Update on and Review of the Incompatibility (S-) Genotypes of Apple Cultivars

Apple cultivars display a self-incompatibility system that restricts self-fertilization and fertilization between cultivars bearing identical S-alleles. There has been considerable progress in identification of S-alleles in apple in recent years and methods are now available for the accurate S-genotyping of cultivars. Following a recently revised numerical identification system for apple S-alleles, we present the first extensive compilation of apple cultivars with their S-genotypes. This list contains data from our own investigations using S-allele-specific PCR methodology, including a number of new data, as well as published data from various other sources. Eighteen different S-alleles are discriminated, which allowed the determination of the S-genotypes for 150 diploid or triploid European, American, and Japanese cultivars. Many of these cultivars are cultivated worldwide for their fruit. Also included are a number of old, obsolete cultivars and a few nondomestic genotypes. We observed a wide variation in the frequency of S-alleles in the apple germplasm. Three S-alleles (S2, S3, and S9) are very common in the cultivars evaluated, presumably as a result of the widespread use of the same breeding parents, and seven alleles are very rare (S4, S6, S8, S16, S22, S23, S26).

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Characterization of three new S-alleles and development of an S-allele-specific PCR system for rapidly identifying the S-genotype in apple cultivars

Tree Genetics & Genomes ◽

10.1007/s11295-009-0237-6 ◽

2009 ◽

Vol 6 (2) ◽

pp. 161-168 ◽

Cited By ~ 19

Author(s):

Shenshan Long ◽

Maofu Li ◽

Zhenhai Han ◽

Kun Wang ◽

Tianzhong Li

Keyword(s):

Specific Pcr ◽

S Alleles ◽

Allele Specific ◽

Apple Cultivars ◽

S Allele ◽

Allele Specific Pcr

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Combined Analysis of S-Alleles in European Pear by Pollinations and PCR-based S-Genotyping; Correlation between S-Phenotypes and S-RNase Genotypes

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.133.2.213 ◽

2008 ◽

Vol 133 (2) ◽

pp. 213-224 ◽

Cited By ~ 23

Author(s):

Javier Sanzol ◽

Timothy P. Robbins

Keyword(s):

Pollen Tube ◽

Fruit Set ◽

Breeding Programs ◽

European Pear ◽

Specific Pcr ◽

S Alleles ◽

Allele Specific ◽

S Allele ◽

Consensus Primers ◽

Allele Specific Pcr

Pollen–pistil incompatibility in european pear (Pyrus communis L.) compromises adequate orchard pollination and fruit set and restricts cross-fertility between cultivars suitable as parents in breeding programs. Genetic control is simple, with a single locus expressed gametophytically in pollen controlling the rejection of the pollen tube in the style. Semicompatible pollination arises when only one allele of a pollen parent matches the pistil. Semicompatible test-crosses using partially S-genotyped european pear cultivars allowed the discrimination of 14 S-alleles (S1 to S14) at the phenotypic level and the assignment of 33 cultivars to 13 incompatibility groups. Partial genomic sequences of the S-RNase gene, spanning between the C1 and C5 conserved regions, were obtained for each new S-allele identified (S6 to S14). These sequences and those reported previously for the S1 to S5 RNases allowed a set of consensus primers amplifying all 14 S-RNase alleles to be designed. Allele-specific PCR allowed discrimination between those S-RNases giving amplification products of similar size with consensus primers. These two approaches provided a method for the molecular identification of all 14 S-alleles in european pear. With this methodology, we demonstrate that the S-RNase genotypes inferred from PCR exactly matches the S-phenotypes deduced from test-crosses. Comparison of the sequences obtained with those of S-RNases already published allowed us to relate S-alleles between studies. This will allow the prediction of cross-incompatibility among an even larger number of european pear cultivars.

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