Genetic polymorphism for cyanogenesis and linkage at the linamarase locus in Trifolium nigrescens Viv. subsp. nigrescens |
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Authors: | W. M. Williams M. L. Williamson |
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Affiliation: | (1) AgResearch Grasslands, Private Bag 11008, Palmerston North, New Zealand e-mail: warren.williams@agresearch.co.nz Tel.: +64 6 351 8005, Fax: +64 6 351 8128, NZ |
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Abstract: | Polymorphisms at two genetic loci conditioning the cyanogenic glucoside linamarin (Ac) and the glucosidase linamarase (Li) are reported for the first time in Trifolium nigrescens Viv. subspecies nigrescens (2n=2x=16). T. nigrescens is one of several possible ancestral species that may have donated a genome to the allotetraploid species white clover (T. repens L., 2n=4x=32). T. nigrescens is a strong candidate because it is the only very close relative that, like white clover, is cyanogenic. Genetic analysis showed that in T. nigrescens, cyanogenesis was inherited as a two-locus genetic system in a similar way to that in white clover. Furthermore, Li, which is linked to the locus Sdh (shikimate dehydrogenase, SDH) at a distance of 6 cM in one genome of white clover, also showed linkage (12 cM) in T. nigrescens. It is concluded that one of the subspecies of T. nigrescens is a likely donor of a genome to white clover. Received: 27 December 2000 / Accepted: 12 April 2001 |
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Keywords: | Trifolium nigrescens Trifolium repens Cyanogenesis Linamarase Shikimate dehydrogenase |
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