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The S-genotypes of a set of Turkish and Hungarian apricot (Prunus armeniaca L.) cultivars were determined by polymerase chain reaction (PCR) amplification of their S-RNase intron regions. In addition, the S-genotyping method was extended to the SFB gene to detect the non-functional S C-haplotype and hence reliably identify self-compatible apricot cultivars. We determined the complete S-genotype of 51 cultivars and the partial S-genotype of four cultivars. A total of 32 different S-genotypes were assigned to the 51 cultivars, and many of them (28) were classified into newly established cross-incompatibility groups III through XIV. Another 12 cultivars demonstrated unique incompatible genotypes and seven self-compatible cultivars were identified in the examined accessions. The fact that Turkish and Hungarian apricot cultivars carry 12 and five S-alleles, respectively, and all five alleles detected in Hungarian cultivars were also present in Turkish apricots furnished molecular evidence supporting the long-suspected historical connection between Hungarian and Turkish apricots. The connection between these two gene pools appeared to be relatively recent and associated with historical events dating back 300 years. Our results confirm that Turkish germplasm contributed considerably to the development of several desirable Hungarian apricot cultivars. Results suggest that the mutation rendering the S C-haplotype non-functional might have occurred somewhere east of central Turkey.
The most commercially grown peach [Prunus persica (L.) Batsch.] cultivars do not require cross-pollination for reasonable fruit set; however, self-incompatibility is a well-known feature within the Prunoideae subfamily. Isoelectric focusing and native polyacrylamide gel electrophoresis of S-ribonucleases; PCR analyses of S-RNase and S-haplotype-specific F-box genes as well as DNA sequencing were carried out to survey the self-(in)compatibility allele pool and to uncover the nature of self-compatibility in peach. From 25 cultivars and hybrids with considerable diversity in phenotype and origin, only two S-haplotypes were detected. Allele identity could be checked by exact length determination of the PCR-amplified fragments and/or partial sequencing of the peach S 1-, S 2-, and Prunus davidiana (Carr.) Franch. S 1-RNases. S-RNases of peach were detected to possess ribonuclease activity, and a single nucleotide polymorphism in the S 1-RNase was shown, which represents a synonymous substitution and does not change the amino acid present at the position in the protein. A 700-bp fragment of the peach SFB gene was PCR-amplified, which is similar to the fragment size of functional Prunus L. SFBs. All data obtained in this study may support the contribution of genes outside the S-locus to the self-compatible phenotype of peaches.
Diploid japanese plum (Prunus salicina Lindl.) cultivars are commonly self-incompatible. To date, 14 incompatibility alleles (S-alleles) have been identified and labeled with alphabetical (S a-S n) and 5 with numeric codes (S 1, S 3-S 6). We applied polymerase chain reaction amplification of the S-RNase alleles with degenerate and allele-specific primers in 10 japanese plum cultivars and two pluots of unknown incompatibility alleles. Besides DNA sequencing, an additional method for the exact length determination of the first intron region was used for the first time for S-genotype japanese plums. The S 3-allele was shown to correspond to S k in the alphabetic nomenclature, S 4 to S c, S 5 to S e, and S 6 to S f. The S 5-allele-specific primer can be used as a reliable marker for self-compatibility in japanese plum. ‘Black Amber’, ‘October Sun’, ‘TC Sun’, and ‘Super Giant’ share the S b S c genotype, which was confirmed by test crosses. These cultivars belong to the widest incompatibility group currently known in japanese plum. An additional incompatibility group (S c S h) was established, including ‘Green Sun’ and ‘Queen Rosa’, a cultivar formerly known as a universal donor. By incorporating all previous and recent results, a table was assembled including 49 cultivars assigned to I–VII incompatibility groups, to the self-compatible group and to the group O of unique genotypes. These data may considerably contribute to further growing and breeding activities.