Domestica Cv Research Articles

Effect of calcium chloride (CaCl 2 ) on postharvest quality of apple fruits

The purpose of this research was to estimate the shelf-life and to study the behavior of ‘ Malus domestica cv . ‘Jonagold’ apple kept at 0 to 2°C in a normal atmosphere. The effects of postharvest CaCl 2 applications on shelf-life and quality attributes of apple after harvest or cold storage up to 5 month were determined. The experiment was carried out in 2010 and 2011 and fruit weight losses, fruit firmness, total soluble solids (TSS), pH, titratable acidity (TA), TSS/TA ratio, ethylene production, peroxidase (POD) and catalase (CAT) enzyme activities were measured at 20, 40, 60, 80, 100, 120, and 150 days of postharvest life. The fruits were immersed in distilled water with calcium concentrations (0, 2 and 4% (W/V). Results showed that fruit weight loss significantly decreased in calcium treatments in comparison to control. Also, results showed that calcium treatments increase fruit firmness, catalase activity, TA and Perlim index, while decreasing of pH, TSS/TA ratio and peroxidase activity during cold storage at 0 to 2°C for 5 month (P ≤ 0.05). The results showed that calcium treatments application was influenced on ethylene in comparison to control. In general, this experiment showed that post-harvest Ca treatments prevented fruit softening and decreased weight losses.

Effects of postharvest applications of calcium nitrate and acetate on quality and shelf-life improvement of "Jonagold" apple fruit

The effects of postharvest application of calcium were investigated on shelf-life and quality of apple fruits (Malus domestica cv. ‘Jonagold’) after harvest or cold storage up to 150 days. The fruits were immersed in deionised water or in different calcium sources (calcium acetate at two calcium concentrations 0.35 and 0.7%w/v and calcium nitrate at two calcium concentrations 0.5 and 1%w/v. The experiment was carried out in 2010 to 2011 and fruit weight losses, fruit firmness, total soluble solids, pH, titratable acidity, total soluble solids /titratable acidity ratio, thiault index, perlim index, ethylene production, peroxidase and catalase enzyme activities were measured at 20, 40, 60, 80, 100, 120, and 150 days after harvest life. Results showed that all immersing conditions leaded to the best results of fruit quality assessments when compared with control. The calcium treatments increase fruit firmness, titratable acidity and catalase enzyme activity, while decreasing total soluble solids, weight losses percentages, ethylene production, TSS/TA ratio and Peroxidase enzyme activity during cold storage at 0-2°C for 150 days. Key words: Shelf-life, “Jonagold“ apple, calcium nitrate, calcium acetate.

Determination S-Genotypes and Identification of Five Novel S-RNase Alleles in Wild Malus Species

Apple (Malus × domestica Borkh.) is a typical Rosaceae species that exhibits gametophytic self-incompatibility (GSI) controlled by polymorphic S-alleles. In this study, the S-alleles of wild Malus species were amplified, sequenced and compared using polymerase chain reaction (PCR) technology. 21 S-alleles were identified in 27 wild Malus species. The results indicated that the overwhelming majority of S-alleles between wild Malus species and cultivars shared identical sequences. Simultaneously, five new S alleles (designated S 48 –S 52 ) were identified in wild Malus species. There are the S 48 -RNase in M. angustifolia (Ation) Michaux, S 49 -RNase in M. orientalis Uglitzk. Ex Juz. and M. sylvestris (L.) Mill., S 50 -RNase in M. tschonoskii (Maxim.) C.K. Schneid. and M. sieversii (Ldb.) Roem., S 51 -RNase in M. komarovii (Sarg.) Rehd. and M. kansuensis (Batal.) C. K. Schneid., S 52 -RNase in M. manshurica (Maxim.) V. Komorov wild Malus species. Additionally, an S 1 -RNase was cloned in wild Malus prunifolia var. ringo, which have the same open reading frame as Malus × domestica cv. Fuji, but lacked whole intron.

Ascorbic Acid Accumulation and Expression of Genes Involved in Its Biosynthesis and Recycling in Developing Apple Fruit

The objective of this study was to investigate ascorbic acid (AsA) accumulation, mRNA expression of genes involved in AsA biosynthesis as well as recycling, activity of key enzymes, and the relationship of them to AsA levels during the development of apple fruit (Malus ×domestica cv. Gala). AsA concentration, which mainly depends on biosynthesis, was the highest in young fruit post-anthesis and then decreased steadily toward maturation. However, AsA continued to accumulate over time because of the increase in fruit mass. Transcript levels of guanosine diphosphate (GDP)-L-galactose phosphorylase, GDP-mannose pyrophosphorylase, D-galacturonate reductase, and the post-transcriptionally regulated L-galactono-1,4-lactone dehydrogenase were not correlated with AsA accumulation in apple. In contrast, patterns of expression for L-galactose dehydrogenase, L-galactose-1-phosphate phosphatase, and GDP-mannose-3′,5′-epimerase showed a pattern of change similar to that of AsA accumulation. Although activities and expression levels of monodehydroascorbate reductase and dehydroascorbate reductase in fruit, which had less capacity for AsA recycling, were much lower than in leaves, they were not clearly correlated with AsA level during fruit development.

On the role of 2,3-dihydro-3,5-dihydroxy-6-methyl-(4H)-pyran-4-one in antioxidant capacity of prunes

Despite available reports on phenolic composition and antioxidant capacity (AOC) of fresh plums and prunes, there is a scarcity of published knowledge on the antioxidants formed and/or released during the drying process in the literature. To evaluate the compounds participating in reducing capacity of prunes, we compared aqueous and methanol extracts of fresh plums, commercial prunes and home-made prunes prepared at different drying temperatures using an HPLC method with amperometric detection (HPLC-ECD). The prunes dried at high temperature (90 °C, 18 h) in kitchen or laboratory oven with restricted ventilation gave up to 3.3 times higher electrochemical capacity (EC) than fresh plums (dry matter; P. domestica cv. Domestica) in dependence on production protocol. Drying at 60 °C (low-temperature drying) for 18 h did not change the EC significantly. Yet, lower EC was found in commercial tenderized prunes with sorbate; they were by a factor of 1.1–8.2 lower in EC than the prepared low-temperature prunes. The principle responsible for the increase in EC in the prunes prepared at high temperatures is 2,3-dihydro-3,5-dihydroxy-6-methyl-(4H)-pyran-4-one (DDMP). It was not detected until 74 °C was set during isothermal 18 h drying or until 6 h of drying passed at 90oC drying. The ultimate acceptable dwell-time for the preparation of conveniently eatable prunes dried at 90oC under the conditions used was assessed to 12 h. The EC of plums and prunes as well as the role of DDMP was confirmed by the use of several methods for the assessment of AOC-DPPH• assay, β-carotene bleaching method, Oxipres test and Schaal oven test.

Gibberellic acid insensitive mRNA transport in both directions between stock and scion in Malus

The sieve tube in higher plants functions as infrastructure for long-distance transport of nutrients, photoassimilates, and growth regulators including hormones. Recently, it was revealed that some protein and RNA molecules also function as movable growth regulators in the sieve tube. In the case of the mRNA of gibberellic acid insensitive (GAI), the transport evidence was obtained through identification of the overproduced transgene transcript. In this work, we investigated the transport of apple (Malus x domestica cv. Fuji and Malus xiaojinensis) endogenous GAI mRNA by grafting experiments. Each GAI mRNA of scion and stock plants was detected in the graft partners as from 5 days after grafting, indicating that the GAI mRNA moves in both upward and downward directions via the graft union.

EFFECT OF DIFFERENT CALCIUM FRUIT CONTENT IN PHYSICAL AND CHEMICAL PROPERTIES OF EUROPEAN PLUM

Fruits from Prunus domestica cv ‘Raínha Claudia Verde’ were harvested in two consecutive years, from two production sites (‘Cano’ and ‘Vila Viçosa’). Fruits were collected and tested periodically for weight, firmness, solids soluble content, titratable acidity and ethylene production rate. It was also evaluated the level of potassium (K), calcium (Ca), magnesium (Mg), and nitrogen (N), in the fruit flesh and in the soil. Fruits from ‘Cano’ exhibited a lower flesh Ca/K ratio and a shorter postharvest life than fruits from ‘Vila Viçosa’. During storage fruits with a lower Ca/K ratio exhibited a lower firmness. The results support the hypothesis that the excessive potassium in ‘Cano’ soil might interfere with calcium uptake and affected the Ca/K fruit content. It is also suggested that high levels of nitrogen in this soil, might caused a dilution of calcium in the fruit flesh due to high vegetative growth.

Transgenic apple plants overexpressing the Lc gene of maize show an altered growth habit and increased resistance to apple scab and fire blight

Transgenic apple plants (Malus x domestica cv. 'Holsteiner Cox') overexpressing the Leaf Colour (Lc) gene from maize (Zea mays) exhibit strongly increased production of anthocyanins and flavan-3-ols (catechins, proanthocyanidins). Greenhouse plants investigated in this study exhibit altered phenotypes with regard to growth habit and resistance traits. Lc-transgenic plants show reduced size, transversal gravitropism of lateral shoots, reduced trichome development, and frequently reduced shoot diameter and abnormal leaf development with fused leaves. Such phenotypes seem to be in accordance with a direct or an indirect effect on polar-auxin-transport in the transgenic plants. Furthermore, leaves often develop necrotic lesions resembling hypersensitive response lesions. In tests, higher resistance against fire blight (caused by the bacterium Erwinia amylovora) and against scab (caused by the fungus Venturia inaequalis) is observed. These phenotypes are discussed with respect to the underlying altered physiology of the Lc-transgenic plants. The results are expected to be considered in apple breeding strategies.

Impact of organic and conventional management on the phyllosphere microbial ecology of an apple crop.

Bacterial communities associated with the phyllosphere of apple trees (Malus domestica cv. Enterprise) grown under organic and conventional management were assessed to determine if increased biological food safety risks might be linked with the bacterial communities associated with either treatment. Libraries of 16S rRNA genes were generated from phyllosphere DNA extracted from a wash made from the surfaces of leaves and apples from replicated organic and conventional treatments. 16S rRNA gene libraries were analyzed with software designed to identify statistically significant differences between bacterial communities as well as shared and unique phylotypes. The identified diversity spanned eight bacterial phyla and 14 classes in the pooled organic and conventional libraries. Significant differences between organic and conventional communities were observed at four of six time points (P < 0.05). Despite the identification of significantly diverse microfloras associated with organic and conventional treatments, no detectable differences in the presence of potential enteric pathogens could be associated with either organic or conventional management. Neither of the bacterial genera most commonly associated with produce-related illness outbreaks (Salmonella and Escherichia) was observed in any of the libraries. The impressive bacterial diversity that was documented in this study provides a valuable contribution to our developing understanding of the total microbial ecology associated with the preharvest phyllospheres of food crops. The fact that organic and conventional phyllosphere bacterial communities were significantly different at numerous time points suggests that crop management methods may influence the bacterial consortia associated with the surfaces of fruits and vegetables.

Isolation of two novel complete Ty1-copia retrotransposons from apple and demonstration of use of derived S-SAP markers for distinguishing bud sports of Malus domestica cv. Fuji

Retrotransposon-based molecular markers are a powerful tool for mapping and diversity studies. The scarcity of retrotransposon long terminal repeat (LTR) sequences limits the application of retrotransposon-based molecular marker systems. Here, we isolated two novel complete Ty1-copia retrotransposons (CTcrm1 and CTcrm2) in apple using a genome walking strategy. The CTcrm retrotransposons are nearly 5 kb long, and they have all the features of Ty1-copia retrotransposons. The differences in gene organization and nucleotide sequence length between the CTcrm retrotransposons and other reported complete retrotransposons in apple showed that CTcrm1 and CTcrm2 are the first two distinct complete Ty1-copia retrotransposons in the apple genome. To investigate the potential utility of the two retrotransposons as molecular markers, primers complementary to the CTcrm LTRs were designed to develop sequence-specific amplification polymorphism markers for discriminating bud sports of Fuji apple. Multiple polymorphisms corresponding to CTcrm1 and CTcrm2 were detected and could easily be used to discriminate bud sports from their Fuji progenitor, as well as from each other.

Characterization of a Midwinter-Expressed Dehydrin (DHN) Gene from Apple Trees (Malus domestica)

To gain a better understanding of the proteins associated with cold acclimation and winter dormancy in apple trees (Malus domestica), we studied the expression of a dehydrin gene encoding one of the important proteins involved in these processes. A novel gene, designated mddhn, was obtained from M. domestica cv. “Golden Delicious”. The full-length complementary DNA (cDNA) consists of 993 nucleotides with an open reading frame of 687 bp. The deduced amino acid sequence of 229 residues shows similarity to members of the dehydrin (DHN) family. The putative DHN presents a structure typical of DHN proteins that are composed of two consensus Y-segments, a stretch of serine residues, and four lysine-rich repeats (Y2SK4). This apple DHN shows the greatest similarity to members of both the YnKn and YnSKn classes of DHNs from peach and almond: 57% to peach (Y2SK3) and almond (Y2SK3 and Y2K4) and a lower percentage (35%) to peach (Y2K9). When we analyzed the available expressed sequence tag databases for additional apple DHNs, we identified a DHN of the class Y2SK4 with a deduced amino acid sequence with 79–98% identity among the cultivars “Royal Gala”, “Goldrush”, and the M9 rootstock that showed high identity to our DHN from “Golden Delicious” (92–98%). The transcripts of mddhn are highly expressed in bark and bud tissues when the plant is dormant and cold hardy in midwinter, but are not expressed in early spring when cold hardiness is lost and the buds are growing.

Characterization of the 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase multigene family of Malus domestica Borkh

Two 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO) genes have been cloned from RNA isolated from leaf tissue of apple ( Malus domestica cv. Royal Gala). The genes, designated MD-ACO2 (with an ORF of 990 bp) and MD-ACO3 (966 bp) have been compared with a previously cloned gene of apple, MD- ACO1 (with an ORF of 942 bp) . MD-ACO1 and MD-ACO2 share a close nucleotide sequence identity of 93.9% in the ORF but diverge in the 3′ untranslated regions (3′-UTR) (69.5%). In contrast, MD-ACO3 shares a lower sequence identity with both MD-ACO1 (78.5%) and MD-ACO2 (77.8%) in the ORF, and 68.4% ( MD-ACO1) and 71% ( MD-ACO2) in the 3′-UTR. Southern analysis confirmed that MD-ACO3 is encoded by a distinct gene, but the distinction between MD-ACO1 and MD-ACO2 is not as definitive. Gene expression analysis has shown that MD-ACO1 is restricted to fruit tissues, with optimal expression in ripening fruit, MD-ACO2 expression occurs more predominantly in younger fruit tissue, with some expression in young leaf tissue, while MD-ACO3 is expressed predominantly in young and mature leaf tissue, with less expression in young fruit tissue and least expression in ripening fruit. Protein accumulation studies using western analysis with specific antibodies raised to recombinant MD-ACO1 and MD-ACO3 produced in E. coli confirmed the accumulation of MD-ACO1 in mature fruit, and an absence of accumulation in leaf tissue. In contrast, MD-ACO3 accumulation occurred in younger leaf tissue, and in younger fruit tissue. Further, the expression of MD-ACO3 and accumulation of MD-ACO3 in leaf tissue is linked to fruit longevity. Analysis of the kinetic properties of the three apple ACOs using recombinant enzymes produced in E. coli revealed apparent Michaelis constants ( K m) of 89.39 μM ( MD-ACO1), 401.03 μM ( MD-ACO2) and 244.5 μM ( MD-ACO3) for the substrate ACC, catalytic constants ( K cat) of 6.6 × 10 −2 ( MD-ACO1), 3.44 × 10 −2 ( Md-ACO2) and 9.14 × 10 −2 ( MD-ACO3) and K cat/ K m (μM s −1) values of 7.38 × 10 −4 μM s −1 ( MD-ACO1), 0.86 × 10 −4 M s −1 ( MD-ACO2) and 3.8 × 10 −4 μM s −1 ( MD-ACO3). These results show that MD-ACO1, MD-ACO2 and MD-ACO3 are differentially expressed in apple fruit and leaf tissue, an expression pattern that is supported by some variation in kinetic properties.

Instructions for Authors

The pollen morphology and exine ornamentation of an important autochthon plum cultivar (Prunus domestica cv. Požegača L.), which has horticultural, medicinal and alimentary uses, was examined in detail using both light and scanning electron microscope (SEM). Acetocarmine and fluorescein diacetate were used to assess the pollen viability of four Požegača plum genotypes. Pollen viability varied from 67% in genotype Pdp1 to 99% in genotype Pdp4. Also, pollen nucleus status was determined, and binucleate mature pollens were detected. The effect of polyethylene glycol-PEG (10, 15 and 20%, w/v) on pollen germination and tube growth was evaluated. Overall, the inclusion of PEG in the medium improved both pollen germination and tube growth. Regardless of the PEG concentration genotype has an effect on germination and length of pollen tubes. Genotype has a pronounced effect on germination and length of pollen tubes, regardless of the PEG concentration used. Genotype Pdp4 had the highest germination percentage and the highest pollen tube length on all media when compared to the other three genotypes. The highest pollen germination (96%) and a tube length (822 μm) of genotype PdP4 was attained in media with 20% PEG.

Content and mean polymerization degree of procyanidins in extracts obtained from clear and cloudy apple juices

The polyphenol profile of apples and that of technologically differently treated apple juices has already been studied thoroughly; nevertheless, the content of polymeric procyanidins has not received much attention up to date. Therefore, procyanidins in extracts made from six blended apple juices and two authentic clear as well as cloudy apple juices (Malus domestica cv. Bohnapfel and Bittenfelder) were investigated. Our determinations revealed significant differences in the total procyanidin content between apple juice extracts obtained from clear and the corresponding cloudy juices under study. Depending on the apple cultivars used average amounts of total procyanidin content determined in the extracts made from clear and cloudy juices ranged from 28.4 +/- 4.4% to 49.0 +/- 5.7% and from 48.3 +/- 0.3% to 60.6 +/- 0.3%, respectively. As the mean degree of polymerization (DPm) is supposed to have an influence on bioavailability and toxicity on different cells lines used in in vitro systems, the average degree of polymerization of the juices under examination were determined. Depending on the cultivar used and the technology of juice processing the DPm ranged between 3.0 and 13.4.

Dietary fibre content and cell wall polysaccharides in prunes

Dietary fibre content and cell wall polysaccharides in prunes

THE FERTILITY OF TRANSGENIC APPLE CARRYING EXOGENOUS COWPEA TRYPSIN INHIBITOR GENE

The Cowpea Trypsin Inhibitor (CpTI) gene was transferred into an apple cultivar of Malus domestica cv. Gala via Agrobacterium-media transformation method in 1998. The transgenic lines confirmed by Southern blot were transferred into the greenhouse. The plants started to flower in 2004. The fertility of the flowers was evaluated in 2004 and 2005. The results showed that the pollen germination rate of the transgenic plants of Gala varied from 38.1% to 56.3% depending on the transgenic lines, and no significant difference was found between the transgenic and the non-transgenic Gala. The fruit set rate of the transgenic Gala apple varied from 64.9 to 79.7% when the pollen collected from the non-transgenic Fuji apple plants were used for the cross. The fruit set rate of the non-transgenic Fuji apple varied from 47.9 to 69.0% when the pollen collected from the transgenic plants were used for the cross. No significant difference was found between transgenic and non-transgenic crossing combinations. Therefore, it could be concluded that the transgenic Gala apple carrying exogenous CpTI gene was as fertile as non-transgenic plants in terms of the pollen germination and fruit set ability.

Identification and characterisation of primary microRNAs from apple (Malus domestica cv. Royal Gala) expressed sequence tags

Microribonucleic acids (miRNAs) are small, non-coding RNAs that play important regulatory roles by down-regulating target transcripts in a sequence-specific manner. The miRBase Registry (Release 8.2) lists 732 miRNAs from flowering plant species, with the majority identified from Arabidopsis, rice and poplar where genome sequence is available. In the absence of genomic sequence and on the basis that sequences of many miRNAs are conserved amongst divergent plant species, we analysed approximately 120,000 Malus domestica cv. Royal Gala expressed sequence tags (ESTs) and identified ten distinct sequences that could be classified into seven conserved plant miRNA families (miR156, miR159, miR162, miR167, miR172, miR393 and miR398). Secondary structure predictions showed these sequences have the characteristic fold-back structures of precursor miRNAs, and northern analysis validated the presence of these miRNA families within Royal Gala tissues. A number of the miRNAs were expressed constitutively in all tissues tested (miR159, miR162 and miR172), while others showed more restricted patterns of expression, being expressed primarily in leaf (miR398), expressed in leaf and floral bud tissue but down-regulated during fruit development (miR156 and miR167) or expressed in fungal pathogen-infected leaf tissue (miR393). Potential targets for six of the miRNA families were identified from the EST dataset and completely sequenced complementary deoxyribonucleic acids. In general, these targets encode proteins shown to be the targets of corresponding miRNAs in other plant species. Demonstrating cleavage of a number of the putative target transcripts within the region of miRNA/messenger RNA complementarity provided further evidence of the functionality of the identified Royal Gala miRNAs.

Effect of host plants on developmental time and life table parameters of Amphitetranychus viennensis (Acari: Tetranychidae)

The effect of host plant species including black cherry (Prunus serotina cv. Irani), cherry (Prunus avium cv. siahe Mashhad) and apple (Malus domestica cv. shafi Abadi) was studied on biological parameters of Amphitetranychus viennensis (Zacher) in the laboratory at 25 +/- 1 degrees C, 70 +/- 10% RH and 16L: 8D photoperiod. Duration of each life stage, longevity, reproduction rate, the intrinsic rate of natural increase (rm), net reproductive rate (R0), mean generation time (T), doubling time (DT), and finite rate of increase (lambda) of the hawthorn spider mite on the three host plants were calculated. Differences in fertility life table parameters of the spider mite among host plants were analyzed using pseudo-values, which were produced by jackknife re-sampling. The results indicated that black cherry might be the most suitable plant for hawthorn spider mite due to the shorter developmental period (10.6 days), longer adult longevity (25.5 days), higher reproduction (65.6 eggs), and intrinsic rate of natural increase (0.194 females/female/day). Cherry was the least suitable host plant. To determine the effect of host shifts, the mite was transferred from black cherry onto cherry and apple. In the first generation after shifting to apple, the developmental period, reproduction and life table parameters were negatively influenced. However, population growth parameters in the first generation on cherry were actually better than after three generations on this new host. This underscores the relevance of the mites' recent breeding history for life table studies.

Variations in the radial gradient of sap velocity in trunks of forest and fruit trees

We studied the radial pattern of sap velocity (v) in trunks of six forest species: Cupressus sempervirens L; Eucalyptus camaldulensis F. Muell; Pinus halepensis Mill. (Alleppo pine); Quercus aegilops L. ssp. ithaburensis [Decne] Boiss; Quercus calliprinos Webb; Quercus rotundifolia Lam. (Syn. Quercus ilex spp. Rotundifolia) and three fruit species: Citrus sinensis L. Osback; Malus domestica cv. Golden Delicious; Persea americana Mill. Data was selected from measurements made over a period of 15 years. For each species, at least data of 1–2 weeks measured on days with clear sky and after a rain event or irrigation were analyzed. Measurements were made with the T max heat pulse method, and six points were measured along the radius of the trunk. Two types of radial pattern were found; in one type the highest v value was recorded near the cambium, decreasing toward the heartwood; and the other type had low v near the cambium increasing toward a depth of 12 to 20 mm below the cambium and decreasing with depth to the heartwood. There was large interspecies variability of v in both the pattern of radial gradient with depth and the distance between the cambium and the border of conducting sapwood. Variations in radial pattern of v between trees within species were generally small with a coefficient of variation of 4–20%. The mean fractions of volumetric flow in the 0–16 and 0–24 mm layers below the cambium were 59% and 79% of the total flow, respectively. The distance between the cambium and the border between conducting and non-conducting sapwood varied from 31 to 66 mm in the various species. The radial distribution of sap velocity with azimuth around the trunk had a coefficient of variation similar to that found between trees of the same species. The amplitude of the azimuthal variation changed during the day; it was high in the mornings and evenings and low at noon. The variation of sap velocity in three azimuths was more affected by the structure of each individual trunk than by the position with respect to the sun.

Identification of differentially expressed genes in Malus domestica after application of the non-pathogenic bacterium Pseudomonas fluorescens Bk3 to the phyllosphere

Biological control of plant diseases by the application of antagonistic micro-organisms to the plant phyllosphere is only marginally understood. Suppression subtractive hybridization (SSH) was used for the identification of genes expressed after application of the non-pathogenic bacterium Pseudomonas fluorescens Bk3 to the phyllosphere of the apple scab-susceptible cultivar Malus domestica cv. Holsteiner Cox. In total, 157 expressed sequence tag (EST) clones were obtained. The sequencing of 113 ESTs which have a significantly elevated transcript level and the comparison of the obtained sequences with databases revealed similarities to different classes of pathogenesis-related proteins, for example, RNase-like PR10 protein and endochitinase, or similarities to proteins expressed under stress conditions that could have a protective function, for example, a germin-like protein, glutathione S-transferase, thioredoxin-like proteins, and heat shock proteins. In addition, several transcripts were identified that code for proteins which have a crucial role at different stages of pathogen recognition and in signalling pathways or an as yet unknown function in plant defence. The results show that a number of transcripts encoding proteins/enzymes which are known to be up-regulated after pathogen infection are also up-regulated after the application of a non-pathogenic bacterium to a M. domestica cultivar. The expression of these proteins might increase the plant resistance towards pathogen infection and damage.