Genomic and cDNA microsatellites from apricot (Prunus armeniaca L.)

We developed primers for the amplification of 24 polymorphic nuclear microsatellites in apricot (Prunus armeniaca L.). Thirteen loci originated from three genomic libraries enriched for TC, TG and AAG motifs. Eight loci were developed from three fruit EST (Expressed‐Sequence‐Tag) libraries and three from a leaf cDNA microsatellite‐enriched library. There were up to nine alleles per polymorphic locus in 12 different cultivars. No difference in allele numbers were shown between cDNA and genomic‐source loci. Mean expected heterozygosity was 0.65 (range: 0.15–0.87). Mendelian segregation was confirmed for all loci. These markers should be helpful for diversity studies, genome mapping and cultivar identification in apricot and related species.     

Effective pollination period in apricot (Prunus armeniaca L.) varieties

A study of the effective pollination period (E.P.P.) of six varieties of apricot has shown that in the warm climate of the South Mediterranean this parameter is extremely short. The percentage of fruit set of emasculated flowers diminishes rapidly with time. Temperature plays an important role in this process and is responsible for the rapid degradation of the stigma, which hinders pollen germination.     

Development of SSR markers located in the G1 linkage group of apricot (Prunus armeniaca L.) using a bacterial artificial chromosome library

Sixteen simple sequence repeats (SSRs) of apricot (Prunus armeniaca L.) were isolated from a bacterial artificial chromosome (BAC) library. Twelve restriction fragment length polymorphism (RFLP) probes mapped on LG1 of the Prunus general map were hybridized to the BAC library in order to select clones belonging to G1 linkage group of apricot. Selected BACs were digested, subcloned and hybridized with probes containing repeat motifs (GA)₁₀ and (TA)₁₀. Sequencing of the positive subclones revealed 18 unique SSR sequences of which 16 allowed the design of primers flanking the SSR. From the 16 primer pairs, 10 amplified polymorphic markers with an average of observed and expected heterozygosities of 0.44 and 0.68, respectively. The procedure described here proves to be a useful technique for obtaining markers in target areas of a genome.     

Detection and inheritance of stylar ribonucleases associated with incompatibility alleles in apricot

 Stylar proteins were surveyed by non-equilibrium pH gradient electrofocusing to identify S-RNases associated with gametophytic self-incompatibility in nine apricot cultivars. RNase activities associated with the alleles of incompatibility S ₁ , S ₂ , S ₅ , and S ₆ and with the allele of compatibility Sc were clearly identified. Two other bands that we considered related to the alleles S ₃ and S ₄ were unique to cultivars Sunglo and Harcot, respectively. Two generations of 17 seedlings from the cross Moniquí× Pepito and 38 from Gitano × Pepito were used to determine the inheritance of the S-RNases. Inheritance of these RNase bands followed the expected segregation ratios and the band combinations correlated perfectly with the known self-incompatibility status of the seedlings determined after self-pollination and observation of pollen tube growth. All evidence presented in this study strongly suggests that RNases are associated with gametophytic self-incompatibility of apricot and that RNases may be the S-gene products. This is the first report identifying S-RNases and describing the inheritance of these S-RNases in apricot. Received: 19 February 1998 / Revision accepted: 2 April 1998     

Ovule development at anthesis in apricot (Prunus armeniaca) varieties in a Mediterranean climate

The stage of ovule development at anthesis has been studied in 2002 and 2003 in 35 apricot varieties and 4 new apricot cultivars grown in a Mediterranean climate. Significant differences were found among varieties as well as a high heterogeneity of the developmental stage of the ovules examined in each variety. In general, a relative delay of the ovule development was observed, the presence of mature ovules at anthesis being negligible. In the 2 years of the study, differences in the developmental stage of primary ovules at anthesis were not significant and correlation to flowering time was not observed, which emphasised the previously reported genetic determination of this trait.     

Agrobacterium-mediated transformation of apricot (Prunus armeniaca L.) leaf explants

A protocol for Agrobacterium-mediated stable transformation for scored, whole leaf explants of the apricot (Prunus armeniaca) cultivar Helena was developed. Regenerated shoots were selected using a two-step increased concentrations of paromomycin sulphate. Different factors affecting survival of transformed buds, including possible toxicity of green fluorescent protein (GFP) and time of exposure to high cytokine concentration in the regeneration medium, were examined. Transformation efficiency, based on PCR analysis of individual putative transformed shoots from independent lines was 5.6%, when optimal conditions for bud survival were provided. Southern blot analysis on four randomly chosen PCR-positive shoots confirmed the presence of the nptII transgene. This is the first time that stable transformation of an apricot cultivar is reported and constitutes also one of the few reports on the transformation of Prunus cultivars.     

Molecular characterization and similarity relationships among apricot ( Prunus armeniaca L.) genotypes using simple sequence repeats

A collection of 48 apricot genotypes, originated from diverse geographic areas, have been screened with 37 SSR primer pairs developed in different species of Prunus in order to identify and characterize the genotypes and establish their genetic relations. Thirty one of those primer pairs resulted in correct amplifications and 20 produced polymorphic repeatable amplification patterns with the 48 genotypes studied. A total of 82 alleles were detected for the 20 loci. All the genotypes studied could be unequivocally distinguished with the combination of SSRs used. The results obtained evidence for the cross-species transportability of microsatellite sequences, allowing the discrimination among different genotypes of a given fruit-tree species with sequences developed in other species. UPGMA cluster analysis of the similarity data grouped the genotypes studied according to their geographic origin and/or their pedigree information. Received: 5 April 2001 / Accepted: 4 May 2001     

Stamen development and winter dormancy in apricot (Prunus armeniaca)

Background and Aims

In temperate woody perennials, flower bud development is halted during the winter, when the buds enter dormancy. This dormant period is a prerequisite for adequate flowering, is genetically regulated, and plays a clear role in possibly adapting species and cultivars to climatic areas. However, information on the biological events underpinning dormancy is lacking. Stamen development, with clear differentiated stages, appears as a good framework to put dormancy in a developmental context. Here, stamen developmental changes are characterized in apricot (Prunus armeniaca) and are related to dormancy.

Methods

Stamen development was characterized cytochemically from the end of August to March, over 4 years. Developmental changes were related to dormancy, using the existing empirical information on chilling requirements.

Key Results

Stamen development continued during the autumn, and the flower buds entered dormancy with a fully developed sporogenous tissue. Although no anatomical changes were observed during dormancy, breaking of dormancy occurred following a clear sequence of events. Starch accumulated in particular places, pre-empting further development in those areas. Vascular bundles developed and pollen mother cells underwent meiosis followed by microspore development.

Conclusions

Dormancy appears to mark a boundary between the development of the sporogenous tissue and the occurrence of meiosis for further microspore development. Breaking of dormancy occurs following a clear sequence of events, providing a developmental context in which to study winter dormancy and to evaluate differences in chilling requirements among genotypes.     

中国南疆栽培杏群体遗传结构的荧光AFLP分析

以中国新疆维吾尔自治区南部塔里木盆地边缘库车、喀什和和田3个栽培杏群体的85个品种类型为试材,利用荧光标记AFLP对群体遗传结构进行了研究,结果表明:对64对EcoRⅠ/MseⅠ引物(其中MseI引物为FAM荧光标记物)进行了筛选,其中8对荧光标记引物谱带清晰,多态性高;同一引物在不同群体以及同一群体不同引物扩增多态性均存在显著差异,种级水平多态带百分率P>库车>和田>喀什3个群体水平;种级水平Nei基因多样度指数H和Shannon信息指数I>库车>和田>喀什3个群体水平。种级水平大于种下群体,各群体以库车最高;杏遗传多样性主要存在于群体内,群体间的遗传分化系数GST为0.0882,即群体间的遗传变异占总变异的8.82%,群体间的基因流Nm为5.1689;群体的遗传一致度在0.9772～0.9811之间,遗传距离在0.0191～0.0232之间,说明群体间的相似程度较高,遗传距离较小;UPGMA聚类分析结果表明,库车、喀什、和田3个亚群可能是相对独立的孟德尔群体,但同时存在部分基因交流;各项研究指标都表明库车群体的遗传多样性都最高,它可能是野杏向栽培杏过渡的中间群体;南疆栽培杏群体拥有极为丰富的遗传多样性,为进一步的选择育种提供了更多的种质资源,为该地区杏群体生物多样性保护和利用提供理论依据。     

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.     

鼠类对山杏（Prunus armeniaca）种子扩散及存活作用研究

虽然有关鼠类搬运森林种子的证据已很清楚,但这些初移走种子的存活情况却知之甚少。提出了一个新的标记和跟踪种子的方法－－标签法,即将种子拴一带有编码的细长金属片,研究了北京东灵山地区山杏（Prunus armeniaca）种子的扩散距离和存活率。于1998年6月19－20日,7月3日和10月23日共在24个样点释放1440粒山杏种子。几科所有释放的种子在10d内被鼠类取走,夏天释放的种子比秋天释放的种子消失的速度快。大多数种子的扩散距离在20m以内,小于鼠类的活动距离,鼠类吃掉种子的速度很快,但当种子变得稀少时,种子存活率有所提高。山杏种子6、7月份的每日存活率小于其它月份的每日存活率。     

Genetic diversity analysis and population structure in apricot (Prunus armeniaca L.) grown under north-western himalayas using ISSR markers

Investigation of genetic variability and population relationship of 50 accessions of the apricot (Prunus armeniaca L.) was carried out using ISSR markers. The results revealed that the number of alleles per locus varied from 4 to 8 with a mean value of 6.75, and the mean effective number of alleles (Ne) per locus was 1.54. Similarly, the polymorphic information content (PIC) values ranged from 0.464 to 0.424, with a mean value of 0.424. The mean heterozygosity, marker index, resolving power, and effective multiplex ratio (EMR) ranged from 0.001 to 0.002, 0.01–0.06, 1.76–3.84, and 1–4.12. The dendrogram clustered genotypes into two main clades based on their origins. The population structure revealed two sub-populations with some admixtures. The average expected heterozygosity and population differentiation within two sub-populations was 0.1428 and 0.216, respectively. The results outcome reveals that the four ISSR markers comprehensively separated the indigenous germplasm from the exotic germplasm. The genetic divergence within indigenous genotypes and exotic genotypes could allow for future insights into apricot breeding programs.     

Phenolic compounds and vitamins in wild and cultivated apricot (Prunus armeniaca L.) fruits grown in irrigated and dry farming conditions

Background

Turkey is the main apricot producer in the world and apricots have been produced under both dry and irrigated conditions in the country. In this study, phenolic compounds and vitamins in fruits of one wild (Zerdali) and three main apricot cultivars (‘Cataloglu’, ‘Hacihaliloglu’ and ‘Kabaasi’) grown in both dry and irrigated conditions in Malatya provinces in Turkey were investigated.

Results

The findings indicated that higher content of phenolic compounds and vitamins was found in apricot fruits grown in irrigated conditions. Among the cultivars, ‘Cataloglu’ had the highest rutin contents both in irrigated and dry farming conditions as 2855 μg in irrigated and 6952 μg per 100 g dried weight base in dry conditions and the highest chlorogenic acid content in irrigated and dry farming conditions were measured in fruits of ‘Hacıhaliloglu’ cultivar as 7542 μg and 15251 μg per 100 g dried weight base. Vitamin C contents in homogenates of fruit flesh and skin was found to be higher than β-caroten, retinol, vitamin E and lycopen contents in apricot fruits both in irrigated and dry farming conditions.

Conclusion

The results suggested that apricot fruits grown in both dry and irrigated conditions had high health benefits phytochemicals and phytochemical content varied among cultivars and irrigation conditions as well. However, more detailed biological and pharmacological studies are needed for the demonstration and clarification of health benefits of apricot fruits.     

Characterization of microsatellite markers in peach [Prunus persica (L.) Batsch]

Microsatellites have emerged as an important system of molecular markers. We evaluated the potential of microsatellites for use in genetic studies of peach [Prunus persica (L.) Batsch]. Microsatellite loci in peach were identified by screening a pUC8 genomic library, a λZAPII leaf cDNA library, as well as through database searches. Primer sequences for the microsatellite loci were tested from the related Rosaceae species apple (Malus×domestica) and sour cherry (Prunus cerasus L.). The genomic library was screened for CT, CA and AGG repeats, while the cDNA library was screened for (CT)_n- and (CA)_n-containing clones. Estimates of microsatellite frequencies were determined from the genomic library screening, and indicate that CT repeats occur every 100 kb, CA repeats every 420 kb, and AGG repeats every 700 kb in the peach genome. Microsatellite- containing clones were sequenced, and specific PCR primers were designed to amplify the microsatellite- containing regions from genomic DNA. The level of microsatellite polymorphism was evaluated among 28 scion peach cultivars which displayed one to four alleles per primer pair. Five microsatellites were found to segregate in intraspecific peach-mapping crosses. In addition, these microsatellite markers were tested for their utility in cross-species amplification for use in comparative mapping both within the Rosaceae, and with the un- related species Arabidopsis thaliana L. Received: 18 June 1999 / Accepted: 6 December 1999     

凯特杏花粉的离体培养及影响因子分析

采用离体培养法,在不同培养基组分含量、pH值、温度及植物生长调节物质的培养条件下,对凯特杏(Prunus armeniacaL.cv Katy)花粉的离体萌发和花粉管生长状况进行观察研究。结果表明:(1)凯特杏花粉离体萌发及花粉管生长的适宜培养基为20%蔗糖 0.04%硼酸 0.01?Cl2,最适pH为6.0,最适温度为20℃,培养20 h后,花粉的萌发率达68.76%,花粉管长度达1 083.53μm。(2)不同植物生长调节物质对花粉萌发和花粉管生长作用不同,赤霉素浓度为5~8 mg/L、矮壮素浓度为10~150 mg/L、多效唑浓度为5~10 mg/L时对凯特杏花粉萌发和花粉管生长都有促进作用,但国光丁酰肼对凯特杏花粉萌发和花粉管生长均有抑制作用。     

Pistil traits and flower fate in apricot (Prunus armeniaca)

Although pollination is essential for both seed and fruit set in most angiosperms, even after an adequate pollination, only a fraction of the flowers develop into fruits. The role played by floral traits on reproductive success is well known, but the possible influence of pistil traits has been overlooked, probably because of the difficulty of non-destructive pistil examination. The aim of this work was to examine the influence of several pistil traits on reproductive success in apricot ( Prunus armeniaca ). For this purpose, in a population of individually labelled flowers, the styles were cut off once the pollen tubes had reached the ovary but prior to the achievement of fertilisation. This approach allowed relating several morphological and physiological pistil parameters in the dissected styles and stigmas to the subsequent set or abscission of the corresponding ovary that remained in the plant. Under the same pollination conditions, the flowers that finally set a fruit show a larger stigmatic area and a higher number of pollen grains, pollen tubes growing along the style and xylem vessels surrounding the transmitting tissue than flowers that abscise before the establishment of fruit set. Furthermore, starch is present in the transmitting tissue of the style in all the flowers that develop into fruits but only in half of the flowers that abscise. The examined pistil traits established prior to fertilisation are related to flower fate, suggesting that the capacity of a flower to become a fruit could be preconditioned at anthesis.     

Origin and dissemination of the pollen-part mutated SC haplotype which confers self-compatibility in apricot (Prunus armeniaca)

In China, its centre of origin, apricot (Prunus armeniaca) is self-incompatible. However, most European cultivars are self-compatible. In most cases, self-compatibility is a result of a loss-of-function mutation within the pollen gene (SFB) in the SC haplotype. Controlled pollinations performed in this work revealed that the cross 'Ceglédi óriás' (S8S9)x'Ceglédi arany' (SCS9) set well, as expected, but the reciprocal cross did not. Apricot S8, S9 and SC haplotypes were analysed using a multilevel approach including fruit set evaluation, pollen tube growth analysis, RNase activity assays, polymerase chain reaction (PCR) analysis and DNA sequencing of the S-RNase and SFB alleles. SFB8 was revealed to be the first known progenitor allele of a naturally occurring self-compatibility allele in Prunus, and consequently SC=The first intron of SC-RNase is a phase one intron, indicating its more recent evolutionary origin compared with the second intron. Sequence analysis of different cultivars revealed that more single nucleotide polymorphisms accumulated in SC-RNase than in SFBC. New methods were designed to allow high-throughput analysis of S genotypes of apricot cultivars and selections. S-RNase sequence data from various sources helped to elucidate the putative origin and dissemination of self-compatibility in apricot conferred by the SC haplotype.     

Genetic linkage map of peach [Prunus persica (L.) Batsch] using morphological and molecular markers

A genetic linkage map of peach [Prunus persica (L.) Batch] was constructed in order to identify molecular markers linked to economically important agronomic traits that would be particularly useful for long-lived perennial species. An intraspecific F₂ population was generated from self-pollinating a single F₁ plant from a cross between a flat non-acid peach, ‘Ferjalou Jalousia^®’ and an acid round nectarine ‘Fantasia’. Mendelian segregations were observed for 270 markers including four agronomic characters (peach/nectarine, flat/round fruit, acid/non-acid fruit, and pollen sterility) and 1 isoenzyme, 50 RFLP, 92 RAPD, 8 inter-microsatellite amplification (IMA), and 115 amplified fragment length polymorphism (AFLP) markers. Two hundred and forty-nine markers were mapped to 11 linkage groups covering 712 centiMorgans (cM). The average density between pairs of markers is 4.5?cM. For the four agronomic characters studied, molecular markers were identified. This map will be used for the detection of QTL controlling fruit quality in peach and, particularly, the acid and sugar content.