A. Pedryc

New self-incompatibility alleles in apricot (Prunus armeniaca L.) revealed by stylar ribonuclease assay and S-PCR analysis

Apricot (Prunus armeniaca L.) shows gametophytic self-incompatibility controlled by a single locus with several allelic variants. An allele for self-compatibility (SC) and seven alleles for self-incompatibility (S1–S7) were described previously. Our experiments were carried out to ascertain whether the number of allelic variants of apricot S-locus was indeed so small. Twenty-seven apricot accessions were analysed for stylar ribonucleases by non-equilibrium pH gradient electrofocusing (NEpHGE) to determine their S-genotype. To validate the results of electrofocusing, the applicability of the S-gene-specific consensus PCR primers designed from sweet cherry sequences was tested. NEpHGE revealed 12 bands associated with distinct S-alleles in newly genotyped cultivars. Cherry consensus primers amplified 11 alleles out from 16 ones, which indicated that these primers could also recognize most of the S-RNase sequences in apricot, and provided an efficient tool to confirm or reject NEpHGE results. By combining the protein and DNA-based methods, complete or partial S-genotyping was achieved for 23 apricot accessions and nine putatively new alleles (provisionally labelled S8–S16) were found. Their identity needs to be confirmed by pollination tests or S-allele sequencing. This study provides evidence that similarly to other Prunus species, the S-locus of apricot is more variable than previously believed.

Genetic Variation of the Endangered Gentiana lutea L. var. aurantiaca (Gentianaceae) in Populations from the Northwest Iberian Peninsula

Gentiana lutea L. (G. lutea L.) is an endangered plant, patchily distributed along the mountains of Central and Southern Europe. In this study, inter-simple sequence repeat (ISSR) markers were used to investigate the genetic variation in this species within and among populations of G. lutea L. var. aurantiaca of the Cantabrian Mountains (Northwest Iberian Peninsula). Samples of G. lutea L. collected at different locations of the Pyrenees and samples of G. lutea L. subsp. vardjanii of the Dolomites Alps were also analyzed for comparison. Using nine ISSR primers, 106 bands were generated, and 89.6% of those were polymorphic. The populations from the Northwest Iberian Peninsula were clustered in three different groups, with a significant correlation between genetic and geographic distances. Gentiana lutea L. var. aurantiaca showed 19.8% private loci and demonstrated a remarkable level of genetic variation, both among populations and within populations; those populations with the highest level of isolation show the lowest genetic variation within populations. The low number of individuals, as well as the observed genetic structure of the analyzed populations makes it necessary to protect them to ensure their survival before they are too small to persist naturally.

Identification of self-(in)compatibility S-alleles and new cross-incompatibility groups in Tunisian apricot (Prunus armeniaca L.) cultivars

Summary Local Tunisian apricot (Prunus armeniaca L.) cultivars are characterised by having abundant flowering and floral self-incompatibility. In this study, PCR amplification provided definitive data on the S-genotypes of eight local and four new Tunisian apricot cultivars. These results were confirmed by field evaluations. Eight local cultivars (‘Oud Rhayem’, ‘Oud Hmida’, ‘Bouthani Ben Friha’, ‘Bedri Ahmar’, ‘Oueld El Oud’, ‘Hamidi’, ‘Bouk Ahmed’, and ‘Adedi Ahmar’) were found to be self-incompatible and three of four INRAT cultivars (‘Sayeb’, ‘Asli’, and ‘Raki’) were self-compatible, as described previously. The INRAT cultivar ‘Ouardi’ was self-incompatible, although it was previously described as a self-compatible cultivar.We also propose three new cross-incompatibility (CIG) groups: CIG XV (S7S8), CIG XVI (S7S11), and CIG XVII (S8S12) which include Tunisian and other cultivars.

Self-(in)compatibility and fruit set in 19 local Moroccan apricot (Prunus armeniaca L.) genotypes

Summary Self-compatibility and fruit set were assessed in 19 local apricot (Prunus armeniaca L.) genotypes identified in four different oasis ecosystems in southern Morocco. Observations on pollen tube growth, as well as examinations of the fruit-set percentages obtained after self-pollination in the field, established the compatibility of their pollen. Fourteen genotypes from different geographical origins were self-compatible, with fruit set percentages ranging from 14.8 – 42.2%, whereas five were self-incompatible, with no fruit set. Consequently, almost all the local apricot genotypes propagated by seed in oasis ecosystems in southern Morocco proved to be self-compatible. In addition, the fruit-set percentages after open-pollination showed high variability among genotypes from the same oasis, among locations, and in the 2 years of study, with medium-to-high fruit set percentages for all genotypes, ranging from 11.9 – 30.1%. Self-compatibility has therefore been identified for the first time, not only in Moroccan apricot genotypes, but also in the North African Prunus gene pool.

Genetic diversity and population structure of apricot (Prunus armeniaca L.) from Northern Pakistan Using Simple Sequence Repeats

Abstract A collection of 44 P. armeniaca accessions and three related species, from diverse geographic areas, covering the entire Northern hemisphere with emphasis on Pakistani apricots, was screened with 10 SSR primer pairs developed in apricot, to characterize the cultivars and establish their genetic relationship. Given the fact that the Central Asian region is considered a center of origin of apricot, particular attention was devoted to accessions from the Hunza region of Pakistan. The primers correctly amplified a repeatable polymorphic pattern, which unequivocally distinguished all genotypes under study. Altogether 123 alleles were identified with an average of 12.30 alleles per locus. The observed heterozygosity for individual loci ranged from 0.28 to 0.77 with an average of 0.64. A neighbour joining method identified four groups from: (A) Central Asia, (B) Irano-Caucasia, (C) Continental Europe and (D) North America. The dendrogram confirms the historic dissemination pathways of apricot from its centre of origin in Asia to the West. Apricot cultivars from the Hunza region (Northern Pakistan) revealed a high variability, as genetic diversity is still conserved due to the traditional practice of planting seeds from the best trees.

Non-TIR-NBS-LRR resistance gene analogs in apricot (Prunus armeniaca L.)

Genes encoding for proteins with nucleotide-binding site and leucine-rich repeat motifs (NBS-LRR) have been suggested to play a general role in plant defence mechanism. In Prunus species, many TIR (Toll / Interleukin-1 Receptor), and only very few non-TIR sequences were identified, which was explained either by the unequal distribution of TIR/non-TIR sequences in the Prunus genome or by the incapability of primers in the amplification of non-TIR RGAs. The objective of this work was to check whether a new semi-nested PCR strategy can be developed for the targeted isolation of non-TIR-NBS-LRR Resistance Gene Analog (RGA) sequences from apricot. Three primers (CUB-P-loop F, CUB-Kin2 F and CUB-HD R) were designed, from which CUB-Kin2 F and CUB-HD R were constructed to anneal selectively to the non-TIR sequences. A colony Polymerase Chain Reaction (PCR) indicated that out of the 96 clones tested 28 showed amplification using the newly developed primers, while no amplification occurred when using the formerly described primers. Half of the 28 positive clones were sequenced and they turned out to represent 11 different non-TIR RGA sequences. A phylogenetic analysis was carried out based on an alignment containing 293 Rosaceae and 21 non-Rosaceaa sequences. A significantly higher ratio (91%) of non-TIR sequences were arranged in multi-genera clades than that of (57%) the TIR groups confirming that non-TIR sequences might be of more ancient origin than TIR sequences.