Click on the image below to download my paper on breeding evening primrose.

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Selected additional papers:

• Fieldsend, A.F. and Singh, H.P. (2013): Biofuel crops, ecosystem services and biodiversity. In B.P. Singh (ed.), Biofuel Crop Sustainability. Wiley-Blackwell Publishing, 357-382.

• Láposi, R., Veres, Sz., Lakatos, Gy., Oláh, V., Fieldsend, A.F. and Mészáros, I. (2009): Responses of leaf traits of beech (Fagus sylvatica L.) saplings to supplemental UV-B radiation and UV-B exclusion. Agricultural and Forest Meteorology 149 (5), 745-755.

• Kiss Trócsányi, Zs., Fieldsend A.F. and Wolf D.D. (2009): Yield and canopy characteristics of switchgrass (Panicum virgatum L.) as influenced by cutting management. Biomass & Bioenergy 33, 442–448.

• Mendoza de Gyves, E., Sparks, C.A., Fieldsend, A.F., Lazzeri, P.A. and Jones, H.D. (2001): High frequency of adventitious shoot regeneration from commercial cultivars of evening primrose (Oenothera spp.) using thidiazuron. Annals of Applied Biology 138, 329-332.

• Fieldsend, A.F. (1995): Borage: a crop with a future? Biologist 42 (5), 203-207.


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My Plant Breeding Work

Although my plant breeding experience includes working with cereals and sugar beet, most of my time has been spent on developing novel oilseed crops, especially evening primrose (Oenothera spp.) and borage (Borago officinalis). This work is briefly described here.

Evening primrose breeding

In recent decades, evening primrose has been grown as an agricultural crop in several parts of the world. Its value is derived from its seed oil which contains unusually high levels of γ-linolenic acid. The Scotia Pharmaceuticals Ltd. breeding programme began with the collection, from many sources, of over 2000 'accessions', the best of which were then used as parents in the crossing programme.

Evening primrose breeding presents two major problems:

  • A unique genetic system, based on the formation of chromosome rings at meiosis, ordered chromosome movement and the presence of lethal genes, limits segregation (and therefore scope for selecting improved lines) in the generations following the initial cross;
  • As a non-domesticated plant, evening primrose exhibits several wild characteristics unsuitable for agriculture. Long-term seed dormancy ensures the survival of the species in unpredictable environments, but leads to weed problems in crops following evening primrose in the farmer's rotation. The seed-bearing capsules of wild evening primrose split as they mature, aiding seed dispersal in the wild, but leading to significant losses in crop yield.

Because of its unique genetic system evening primrose behaves as a true breeding F1 hybrid. The progeny of self pollination are identical to the parent, whilst the progeny of a cross will show features of both parents, but will be uniform and will not show segregation in later generations. This problem was minimised by the use of a modified pedigree breeding method, entailing a large number of crosses and small F2 populations. A source of non-splitting capsules was identified and the character successfully incorporated into improved genetic material, whilst levels of seed dormancy were much reduced.

Other breeding objectives are shared with mainstream crops. These include higher seed yield, oil content and γ-linolenic acid content, plus earlier maturity and improved disease resistance, particularly to Septoria oenotherae and Botrytis cinerea. Cultivars incorporating these improvements have entered agricultural production in various parts of the world, and seven cultivars, with names such as Cossack, Constable, Juno, Orion, Merlin and Starfire, have been awarded Plant Breeders Rights in four countries.

In the cultivar Rigel the γ-linolenic acid content in evening primrose oil was increased by 50 per cent (13.5 per cent c.f. 9 per cent) over previously available levels (Figure 1).

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The combination of a high oil content and a high γ-linolenic acid content (Figure 2) meant that Rigel oil provided Scotia Pharmaceuticals Ltd. with a unique selling advantage for its nutritional supplements and allowed an 18 per cent reduction in the company's pharmaceutical product manufacturing costs.

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The genetic diversity available within evening primrose offered the potential for further improvements in the crop, including the production of high GLA, daylength-neutral lines. The use of plant transformation techniques promised the prospect of further significant improvements in oil quality (Figure 3).

Graph

Borage breeding

For the plant breeder borage differs from evening primrose in several significant respects:

  • It has a conventional genetic system;
  • It is insect pollinated, rather than self pollinated;
  • The growing season is much shorter;
  • The seed multiplication ratio is much lower.

The Scotia Pharmaceuticals Lts. borage breeding programme commenced in 1984 with the acquisition and evaluation of genetic material. Over 800 borage ‘accessions’ were trialled in single-row, unreplicated plots and assessed for various characters including height, disease resistance, flower colour, seed holding ability, yield, oil content and fatty acid profile. A crossing programme using the best accessions started in 1987. Controlled cross-pollinations were carried out in an insect-proof glasshouse. Scotia’s first borage replicated yield trial was conducted in 1990.

The crossing programme has pursued two primary objectives, initially as separate programmes:

  • Development of ‘non-shedding’ lines. One of the accessions proved to retain its seed through to maturity. This character was incorporated into a range of genetic material and its genetic control has been studied. The cultivar Penny is non-shedding. Trials results demonstrated that Penny will yield 33 per cent more seed than conventional borage (conventional borage yields 0.6 t ha-1, Penny will yield 0.8 t ha-1). It is a dwarf variety and is suited to farms which have a high level of management input and in these conditions will give a high return in terms of seed yield;
  • Improvement in GLA content. Borage oil was envisaged as a feedstock for GLA concentration. An oil with improved GLA content would lead to a reduction in manufacturing costs. The cultivar Florin is a product of this work. Florin is a robust, easy-to-grow cultivar, well suited to all growers with experience of producing borage.

Penny and Florin have both been awarded Plant Variety Rights across the EU.

The γ-linolenic acid content in the oil of Florin is 10 per cent higher than that of other cultivars (Figure 4). This was critically important to Scotia. Even allowing for the annual variation in γ-linolenic acid contents caused by differing temperatures during seed ripening, these lines should reliably produce an oil containing at least 22 per cent GLA, the specification demanded by Scotia for cost-efficient pharmaceutical concentrate production.

Graph

The breeding line ATK which was first yield trialled in 1998 combined the non-shedding character with a good yield and a high γ-linolenic acid content in the oil.

Maintenance of uniform stocks of borage, which is readily cross-pollinated by bees, is fairly difficult. The non-shedding character is particular problem, as non-shedding plants can only be identified at maturity, i.e. after pollination has occurred. The 1998 crossing programme included non-shedding lines, high γ-linolenic acid lines and genetic material containing ‘marker’ genes (e.g. white, rather than blue, flowers). In the cultivars which will result, it can be assumed that plants present with ‘wild-type’, genetically dominant pigmentation are off-types. In seed multiplication plots these can thus be identified and removed before they flower and ‘off-type’ pollen is dispersed.

Although improvement in oil content was not in itself a primary breeding objective, lines in trial were identified which combine a particularly high oil content with good all-round performance.

Conclusion

Very significant improvements in the yield and quality of both evening primrose and borage achieved through plant breeding were coupled with the prospect of further improvements to follow.

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