerase (PGI) as a marker. Another 6 plants were identified as partial hybrids using a T. perfoliatum-specific repetitive DNA sequence. Slot blot experiments were performed to estimate the copy number of the repetitive DNA sequence in the parental species and in the hybrids. In T. perfoliatum there were approximately 10(5) copies per haploid genome, and the range in the hybrids was 1-37% of the value in T. perfoliatum. When the nuclear DNA content of the regenerated shoots was analysed we found partial as well as symmetric hybrids. Even though the rooting and establishment of hybrid shoots in the greenhouse were difficult, resulting in the death of many plants, 19 plants were cultured to full maturity. Seeds obtained from 15 plants were analysed to determine whether they contained nervonic acid, and 5 of the hybrids were found to contain significantly greater amounts of nervonic acid than B. napus.

Intergeneric Somatic Hybridization Between Brassica napus L. and Sinapis alba L.

“…Fahleson et al (1994) produced intertribal somatic hybrids between B. napus and Thlaspi perfoliatum and seeds of the hybrids contained 4.9% nervonic acid, which does not exist in B. napus. Skarzhinskaya et al (1996) generated asymmetric somatic hybrids between B. napus and Lesquerella fendleri (Gray) Wats., leading to a production of 4.3% ricinoleic acid in the F 1 plant.…”

“…The oil quality of B. napus depends on the composition, chain length, degree of desaturation, and functional groups of fatty acids (Friedt and Lühs 1998). In order to make the oil suitable for industrial purposes, some attempts have been made to modify the fatty acid composition of rapeseed using modern biotechnology, such as somatic hybridization (Fahleson et al 1994;Earle 1995, 1997;Wang et al 2003) and genetic transformation (Voelker et al 1992;Weier et al 1998;Schröder-Pontoppidan et al 2000;Taylor et al 2001;Wang et al 2004a).…”

Erucic acid rapeseed: 1. Prospects of improvements

“…Thus, fertile hybrids between B. napus and Arabidopsis thaliana (Forsberg et al, 1994;Friedt and Lühs, 1995) or between B. napus and Thlaspi perfoliatum (Fahleson et al, 1994;Friedt and Lühs, 1995) were obtained. However, this method is limited by several factors: the problem of sustainability of plants, fewer fertile plants, new obtained material far from being cultivable (and therefore requiring series of backcrosses, i.e.…”

Protoplast cultures and protoplast fusion focused on Brassicaceae: A review

“…After pollination with the radish pollen, seeds did not develop, but after pollination with the cabbage pollen, seeds developed. According to morphology, number of chromosomes, isoenzyme patterns and frag- FAHLESON et al (1994b) Thlaspi caerulescens + B. napus BREWER et al (1999) ments of chloroplast DNA, the plants were intergeneric hybrids containing the nucleus of cabbage and the chloroplasts of radish. Their findings suggest the possibility of inducing male cytoplasmic sterility between distant related species.…”

“…Nervonic acid is valued for technical purposes, but in Brassica napus it is present in only small volumes, therefore there is an interest in transferring the genes regulating the creation of this fatty acid into B. napus (rape). FAHLESON et al (1994b) carried out protoplast fusions between hypocotyl protoplasts of B. napus and mesophyll protoplasts of Thlaspi perfoliatum. Isoenzymes were used as markers for the testing of hybridity.…”