The number, age, sharing and relatedness of S-locus specificities in Prunus

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Vieira, J (Author) Other; Nuno A Fonseca (Author) Other; Santos, RAM (Author) Other; Habu, T (Author) Other; Tao, R (Author) Other; Cristina Vieira (Author) Other

Journal

Title: Genetics Research

Vol. 90

Pages: 17-26

ISSN: 0016-6723

Indexing

ISI Web of Knowledge - 15 Citations

Scopus - 14 Citations

Other information

Authenticus ID: P-004-1R2

DOI: 10.1017/s0016672307009044

Abstract (EN): In gametophytic self-incompatibility systems, many specificities (different 'lock-and-key' combinations) are maintained by frequency-dependent selection for very long evolutionary times. In Solanaceae, trans-specific evolution (the observation that an allele from one species may be more closely related to an allele from another species than to others from the same species) has been taken as an argument for the very old age of specificities. In this work, by determining, for the first time, the age of extant Prunus species, we show that this reasoning cannot be applied to Prunoideae. Furthermore, since our sample size is large (all S-RNase encoding the female component and SFB encoding the male component GenBank sequences), we were able to estimate the age of the oldest Prunus specificities. By doing so, we show that the lower variability levels at the Prunus S-locus, in comparison with Solanaceae, is due to the younger age of Prunus alleles, and not to a difference in silent mutation rates. We show that the ancestor to extant Prunus species harboured at least 102 specificities, in contrast to the maximum of 33 observed in extant Prunus species. Since the number of specificities that can be maintained in a population depends on the effective population size, this observation suggests a bottleneck in Prunus evolutionary history. Loss of specificities may have occurred during this event. Using only information on amino acid sites that determine specificity differences, and a simulation approach, we show that a model that assumes closely related specificities are not preferentially lost during evolution, fails to predict the observed degree of specificity relatedness.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10