Summary
We have shown in previous papers that self-incompatibility in Lolium perenne and L. multiflorum is determined, as in the other grasses that have been adequately investigated, by a pair of multi-allelic genes and that the control of the pollen phenotype is gametophytic (Cornish, Hayward and Lawrence, 1979; Fearon, Hayward and Lawrence, 1983). We also attempted to show in these papers that the claim by Spoor (1976) and Hay (1978) that self-incompatibility in these species was determined by at least three genes was based on data which was open to question on technical grounds. Despite this criticism, however, McCraw and Spoor (1983a, b) have repeated this claim. In the present paper we show that their claim cannot be supported by their data because (i) they have not fully classified their pollinations into grades of compatibility; (ii) they have not attempted to fit a specific genetical model to their data; and (iii) the probability that their data, even if this is taken at face value, is consistent with their claim is very small. We argue, therefore, that these data and the conclusions that are drawn are too untrustworthy to be taken seriously. Since the only other case, not superseded by more recent work, is also vulnerable to this criticism (Murray, 1979), there is no justification for supposing that self-incompatibility, either in the genus Lolium or in the grasses in general, is determined by more than two genes. It follows, therefore, that an attempt by Østerbye, Larsen and Lundqvist (1980) to argue that our conclusions are consistent with those of Spoor and McCraw (née Hay) is unnecessary.
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Lawrence, M., Fearon, C., Cornish, M. et al. The genetical control of self-incompatibility in ryegrasses. Heredity 51, 461–466 (1983). https://doi.org/10.1038/hdy.1983.56
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DOI: https://doi.org/10.1038/hdy.1983.56
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