Resynthesized Brassica napus L.: A review of its potential in breeding and genetic analysis

Abstract

Brassica napus (AACC) is an important oleiferous crop species which is believed to have originated spontaneously as an amphidiploid between B. campestris (AA) and B. oleracea (CC). Thus, resynthesizing B. napus has been widely adopted as a breeding strategy to introduce desirable variation from the parental diploids into this species, which has been greatly facilitated by the development of in vitro techniques. Examples of using resynthesized B. napus in practical breeding are attempts to breed for yellow-seeded character, sterility maintainer function in the nap cytoplasmic male sterility system, high oleic acid content, spontaneous diploid androgenesis, and the character of apetaly. The usefulness of newly resynthesized B. napus in genetic analysis is indicated by examples such as the detection of the silent A-genome locus for the enzyme glucosephosphate isomerase in cultivated rapeseed, and the independent inheritance of flower colour and erucic genes in the C-genome. By comparing genotypes of resynthesized B. napus with those of the actual parental species, we have been able to identify genome specific isozyme loci which can be used as chromosome markers. In conclusion, resynthesisof B. napus will continue to be adopted as an effective strategy for both practical and academic interests. The Swedish University of Agricultural Sciences at Svalov for providing facilities. material and equipment for this work. The senior author is also deeply indebted to the Ministry of Agriculture, China, and to Svalof AB for granting scholarships. Financial support from the Swedish Council for Forestry and Agricultural Research, and the Royal Physiographic Society is gratefully acknowledged. References ABRAHAM, V. and BHATA. C. R. 1986. Development of strains with yellow seedcoat in Indian Mustard (Brassica juncea Czern. & Coss.). -PIanr Breed. 97: RM8 AKRAR, M. D. 1987a. Artificial Brassico napus flowering in Bangladesh. -Theor. Appl. Genet. 73.465466 AKRAR. M. D. 1987b. Resynthesis of Brassica napus for earliness and daylength insensitivity. -Thesis, Swed. Univ. Agric. Sci., Uppsola, Sweden Hereditus I l l (1989) POTENTIALS OF RESYNTHESIZED BRASSICA NAPUS 26 1 ATTIA, T. and ROBBELEN, G. 1986a. Cytogenetic relationships within cultivated Brussica analyzed in amphidiploids from the three diploid ancestors. -Can. J. Genet. Cytol. 28: 325329 ATTIA, T. and ROBBELEN, G. 1986b. Meiotic pairing in haploids and amphidiploids of spontaneous versus synthetic origin in rape, Brassica napus L. -Can. 1. Genet. Cytol. 28: 33&334 BANGA, S . S . 1986. Hybrid pollen-aided induction of matromorphy in Brassicu. -Z . Pflanzenziicht. 96: 86-89 (eds G. P. CHAPMAN el al.), Longmun, Great Britain, p. 164176 JARL, C. I. 1988. Photosynthesis defective male-sterile rapeseed: characterization and correction. -Thesis, Swed. Univ. Agric. Sci., Svulov, Sweden JONSSON, R. 1977. Breeding for improved oil and meal quality in rape (Brassica napus L.) and turnip rape (Brassicu campestris L.). -Hereditas 87: 205-218 JOURDAN, P, S., MUTSCHLER, M. A. and EARLE, E....

Plant Breeding: Assessment of Genetic Diversity in Crop Plants and its Exploitation in Breeding

“…Here, resynthesis of novel B. napus genotypes through artificial crosses between the diploid parents, assisted by embryo rescue, has repeatedly been shown to be useful for broadening the genetic basis of rapeseed. Both progenitor species exhibit an extremely broad genetic and phenotypic diversity that is the potential for a huge variety of different RS rapeseed forms (Chen and Heneen 1989, Song et al 1993. The relatively high extent of intergenomic recombination between A and C genome chromosomes in early generations of RS rape further increases the potential for creation of novel genotypes through resynthesis (Song et al 1993;Lydiate et al 1995).…”

Resistance to infection by stealth: Brassica napus (winter oilseed rape) and Pyrenopeziza brassicae (light leaf spot)

“…The introgression of genes from other Brassica species using synthetic lines is possible and can provide a useful source of novel resistance, but it can be difficult to recover agronomically acceptable cultivars because undesirable traits are introduced with the target genes (Chen and Heneen 1989;Bradburne et al 1999). Furthermore, deployment of major gene-mediated resistance derived from wild Brassica species may offer only a short-term yield benefit, as virulent pathogen strains are already likely to exist, as seen in the L. maculans--B. napus pathosystem (Li et al 2005;Rouxel et al 2003;Sprague et al 2006).…”

“…Some quantitative trait loci (QTL) involved in resistance have also been identified by assessing light leaf spot severity on leaves and stems (Pilet et al 1998) but their functions are unknown. The breeding of new resistant cultivars is hindered by both the narrow genetic base of B. napus (Chen and Heneen 1989) and the poor understanding of the P. brassicae--B. napus interaction in relation to the epidemiology of the disease.…”

Erucic acid rapeseed: 1. Prospects of improvements

“…This wide variability of the parents can be exploited by manipulation and re-synthesis of B. napus from the original parents. The new variety of B. napus obtained is genetically intermediate between the two parents, but very different from the natural forms of B. napus (Becker et al, 1995;Chen and Heneen, 1989;Engqvist and Becker, 1994;Friedt and Lühs, 1995;Kräling, 1987;Lydiate et al, 1993;Olsson, 1986;Song et al, 1993;Thierfelder et al, 1993).…”