Self-incompatibility of Prunus tenella and evidence that reproductively isolated species of Prunus have different SFB alleles coupled with an identical S-RNase allele
Article first published online: 25 APR 2007
The Plant Journal
Volume 50, Issue 4, pages 723–734, May 2007
How to Cite
Šurbanovski, N., Tobutt, K. R., Konstantinović, M., Maksimović, V., Sargent, D. J., Stevanović, V., Ortega, E. and Bošković, R. I. (2007), Self-incompatibility of Prunus tenella and evidence that reproductively isolated species of Prunus have different SFB alleles coupled with an identical S-RNase allele. The Plant Journal, 50: 723–734. doi: 10.1111/j.1365-313X.2007.03085.x
- Issue published online: 25 APR 2007
- Article first published online: 25 APR 2007
- Received 26 October 2006; revised 26 January 2006; accepted 1 February 2007.
Many species of Prunus display an S-RNase-based gametophytic self-incompatibility (SI), controlled by a single highly polymorphic multigene complex termed the S-locus. This comprises tightly linked stylar- and pollen-expressed genes that determine the specificity of the SI response. We investigated SI of Prunus tenella, a wild species found in small, isolated populations on the Balkan peninsula, initially by pollination experiments and identifying stylar-expressed RNase alleles. Nine P. tenella S-RNase alleles (S1–S9) were cloned; their sequence analysis showed a very high ratio of non-synonymous to synonymous nucleotide substitutions (Ka/Ks) and revealed that S-RNase alleles of P. tenella, unlike those of Prunus dulcis, show positive selection in all regions except the conserved regions and that between C2 and RHV. Remarkably, S8-RNase, was found to be identical to S1-RNase from Prunus avium, a species that does not interbreed with P. tenella and, except for just one amino acid, to S11 of P. dulcis. However, the corresponding introns and S-RNase–SFB intergenic regions showed considerable differences. Moreover, protein sequences of the pollen-expressed SFB alleles were not identical, harbouring 12 amino-acid replacements between those of P. tenella SFB8 and P. avium SFB1. Implications of this finding for hypotheses about the evolution of new S-specificities are discussed.