**5. Sharka (***Plum pox virus***) resistance in genetic diversity of apricot**

Sharka or Plum pox virus (PPV) is the most serious disease of Prunus trees. The disease has spreaded throughout many European countries, especially in Mediterranean countries. Resistant cultivars are limited and only some North American cultivars are known to be resistant to the disease. 'Stark Early Orange' (SEO), 'Goldrich', 'Harlayne', 'Stella', and 'Harcot' are the resistant cultivars mostly used as resistant source for breedings (Martinez-Gomez et al. 2000). The resent focus on the disease increased also cruiosty on the source of resistance of American cultivars. It is believed that North American cultivars originated from a limited number of European cultivars. The source of the resistance is unknown. However, recent studies shows that Central Asian apricots is the most likely source of resistant genes in the North American donors. *Prunus mandshurica* was first to be offered as PPV resistance into North American germplasm (Badenes et al. 1996). Zhebentyayeva et al. (2003) showed that 'Harlayne' and 'Goldrich' clusters with native Central Asian cultivars. 'Stark Early Orange', LE 2904, LE 3276, and 'Vestar' are also grouped with native Chinese material on the genetic diversity study (Zhebentyayeva et al. 2003). Hormaza (2002) also demonstrated that Chinese cultivars contributed to the pedigree of 'Stark Early Orange'. The recent research of Zhebentyayeva et al. (2008) shows that cultivars 'Harlayne', 'Goldrich', and 'Stark Early Orange' has genetic similarity with native Central Asian genotypes. The researchers also showed that *Prunus davidiana* alleles in 'Stark Early Orange' and *Prunus mume* alleles in 'Stark Early Orange' and 'Goldrich' pointed out a contribution of these species to PPV resistance as well (Zhebentyayeva et al. 2008).

#### **6.** *S***-genotyping in genetic diversity of apricot**

Like to other Prunus species, apricots show gametophytic self-incompatibility controlled by a single locus with multiple genes, *S*-haplotypes (De Nettancourt, 2001). The *S*-haplotype contains a female determinant, (*S-RNase*) encoding for a ribonuclease enzyme (McClure et al. 1989), and the recently identified male determinant, *S-haplotype-specific F-box* gene (Entani et al. 2003; Romero et al. 2004; Halasz et al. 2010).

The Irano – Caucasian group are usually self-incompatible whereas Europan apricots are mostly self-compatible (Halasz et al. 2005; Kostina, 1970). Mehlenbacher et al. (1991) stated Central Asian apricots are also mostly self-incompatible.

Cross-incompatibility between a pair of cultivars occurs frequently self-incompatible species. Cross-incompatibility was observed among the North American cultivars, Goldrich, Hargrand and Lambertin No.1 (Egea & Burgos, 1996), and also among giant-fruited Hungarian apricots (Szabo & Nyeki, 1991; Halasz et al. 2010). Halasz et al. (2010) determined total 12 cross-incompatiblity groups between Irano-Caucasian eco-geographical groups (Turkish apricots) and European eco-geographical groups (Hungarian and North American apricots) (Table 2).


Table 2. Cross-incompatibility groups of apricot (Halasz et al. 2010; Egea & Burgos, 1996; Halasz et al. 2005)

To date, 21 *S-RNase* alleles are known in European apricots, 20 of which (*S1-S20*) code for self-incompatibility and one (*Sc*) allowing self-compatibility (Burgos et al. 1998; Halasz, 2007; Halasz et al. 2005, 2007) and recently it was confirmed that *SC* haplotype is a pollen part mutant of *S8* haplotype (Halasz et al. 2007). Beside, some additional *S*-alleles have been also identified in Chinese cultivars (Wu et al. 2009; Halasz et al. 2010).

A gradually decreasing allele number was detected in apricot landraces from China to Western Europe, with some allelic exclusivity occuring in certain geographic areas (Halasz, 2007; Halasz et al. 2010).

contains a female determinant, (*S-RNase*) encoding for a ribonuclease enzyme (McClure et al. 1989), and the recently identified male determinant, *S-haplotype-specific F-box* gene (Entani

The Irano – Caucasian group are usually self-incompatible whereas Europan apricots are mostly self-compatible (Halasz et al. 2005; Kostina, 1970). Mehlenbacher et al. (1991) stated

Cross-incompatibility between a pair of cultivars occurs frequently self-incompatible species. Cross-incompatibility was observed among the North American cultivars, Goldrich, Hargrand and Lambertin No.1 (Egea & Burgos, 1996), and also among giant-fruited Hungarian apricots (Szabo & Nyeki, 1991; Halasz et al. 2010). Halasz et al. (2010) determined total 12 cross-incompatiblity groups between Irano-Caucasian eco-geographical groups (Turkish apricots) and European eco-geographical groups (Hungarian and North

I Goldrich, Hargrand, Lambertin No.1 S1S2 II Cologlu, Kadioglu, Seftalioglu, Cegledi orias, Ligeti orias

II Iri Bitirgen, Moniqui S2S6 IV Artvin PA, Priana S2S7 V Alyanak, Ziraat Okulu S2S8 VI Dortyol-4, Sebbiyiki S2S19 VII Sakit-3, Tokaloglu Izmir S3S19 VIII Cataloglu, Ozal, Soganci S6S9 IX Zerdali No.1, XI Zerdali S6S12 X Ordubat, X2 Zerdali S7S12 XI Adilcevaz-5, Hacihaliloglu, Kabaasi, Kamelya, Zerdali No.2

XII Shalakh (Aprikoz), Voski S11S13 XIII Levent, Sakit-1 S6S19 XIV Cekirge 52, X3 Zerdali S9S20

Sam (ScS2), Yerli Izmir (ScS7) Table 2. Cross-incompatibility groups of apricot (Halasz et al. 2010; Egea & Burgos, 1996;

identified in Chinese cultivars (Wu et al. 2009; Halasz et al. 2010).

To date, 21 *S-RNase* alleles are known in European apricots, 20 of which (*S1-S20*) code for self-incompatibility and one (*Sc*) allowing self-compatibility (Burgos et al. 1998; Halasz, 2007; Halasz et al. 2005, 2007) and recently it was confirmed that *SC* haplotype is a pollen part mutant of *S8* haplotype (Halasz et al. 2007). Beside, some additional *S*-alleles have been also

A gradually decreasing allele number was detected in apricot landraces from China to Western Europe, with some allelic exclusivity occuring in certain geographic areas (Halasz,

Canakkale (ScSc), Ethembey (ScS8), Karacabey (ScS2), Mektep (ScS8), Pasa Mismisi (ScS8),

Cultivars *S*-genotype

S8S9

S9S13

et al. 2003; Romero et al. 2004; Halasz et al. 2010).

American apricots) (Table 2).

Cross-incompatibility groups

0: Universal pollen

Halasz et al. 2005)

2007; Halasz et al. 2010).

donors

Central Asian apricots are also mostly self-incompatible.
