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Santiago Vilanova, Carlos Romero, Gerardo Llácer, María Luisa Badenes, and Lorenzo Burgos

This report shows the PCR-based identification of the eight known self-(in)compatibility alleles (S 1 to S 7 and S c) of apricot (Prunus armeniaca L.). Two sets of consensus primers, designed from P. armeniaca S-RNase genomic sequences and sweet cherry (P. avium L.) S-RNase-cDNAs, were used to amplify fragments containing the first and the second S-RNase intron, respectively. When the results obtained from the two PCRs were combined, all S-alleles could be distinguished. The identity of the amplified S-alleles was verified by sequencing the first intron and 135 base pairs (bp) of the second exon. The deduced amino acid sequences of these fragments showed the presence of the C1 and C2 Prunus L. S-RNase conserved regions. These results allowed us to confirm S-genotypes previously assigned by stylar ribonuclease analyses and to propose one self-(in)compatibility group (I) and one universal donor group (O) containing unique S-genotypes and self-compatible cultivars (SC). This PCR-based typing system also facilitates the identification of the S c-allele and might be a very useful tool for predicting self-compatibility in apricot breeding progenies.

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D.E. Kester, T.M. Gradziel, and W.C. Micke

Six cross-incompatibility groups, which contain most of commercially important California almond cultivars [Prunus dulcis (Mill.) D.A. Webb, syn. Prunus amygdalus Batch], and their self-incompatibility (S) allele genotypes are identified. Incompatibility groups include `Mission' (SaSb), `Nonpareil' (ScSd), and the four groups resulting from the `Mission' × `Nonpareil' cross: (SaSc), (SaSd), (SbSc), and (SbSd), as represented by `Thompson', `Carmel', `Merced' and `Monterey', respectively. All seedlings from the `Mission' × `Nonpareil' cross were compatible with both parents, a result indicating that these two cultivars have no alleles in common. Crossing studies support a full-sib relationship for these progeny groups and the origin of both parents from common germplasm. Cultivars in these six groups account for ≈ 93% of present California production, a result demonstrating a limited genetic base for this vegetatively propagated tree crop.

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Kirk W. Pomper, Anita N. Azarenko, Joel W. Davis, and Shawn A. Mehlenbacher

Random amplified polymorphic DNA (RAPD) markers were identified for self-incompatibility (SI) alleles that will allow marker-assisted selection of desired S-alleles and assist in cloning the locus responsible for the sporophytic SI displayed in hazelnut (Corylus avellana L.). DNA was extracted from young leaves collected from field-planted parents and 27 progeny of the cross OSU 23.017 (S1 S12) × VR6-28 (S2 S26). Screening of 10-base oligonucleotide RAPD primers was performed using bulked segregant analysis. DNA samples from six trees each were pooled into four “bulks,” one for each of the following: S1 S2, S1 S26, S2 S12, and S12 S26. “Super bulks” of twelve trees each for S1, S2, S12, and S26 then were created for each allele by combining the appropriate bulks. The DNA from these four super bulks and also the parents was used as a template in the PCR assays. Amplification products were electrophoresed on 2% agarose gels and photographed under UV light after ethidium bromide staining. 200 primers were screened and one RAPD marker each was identified for alleles S2 (OPI-07700) and S1 (OPJ-141700).

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Bindu Chawla, Robert Bernatzki, and Michael Marcotrigiano

Lycopersicon peruvianum is a wild species of tomato that exhibits gametophytic self-incompatibility (S), wherein the SI response is controlled by the genotype of the pollen. Cultivated tomato (L. esculentum) is a self-compatible species. Assisted by phenotypic markers, periclinal graft chimeras between these two species have been obtained. Fruit set analysis following breeding demonstrated that the available five chimeras (PPE, PEE, PEP, EPP, and EEP) are able to accept pollen from L. peruvianum, suggesting that there is a failure of the SI response. SI response is known to be dependent on S-locus associated proteins. These proteins are present in the style, which is mainly derived from the L1 and L2 layers of meristem. RNA analysis of the style tissue using a cloned S-locus cDNA as a probe showed that, except for EEP, all chimeras expressed the S-allele. This was also confirmed by SDS-PAGE analysis of stylar proteins that were present in variable amounts depending on the periclinal combination. Thus, the breakdown of SI is not associated with the lack of expression of the S-locus. Further work is being conducted to understand the nature of this breakdown.

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Shawn A. Mehlenbacher and David C. Smith

The cutleaf hazelnut [Corylus avellana L. f. heterophylla (Loud.) Rehder] is an ornamental form with strongly dissected leaf morphology. Its stigmas express incompatibility allele S20 but none of the other 25 S-alleles was detected with fluorescence microscopy. Three seedlings from a cross of the cutleaf hazelnut and VR6-28 lacked S20 and were investigated further. Each expressed an allele from the parent VR6-28 (S2 S26), S26 in OSU 562.031 and OSU 562.048 and S2 in OSU 562.049. S2 and S26 are low in the dominance hierarchy, so we expected the new allele from the cutleaf hazelnut to be expressed in their pollen. Unexpectedly, fluorescence microscopy showed that pollen of all three selections was compatible on their cutleaf parent and on each other, and furthermore, self-pollinations showed the excellent germination and long parallel tubes in the styles that are typical of a compatible pollination. Controlled self- and cross-pollinations in the field verified the self-compatibility of two selections. Cluster set for self-pollinations was very high (75-90%) and within the range observed for compatible cross-pollinations. Furthermore, the frequency of blank nuts was low (<10%). The second allele in the cutleaf hazelnut is designated S28, and its presence in seedlings of `Cutleaf' is indicated by the absence of S20. Controlled pollinations in the field also showed that selection OSU 562.069 (S2 S28) from the cross `Cutleaf' × `Redleaf #3' was self-compatible. Fluorescence microscopy showed that two additional seedlings were self-incompatible [OSU 367.052 (S1 S28) and OSU 367.076 (S6 S28)] while a third [OSU 706.071 (S9 S28)] was self-compatible. Self-compatibility may be limited to genotypes that combine S28 with a second allele that is low in the dominance hierarchy.

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Shawn A. Mehlenbacher and Maxine M. Thompson

The style color of standard hazelnut (Corylus avellana L.) cultivars ranges from pink to dark purple. Styles with an unusual yellow color were first noted in seedlings of the progeny `Goodpasture' × `Compton', and the ratio was ≈3 red: 1 yellow. Controlled crosses were made to investigate the genetic control of style color. The same 3:1 ratio was observed in four additional crosses in which both parents had red styles. Two crosses of a red and a yellow parent gave ≈50% yellow styles, while a cross of two selections with yellow styles gave only seedlings with yellow styles. These segregation ratios indicate control by a single locus, with yellow style color recessive to red. Seedlings with yellow styles have green buds and catkins and a more upright growth habit than their siblings with red styles. Inspection of the pedigrees of these progenies shows that `Daviana', `Willamette', `Butler', `Compton', `Goodpasture', and `Lansing #1' are heterozygous. `Daviana' appears to be the original source of the allele for yellow styles, as it is a known or suspected parent or ancestor of the others. Ratios in a progeny segregating simultaneously for growth habit (normal vs. contorted) and style color indicated independence of the traits. However, in a progeny segregating simultaneously for leaf color (red vs. green) and style color, no redleaf seedlings had yellow styles. The S-alleles of eight genotypes with yellow styles were determined, and indicate a possible linkage between the yellow style locus and the S locus that controls pollen-stigma incompatibility. One explanation is that the yellow style trait is conferred by an allele (a ys) at the anthocyanin (A) locus that controls leaf color. A second explanation is that there is a yellow style locus closely linked to the A locus. The A locus is known to be loosely linked to the S locus.

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J. Carapetian, A. Estilai, and A. Hashemi

To detect isozyme variation, leaf extracts of more than 460 plants from 20 safflower (Carthamus tinctorius L.) entries with diverse geographic origins were analyzed. Entries included seven Iranian spring-type selections, eight Iranian late rosette winter-type selections, four U.S. cultivars, and one Indian introduction. Starch gel electrophoresis produced distinct and repeatable banding patterns for nine of the 15 enzymes assayed. Five of these enzymes, aldolase (ALD, EC 4.1.2.13), isocitrate dehydrogenase (IDH, EC 2.7.5.1), malate dehydrogenase (MDH, EC 1.1.1.37), malic enzyme (ME, EC 1.1.1.40), and phosphoglucomutase (PGM, EC 2.7.5.1), were monomorphic. Menadione reductase (MR, EC 1.6.99.2), 6-phosphogluconate dehydrogenase (6-PGDH, EC 1.1.1.44), phosphoglucoisomerase (PGI, EC 5.3.1.9), and triosephosphate isomerase (TPI, EC 5.3.1.1) were polymorphic. 6-PGDH revealed an invariable cathodal and a variable anodal zone of activity. Crosses were made between appropriate parents and F1, BC1, and F2 progenies were generated for segregation analyses. Two multibanded phenotypes that bred true were observed for MR. Crosses between these types produced 7-banded F1 plants. F2 progenies segregated in parental and hybrid phenotypes in the expected 1:2:1 ratio. Both PGI and TPI showed one monomorphic and one polymorphic zone of activity. Segregation data indicated that Pgi-2 and Tpi-1 are monogenic and controlled by two codominant F and S alleles. The observation of the parental bands plus an intermediate band with a higher intensity in hybrid plants suggested that PGI and TPI act as dimeric enzymes in safflower. Isozyme genetic markers described in this study are useful tools for identification of hybrid individuals in this predominantly inbreeding species.

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Hitomi Umemura, Katsuhiro Shiratake, Shogo Matsumoto, Tsutomu Maejima, and Hiromitsu Komatsu

Pearl’ is tightly linked with its S 3 -RNase allele ( Sekido et al., 2010a ). Because the flesh and skin color trait within the Rni locus (the site of MdMYB 1 and 10 ) located in linkage group 9, not 17 of the S -allele location, and which is called

Open access

Paul W. Bosland and Danise Coon

sallele. The “ sallele is a trait associated with domestication. Most types (e.g., jalapeno, bell pepper, New Mexican, Hungarian wax, etc.) have the “ sallele; therefore, harvesting with the “ sallele is common. A pedigree breeding method

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Jung Hyun Kwon, Ji Hae Jun, Eun Young Nam, Kyeong Ho Chung, Ik Koo Yoon, Seok Kyu Yun, and Sung Jong Kim

-incompatibility, which is genetically controlled by at least two loci encoding the pollen and pistil allelic determinants ( Kao and Tsukamoto, 2004 ; Tao and Iezzoni, 2010 ). In this mechanism, when the S -allele expressed in the pollen is identical to either of the