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Valley of the genes
Plant breeders are constantly searching for useful genetic variation. For 'old' and/or intensively selected crops, such variation may be hard to find: much of it has already been identified and incorporated into breeding programmes. Breeders may then attempt wider interspecies hybridizations or may use GM techniques to transfer genes across species barriers. However, for 'newer' and/or less intensively selected crops there may be extensive unexploited variation within the species. A good example of this is white lupin, Lupinus albus. It is already widely grown in mainland Europe and is considered to have potential as a 'high-protein' crop for the UK (see Kerley et al., pp. 341-349). However, the major European cultivars are calcifuges (lime-intolerant) and this will limit the potential area for cultivation. Lime-intolerance shows itself in several ways, including failure to regulate calcium concentrations (which may lead to growth abnormalities) and inhibition of iron uptake, leading to chlorosis and photosynthetic inefficiency. These symptoms, clearly visible when L. albus is grown on limed soil, do not occur in the lime-tolerant species, L. pilosus. Three questions then arise. First, what is the molecular basis for tolerance? Secondly, which of the responses to lime, if any, are suitable for use as a rapid screen during breeding programmes? Thirdly, where will the desired traits come from? In ancient times, the children of Israel found corn in Egypt during a famine. Many centuries later, modern plant breeders have looked to Egypt for a possible solution to their needs: certain Egyptian varieties of lupin are lime-tolerant. And thus, an intensive trialling and screening programme is underway, combined with molecular studies aimed at identifying the relevant genes. It is as yet too soon to say whether the Egyptian lime-tolerance trait can be introgressed into UK varieties but early results give hope for the future.
Professor J. A. Bryant
University of Exeter, UK
j.a.bryant{at}exeter.ac.uk
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