Genetic diversity of Cannabis sativa germplasm based on RAPD markers

Random amplified polymorphic DN A (RAPD) markers were generated from 13 cultivars and accessions of Cannabis sativa L. Approximately 200 fragments generated by 10 primers of arbitrary sequence were used to assess the level of DNA variation. Statistical analysis was performed using the Dice coefficient of similarity and principal coordinate analysis. The grouping of the accessions according to the cluster analysis was in good agreement with their origin and lines with common ancestors were grouped together. Principal coordinates 1 and 2 revealed a clear separation of Italian and Hungarian germplasm and a third group, including a mixture of genotypes coming from different places; the third coordinate separated the Korean group which is probably the most divergent germplasm. Variability within the two cultivars ‘Carmagnola’ and ‘Fibranova1’ was also shown, suggesting good possibilities for long–term selection work. RAPD markers provide a powerful tool for the investigation of genetic variation in cultivars/accessions of hemp.     

Limited application of homozygous genotypes in apple breeding

Apple is a temperate fruit species with several breeding disadvantages such as the highly heterozygous nature of the genome and a long reproductive cycle. It is expected that homozygous apple genotypes can increase breeding efficiency, but inbreeding is prevented by the gametophytic self‐incompatibility mechanism. In this paper, the production and characterization of homozygous genotypes, generated from anther culture in Malus × domestica cv. ‘Braeburn’, is described as well as their potential for use in breeding programmes. After determination of large scale anther culture efficiency, anther culture‐derived genotypes were simple sequence repeat (SSR)‐fingerprinted to determine their homozygous nature and confirm their androgenic origin. Their value for breeding was estimated based on growth and fertility measurements. The use of homozygous androgenic genotypes from ‘Braeburn’ in apple breeding programmes is currently not a realistic approach, partly because of the low efficiency of anther culture, but mainly because of the reduced vigour and severe sterility of the androgenic genotypes produced.     

Introducing host‐plant resistance to anthracnose in Kyrgyz common bean through inoculation‐based and marker‐aided selection

Common bean (Phaseolus vulgaris L.) is one of the most important legume crops for human consumption. However, its grain yield can be reduced by up to 90% by the seedborne disease, anthracnose. Fungicide treatment is costly and time‐consuming. The introduction of host plant resistance against this disease appears, therefore, to be crucial for enhancing the productivity of this crop in Kyrgyzstan. The use of DNA‐based markers in backcrossing programmes may help speed up the breeding for resistance. In this study, we used a combination of inoculation tests and a DNA marker (SCAreoli marker) to track the transfer of host‐plant resistance (Co‐2 gene) from two donor cultivars, ‘Vaillant’ and ‘Flagrano’, to susceptible Kyrgyz cultivars ‘Ryabaya’, ‘Kytayanka’ and ‘Lopatka’, which are widely grown in the country. The segregating offspring were evaluated to test the reliability of the SCAreoli marker as selection aid for host‐plant resistance to anthracnose. Our study showed that a co‐dominant DNA marker can successfully be used in backcross breeding to distinguish segregating material in different market classes of common bean.     

Genotypic difference for the susceptibility of Japanese, Chinese and European pears to Venturia nashicola, the cause of scab on Asian pears

Venturia nashicola, the cause of scab on Asian pears, is distinct from Venturia pirina, a causal fungus of European pear scab. Although scab caused by V. nashicola is one of the most serious diseases in the Japanese pear (Pyrus pyrifolia Nakai var. culta Nakai), information available regarding resistant breeding against V. nashicola is limited. In this study, 12 genotypes of Japanese pear, seven genotypes of Chinese pear (Pyrus ussuriensis Maxim.) and four genotypes of European pear (Pyrus communis L. var. sativa DC.) and/or their offspring were evaluated for susceptibility to V. nashicola with leaf and fruit inoculation tests. At 30–40 days after full bloom in their developmental stage, unfolded young leaves and fruit were inoculated with conidial suspensions of V. nashicola for each genotype, and the responses were rated at 30 days postinoculation for the inoculated leaves and at 42 days postinoculation for the inoculated fruits. No visible symptoms were found in European pear ‘Bartlett’ and ‘La France’ and their respective offspring ‘290‐36’ and ‘282‐12’, in the Japanese pear ‘Kinchaku’ and in the Chinese pears ‘Cangxili’ and ‘Hongli’; these genotypes were evaluated as highly resistant to V. nashicola. Necrotic lesions without sporulation were observed in the Chinese pears ‘Qiubaili’, ‘Manyuanxiang’, ‘Yuanbali’ and ‘Xiangyali’, which were regarded as resistant. Sporulating lesions were formed on the other genotypes, such as the major Japanese pear cultivars ‘Kosui’ and ‘Nijisseiki’, which were regarded as susceptible. The response of inoculated leaves coincided well with that of inoculated fruit for each genotype. When the severity of scab symptoms on scab‐susceptible genotypes was further rated with disease severity (DS) values, a genotypic difference was observed for overall DS values in a successive 2‐year measurement among the susceptible genotypes. Based on the DS values of leaf and fruit scabs, the Japanese pears ‘Niitaka’, ‘Shinko’, ‘Nijisseiki’, ‘Gold Nijisseiki’, ‘Osa Nijisseiki’ and ‘Shinsui’ were considered to be less susceptible to V. nashicola than the typical susceptible cultivar ‘Kosui’.     

Genotype analysis of the wheat semidwarf Rht‐B1b and Rht‐D1b ancestral lineage

In wheat, semidwarfism resulting from reduced height (Rht)‐B1b and Rht‐D1b was integral to the ‘green revolution’. The principal donors of these alleles are ‘Norin 10’, ‘Seu Seun 27’ and ‘Suwon 92’ that, according to historical records, inherited semidwarfism from the Japanese landrace ‘Daruma’. The objective of this study was to examine the origins of Rht‐B1b and Rht‐D1b by growing multiple seed bank sources of cultivars comprising the historical pedigrees of the principal donor lines and scoring Rht‐1 genotype and plant height. This revealed that ‘Norin 10’ and ‘Suwon 92’ sources contained Rht‐B1b and Rht‐D1b, but the ‘Seu Seun 27’ source did not contain a semidwarf allele. Neither Rht‐B1b nor Rht‐D1b could be definitively traced back to ‘Daruma’, and both ‘Daruma’ sources contained only Rht‐B1b. However, ‘Daruma’ remains the most likely donor of Rht‐B1b and Rht‐D1b. We suggest that the disparity between historical pedigrees and Rht‐1 genotypes occurs because the genetic make‐up of seed bank sources differs from that of the cultivars actually used in the pedigrees. Some evidence also suggests that an alternative Rht‐D1b donor may exist.     

Inheritance of tolerance to zinc deficiency in barley

Barley (Hordeum vulgare L.) is often grown on alkaline zinc (Zn)‐deficient soils where reductions in yield and grain quality are frequently reported. Currently, the use of Zn‐based fertilizer along with Zn‐deficiency‐tolerant genotypes is considered the most thorough approach for cropping the Zn‐deficient soils; however, developing or breeding genotypes with higher Zn efficiency requires a good understanding of the inheritance of tolerance to Zn deficiency. This study was conducted to determine genetic control of this trait in barley. Two parental cultivars ('Skiff, moderately tolerant; and ‘Forrest’, sensitive), 185 F₂ plants, and 48 F₂‐derived F₃ families from this cross were screened to determine inheritance of tolerance to Zn deficiency using a visual score of deficiency symptoms. The segregation ratios observed indicated that greater tolerance to Zn deficiency in ‘Skiff compared with ‘Forrest’ at the seedling stage is controlled by a single gene with no dominance. The results also indicate that visual scores are useful for genetic analysis of tolerance to Zn deficiency.     

Genes for wheat stem rust resistance postulated in German cultivars and their efficacy in seedling and adult‐plant field tests

Stem rust of wheat (caused by Puccinia graminis f.sp. tritici) gained high international attention in the last two decades, but does not occur regularly in Germany. Motivated by a regional epidemic in 2013, we analysed 15 spring and 82 winter wheat cultivars registered in Germany for their resistance to stem rust at the seedling stage and tested 79 of these winter wheat cultivars at the adult‐plant stage. A total of five seedling stem rust resistance genes were postulated: Sr38 occurred most frequently (n = 29), followed by Sr31 (n = 11) and Sr24 (n = 8). Sr7a and Sr8a occurred only in two spring wheat genotypes each. Four cultivars had effective seedling resistance to all races evaluated that could only be explained by postulating additional resistance genes (‘Hyland’, ‘Pilgrim PZO’, ‘Tybalt’) or unidentified gene(s) (‘Memory’). The three winter wheat cultivars (‘Hyland’ ‘Memory’ and ‘Pilgrim PZO’) were also highly resistant at the adult‐plant stage; ‘Tybalt’ was not tested. Resistance genes Sr24 and Sr31 highly protected winter wheat cultivars from stem rust at the adult‐plant stage in the field. Disease responses of cultivars carrying Sr38 varied. Mean field stem rust severity of cultivars without postulated seedling resistance genes ranged from 2.71% to 41.51%, nine of which were significantly less diseased than the most susceptible cultivar. This suggests adult‐plant resistance to stem rust may be present in German wheat cultivars.     

Genetic diversity and phylogenetic relationships among accessions of hop, Humulus lupulus, as determined by amplified fragment length polymorphism fingerprinting compared with pedigree data

DNA fingerprinting using amplified fragment length polymorphisms (AFLPs) was successfully employed to detect genetic relationships and variability among 90 hop cultivars and breeding lines comprising a collection of the world's hop germplasm. Seven AFLP primer combinations produced a total of 347 fragments of which 151 (43.5%)) were polymorphic. One‐hundred and thirty informative, highly reproducible DNA polymorphisms were used to estimate the genetic similarity (GS) which varied between 1.0 (e.g. ‘Saazer’ vs. ‘Tettnanger’) and 1.17 (‘Columbus’ vs. ‘Tettnanger’, ‘Spalter’ and ‘Saazer’). UPGMA (unweighted pair‐group method with arithmetic averages) clustering revealed two main clusters, reflecting the two main sources of origin and the two main breeding objectives: one cluster of mainly European origin representing the aroma pool and a second cluster associating accessions with European germplasm infiltrated by wild American genes with less aroma quality, but a higher bittering potential. Each main branch was composed of four or three subclusters with subgroups, respectively. Assignment of almost all genotypes in the dendrogram was consistent with the pedigree data as far as they are known. Consequently, AFLPs are shown to be suitable for assessing the genetic variability in hop germplasm and are useful for describing the genetic relationships among cultivars and accessions, which allows phylogenetic questions to be addressed.     

Inheritance of insensitivity to culture filtrate of Pyrenophora tritici-repentis, race 2, in wheat (Triticum aestivum L.)

Tan spot of wheat is caused by the fungus Pyrenophora tritici‐repentis. On susceptible hosts, P. tritici‐repentis induces two phenotypically distinct symptoms, tan necrosis and chlorosis. This fungus produces several toxins that induce tan necrosis and chlorosis symptoms in susceptible cultivars. The objectives of this study were to determine the inheritance of insensitivity to necrosis‐inducing culture filtrate of P. tritici‐repentis, race 2, and to establish the relationship between the host reaction to culture filtrate and spore inoculation with respect to the necrosis component. The F₁, F₂, and BC₁F₁ plants and F_2:8 lines of five crosses involving resistant wheat genotypes ‘Erik’, ‘Red Chief’, and line 86ISMN 2137 with susceptible cultivars ‘Glenlea’ and ‘Kenyon’ were studied. Plants were spore‐inoculated at the two‐leaf stage. Four days later, the newly emerged uninoculated third leaf was infiltrated with a culture filtrate of isolate Ptr 92–164 (race 2). Reactions to the spore inoculation and the culture filtrate were recorded 8 days after spore inoculation. The segregation observed in the F₂ and BC₁F₁ generations and the F_2:8 lines of all crosses indicated that a single recessive gene controlled insensitivity to necrosis caused by culture filtrate. This gene also controlled resistance to necrosis induced by spore inoculation.     

Morphological traits and high resolution RAPD markers for the identification of the main strawberry varieties cultivated in Argentina

Eight genotypes of the main Fragaria×ananassa cultivars grown in Argentina were analysed using the random amplified polymorphic DNA (RAPD) technique combined with electrophoresis in polyacrylamide gels. The high resolution of this procedure allowed the detection, with only 13 random primers, of 37 genotype‐specific bands that can be used as markers for verifying the identity of cultivars. By using this approach, three different accessions of the cultivar ‘Pájaro’ exhibited differences in amplification profiles, confirming the need for DNA analysis to prevent misidentification of cultivars. In addition, RAPD bands and morphological traits were used to assess genetic relatedness among cultivars. Comparison of both dendrograms revealed that there is no correlation between the clustering obtained with molecular and morphological characters.     

Leaf shape × sowing density interaction affects chickpea grain yield

Modifying plant architecture is considered a promising breeding option to enhance crop productivity. Modern chickpea (Cicer arietinum L.) cultivars with either compound (wild‐type) or simple leaf shapes are commercially grown but the relationships between leaf shape and yield are not well understood. In this study, a random sample of ‘Kabuli’ type progeny lines of both leaf types, derived from two crosses between modern American simple leaf cultivars and early‐flowering wild‐type breeding lines, were planted at different sowing densities. Leaf area development and final grain yield in genotypes of the two leaf types responded differently to changes in sowing densities. Compound leaf lines attained higher leaf area indices and higher grain yields at both low and high sowing densities. Yield responses of the simple leaf lines to increasing sowing density were significantly higher compared to compound leaf genotypes in two of three field experiments. The prospects for utilizing the simple leaf trait as a breeding target for short‐season growing areas are discussed.     

Powdery mildew resistance in Czech and Slovak barley cultivars

Fifteen powdery mildew resistance genes and the gene MlaN81 derived from ‘Nepal 81’were found in 76 Czech and Slovak spring and winter barley cultivars when tested for reaction to a set of powdery mildew isolates. Nine cultivars (‘Donum’, ‘Expres’, ‘Jubilant’, ‘Orbit’, ‘Primus’, ‘Progres’, ‘Stabil’, ‘Vladan’ and ‘Zlatan’) are composed of lines with different resistance genes. The Mlat gene is present in nine cultivars and was transferred from the Anatolian landrace ‘A‐516′. The resistances derived from ‘KM‐1192’and ‘CI 7672’were identical and designated Ml(Kr). Five winter barley cultivars possess the Ml(Bw) resistance. The winter barley line ‘KM‐2099’carries the mlo gene. The parental cultivar ‘Palestine 10’was also tested in which the genes Mlk1, MlLa were identified. The German cultivar ‘Salome’, a parent of seven cultivars tested, probably carries the gene MlLa in addition to mlo and Mla7. The gene mlo6 may be present in the cultivar ‘Heris’. Most of the results were confirmed by the pedigrees of the cultivars.     

Incompatibility and resistance to woolly apple aphid in apple

The study investigated the reported linkage of the locus for resistance to woolly apple aphid with the locus for incompatibility. Apple seedlings from the cross ‘Northern Spy’(heterozygous for resistance) בTotem’(susceptible) were scored for resistance, and for incompatibility genotype, by analysis of stylar ribonucleases, and for Got‐1, the isoenzyme marker for incompatibility. Cosegregation analysis provided no evidence that the loci for resistance and incompatibility are linked. Two rootstock cultivars,‘M9’and ‘Merton 789′, which in early work had been reported to give poor set in crosses with ‘Northern Spy’, were found to have the same incompatibility genotype as ‘Northern Spy’, namely S₁S₃.‘M4’and ‘Irish Peach’, two other cultivars that had given poor set when crossed on to ‘Northern Spy’, appeared to be homozygous at the incompatibility locus and to have the genotypes S₃S₃ and S₁S₁, respectively.     

Effectiveness and environmental stability of quantitative powdery mildew (Blumeria graminis) resistance among winter wheat cultivars

Powdery mildew in wheat (Blumeria graminis f. sp. tritici) is a major disease in Northern and Central Europe. The aim of the study was to analyse the effectiveness and environmental stability of quantitative powdery mildew resistance under high epidemic pressure in the field across years in the absence/presence of ineffective race‐specific resistances. Cultivars with and without Pm (major) genes were inoculated in three experiments with a genetically broad mildew population with all matching virulences. Resistance was measured three times by assessing the percentage of leaf area covered by powdery mildew on a plot basis (0–100%). Mean powdery mildew severity of the highly susceptible cv. ‘Kanzler’ varied across 10 years from 24% to 66% (Exp. 1). Means of three cultivars without Pm genes, ‘Ramiro’, ‘Miras’ and ‘Zentos’, and several cultivars with ineffective Pm genes varied quantitatively from 4% to 13%. Environmental stability of the quantitative resistances was on average higher than that of susceptible genotypes, as revealed by a regression approach. In the second experiment, all groups of cultivars with ineffective Pm gene(s) contained a large proportion of entries with a similar low mildew rating as the quantitatively resistant standard ‘Miras’. Mildew severity of pairs of cultivars with the same Pm gene(s) was significantly different across 6 years (Exp. 3) indicating the presence of additional quantitative resistances in some of these cultivars. In the analysis of variance, genotypic variance had a high impact (P < 0.01) with low importance of genotype × environment interaction. Consequently, heritabilites were high (0.95–0.97). In conclusion, breeders have already accumulated effective minor genes for powdery mildew resistance in many of the released German winter wheat cultivars. These quantitative resistances are long lasting, environmentally stable and provide a high level of protection to powdery mildew.     

Genetic Relationships in Malus Evaluated by RAPD 'Fingerprinting' of Cultivars and Wild Species

The potential use of RAPD markers for taxonomic studies in Malus was investigated using 18 accessions of wild species and 27 apple cultivars. 29 preselected random decamer primers were applied to three sets of Malus genotypes. Random amplified polymorphic DNA (RAPD) ‘fingerprints’ were analysed for polymorphic amplification fragments, and coefficients estimating genetic similarity were calculated on the basis of about 50 polymorphic RAPD loci in each set of genotypes. Cluster analysis by an unweighted pair-group method with arithmetic averages (UPGMA) revealed that, in the cultivars, the molecular classification was in good agreement with the known lineage. A dendrogram generated for the wild species gave relationships that were, in principle, in accordance with the known phylogenetic information. Closely related species from section I were clearly distinguishable from those of sections III and IV. On the molecular level, a high degree of genetic diversity was found among both different apple cultivars and wild species of the genus Malus. The results gave additional evidence for the hypothesis that M. pumila and M. sylvestris were involved in the origin of the cultivated apples.     

Genetic mapping of the barley lodging resistance locus Erectoides‐k

The barley (Hordeum vulgare L.) mutant erectoides‐k.32 (ert‐k.32) was isolated in 1947 from an X‐ray‐mutant population of cultivar ‘Bonus’. The mutant was released as a cultivar in 1958 with the name ‘Pallas’ – one of the first cereal crop cultivars developed from induced mutants. ‘Pallas’ is a semi‐dwarf barley cultivar known for its culm stability and resistance to lodging. In total, eight allelic ert‐k mutants are known that show different phenotypic strength concerning culm length and spike architecture. They represent alternatives to the widely used, but pleiotropic ‘Green Revolution’ alleles of the Sdw1 (semidwarf1/denso) and Uzu1 (semi‐brachytic1) genes in breeding of robust elite barley cultivars. In the present study, we locate Ert‐k to a 15.7‐cM region in the centromeric region of chromosome 6H. Although the interval is estimated to contain approximately 700 genes, the work provides a solid foundation for the identification of the underlying mutations causing the ert‐k lodging‐resistant phenotype. In addition, the linked markers could be used to follow the ert‐k mutant genotype in marker‐assisted selection of new lodging‐resistant barley cultivars.     

Evaluation of cold hardiness in two sets of near-isogenic lines of wheat (Triticum aestivum) with polymorphic vernalization alleles

In wheat, variation at the orthologus Vrn‐1 loci, located on each of the three genomes, A, B and D, is responsible for vernalization response. A dominant Vrn‐1a allele on any of the three wheat genomes results in spring habit and the presence of recessive Vrn‐1b alleles on all three genomes results in winter habit. Two sets of near‐isogenic lines (NILs) were evaluated for DNA polymorphisms at their Vrn‐A1, B1 and D1 loci and for cold hardiness. Two winter wheat cultivars, ‘Daws’ and ‘Wanser’ were used as recurrent parents and ‘Triple Dirk’ NILs were used as donor parents for orthologous Vrn‐1 alleles. The NILs were analysed using molecular markers specific for each allele. Only 26 of 32 ‘Daws’ NILs and 23 of 32 ‘Wanser’ NILs had a plant growth habit that corresponded to the marker genotype for the markers used. Freezing tests were conducted in growth chambers programmed to cool to ?21.5°C. Relative area under the death progress curve (AUDPC), with a maximum value of 100 was used as a measure of death due to freezing. The average relative AUDPC of the spring habit ‘Daws’Vrn‐A1a NILs was 86.15; significantly greater than the corresponding winter habit ‘Daws’Vrn‐A1b NILs (42.98). In contrast, all the ‘Daws’Vrn‐A1bVrn‐B1aVrn‐D1b and Vrn‐A1bVrn‐B1bVrn‐D1a NILs (spring habit) had relative AUDPC values equal to those of their ‘Daws’ sister genotypes with Vrn‐A1bVrn‐B1bVrn‐D1b NILs (winter habit). The average AUDPC of spring and winter habit ‘Wanser’ NILs differed at all three Vrn‐A1, Vrn‐B1 and Vrn‐D1 locus comparisons. We conclude that ‘Daws’ and ‘Wanser’ have different background genetic interactions with the Vrn‐1 loci influencing cold hardiness. The marker for Vrn‐A1 is diagnostic for growth habit and cold hardiness but there is no relationship between the Vrn‐B1 and Vrn‐D1 markers and the cold tolerance of the NILs used in this study.     

An STS marker distinguishing the rye-derived powdery mildew resistance alleles at the Pm8/Pm17 locus of common wheat

A sequence‐tagged site marker has been developed from restriction fragment length polymorphism marker probe IAG95 for the rye‐derived powdery mildew resistance Pm8/Pm17 locus of common wheat. This polymerase chain reaction marker enables the amplification of DNA fragments with different sizes from T1AL.1RS and T1BL.1RS wheat‐rye translocation cultivars with chromatin from ‘Insave’ and ‘Petkus’ rye, respectively, and therefore will be very useful in distinguishing Pm8‐carrying cultivars from Pm17‐carrying cultivars. Results obtained with that marker were compared with resistance tests performed on detached primary leaves of 29 wheat lines from two populations derived from doubled haploid production. The molecular assay corresponded well with the resistance tests in all the lines, and therefore will be helpful for the identification of Pm17 in lines in which other Pm genes or quantitative trait loci are present.     

The Physiology and Stability of Leaf Carbon Isotope Discrimination as a Measure of Water‐Use Efficiency in Barley on the Canadian Prairies

Temporal and seasonal water deficit is one of the major factors limiting crop yield on the Canadian prairie. Selection for low carbon isotope discrimination (Δ¹³C) or high water‐use efficiency (WUE) can lead to improved yield in some environments. To understand better the physiology and WUE of barley under drought conditions on the Canadian prairie, 12 barley (Hordeum vulgare L.) genotypes with contrasting levels of leaf Δ¹³C were investigated for performance stability across locations and years in Alberta, Canada. Four of those genotypes (‘CDC Cowboy’, ‘Niobe’, ‘170011’ and ‘Kasota’) were also grown in the greenhouse under well‐watered and water‐deficit conditions to examine genotypic variations in leaf Δ¹³C, WUE, gas exchange parameters and specific leaf area (SLA). The water‐deficit treatment was imposed at the jointing stage for 10 days followed by re‐watering to pre‐deficit level. Genotypic ranking in leaf Δ¹³C was highly consistent, with ‘170011’, ‘CDC Cowboy’ and ‘W89001002003’ being the lowest and ‘Kasota’‘160049’ and ‘H93174006’ being the highest leaf Δ¹³C. Under field and greenhouse (well‐watered) conditions, leaf Δ¹³C was significantly correlated with stomatal conductance (g_s). Water deficit significantly increased WUE, with ‘CDC Cowboy’– a low leaf Δ¹³C genotype with significantly higher WUE and lower percentage decline in assimilation rate (A) and g_s than the other three genotypes (‘Niobe’, ‘170011’ and ‘Kasota’). We conclude that leaf Δ¹³C is a stable trait in the genotypes evaluated. Low leaf Δ¹³C of ‘CDC Cowboy’ was achieved by maintaining a high A and a low g_s, with comparable biomass and grain yield to genotypes showing a high g_s under field conditions; hence, selection for a low leaf Δ¹³C genotype such as ‘CDC Cowboy’ maybe important for maintaining productivity and yield stability under water‐limited conditions on the Canadian prairie.     

Mitochondrial DNA Restriction Fragment Length Polymorphisms in Malus Species

Three apple (Malus×domestica) cultivars and 11 Malus accessions have been investigated by the probe hybridization method on their mitochondrial DNA (mtDNA). The gene probes used were: coxI, coxII, atpA, atp6, and atp9. Our results revealed enough variation to characterize ten mtDNA haplotypes among the Malus genotypes examined. The taxonomic and phylogenetic implications of mtDNA polymorphism are also discussed.