Evaluation of genetic variability in choosen apple (<Emphasis Type="Italic">Malus</Emphasis> × <Emphasis Type="Italic">domestica</Emphasis> Borkh.) cultivars by ISSR-PCR analysis

The aim of the study was to determine the genetic variability in eight apple cultivars: Delikates, Cortland, James Grieve, Lired, Jonathan, Golden Delicious, Jonagold, and Idared from the collection of Fruit Growing Research Station in Rajkowo of the West Pomeranian University of Technology, Szczecin. The cultivar Delikates was obtained from the crossing of two cultivars: Cortland, and James Grieve, whereas cultivar Lired is a James Grieve’s sport. The second one cultivar—Jonagold was obtained from the crossing of Jonathan and Golden Delicious. The cultivar Idared is a hybrid obtained from the crossing of Jonathan and Wagener. Out of 40 primers, 17 were chosen for the final study. Those amplified a total of 183 loci (872 amplicons) out of which 34 (18.5%) were monomorphic, 128 (69.5%) were polymorphic and 22 (12%) cultivar-specific. Specific ISSR products were detected for each apple cultivar. A dendrogram was constructed using the UPGMA method which revealed two distinct clusters: I—Delikates, Cortland, James Grieve and Lired, II—Jonathan, Golden Delicious, Jonagold and Idared. Genetic similarity between Delikates, Cortland and James Grieve was 68.6, 70.8%, respectively and between cultivar Jonagold, Jonathan and Golden Delicous was 79.8, 85.2%, respectively.     

Study of tree architecture of apple (<Emphasis Type="Italic">Malus</Emphasis> × <Emphasis Type="Italic">domestica</Emphasis> Borkh.) by QTL analysis of growth traits

Apple tree architecture is naturally very diverse, but for fruit production, certain tree habits are more desirable than others. Here we describe the results of a QTL analysis performed to study the genetic control of growth traits in apple. This was carried out on the progeny of a cross between two apple cultivars of contrasting tree architectures. “Telamon” has a columnar tree form and “Braeburn” has a more standard, “normal” growth habit. The growth traits were measured on the F ₁ seedlings of the Telamon × Braeburn population for two consecutive years of growth on own roots and for the first year of growth on M9 rootstock. QTL analysis was carried out using either the Kruskal–Wallis method or the Multiple QTL Method. For all but one growth characteristic, significant QTLs were detected. A major cluster of QTLs was located in the Co gene region of “Telamon”, confirming the major influence of the Co gene on tree architecture, although this influence changed as the plant material aged and was generally more pronounced for rootstock-grown plants. Additional QTL results suggest the occurrence of genes with pleiotropic effects on tree architecture. The observed QTL instability over different years and for different root systems indicates that the genetic control of tree architecture is largely influenced by environmental factors and probably changes as the tree matures. Finally, a major influence of the root system on all the traits determining tree architecture was clearly demonstrated.     

Inheritance of the<Emphasis Type="Italic"> Md-ACS1</Emphasis> gene and its relationship to fruit softening in apple (<Emphasis Type="Italic">Malus</Emphasis> ×<Emphasis Type="Italic"> domestica</Emphasis> Borkh.)

The 1-aminocyclopropane-1-carboxylic acid synthase (ACS) gene is a member of the ACS gene family that is involved in apple (Malus × domestica Borkh.) fruit ripening. Presence of an allele (Md-ACS1-2) of this gene is associated with low internal ethylene concentration in some apple cultivars. In this study, inheritance of Md-ACS1 was determined for 50 apple cultivars/advanced selections and 101 F₁ seedlings from five populations. Following this, the softening pattern of apples stored at 20°C for up to 40 days was examined using 35 fruiting cultivars/selections of defined Md-ACS1 status. Md-ACS1 is inherited in a Mendelian fashion and was found to be linked to fruit softening. Maturity season of genotypes also significantly affected fruit softening. Late-season genotypes in the Md-ACS1-2/2 class had the slowest rate of softening, while early-season Md-ACS1-1/1 genotypes had the most rapid softening rate. The implications of these results are discussed in relation to parental selection and breeding for storage ability in apple.Communicated by H. Nybom     

Genome-wide analysis and identification of the <Emphasis Type="Italic">SMXL</Emphasis> gene family in apple (<Emphasis Type="Italic">Malus</Emphasis> × <Emphasis Type="Italic">domestica</Emphasis>)

Strigolactones (SLs) are a recently discovered type of plant hormone that controls various developmental processes. The DWARF53 (D53) protein in rice and the SMAX1-LIKE (SMXL) family in Arabidopsis repress SL signaling. In this study, bioinformatics analyses were performed, and 236 SMXL proteins were identified in 28 sequenced plants. A phylogenetic analysis indicated that all potential SMXL proteins could be divided into three groups and that the SMXL proteins may have originated in Bryophytes. An analysis of the SMXL chromosomal locations suggested that gene duplication events at different times led to expansion of the SMXL family members in Angiospermae. Subsequently, the gene structure and protein modeling of MdSMXLs showed that they are highly conserved. The expression patterns of MdSMXLs indicated that they were expressed in different organs of apple (stems, roots, leaves, flowers, and fruits) at varying levels and that MdSMXLs may participate in the SL signaling pathway and the response to abiotic stress. This study provides a valuable foundation for additional investigations into the function of the SMXL gene family in plants.     

Genetic linkage maps of two apricot cultivars (<Emphasis Type="Italic">Prunus armeniaca</Emphasis> L.) compared with the almond Texas × peach Earlygold reference map for<Emphasis Type="Italic"> Prunus</Emphasis>

Several genetic linkage maps have been published in recent years on different Prunus species suggesting a high level of resemblance among the genomes of these species. One of these maps (Joobeur et al., Theor Appl Genet 97:1034–1041 [(1998); Aranzana et al., Theor Appl Genet 106:819–825 (2002b)] constructed from interspecific almond Texas × peach Earlygold F₂ progeny (T×E) was considered to be saturated. We selected 142 F₁ apricot hybrids obtained from a cross between P. armeniaca cvs. Polonais and Stark Early Orange for mapping. Eighty-eight RFLP probes and 20 peach SSR primer pairs used for the reference map were selected to cover the eight linkage groups. One P. davidiana and an additional 14 apricot simple sequence repeats (SSRs) were mapped for the F₁ progeny. Eighty-three amplified fragment length polymorphisms were added in order to increase the density of the maps. Separate maps were made for each parent according to the double pseudo-testcross model of analysis. A total of 141 markers were placed on the map of Stark Early Orange, defining a total length of 699 cM, and 110 markers were placed on the map of Polonais, defining a total length of 538 cM. Twenty-one SSRs and 18 restriction placed in the T×E map were heterozygous in both parents (anchor loci), thereby enabling the alignment of the eight homologous linkage groups of each map. Except for 15 markers, most markers present in each linkage group in apricot were aligned with those in T×E map, indicating a high degree of colinearity between the apricot genome and the peach and almond genomes. These results suggest a strong homology of the genomes between these species and probably between Prunophora and Amygdalus sub-genera.Communicated by C. Möllers     

Genetic mapping in (<Emphasis Type="Italic">Populus tomentosa</Emphasis> ×<Emphasis Type="Italic"> Populus bolleana</Emphasis>) and<Emphasis Type="Italic"> P. tomentosa</Emphasis> Carr. using AFLP markers

The AFLP genetic linkage maps for two poplar cultivars were constructed with the pseudo-test-cross mapping strategy. The hybrids were derived from an interspecific backcross between the female hybrid clone TB01 (Populus tomentosa × Populus bolleana) and the male clone LM50 (P. tomentosa). A total of 782 polymorphic fragments were obtained with a PCR-based strategy using 49 enzyme-nested (EcoRI/MseI) primer combinations. Six hundred and thirty two of these fragments segregated in a 1:1 ratio (P<0.01), indicating that these DNA polymorphisms are heterozygous in one parent and null in the other. The linkage analysis was performed using Mapmaker version 3.0 with LOD 5.0 and a maximum recombination fraction () of 0.3. Map distances were estimated using the Kosambi mapping function. In the framework map for LM50 (P. tomentosa), 218 markers were aligned in 19 major linkage groups. The linked loci spanned approximately 2,683 cM of the poplar genome, with an average distance of 12.3 cM between adjacent markers. For TB01 (P. tomentosa × P. bolleana), the analysis revealed 144 loci, which were mapped to 19 major linkage groups and covered about 1,956 cM, with an average distance of 13.6 cM between adjacent markers. These maps covered about 87% and 77% of the estimated genome size of parents LM50 and TB01, respectively. The maps developed in this study lay an important foundation for future genomics research in poplar, providing a means for localizing genes controlling economically important traits in P. tomentosa.Communicated by O. Savolainen     

Peculiarities of polyphenolic profile of fruits of Siberian crab apple and its hybrids with <Emphasis Type="Italic">Malus</Emphasis> × <Emphasis Type="Italic">Domestica</Emphasis> Borkh

For the first time, we have studied the polyphenolic profile of fruits of Siberian crabapple and its hybrids (F1, F2, and F3) with domestic apple cultivated in East Siberia. It is shown that the chemical composition of polyphenolics of Siberian crabapple fruits is overwhelmingly characteristic of the genus Malus; on the other hand, it has clearly identifiable features: low content of flavan-3-ols and derivatives of cinnamic acid; high content of procyanidin B1, phloridzin, anthocyanes, and quercetin glycosides. Procyanidin B2 was not found in both peel and flesh of Siberian crabapple. In the case of hybridization with domestic apple, the fruits of resulting cultivars show a substantial change in the flavan-3-ol content ratio because of the synthesizing of procyanidin B2 in tissues and an increase in (?)-epicatechin content.     

The isolation of the <Emphasis Type="Italic">IGT</Emphasis> family genes in <Emphasis Type="Italic">Malus × domestica</Emphasis> and their expressions in four idiotype apple cultivars

IGT family genes share the highly conserved motif GφL-(A/T) IGT in domain II and play an essential role in plant form. The tree architecture of apple (Malus ×?domestica Borkh.) affects fruit quality and yield. However, little information is available regarding IGT family genes in apple. Apple cultivars of four ideotypes (columnar, tip bearer, spur, and standard) were selected to characterize IGT family genes. Four IGT family members named MdoTAC1a, MdoTAC1b, MdoLAZY1, and MdoLAZY2 were found in the apple genome, sharing four conserved domains. In addition, MdoLAZY1 and MdoLAZY2 contain a fifth domain (EAR motif) at the C-terminus. There was no difference in the coding sequences of each gene in the four cultivars, but several mutated sites were found in their promoters. The four genes displayed lower expression levels in all tested tissues and organs of the columnar cultivar than in the other three cultivars, while expression levels of MdoTAC1a and MdoTAC1b in shoot tips and vegetative buds were highest in the standard cultivar, followed by spur, tip bearing, and columnar cultivars in decreasing order. These results indicate that IGT gene promoters are of great importance in the development of apple tree architecture and lay a theoretical basis for developing gene-specific markers for marker-assisted selection in breeding programs.     

Screening interspecific hybrids of<Emphasis Type="Italic"> Populus</Emphasis> (<Emphasis Type="Italic">P. ciliata</Emphasis> ×<Emphasis Type="Italic"> maximowiczii</Emphasis>) using AFLP markers

Hybrids of Populus ciliata × maximowiczii are very vigorous and outperform both the parents in growth performance and yield. Genetic evaluation of 24 of these interspecific hybrids along with the two mother trees (Populus ciliata), and five male-parent (Populus maximowiczii) genotypes was carried out using the AFLP marker assay. Eight AFLP primer combinations detected 428 markers, of which 280 (66%) were polymorphic. Genetic relationships within the samples were evaluated by generating the similarity matrix based on Jaccards coefficient. The phenetic dendrograms, as well as the PCO plots, separated the hybrids and the two parent species into three distinct clusters. The hybrids grouped closer to the P. ciliata (female parent) cluster as compared to the P. maximowiczii (male parent) cluster. The hybrid cluster contained internal groupings, which correlated to some extent with growth performance. The four best performing hybrids (42m1, 65m1, 23m2, Cm2-5-20/91) formed a distinct sub-cluster. Data from a single primer combination was sufficient for distinguishing the hybrids from the parents and assigning paternity. The hybrids showed 22 markers that were absent in P. ciliata but were monomorphically present in all the hybrids, suggesting outcrossing and common paternity. Further, these 22 markers were found in all the P. maximowiczii genotypes confirming it as the male parent. These male-specific markers can be converted to SCAR markers and used for rapid screening of the P.ciliata × maximowiczii hybrids. The primer combination E-AAC × M-CAA was identified as most suitable for ascertaining true hybridity. AFLP proves to be a useful tool for screening of P. ciliata × maximowiczii hybrids at the early stages of development.Communicated by H.F. Liskens     

A reliable multiplexed microsatellite set for genotyping <Emphasis Type="Italic">Fragaria</Emphasis> and its use in a survey of 60 <Emphasis Type="Italic">F</Emphasis>. × <Emphasis Type="Italic">ananassa</Emphasis> cultivars

We have identified a reliable set of multiplexed microsatellite (SSR) markers for the genotyping of strawberry cultivars and their octoploid progenitors. Over 100 SSRs were screened in two F. × ananassa genotypes and from these, 32 that showed promise for genotyping were selected for further analysis. These SSRs were used to screen a set of 16 strawberry cultivars and a set of fingerprints were produced. Those SSRs that produced reliable, reproducible and easy to interpret fingerprints, that could also distinguish readily between the 16 strawberry cultivars screened, and which could be conveniently included in three multiplex reactions, were selected to form the genotyping set. The genotyping set, consisting of 10 previously-reported SSRs was used to fingerprint a total of 56 cultivated strawberry, and four octoploid Fragaria species accessions. The SSRs used could reliably distinguish between all 60 genotypes surveyed, including sibling cultivars derived from the same parental lines. The primers could be combined for multiplex PCR and represent a useful and convenient genotyping set for Fragaria that will permit fingerprinting data to be shared between laboratories.     

AFLP and SSR polymorphism in a <Emphasis Type="Italic">Coffea</Emphasis> interspecific backcross progeny [(<Emphasis Type="Italic">C. heterocalyx</Emphasis> × <Emphasis Type="Italic">C. canephora</Emphasis>) × <Emphasis Type="Italic">C. canephora</Emphasis>]

An interspecific cross (BC 1) involving a species with one of the largest genomes in the Coffea genus [Coffea heterocalyx (HET), qDNA = 1.74 pg] and a species with a medium-sized genome [Coffea canephora (CAN), qDNA = 1.43 pg] was studied using two types of molecular markers, AFLP and SSR. One hundred and eighty eight AFLP bands and 34 SSR primer pairs were suitable for mapping. The total map length was 1,360 cM with 190 loci distributed in 15 linkage groups. The results were compared to those obtained previously on an interspecific BC 1 progeny involving a species with a medium-sized genome (Coffea liberica var dewevrei, DEW) and a species with one of the smallest genomes (Coffea pseudozanguebariae, PSE). They are discussed relative to three main points: (1) the relevance of the different marker types, (2) the genomic distribution of AFLP and SSR markers, and (3) the relation between AFLP polymorphism and genome size.Communicated by H.F. Linskens     

<Emphasis Type="Italic">Carex</Emphasis> × <Emphasis Type="Italic">involuta</Emphasis> and <Emphasis Type="Italic">Carex juncella</Emphasis> in the flora of Slovakia

The paper brings information on an isolated occurrence and morphological characters of Carex × involuta and C. juncella populations in the Vel’ká Fatra Mts. Their presence has been known neither from the territory of Slovakia nor from the whole Western Carpathians till now.     

Regeneration of transformed verbena (<Emphasis Type="Italic">Verbena </Emphasis>× <Emphasis Type="Italic">hybrida</Emphasis>) by <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

Verbena (Verbena x hybrida), an important floricultural species, was successfully regenerated from stem segments on Murashige and Skoog's basal medium supplemented with thidiazuron and indole-3-acetic acid. A transformation system was developed using cvs. Temari Scarlet, Temari Sakura, Tapien Rose and TP-P2. Agrobacterium tumefaciens strain Agl0 harboring the sGFP gene was infected into stem segments. Transformation efficiency was improved by evaluating and manipulating the age of the plant material, the concentration of kanamycin in the medium during selection, and the length of the culture period in the dark. After 2-3 months of culture on the selection medium, GFP-positive shoots were obtained in all four of the cultivars tested. These shoots were successfully acclimated and set flowers within 2-3 months in a greenhouse. GFP was expressed in all of the organs including the floral parts. Stable genomic transformation was confirmed by Southern blot analysis. No morphological differences were observed between the transformed plants and their host plants.     

AFLP markers closely linked to a major gene essential for nucellar embryony (apomixis<Emphasis Type="Italic">)</Emphasis> in <Emphasis Type="Italic">Citrus maxima</Emphasis> × <Emphasis Type="Italic">Poncirus trifoliata</Emphasis>

Some citrus varieties express a form of apomixis termed nucellar embryony in which the adventive embryos develop from nucellus tissue surrounding the embryo sac. This trait results in many seeds containing multiple embryos (polyembryony). Inheritance of the frequency of polyembryony was studied in 88 progeny from a cross of Citrus maxima (monoembryonic) × Poncirus trifoliata (polyembryonic). The frequency of polyembryonic seed produced by each progeny was determined by scoring 100–500 seeds for the number of seedlings to emerge from each seed. Two groups of eight individuals from each extreme of the population were chosen for bulked segregant analysis with amplified fragment length polymorphism markers amplified with 256 primer combinations. Candidate markers identified in the bulks as linked to the trait were tested on the 32 individuals used to create the bulks and then on the remaining plants in the population. Five candidate markers tightly linked to polyembryony in P. trifoliata were identified. Specific marker alleles were present in nearly all progeny that produced polyembryonic seed, and alternate alleles were present in nearly all progeny that produced only monoembryonic seed. The region defined by these markers very likely contains a gene that is essential for the production of polyembryonic seeds by apomixis, but also shows segregation distortion. The proportion of polyembryonic seeds varied widely among the hybrid progeny, probably due to other genes. Scoring 119 progeny of a P. trifoliata selfed population for the closely linked markers and the proportion of polyembryonic seeds confirmed close linkage between these markers and polyembryony.     

Cryopreservation of cell suspension cultures of <Emphasis Type="Italic">Taxus</Emphasis> × <Emphasis Type="Italic">media</Emphasis> and <Emphasis Type="Italic">Taxus floridana</Emphasis>

Different lines of cell suspension cultures of Taxus × media Rehd. and Taxus floridana Nutt. were cryopreserved with a two-step freezing method using a simple and inexpensive freezing container instead of a programmable freezer. Four to seven days old suspension cell cultures were precultured in growth medium supplemented with 0.5 M mannitol for 2 d. The medium was then replaced with cryoprotectant solution (1 M sucrose, 0.5 M glycerol and 0.5 M dimethylsulfoxide) and the cells incubated on ice for 1 h. Before being plunged into liquid nitrogen, cells were frozen with a cooling rate of approximately −1 °C per min to −80 °C. The highest post-thaw cell viability was 90 %. The recovery was line dependent. The cryopreservation procedure did not alter the nuclear DNA content of the cell lines. The results indicate that cryopreservation of Taxus cell suspension cultures using inexpensive freezing container is possible.     

<Emphasis Type="Italic">TNF</Emphasis><Emphasis Type="Italic">α</Emphasis> and <Emphasis Type="Italic">LT</Emphasis><Emphasis Type="Italic">α</Emphasis> gene polymorphisms as additional markers of celiac disease susceptibility in a DQ2-positive population

TNFalpha and TNFbeta, or linfotoxin (LTalpha), are two molecules playing an important role in inflammation. Their genes map on Chromosome 6, between the HLA class II and class I loci. Polymorphisms in, or near, TNF genes have been associated with susceptibility to several autoimmune diseases. Studies of TNF genes in celiac disease (CD) have presented contradictory results. We have assessed the role of TNFalpha and linfotoxin alpha (TNFbeta) in CD and their relative value as CD markers in addition to the presence of DQ2. The TNFA -308 polymorphism and the polymorphism at the first intron of the LTA gene were typed in CD patients and healthy controls and the results were correlated with the presence of DQ2. Significant differences were found in genotype and allele frequencies for the TNFA and LTA genes between CD patients and controls, with an increase in the presence of the TNFA*2 and LTA*1 alleles in CD patients. These differences increase when DQ2-positive CD patients and DQ2-positive controls are compared. In DQ2-positive individuals, allele 2 (A) in position -308 of the promoter of TNFA and allele 1 (G) of the NcoI RFLP in the first intron of LTA are additional risk markers for CD.     

Brood cell size of <Emphasis Type="Italic">Apis</Emphasis> <Emphasis Type="Italic">mellifera</Emphasis> modifies the reproductive behavior of <Emphasis Type="Italic">Varroa</Emphasis> <Emphasis Type="Italic">destructor</Emphasis>

We undertook a field study to determine whether comb cell size affects the reproductive behavior of Varroa destructor under natural conditions. We examined the effect of brood cell width on the reproductive behavior of V. destructor in honey bee colonies, under natural conditions. Drone and worker brood combs were sampled from 11 colonies of Apis mellifera. A Pearson correlation test and a Tukey test were used to determine whether mite reproduction rate varied with brood cell width. Generalized additive model analysis showed that infestation rate increased positively and linearly with the width of worker and drone cells. The reproduction rate for viable mother mites was 0.96 viable female descendants per original invading female. No significant correlation was observed between brood cell width and number of offspring of V. destructor. Infertile mother mites were more frequent in narrower brood cells.