Showing papers in "Plant Breeding in 2003"

Validation of a major QTL for scab resistance with SSR markers and use of marker-assisted selection in wheat

Abstract: The objectives of this study were to validate the major quantitative trait locus (QTL) for scab resistance on the short arm of chromosome 3B in bread wheat and to isolate near-isogenic lines for this QTL using marker-assisted selection (MAS). Two resistant by susceptible populations, both using ‘Ning7840’ as the source of resistance, were developed to examine the effect of the 3BS QTL in different genetic backgrounds. Data for scab resistance and simple sequence repeat (SSR) markers linked to the resistance QTL were analyzed in the F2:3 lines of one population and in the F3:4 lines of the other. Markers linked to the major QTL on chromosome 3BS in the original mapping population (‘Ning7840’/‘Clark’) were closely associated with scab resistance in both validation populations. Marker-assisted selection for the QTL with the SSR markers combined with phenotypic selection was more effective than selection based solely on phenotypic evaluation in early generations. Marker-assisted selection of the major QTL during the seedling stage plus phenotypic selection after flowering effectively identified scab resistant lines in this experiment. Near-isogenic lines for this 3BS QTL were isolated from the F6 generation of the cross ‘Ning7840’/‘IL89-7978’ based on two flanking SSR markers, Xgwm389 and Xbarc147. Based on these results, MAS for the major scab resistance QTL can improve selection efficiency and may facilitate stacking of scab resistance genes from different sources.

Molecular marker analysis of kernel size and shape in bread wheat

Abstract: The economic value of wheat grain is determined by the kernel morphology which is an important parameter for manufacturing different food products requiring specific grain characteristics. Although kernel size and shape have emerged as important breeding objectives, not much information is available about the number or location of associated gene(s)/quantitative trait loci. In the present study, a recombinant inbred line population of 106 plants (F 7 ) was phenotyped for four traits, namely kernel length. width, weight and factor form density (FFD) and genotyped with different polymerase chain reaction-based markers. Transgressive segregants were observed for all the traits and genetic correlation studies showed positive correlations between the majority of the traits. The number of markers associated with each trait ranged from two to nine and the phenotypic contribution by an individual marker ranged from 3.3 to 16.6%. Many of the markers showed linkage to more than one trait. Strategies for improving the wheat grain quality traits and the utility of such markers in marker-assisted selection (MAS) efforts are discussed.

Identification and characterization of microsatellites in eggplant

Abstract: The potential of microsatellite markers for use in genetic studies in eggplant, Solanum melongena, has been evaluated. A genomic library of eggplant was screened for GA and GT repeat motifs to isolate microsatellite clones. The frequency of each repeat motif in the eggplant genome was found to be every 3200 kb for GA repeats and every 820 kb for GT repeats. Sixty-one per cent of GT repeats were found to directly flank AT repeats. A total of 37 polymerase chain reaction (PCR) primer pairs were designed, 23 of which amplified a single product or several products. The level of microsatellite polymorphism was evaluated by using S. melongena lines and related Solanum species. Two to six alleles per primer pair were displayed in the S. melongena lines and two to 13 alleles were displayed in the Solanum relatives. Seven microsatellites showed polymorphism between parental lines of the mapping population and segregated in a codominant Mendelian manner. These microsatellite loci were distributed throughout the linkage map.

Genetic variability in melon based on microsatellite variation

Abstract: A set of 18 simple-sequence repeat (SSR or microsatellite) markers was used to study genetic diversity in a collection of 27 melon (Cucumis melo L.) accessions, representing a broad range of wild and cultivated melons. The materials studied were highly polymorphic for SSRs and a total of 114 alleles were detected (average of 6.3 alleles per locus) Cluster analysis suggests the division of these accessions into two major groups, largely corresponding to the division of C. melo in the two subspecies agrestis and melo. The assignment of the accession to the subspecies was generally in agreement with published reports, except for those corresponding to the 'dudaim' and 'chito' cultivar groups, which, according to the observed SSR variability-, should be included in subspecies agrestis. Based on cluster analysis, five groups of accessions were defined. The two most divergent groups include mainly accessions from the Mediterranean which form one group, and accessions from China, Japan, Korea and India forming the other. Both groups shared a low level of intra-accession variation compared with the other groups, which suggests an erosion of their genetic variability because of drift and/or inbreeding. The remaining accessions, mainly from Central Africa and India, were more variable and may be an important source of genetic variation for melon breeding.

Molecular characterization of novel resynthesized rapeseed (Brassica napus) lines and analysis of their genetic diversity in comparison with spring rapeseed cultivars

Abstract: Resynthesized (RS) rapeseed generated from interspecific hybridization between suitable forms of Brassica rapa L. (syn. campestris; genome AA, 2n = 20) and B. oleracea L. (CC, 2n = 18) represents a potentially important resource to expand genetic diversity in the narrow gene pool of oilseed rape (B. napus L., AACC, 2n = 38). In this study 165 RS rapeseed lines originating from crosses between an Indian Yellow Sarson (B. rapa ssp. trilocularis) and five different cauliflower (B. oleracea convar. botrytis) cultivars were studied using amplified fragment length polymorphism (AFLP) markers and their genetic diversity was compared in relationship to an assortment of 40 diverse spring oilseed and fodder rape varieties. Using three AFLP primer combinations, a total of 467 polymorphic bands were scored. Cluster analysis allowed differentiation among the different RS lines, which, as expected, were genetically highly divergent from the cultivars. The genetic diversity of the material is discussed in relation to its morphological variability with a view to the implementation of RS lines in oilseed rape breeding.

Marker‐assisted backcross introgression of the Yd2 gene conferring resistance to barley yellow dwarf virus in barley

Abstract: YLM, a codaominant polymerase chain reaction (PCR) marker linked to Yd2, could substantially improve the precision and efficiency of barley yellow dwarf virus (BYDV) resistance breeding. The aim of this study was to assess the effectiveness of YLM in a marker-assisted introgression programme and to quantify associations between the presence of Yd2 and other agronomic and quality traits. The Yd2 gene was introgressed into a BYDV-susceptible background through two cycles of marker-assisted backcrossing. BC2 F2-derived lines, either carrying or not carrying the YLM allele associated with resistance, were compared in the presence and absence of BYDV. The YLM marker was shown to be effective in the introgression of Yd2. Lines carrying the YLM allele associated with resistance produced significantly fewer leaf symptoms and showed a reduction in yield loss when infected with BYDV. There were no deleterious effects associated with the introgression of Yd2 on grain yield, grain size or malting quality. The implications of marker-assisted selection for Yd2 on barley improvement are discussed.

Identification of incompatibility genotypes in almond (Prunus dulcis Mill.) using specific primers based on the introns of the S-alleles

Abstract: Identification of the incompatibility genotypes of almond cultivars is important in breeding programmes for designing crosses and for selecting progeny. This paper describes a novel molecular technique for the identification of S-alleles in almond based on the use of PCR primers designed from the sequences of the introns without the need for restriction enzyme digestion. Nine specific pairs of primers have been designed for the S1, S2, S5, S7, S8, S9, S10 (putative), S23 and Sf alleles, and these confirmed the S-allele specificities for 22 of the 23 accessions for which published information is available. This technique provides a precise method for identifying S-alleles from the genomic DNAs of almond cultivars, and will be useful for confirming the segregation of alleles in breeding progeny.

Detection of loci controlling seed glucosinolate content and their association with Sclerotinia resistance in Brassica napus

Abstract: A genetic linkage map of Brassica napus constructed from a cross between a low glucosinolate cultivar 'H5200' and a high glucosinolate line 'NingRS-1' was used to identify loci associated with seed glucosinolate content and to understand the association between specific glucosinolate components and Sclerotinia resistance. Seed glucosinolate content was assessed by standard High pressure Liquid Chromatogram (HPLC) protocol. Seven components of seed glucosinolate, including four types of aliphatic glucosinolate, two types of indolyl glucosinolates and one aromatic glucosinolate were detected in the seeds. Three quantitative trait loci (QTLs) were identified for seed total glucosinolate content. From three to 15 loci were found to be responsible for different types of glucosinolates, and by comparing the overlapped intervals, eight genomic regions were defined. One of the nine loci associated with aliphatic glucosinolate content was found to be associated with Sclerotinia resistance on the leaf at the seedling stage, and one locus, responsible for 3-indolyl-methyl glucosinolate content, was probably linked with Sclerotinia resistance on the stem of the maturing plant. The association between seed glucosinolate content and Sclerotinia resistance is discussed.

Associations of simple sequence repeats with quantitative trait variation including biotic and abiotic stress tolerance in Hordeum spontaneum

Abstract: A total of 33 simple sequence repeats (SSRs) was analyzed in 52 genotypes of Hordeum spontaneum originally collected from two different soil types (Terra rossa and Basalt) at Tabigha in Israel. Data on the performance of developmental, morphological, and yield-related traits under well-watered control and water-stress conditions were available from previous experimentation, and powdery mildew susceptibility was scored. Regression analyses based on SSR allele class differences were performed. Highly significant associations were detected at the SSR loci Bmac181 (on chromosome 4H) and Bmac316 (6H) for water -stress tolerance and powdery mildew resistance, respectively. The study shows that association mapping using SSRs and genetically diverse germplasm provides an effective means of relating genotypes to complex quantitative phenotypes.

Fluorescence in situ hybridization polymorphism using two repetitive DNA clones in different cultivars of wheat

Abstract: Twenty-two wheat cultivars and a wheat line were analysed with two-colour fluorescence in situ hybridization (FISH) using the pSc119.2 and pAs1 repetitive DNA clones to detect if polymorphism could be observed in the hybridization patterns of different wheat cultivars. The FISH hybridization pattern of ‘Chinese Spring’ was compared with wheat cultivars of different origins. Differences were observed in the hybridization patterns of chromosomes 4A, 5A, 1B, 2B, 3B, 5B, 6B, 7B, 1D, 2D, 3D and 4D. Although a low level of polymorphism exists in the FISH pattern of different wheat cultivars, it is possible to identify 17 pairs of chromosomes according to their hybridization patterns with these two probes. This study will help to predict the expected variation in the FISH pattern when analysing wheat genetic stocks of different origin. It is presumed that variation in hybridization patterns are caused by chromosome structural rearrangements and by differences in the amount and location of repetitive sequences in the cultivars analysed.

Identification of a molecular marker linked to the closed capsule mutant trait in sesame using AFLP

Abstract: The identification of an amplified fragment length polymorphism (AFLP) marker linked to an agronomically useful trait in sesame is reported. A bulked segregant analysis (BSA) approach was adopted on segregating progenies of a cross between the closed capsule mutant line ‘cc3’, and the Turkish variety ‘Muganli-57′. A total of 72 primer combinations were screened for linkage to the trait, but only one closely linked amplified fragment length polymorphism (AFLP) marker was identified. The linkage was confirmed by analysing the AFLP profile from single plants. The marker has the potential to accelerate breeding programmes aimed at modifying unwanted side-effects of the closed capsule mutation by marker-assisted selection.

Modification of tomato taste in transgenic plants carrying a thaumatin gene from Thaumatococcus daniellii Benth

Abstract: Fruit taste is an important component of fruit quality, but its genetic basis is complex, making it difficult to alter by plant breeding. Thaumatin is a sweet-tasting, flavour-enhancing protein produced by fruits of the African plant Thaumatococcus daniellii Benth. Agrobacterium-mediated transformation was used to produce two transgenic tomato lines expressing biologically active thaumatin in fruits. Transgenic tomato fruits from the T 2 plant generation were sweeter than the controls and possessed a specific aftertaste as determined by sensory evaluation. These results demonstrate that transgenic expression of thaumatin could be useful for modifying tomato fruit taste, especially in breeding lines possessing poor fruit taste, such as those carrying a non-ripening (nor) mutation.

The use of AFLP markers for cultivar identification in apricot

Abstract: Amplified fragment length polymorphism (AFLP) molecular markers were employed for the fingerprinting of 118 accessions of apricot, including cultivated varieties and related apricot species. Five primer combinations were tested and 165 polymorphic bands produced which could uniquely differentiate all accessions under investigation. Primer combinations were rated according to the multiplex ratio, the polymorphic index content and the discrimination power parameters and superior combinations were identified. AFLP markers were used in cluster analysis carried out with the UPGMA and the neighbour-joining methods and parsimony analysis. Four groups of similar accessions were identified: (i) those from the Mediterranean basin, (ii) from China, (iii) from continental Europe and (iv) mixed Europe-North America accessions. In the principal component analysis the first three components accounted for 17% of the total variability existing among accessions. Because the most important regions where apricot is cultivated in the world were represented in the analysis, with a large number of varieties, it was possible to discuss the data in the light of current phylogenetic hypotheses on the origin and evolution of the species.

Two genes and linked RAPD markers involved in resistance to Fusarium oxysporum f. sp. Ciceris race 0 in chickpea

Abstract: The inheritance of resistance to fusarium wilt race 0 of chickpea and linked random amplified polymorphic DNA (RAPD) markers were studied in two F 6:7 recombinant inbred line (RIL) populations. These RILs were developed from the crosses CA215A × JG62 (susceptible x resistant) and CA2139 × JG62 (resistant x resistant), and were sown in a field infected with fusarium wilt race in Beja (Tunisia) over 2 years. A 1:1 resistant to susceptible ratio was found in the RIL population from the CA2156 × JG62 cross indicating that a single gene with two alleles controlled resistance. In the second RIL population (CA2139 × JG62) a 3:1 resistant to susceptible ratio indicated that two genes were present and that either gene was sufficient to confer resistance. Linkage analysis showed a RAPD marker, OPJ20 600 linked to resistance in both RIL populations, which is present in the resistant parent JG62.

Detection of endophytic fungi in Festuca spp. by means of tissue print immunoassay

Abstract: Many wild and cultivated grasses live in mutualistic symbiosis with endophytic fungi of the genera Neotyphodium and Epichloe. These associations are of agronomic importance because endophytes may induce a range of beneficial effects for the host plant but also produce alkaloids detrimental to livestock. Conventional detection of endophytes by means of histological staining is time-consuming and not suited for large numbers of samples. Therefore, in order to simplify the detection of endophytic fungi the utility of tissue print immunoassay (TPIA) was studied and compared with the commonly used microscopic analysis. Ecotypes collected from natural grassland habitats and plants from field experiments were analyzed for endophyte infection. Both methods provided similar results. Based on stained or non-stained mycelium in tissue prints, endophyte-infected (E +) and endophyte-free (E-) tillers and inflorescences of Festuca pratensis, F. arundinacea and F. rubra were clearly distinguishable. Prints of cross sections of tillers allow the precise localization of endophyte infection within the plant tissues. Because TPIA allows the examination of endophytes in individual branches and segments of inflorescences it is a useful method for dissemination studies. Tissue print immunoassay appears to be a reliable method suited for routine work in research, practical grassland management and selection of defined E + or E- material for breeding.

Genetic diversity of wild and cultivated soybeans growing in China revealed by RAPD analysis

Abstract: To evaluate the genetic diversity and to clarify the genetic relationships of wild and cultivated soybeans growing in China, 21 wild soybean accessions and 27 cultivated soybean landraces were analysed by using the random amplified polymorphic DNA method. The data show that wild soybean has a higher genetic variation than cultivated soybean, indicating that genetic variation has been reduced by domestication of wild soybean. Based on Nei's genetic similarity coefficient, all the accessions were classified into two major clusters, corresponding to wild and cultivated varieties of soybean. Furthermore, within each species, the accessions tend to form sub-clusters that are in agreement with their geographical origins, demonstrating that an extensive geographical genetic differentiation exists in both species. For cultivated soybean, the varieties from the same geographical region but with different seasonal types were found to have closer genetic relationships than varieties from different geographical regions but with the same seasonal type. This result indicates that geographical differentiation plays a key role in the genetic differentiation of both wild and cultivated soybeans. Cultivated soybean varieties with different seasonal types in a region might have been established mainly from the local genotypes.

Identification of a major QTL in cocoa (Theobroma cacao L.) associated with resistance to witches’ broom disease

Abstract: The witches' broom disease caused by the fungus Crinipellis perniciosa is the main limiting factor for cocoa production in South America and the Caribbean. In Brazil, this disease affects almost all cocoa-growing regions, causing serious economic, social and ecological damage. The aim of this study was to map genomic regions associated with resistance to C. perniciosa using an F 2 population derived from a cross between 'Scavina-6' (resistant) and 'ICS-1' (susceptible). The phenotypic index was determined as the average number of vegetative witches' brooms per canopy area of each plant, the witches' brooms were counted and eliminated during six field evaluations between May 1998 and August 1999. A total of 124 random amplified polymorphic DNA (RAPD) and 69 amplified fragment length polymorphism (AFLP) markers were mapped along 25 linkage groups covering 1713 cM of cocoa genome. After employing single factor and composite interval mapping analyses, a major quantitative trait loci (QTL) flanked by the marker AV14.940 was identified in the linkage group 11, explaining almost 35% of the resistance to witches' broom. The present result suggests that this QTL acts as a major dominant component of resistance to this pathogen, with great potential for use in marker-assisted selection procedures in cocoa breeding programmes.

Identification of a single dominant allele for resistance to blackleg in Brassica napus‘Surpass 400’

Abstract: The inheritance of resistance to blackleg (caused by Leptosphaeria maculans) was examined in the F 1 and F 2 of a cross between highly resistant canola 'Surpass 400' and susceptible 'Westar' in the field. Blackleg-infected canola straw was collected from the field and scattered among plants to increase disease development with the aid of natural rainfall. Disease severity on seedlings was assessed as the average number of lesions on leaves 1 and 2, and on adult plants as the percentage necrosis on a cross-section of stems immediately above the crown. All 'Westar' plants were susceptible (S) and all 'Surpass 400' and F 1 plants were resistant (R) at both growth stages. Disease severity on F 2 plants segregated 3 : 1 (R : S) as expected for a single dominant resistance allele in both the seedling and adult plant stages. There was a high proportion (91.1%) of matching reactions (R-R and S-S) between seedling and adult plants. 'Surpass 400' is the source of a single dominant allele for blackleg resistance in Brassica napus that is expressed strongly in both seedlings and adult plants.

Effects of the 7DL.7Ag translocation from lophopyrum elongatum on wheat yield and related morphophysiological traits under different environments

Abstract: The 7DL.7Ag translocation from Lophopyrum elongatum that carries Lr19, a leaf rust resistance gene, was found to be associated with a significant increase in grain yield under irrigated, disease-free conditions, but a generally lower yield under moisture stress conditions. These studies, however, involved a limited number of genetic recipients and environments, and the effect of the translocation on physiological traits was not considered. We examined the translocation effect in six different recipient genotypes and under five environmental conditions, including drought and heat stress. The increase in grain yield under irrigated conditions was associated with a higher rate of biomass production in the 7DL.7Ag lines and may be attributed to higher sink strength. Effect of the translocation on physiological traits was noted only under heat stress and was not associated with difference in yield. Under moisture stress conditions, 7DL.7Ag lines yielded less than their corresponding recipients, possibly because of a longer growing cycle. It is concluded that the effect of the 7DL. 7Ag translocation may very much depend on the phenological adaptation of the recipient genotype and the translocation may be useful for enhancing yield, mainly under favourable conditions.

AFLP, ISSR and RAPD markers reveal high levels of genetic diversity among Lupinus spp.

Abstract: The Lupinus genus includes a number of important crop species. The use of defined nucleotide sequences for the analysis of genetic diversity among these species has revealed modest levels of diversity. The aim of this study was to access AFLP, ISSR and RAPD markers to evaluate the genetic diversity among L. albus, L. angustifolius, L. cosentinii, L. hispanicus, L. luteus, L. mutabilis, L. pilosus and L. polyphyllus. Unexpectedly, low levels of genetic similarity were found (ranging from 0.205 to 0.432), regardless of the type of molecular marker used. Nevertheless, these techniques consistently showed a greater genetic similarity between L. pilosus and L. cosentinii, L. mutabilis and L. polyphyllus and among L. luteus, L. hispanicus and L. angustifolius, clearly separating the Old World from the New World species. Such low genetic similarity among Lupinus spp. is most unlikely to be due to differences in coding sequences but could be the result of a long diverging process concerning non-coding regions, which would represent a very important proportion of these genomes.

Identification of Brassica oleracea germplasm with improved resistance to Verticillium wilt

Abstract: Two hundred and ninety-nine accessions representing 11 cultivar groups of Brassica oleracea and eight additional accessions of the wild species B. cretica, B. incana, B. insularis and B. villosa were screened for resistance to Verticillium wilt. A disease index (DI) was calculated for each accession, and a correction of the DI was carried out to compensate for a fluctuating infection level between 11 independent trials. A total of 235, or 77% of the accessions tested, had a DIcorr less or equal to the oilseed rape cv. ‘Express’ (DIcorr= 2.81), the reference cultivar. Only one accession of the wild species, B. incana, showed an enhanced level of resistance (DIcorr= 2.01). Twenty-four accessions, distributed over eight cultivar groups of B. oleracea were selected for subsequent crosses involving B. rapa. Hybrid plants with 14 accessions were resultant and seed was obtained from crosses where the cultivar groups acephala, alboglabra, botrytis, capitata, gemmifera, italica and sabellica were used as female parents. When progeny of the produced resynthesized rapeseed lines were evaluated for Verticillium wilt resistance, three lines showed a significantly lower disease index (P ≥ 0.01) compared with the cv. ‘Express’. This source of resistance is now being crossed to advanced breeding material of oilseed rape.

Chromosome number and microsporogenesis in a pentaploid accession of Brachiaria brizantha (Gramineae)

Abstract: Chromosome number, microsporogenesis and mode of reproduction are described for an accession of Brachiaria brizantha, a grass of African origin. Cytological analysis revealed that the accession BRA005886 is pentaploid (2n = 5x = 45), with a base number of x = 9. Multivalent chromosome associations, from tri- to pentavalents, were recorded in diakinesis, and the further meiotic behaviour was highly irregular as well. Most abnormalities were related to irregular chromosome segregation commonly found in polyploids. Micronuclei were observed following telophases I and II. Some micronuclei near the cell wall were released as microcytes, whereas others remained in the tetrad. Other meiotic abnormalities, such as cell fusion and the absence of cytokinesis causing the formation of dyads and triads were also recorded. Binucleate microspores and 2n microspores resulting from nucleus restitution were observed among the normal ones. Limitations of this accession for use in hybridization programmes are discussed.

Intraspecific olive diversity assessed with AFLP

Abstract: Amplified fragment length polymorphism (AFLP) was used to study diversity within and among Spanish olive varieties. A high degree of diversity was found among the varieties present in each growing region. Olive oil production and quality relies on appropriate cultivar selection as well as good orchard management. Production based only on a few superior cultivars would result in improved yield, oil quality, and production management. Amplified fragment length polymorphism were evaluated as a tool to identify the intraspecific and intravarietal diversity of olive. Amplified fragment length polymorphism analysis of 38 accessions belonging to 10 cultivars using six primer combinations produced 106 polymorphic bands. Results were analyzed for similarity among accessions via unweighted pair-group means cluster analysis, resulting in 10 clusters corresponding to named variety designations. Similarity among varieties ranged from 0.60 to 0.72. Diversity within varieties was identified. Similarity within named varieties (accessions with the same varietal name) ranged from 0.75 to 0.96. Differences in several markers were found among 34 accessions. Intravarietal diversity was shown to exist within the Spanish olive varieties grown in the region surrounding Valencia.

Stylar ribonucleases in almond: correlation with and prediction of incompatibility genotypes

Abstract: To clarify incompatibility relationships among almond cultivars, 35 were analysed for stylar ribonucleases, which have previously been shown to correlate with incompatibility S alleles. Stylar proteins were extracted and separated electrophoretically and the zymograms compared with ladders of ribonucleases corresponding to the 12 S alleles previously reported. Sixteen cultivars showed a band corresponding to two of the known ribonucleases, 17 showed one known ribonuclease and one 'new' band, and two showed two new bands. Twelve new ribonucleases were detected; 11 were attributed to new S alleles (S 13 to S 23 ) and a mutant form of S 7 was attributed to S 7A . Genotypes were proposed for nine cultivars of five incompatibility groups that had not been genotyped previously, VII, X, XI, XII and XIII. Twenty-four cultivars of unknown incompatibility relationships were provisionally genotyped: six of these could be assigned to existing groups and two new groups were established, XIV and XV, along with group O of cultivars with unique genotypes. Test crosses confirmed that eight pairs of cultivars showing similar zymograms were indeed cross-incompatible, including the two representatives of each of the two new groups. Virtually all self-incompatible cultivars of known genotype are listed in a table. The data should be useful for planning cultivar combinations for orchards and for designing crosses for breeding programmes.

A melon genotype with superior competence for regeneration and transformation

Abstract: Transformation efficiency of melon is low and is still regarded as a challenge. In this paper, the regeneration and transformation response of ‘BU-21/3′, a newly characterized melon breeding line, is described. The line seems to be superior in this regard to previously evaluated genotypes. Agrobacterium-mediated delivery of the GUS or GFP reporter genes into cotyledon explants was used to evaluate efficiency of transient and stable transformation. Good transient expression was observed, and stable transformation frequencies of 0.4-1.5 transgenic shoots per explant were obtained. Transgenic plantlets were transferred to a contained greenhouse as early as 8-10 weeks after transformation. Transgenic plants are fertile and exhibit a true-to-type phenotype. The ‘BU-21/3’ line may become a useful tool for the facilitation of transgenic breeding in melon.

Identification of a molecular marker linked to an Agropyron elongatum‐derived gene Lr19 for leaf rust resistance in wheat

Abstract: The leaf rust resistance gene Lr19, transferred from Agropyron elongatum into wheat (Triticum aestivum L.) imparts resistance to all pathotypes of leaf rust (Puccinia recondita f.sp. tritici) in South-east Asia. A segregating F 2 population from a cross between the leaf rust resistant parent 'HW 2046' carrying Lrl9 and a susceptible parent 'Agra Local' was screened in the phytotron against a virulent pathotype 77-5 of leaf rust with the objective of identifying the molecular markers linked to Lr19. The gene was first tagged with a randomly amplified polymorphic DNA (RAPD) marker S73 728 . The RAPD marker linked to the gene Lrl9 which mapped at 6.4 ± 0.035 cM distance, was converted to a sequence characterized amplified region (SCAR) marker. The SCAR marker (SCS73 719 ) was specific to LrI9 and was not amplified in the near-isogenic lines (NILs) carrying other equally effective alien genes Lr9, Lr28 and Lr32 enabling breeders to pyramid LrI9 with these genes.

Influencing combustion quality in Miscanthus sinensis Anderss.: identification of QTLs for calcium, phosphorus and sulphur content

Abstract: Quantitative trait locus (QTL) analyses for combustion-related traits including calcium, phosphorus and sulphur content have been carried out using two years of field trial data. Nine putative QTLs were detected using the Multiple QTL Model approach and the programme MapQTL 4.0. Two QTLs were found for calcium, two for sulphur and five for phosphorus. Out of the QTLs for phosphorus, P1 is probably the same locus as P3, and P2 as P4, although their confidence intervals do not agree. Ca1 was also consistently detected. These results may constitute the first step in developing a Marker-Assisted Selection programme in Miscanthus for combustion-related traits.

Molecular and agronomic evaluation of wheat doubled haploid lines obtained through maize pollination and anther culture methods

Abstract: Although maize pollination (MP) and anther culture (AC) are alternative techniques widely used for wheat doubled haploid (DH) production, there is only limited information on the attributes of the plant materials produced through both methods. This study was conducted to evaluate genetic fidelity, transmission of parental gametes, and to compare field performance of DH populations produced by the MP and AC methods from the F 1 s of two crosses between spring bread wheat cultivars. The DH populations were compared to single seed descent (SSD) lines created from the same crosses. In total, 76 MP and 122 AC lines of the cross between cultivars of divergent origin were subjected to RAPD and AFLP analysis. Only changes in AFLP banding patterns, at similarly low frequencies, 0.18% (MP) and 0.21% (AC), were detected. The frequency of the DH lines affected by the variation, 14.5% (MP) and 14.8% (AC), was similar in birth populations. For most of the DH lines, variation in 1 2 loci only, out of several hundreds scored, was observed. A total of 14.3% (MP) and 22.2% (AC) marker loci showed the significant segregation distortion from the expected 1:1 ratio, but in at least one polymorphic locus the within-cultivar variation was responsible for the skewed segregation. The field performance of the corresponding MP and AC lines derived from two crosses confirmed the equivalency of both DH populations. In most of the traits analyzed, the MP and AC lines performed the same as the SSD populations created from the same crosses. No, or very small differences in means and ranges, were observed when the best 10% of the lines from all three methods were compared. Moreover, the best 10% of the lines of the cross between Polish wheat cultivars adapted to the local environment performed significantly better for some traits than different groups of checks used in the study.

Applicability of molecular markers in the context of protection of new varieties of cucumber

Abstract: The growing number of candidate varieties presented every year at each national Plant Variety Protection Office and their decreasing genetic variability forces strategies to be adopted that will reduce costs without losing rigour when deciding about the acceptance or rejection of a candidate variety. Molecular markers have been envisaged as a reliable tool to establish differences, but can molecular markers be used for assessing distinctness? A comparison between a molecular and a morphological characterization of 41 seed samples belonging to 36 cucumber varieties and including several external controls has been carried out to investigate the applicability of molecular markers in the context of distinctness, uniformity and stability (DUS) tests and the protection of new varieties. Both types of character indicate the same relationships among main groups, Dutch and Beth-Alpha types, and Gerking and Slice types, the correlation between distance matrices being only 0.6489. Varieties considered uniform for morphological traits proved not to be so for molecular markers. Therefore, molecular characterization is not offering the same estimates of uniformity and relatedness between varieties as does morphological characterization. External controls were used to establish distinction limits with morphological and molecular dendrograms to focus on those varieties, which were suspiciously similar. The results with cucumber show that molecular identity could be used to assess any lack of distinctness and so corroborate the morphological assessment of candidate varieties. The morphological trait ‘type’ provides distinct characterization of varieties and the molecular characterization of candidate varieties could be used to design better field experiments to assess distinction within each group of morphological cucumber type.

RFLP diversity within and between major groups of barley in Europe

Abstract: Restriction fragment length polymorphism (RFLP) diversity has been determined and analyzed as expressed by 33 single- or low-copy clone/ enzyme combinations at 32 loci distributed over all chromosomes of the barley genome within a sample of 223 European barley accessions comprised of pure line (single-head progenies) genotypes. The accessions have been selected to include landraces and widely grown cultivars derived from crossbreeding during the 20th century in North-, West- and Central European countries. Genetic diversity obtained from 83 alleles across all accessions is characterized by the diversity index H = 0.385. The diversity indices determined for landraces and cultivars were almost equal, with the difference between spring (H = 0.260) and winter (H = 0.415) barley approaching statistical significance, while comparisons of other groupings only revealed statistically insignificant trends. A more detailed analysis based on differences in allele frequency distributions at each locus (clone/enzyme combinations resp.) revealed very clear differences related to the existence, continuity and dynamics of changes in group-specific RFLP profiles. With the majority (69%) of RFLP alleles at 23 out of 32 loci on all barley chromosomes involved, contributions from chromosomes 1H, 3H, 4H and 5H seem to be of special importance. Differences in the overall average of abundance indicate higher levels of genetic diversity within both groups of winter barley compared with both groups of spring barley, from which the most frequent alleles at 15 (2-rowed spring barley) and 17 (6-rowed spring barley) RFLP loci approach fixation. The results of this study are discussed in relation to the history of barley cultivation and barley breeding in Europe, and possible explanations for group-specific differences in the RFLP profiles of landraces and cultivars as well as for the high levels of (nearly) fixed alleles of both subsets of spring barley, and with respect to progress in barley breeding that it has been possible to obtain within the rather narrow RFLP profiles.