bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for common genetic mechanisms controlling the tolerance of sudden salt stress in the tribe Triticeae
Authors: Zhong Gan‐Yuan , Dvořák Jan
Published: April 2006

Previous studies in several Triticeae species have suggested that salt tolerance is a polygenic trait, but that genes on some chromosomes confer better tolerance to salt stress than others. This suggests an intriguing possibility that there may be a similar basis for salt tolerance in the species of the tribe Triticeae. In this study, chromosomal control of the tolerance to sudden salt stress, measured as the mean rate of leaf elongation in solution cultures with a single increment of 200 mM NaCl, was investigated in the genomes of cultivated barley (Hordeum vulgare L.), rye (Secale cereale L.), and Dasypyrum villosum (L.) Can‐dargy by using disomic addition lines of individual pairs of chromosomes or chromosome arms of each of the three species in the ‘Chinese Spring’ wheat genetic background. It was observed that the chromosomes of homoeologous groups 3, 4, and 5 in barley, 5 and 7 in rye, and 4 and 6 in D. villosum carry loci with significant positive effects on salt tolerance. Increased doses of chromosomes of group 2, however, reduce or do not increase the tolerance to salt stress. These results are in agreement with a previous study of the tolerance of this salt stress regime in wheat and wheatgrass Lophopyrum elongatum. A ranking analysis of the chromosomal effects within each genome of the five Triticeae species investigated in this and previous studies revealed that the chromosomes of homoeologous groups 3 and 5 consistently confer large positive effects on the tolerance of sudden salt stress, while the chromosomes of homoeologous group 2 in increased dose have no or negative effects on the tolerance. This strongly suggests that species of the tribe Triticeae share some common genetic mechanisms of tolerance of sudden salt stress. The findings in this study give credence to the proposal that wild relatives can be exploited in the development of wheat cultivars with greater tolerance to salt stress.
In vitro breeding of high‐linolenic, doubled‐haploid lines of linseed (Linum usitatissimum L.) via androgenesis
Authors: Friedt W. , Bickert C. , Schaub H.
Published: April 2006

In the course of a breeding programme for high‐linolenic‐acid linseed (oilflax, Linum usitatissimum L.) doubled‐haploid lines (DH‐lines) of three F1 hybrids were generated using an anther‐culture technique. A total of 82 DH‐lines were generated and multiplied in 1993, of which 39 were suitable for testing in a repeated field trial in 1994. Yield, fat content and fatty‐acid composition were determined. The yield of the DH‐lines was not significantly different from that of respective mid‐parent values. Fatty‐acid composition and fat content showed remarkable variation, and DH‐lines exceeded cross parents in some cases for both fat content and linolenic‐acid proportion. Superior DH‐lines surpassed mid‐parent linolenic‐acid‐content values by 4.5% and fat content by 1.9%. The results indicate that anther culture is a useful tool in linseed breeding.
Genetic variation and control of plant regeneration in leek (Allium ampeloprasum L.)
Authors: Silvertand B. C. H. J. , Jacobsen E. , van Harten A. M
Published: April 2006

Zygotic embryos of leek (Allium ampeloprasum L.) were isolated from mature seeds of different cultivars, selfings and full‐sib families. The embryos were cultured on callus induction and shoot regeneration medium and employed to study several parameters: percentage of embryos forming calluses, percentage of embryos forming compact calluses, callus weight, percentage of regenerating calluses, numbers of shoot primordia and numbers of regenerated shoots. Differences between cultivars and selfings were found for most parameters studied. For all cultivars all parameters, except callus weight, decreased after one generation of selfing. Compact callus types enhanced primordia formation and shoot regeneration. Genetic characteristics of callus development and plant regeneration were studied in a 4 × 4 diallel cross. Analysis of variance revealed significant differences between full‐sib families. The diallel analysis showed that additive gene effects were significant for all parameters. The predominance of additive gene effects indicated high narrow‐sense heritability. Breeding for an increased number of regenerated shoots was successful.
Direct plant regeneration from leaf explants in cucumber (Cucumis sativus L.) is free of stable genetic variation
Authors: Burza W. , Malepszy S.
Published: April 2006

A new procedure is described for rapid and efficient plant regeneration from leaf explants of Cucumis sativus and C. anguria. The following factors were most important: young leaves, the NO3: NH4 ratio in the plant induction medium, small explants and the growth regulator combination. After about 4 weeks of culture under optimal growth conditions, the frequency of regeneration was 10–100% of explants. Six to 7 weeks were required to obtain well‐rooted plants, which were mostly able to survive after transfer into soil. From a single young leaf of C. sativus cv. ‘Borszezagowski’, 135 plants could be regenerated. All plants transferred to a greenhouse were free of morphological or physiological abnormalities, flowered normally and bore fruits. The analysis of R0 plants showed no genetic variation, whereas in the R1 two new phenotypes, which were not transmittable to the R2, were observed. This procedure is recommended for its production of homogeneous cucumber plants.
Two host genes in Vicia faba for nodulation deficiency with strain specificity for Rhizobium leguminosarum
Authors: Esser‐Mönning K. , Roskothen P. , Röbbelen G.
Published: April 2006

In greenhouse tests, two inbred lines of faba bean, I 40 and I 25, proved to be nodulation resistant and F2 progenies were used to determine the genetic control of this nodulation deficiency. The defect is strain‐specific for the Rhizobium strains St 48 and St 53. In inbred line I 40, the deficient nodulation character is controlled by a dominant gene which is called Sym‐2, while another recessive gene sym‐3 is assumed for line I 25; Sym‐2 is epistatic over sym‐3.
Association between resistance to Cercospora and yield in commercial sugarbeet hybrids
Authors: Smith G. A. , Campbell L. G.
Published: April 2006

This report documents the difficulty breeders have experienced in combining resistance to Cercospora leaf spot (causal agent Cercospora beticola Sacc.) with high yield in sugarbeet (Beta vulgaris L.). Forty commercial hybrids, all recommended for Cercospora‐threat areas, were grown in a Cercospora‐free and a diseased (inoculated) environment in 1991 and 1992. A 2.9 Mg/ha decrease in root yield associated with each increment increase in susceptibility confirmed that under a severe epiphytotic (1991) Cercospora resistance provided substantial protection. Under less‐severe disease conditions (1992) there was no apparent relationship between yield and resistance, suggesting that the benefits of resistance were similar to the yield potential sacrificed to obtain the resistance. In the absence of the disease, root yields increased 2.7 Mg/ha for each increment of increased susceptibility. There was no evidence of association between sucrose concentration and resistance in the Cercospora‐free environment. Despite the limited efforts and/or success in developing resistant commercial hybrids, the demonstrated ability of Cercospora to produce fungicide‐resistant strains and the possibility that effective fungicides will not be available provide incentives to seek genetic resistance through breeding efforts.
Application of quantitative trait locus mapping to the development of winter‐habit malting barley*
Authors: Oziel A. , Hayes P. M. , Chen F. Q. , Jones B.
Published: April 2006

Malting quality and winter‐hardiness in barley are ‘ultimate’ phenotypes composed of constituent quantitatively inherited traits. A synthesis of molecular‐marker linkage data and field phenotyping to reveal the location of quantitative trait loci (QTL) may assist in the development of winter‐habit malting barley varieties. One‐hundred doubled haploid progeny from a winter x spring cross were evaluated under fall and spring‐planted conditions. Malting quality phenotypes and a 76‐point map were used to identify QTL and to assess the effect of spring‐and autumn‐sowing on QTL expression. Many QTL effects were common to both environments and corresponded to QTL detected in other barley germplasm. While there were significant differences in the magnitude of effects across environments, there were no changes in the favourable allele phase. QTL effects for grain protein and diastatic power level coincided with the locations of known function genes. Coincident QTL for a number of mailing‐quality traits on chromosome 7 suggests either the presence of a multi‐locus cluster of genes controlling components of malting quality or a regulatory gene or genes controlling the cascade of enzymatic processes that function during the malting process. Based on these results, simultaneous selection for malting quality and cold tolerance should be possible in this genetic background.
Response to selection for root dimension in a Mediterranean natural population of Lolium rigidum Gaud
Authors: Bullitta S.
Published: April 2006

In the Mediterranean environment, root systems are very important for water utilization. For this reason, the effects of selection for increased root dimensions upon root and shoot characteristics of a natural population of Lolium rigidum Gaud, were analysed. Two cycles of phenotypic recurrent selection were carried out on a population collected in Nurra (north‐western Sardinia, Italy). Plants derived after two cycles of selection, together with unselected plants, were grown hydroponically in a greenhouse. Data on root volume, longest root length, number of stems and leaves, leaf length, shoot and root dry weight were collected from the selected material and also from unselected material for use as a control. An analysis of variance was performed and correlation coefficients were calculated. The increased size of the root system did not have a negative effect on the above‐ground biomass and there was genetic variation for root traits in the ‘Nurra’ population. The improved population will be utilized for further breeding work to obtain L. rigidum varieties capable of withstanding dry periods during the vegetative phase.
Patterns and heritability of carboxylic acids and soluble sugars in fruits of apricot (Prunus armeniaca L.)
Authors: Bassi D. , Bartolozzi F. , Muzzi E.
Published: April 2006

The investigation of acid and sugar content in an array of apricot cultivars and progenies indicates the existence of marked variability. Citric acid varied from 0.17 to 1.20% and malic acid from 0.21 to 1.51% on fresh weight. Fructose varied from 0.27 to 1.60%, glucose from 0.90 to 3.13% and sucrose from 1.92 to 6.92%. The estimate of heritability was high for total and main sugars, reaching over 0.50%. Acids generally showed low coefficients, although those for citric (0.27) and malic (0.36) were good. With the exception of one progeny, all genotype/year comparisons were not significant, showing constant patterns for acid and sugars over the years regardless of the variability in absolute values. This means that the patterns of each genotype are under genetic control. The wide range of diversity in acid and sugar content in apricot germplasm and the independent heritability for most of these compounds make it possible to breed and select cultivars with improved flavour on the basis of superior phenotypes.
Use of gamma rays to induce mutants resistant to cocoa swollen shoot disease in Theobroma cacao L.
Authors: Adu‐Ampomah Y. , Owusu G. K. , Sackey S. , Padi B. , Abdul‐Karimu A.
Published: April 2006

Vegetative buds of three cocoa varieties, ‘Amelonado’ (P30), ‘Trinitario’ (K5) and ‘Upper Amazon’ (T85/799) were irradiated with 15, 20 and 25 Gy of γ‐rays, respectively, and budded on to rootstocks to generate MV1 shoots. The terminal buds of the shoots were removed to induce the formation of MV2 shoots, from which MV3 shoots were similarly derived. The MV3 plants were screened for resistance to the Cocoa Swollen Shoot Virus (CSSV) by patch‐graft inoculation of the root‐stocks. Only a few plants from each of the three cocoa varieties were found to be symptomless after indexing. These plants were multiplied by budding to the MV4 and MV5 stages and screened at each stage for CSSV resistance by inoculation using virus‐carrying mealybugs. At the MV5 stage, some plants still remained symptomless and this was confirmed with enzyme‐linked immunosorbent assay (ELISA). The study reveals that γ‐rays can be used to induce genetic variability for resistance to CSSV in cocoa, as well as for other traits such as chlorophyll deficiency.
Meiotic restitution mechanisms and 2n pollen formation in a Solanum tuberosum dihaploid and in dihaploid × wild species hybrids*
Authors: Conicella C. , Genualdo G. , Errico A. , Frusciante L. , Monti L. M.
Published: April 2006

A Solatium tuberosum dihaploid that proved to be a 2n pollen producer, exhibited two types of meiotic abnormality involved in 2n pollen formation: premature cytokinesis at prophase II and parallel/tripolar spindles in meiosis II. For this reason such a dihaploid was preferentially used as a seed parent in crosses with the diploid species S. tarijense, S. sanctae‐rosae, and S. phureja. Diploid interspecific hybrids were evaluated for male fertility, for 2n pollen production and stability over three years and for meiotic nuclear restitution mechanisms. Pollen stainability ranged from 6 to 85% and 2n pollen from 5 to 35% among hybrids. The meiotic mechanism generating 2n pollen was that of spindle abnormality in meiosis II and consequent dyad/triad formation. High correlation was found between fused/parallel spindles and dyads.
Development of diploid and triploid interspecific hybrids between Lilium longiflorum and L. concolor by ovary slice culture
Authors: Fernández A. M. , Nakazaki T. , Tanisaka T.
Published: April 2006

Ovary slice culture, after cut‐style pollination, was used to develop interspecific hybrids between Lilium longiflorum and L. concolor. Reciprocal crosses between diploid cultivars (2n = 2x = 24) were carried out. On the days 30, 35, 40 and 45th after pollination (DAP), ovaries were sliced and cultured on a modified hormone‐free Murashige‐Skoog (M–S) medium without NH4NO3, supplemented with 6% sucrose, 50 mg/1 yeast extract and 0.25% gelrite at pH 6.3. For the L. longiflorum × L. concolor cross, ovule germination was found to be best at 30 DAP. After transfer to a M–S (half‐strength) medium supplemented with 1.5% sucrose and 0.25% gelrite at pH 5.8, diploid and triploid hybrid plants were established. In contrast, ovules from the L. concolor × L. longiflorum cross did not germinate. The hybridity of the plantlets obtained was verified by karyotype and isozyme analysis. The importance of the ovary slice culture technique as a tool to develop new hybrids between incompatible lilly plants is discussed.
Genetic resistance to root‐knot nematode (Meloidogyne javanica) in eggplant (Solanum melongena)
Authors: Boiteux L. S. , Charchar J. M.
Published: April 2006

A germplasm collection of 39 eggplant Solanum melongena genotypes and one accession of S. torvum was evaluated for resistance to the root‐knot nematode (Meloidogyne javanica) by using controlled greenhouse tests. Different degrees of resistance to the disease caused by this nematode species were observed among the genotypes tested. Complete resistance (no nematode egg mass formation up to 7 weeks after inoculation) was detected in one accession belonging to domesticated S. melongena species. Good levels of incomplete resistance were also observed in some commercial eggplant genotypes. This is apparently the first report of a source of complete resistance to M. javanica within the S. melongena gene pool and our finding could greatly facilitate the incorporation of this trait into commercial eggplant cultivars. S. torvum, previously described as resistant to several root‐knot nematode species (including M. javanica, M. arenaria, and M. incognita) was also confirmed as a source of resistance to this Brazilian population of M. javanica. Therefore, S. torvum can be considered as one of the most promising sources of broad‐spectrum resistance genes against root‐knot nematodes. Broad‐spectrum resistance is of paramount importance for breeding programmes focused on the development of cultivars for tropical and subtropical areas of the world where multiple infestation of soils with distinct Meloidogyne species is a very common feature.
Screening for resistance to broomrape (Orobanche cernua) in cultivated sunflower
Authors: Dominguez J. , Melero‐Vara J. M. , Miller J. , Fernández‐Martinez J. M.
Published: April 2006

Racial evolution of sunflower broomrape (Orobanche cernua) has been very rapid in Spain during recent years, in which resistance has been overcome several times and there has been an important increase in areas infested with this parasitic angiosperm. In order to find resistance to a highly virulent population of sunflower broomrape that could be used directly in breeding programmes, three different sets of cultivated plant material composed of 429 entries were tested by artificial inoculation. All evaluated inbred lines from Moden, Canada, were fully susceptible. Out of the 240 P.I. accessions tested, only 10 segregated for resistance to broomrape, the rest being susceptible. From the 160 USDA breeding lines evaluated, 5% were resistant and 19% segregated for resistance to O. cernua. These lines traced back mainly to crosses of RHA 274 and RHA 801 with Russian, Turkish and Romanian hybrids. The origin of P.I. accessions that segregated for resistance were primarily derived from the former USSR and from Romania.
Improved RAPD amplification of recalcitrant plant DNA by the use of activated charcoal during DNA extraction
Authors: Bi I. Vroh , Harvengt L. , Chandelier A. , Mergeai G. , Du Jardin P.
Published: April 2006

An efficient procedure has been developed for DNA extraction from cotton by modifying the original CTAB method. The major improvement concerns the use of activated charcoal to bind resinous and coloured compounds which copurify with the DNA. The efficiency of amplification by RAPD was used as a criterion to evaluate the action of activated charcoal. Twenty‐five random decamers from Operon Technologies were used to compare DNA samples extracted in the presence or absence of activated charcoal. The results in terms of amplification suggest that the use of activated charcoal in DNA extraction enhances RAPD amplification. This technique was initially developed for cotton but it has been applied successfully to other recalcitrant plants such as coffee, rubber tree, cassava and banana.
Impact of low linolenic acid content on seed yield of winter oilseed rape (Brassica napus L.)
Authors: Rücker B. , Röbbelen G.
Published: April 2006

An essential quality improvement of rapeseed oil can be obtained by reduction of its linolenic acid (C18:3) content from about 10% to less than 3% of the total fatty acids. Genotypes low in C18:3 have been developed by mutagenesis. The initial summer rapeseed mutant had been low yielding and highly susceptible to various diseases. It has been debated whether the low C18:3 character can be successfully combined with high seed yield for physiological reasons. Therefore, the low linolenic character of mutant M48 was transferred into high‐yielding genotypes by repeated backcrossing to well‐adapted low erucic acid, low glucosinolate (00‐) winter rapeseed cultivars. Lines with low C18:3 content were selected from BC3 and BC4 generations and examined in 1990–95. Positive selection response for seed yield was shown to continue over the years. Presently, the best lines are yielding as well as the control cultivars being equivalent also in oil and glucosinolate contents.

In order to test the effect of a low C18:3 content on seed yield, plants with low and with high C18:3 content, respectively, were selected from 16 segregating BC5‐F2 populations and bulked to form 32 F3 populations. These ‘isogenic’ bulk populations were tested for field performance at four locations in 1995. The results show that C18:3 content of the seed oil is not associated with seed yield, oil content, beginning of flowering, plant height and disease resistance. Means of relative seed yield for the high and the low linolenic F3 bulk populations were not significantly different with 88.0% and 86.9% of the control cultivars, respectively. There was a significant interaction between genotypes with high or low C18:3 content and location. This shows that under specific environmental conditions a low C18:3 content may be either favourable or unfavourable. The results indicate that the low C18:3 character of the original mutants per se does not cause a decrease in seed yield, oil content or general field performance.
First in vivo assessment of feeding value of Festulolium hybrids derived from Festuca arundinacea var. glaucescens and selection for palatability
Authors: Ghesquière M. , Emile J.‐C. , Jadas‐Hécart J. , Mousset C. , Traineau R. , Poisson C.
Published: April 2006

This paper reports on the first results of feeding value experiments, assessed with sheep, of hybrids between tetraploid Italian ryegrass (Lolium multiflorum, 2n = 4×= 28) and a progenitor of tall fescue, Festuca arundinacea var. glaucescens (2n = 4×= 28). Three hybrid populations resulting from either high, low or no selection for palatability were compared with a variety of Italian ryegrass as control and two varieties of the cultivated hexaploid (2n = 6×= 42) tall fescue, one of which had been selected for high palatability. On average, the hybrid populations were found to be as palatable as the improved tall fescue with voluntary intake (VI), in vivo digestibility of organic matter (DOM), and net energy expressed in fodder units for milk, similar to the best palatable tall fescue and to Italian ryegrass. However, selection for improved palatability among hybrids did not result in any further improvement of other traits, except VI in the hybrid selected for high palatability which significantly exceeded VI of Italian ryegrass. In conclusion, intergeneric hybridization between L. multiflorum and F. arundinacea var. glaucescens led to an immediate increase of feeding value compared with selection for palatability in tall fescue. However, to improve feeding value of hybrids further, similar selection for high palatability appeared questionable and possibly detrimental for other agronomic traits because of complicated inheritance in tetraploid L. multiflorum×F. glaucescens hybrids.
Genetic analysis of salt tolerance during vegetative growth in tomato, Lycopersicon esculentum Mill.
Authors: Foolad M. R.
Published: April 2006

Breeding for salt tolerance in tomato has been impeded by insufficient knowledge of the genetic control of tolerance. The genetic basis of salt tolerance during vegetative growth was investigated by growing a salt‐tolerant (PI174263) and a salt‐sensitive tomato cultivar (UCT5) and their F1, F2 and backcross progeny in saline solutions with electrical conductivity of 0.5 (control) and 20 dS/m (salt‐stress). The relative salt‐tolerance of each generation was determined as the percentage of growth (i.e. dry matter production) under salt‐stress relative to growth under control conditions. In all generations, shoot growth was significantly reduced by salt stress. The reduction was largest in UCT5 (56.1%) and smallest in the F1 (27.4%), followed by PI174263 (32.3%). Analysis of the absolute and relative growth under salt‐stress indicated that genes contributing to vigour might be different from genes conferring tolerance. Generation means analyses of the absolute and relative growth indicated that the majority of the genetic variation among generations were due to simple (additive and dominance) genetic effects; nonallelic interactions, although significant, were far less important. Partitioning of the total genetic variance by weighted least‐square regression analysis and variance component analysis indicated that 88% or more of the variation was due to additive genetic effects. A moderate estimate of narrow sense heritability (0.49 ± 0.09) was obtained for shoot DW under salt‐stress treatment. The results indicate that tomato salt‐tolerance during vegetative growth can be improved by breeding and selection.
Efficient hybridization between Lycopersicon esculentum and L. peruvianum via ‘embryo rescue’ and in vitro propagation
Authors: LanZhuang Chen , Adachi Taiji
Published: April 2006

For the transfer of valuable traits from wild species into the cultivated tomato, excised globular‐stage embryos 13 and 15 days after pollination (DAP) were cultured in vitro. Plants were regenerated from interspecific crosses of Lycopersicon esculentum cv. ‘Early pink’×L. peruvianum PI270435, and backcrosses of L. esculentum‘Giban (JF) No. 1’× (‘Early pink’× PI270435). Somatic embryos and single cotyledons emerged on hypocotyl sections of the embryos. Five to nine plantlets per embryo were obtained by clonal propagation. The hybrid nature of the plants is confirmed by comparing hybrids and parents in their ability to regenerate shoots from leaf segments in vitro, by comparing plant morphology and characteristics and by chromosome number. This study describes an efficient ‘embryo rescue’ method, as well as somatic embryogenesis by clonal propagation. A novel and simple method for the characterization of the interspecific hybrids is also reported.
Single‐gene resistance to Septoria tritici blotch in the spring wheat cultivar ‘Tadinia’
Authors: Somasco O. A. , Qualset C. O. , Gilchrist D. G.
Published: April 2006

Resistance to Mycosphaerella graminicola causal agent of Septoria tritici blotch, was identified in progenies of crosses with European winter wheat cultivars, Tadorna and Cleo. This resistance was used to develop the resistant spring wheat cultivar Tadinia, selected from ‘Tadorna’/‘Inia 66’ released in 1985. Evaluation of the progeny of intercrosses between ‘Tadorna’, ‘Cleo’, ‘Tadinia’, and two short‐statured resistant lines derived from hybrids with ‘Tadinia’ as one parent indicate the resistance was inherited as a single gene showing partial to strong dominance. The gene in ‘Tadinia’ was designated Stb4. Crosses between another resistant cultivar, ‘Bulgaria 88’, and ‘Tadinia’ suggest that ‘Bulgaria 88’ does not have Stb4. Successful introgression of Stb4 into Rht1+Rht2 short‐statured lines revealed that plant stature and resistance to M. graminicola segregated independently. The Stb4 gene has been effective since 1975 against M. graminicola extant in California. A high positive correlation between seedling and adult plant disease scores, based on scoring of lesions producing pycnidia, indicated that the Stb4 gene is expressed throughout the life cycle under both field and greenhouse conditions, confirming that disease screening can be carried out on seedling plants. Separate assessment of necrotic lesions with and without pycnidia indicated that leaf necrosis without pycnidia, observed, especially under greenhouse conditions, can confound disease evaluations and lead to inaccurate genotype classification.
Linkage relations among eyespot resistance gene Pch2, endopeptidase Ep‐A1b, and RFLP marker Xpsr121 on chromosome 7A of wheat
Authors: de la Peña R. C. , Murray T. D. , Jones S. S.
Published: April 2006

Marker‐based selection of Ep‐D1b has been used successfully to incorporate Pch1, the gene for eyespot resistance on chromosome 7D, into commercial wheat. However, attempts to transfer resistance conferred by Pch1 (on chromosome 7A) through selection for Ep‐A1b have not always been successful. Linkage relations among eyespot resistance gene Pch2, a gene encoding for an isozyme of endopeptidase, Ep‐A1b, and RFLP marker Xpsr121 on chromosome 7A were determined using 80 homozygous recombinant substitution lines. The recombinant lines were derived from eyespot susceptible ‘Chinese Spring’ hybridized with a resistant disomic substitution line of ‘Cappelle Desprez’ that has chromosome 7A substituted into ‘Chinese Spring’. Segregations of Pch2, Ep‐A1b and Xpsr121 fit an expected 1:1 single‐locus ratios based on χ2 tests. Linkage analysis revealed that Pch2 was not tightly linked to Ep‐Alb (15% recombination). However, close linkage (3.8% recombination) existed between Ep‐A1b and Xpsr121. The order of these loci is Pch2‐Xpsr121‐Ep‐A1b. Unlike Pch1 and Ep‐D1b, where little or no recombination is found, Pch1 and Ep‐A1b showed considerable recombination and therefore linkage cannot be utilized efficiently in marker‐based selection.
First report of leaf rust pathotypes virulent to highly effective Lr‐genes transferred from Agropyron species to bread wheat
Authors: Sibikeev S. N. , Krupnov V. A. , Voronina S. A. , Elesin V. A.
Published: April 2006

The gene pool of effective sources of leaf rust resistance used in the breeding of wheat (Triticum aestivum L.) includes several species of the genus Agropyron. The genes deriving therefrom (Lr 19, 19d, 29, Agi1, Agi2, 38) are highly effective to pathotypes of Puccinia recondita Rob. ex Desm. In the Saratov and Orenbhurg districts of Russia, however, pathotypes virulent to these genes have been discovered. These pathotypes are virulent to Saratov‐bred cultivars carrying Lr 19, to ‘Indis’ (Lr 19d) and RL 6097 (Lr 38). The distribution of virulence on the ‘Thatcher’ near‐isogenic lines with different Lr genes shows that most of the Lr genes tested are susceptible to these new pathotypes of P. recondita, but the Lr genes Lr 9, 23, 24, 26 were exceptions. The inoculation of Mexican bread wheat cultivars, which carry widespread Lr gene combinations, by these pathotypes disclosed different infection types. Out of 10 Lr‐gene combinations, four were highly effective; namely the combinations Lr 13 + 26, Lr 26 +?, Lr 23+26 and Lr 23+26+34.
Utilization of deletions to localize a gene for resistance to the cereal cyst nematode, Heterodera avenue, on an Aegilops ventricosa chromosome
Authors: Jahier J. , Tanguy A. M. , Abelard P. , Rivoal R.
Published: April 2006

A previous RFLP analysis showed that the Aegilops ventricosa chromosome 6MV which compensates for the absence of 6D in 6MV (6D) wheat substitution lines was a 2/6 translocated chromosome, either 2S–6S.6L or 2S–6L.6S. The distal part of its long arm consists of a translocated segment belonging to homoeologous group 2. Chromosome 6MV carries a gene(s) for resistance to cereal cyst nematode. In order to define the part of 6MV (2S or 6S or 6L) involved in this resistance, addition lines with a 6MV deleted either for its short arm or for the distal part of its long arm were evaluated. It was shown that the gene(s) is carried by the group 2 translocated segment. The hypothesis that the gene(s) could be allelic to Cre2, another gene conferring resistance to the nematode introduced into the wheat complement from Ae. ventricosa is discussed.
RAPD‐mapping of the distal portion of chromosome 3 of barley, including the BaMMV/BaYMV resistance gene ym4
Authors: Weyen J. , Bauer E. , Graner A. , Friedt W. , Ordon F.
Published: April 2006

Experiments were carried out in order to identify RAPD‐markers for the BaMMV/BaYMV resistance gene ym4 to facilitate efficient marker‐based selection in practical breeding programmes. Linkage analysis was carried out with 283 doubled haploid (DH) barley lines out of a cross between the BaMMV/BaYMV susceptible cv. ‘Igri’ and the resistant cv. ‘Franka’. Using bulked segregant analysis, 310 RAPD‐primers were screened for polymorphism between the parents. Four of these primers gave rise to specific bands linked to the resistance gene ym4.
A comparison of somaclonal variation in rice plants derived and not derived from protoplasts
Authors: Yamagishi M. , Otani M. , Shimada T.
Published: April 2006

To clarify the effect of the type of in vitro culture on the generation of somaclonal variation, protoplast‐derived rice plants were compared with rice plants derived from suspension culture or primary calli (not derived from protoplasts). Regenerated plants showing polyploid‐like phenotypes appeared at a higher frequency (33–70%) in plants derived from protoplasts than in those not derived from protoplasts (3–6%). In the first progeny (R1) generation of all regenerated plants, 120 of 368 lines (33%) segregated plants with mutated characters such as albino, dwarf and sterile. In quantitative traits, 62 (21%) and 144 (50%) of 290 Rj lines showed shorter culm and lower seed‐fertility, respectively, compared with the control line derived from the selfed seeds of the original cultivar. The frequency of the mutant‐possessing R1 lines among lines derived from protoplasts was not significantly different from those not derived from protoplasts. These results indicate that isolation and culture of protoplasts does not enhance genetic changes other than cytogenetical changes.
A genetic analysis of low‐temperature‐sensitive sterility in indica‐japonica rice hybrids
Authors: Li H. B. , Zhang Q. , Liu A. M. , Zou J. S. , Chen Z. M.
Published: April 2006

Low‐temperature‐sensitive sterility has become one of the major obstacles in indica–japonica hybrid rice breeding. The objectives of this paper were to evaluate the extent of the fertility reduction and to determine the genetic basis of low‐temperature‐sensitive sterility. Seventeen varieties were crossed in various ways to produce 21 F1s including 16 indica‐japonica hybrids. Fertility of the F1s and their parents was examined under both high and low temperature conditions. Considerable reduction in spikelet fertility was observed under low‐temperature conditions in the majority of the indica–japonica hybrids having at least one wide compatibility parent. However, the extent of fertility reduction varied greatly, depending on the parental genotypes. Data from five pairs of reciprocal crosses indicated that the cytoplasm had no effect on fertility reduction. The more‐or‐less bimodal distribution of the fertility segregation of one BC1F1 and two F2: populations under low‐temperature conditions suggested that the low‐temperature‐sensitive sterility was controlled by only one or a few genes. It was also shown that the low‐temperature‐sensitivity is not related to wide compatibility. We conclude that it is possible to develop indica‐japonica hybrids with wide compatibility and also insensitivity to the low‐temperature conditions.
Quantitative trait loci influencing grain protein content in tetraploid wheats
Authors: Blanco A. , Giovanni C. de , Laddomada B. , Sciancalepore A. , Simeone R. , Devos K. M. , Gale M. D.
Published: April 2006

Seed storage protein content of durum wheat (Triticum turgidum var. durum) has an important effect on nutritional value and pasta‐making characteristics. The objective of this study was to determine by association with genetic markers the number, chromosomal location, and magnitude of effect of quantitative trait loci (QTLs) controlling protein concentration in kernels. A set of 65 recombinant inbred lines (RIs) was developed by single seed descent from a cross between cultivated durum wheat cv. ‘Messapia’ (low protein content) and accession MG4343 of the wild tetraploid wheat var. dicoccoides (high protein content). This population was characterized for eight morphological, six storage protein, one isozyme and 124 RFLP loci. Field trials were conducted in one location in 1993 and two locations in 1994. QTLs were mapped by regression analysis on each marker locus for each location and for the average across environments. A total of six putative QTLs were located on chromosome arms 4BS, SAL, 6AS, 6BS and 7BS. The number and size of QTLs detected varied across environments. The marker with the highest r2 value per QTL in each environment and across environments was chosen for a multiple linear regression analysis, which explained 49.2‐ 56.4% of the phenotypic variation for protein content. Only some of the markers were found to be negatively associated with plant grain yield and/or seed weight in one or two of the environments.
Genotypic variation for competitive ability in spring wheat
Authors: Huel D. G. , Hucl P.
Published: April 2006

Herbicides are the primary method of weed control for crop production in developed countries. For economic and environmental reasons alternative control strategies are being devised. One of these strategies is the development of competitive crop cultivars. The objectives of this research were to establish whether spring wheat (Triticum aestivum L.) genotypes differed in competitive ability and if those differences were related to specific growth characteristics. Sixteen genotypes of spring wheat were grown under simulated weed competition conditions at Saskatoon, Canada over a 3–year period. Four high and four low tillering genotypes from each of two crosses (Neepawa/M1417 and Ingal/M1417) were studied. Weeds consisted of cultivated oat (Avena saliva cv. ‘Waldern’) and oriental mustard (Brassicajuncea cv. ‘Cutlass’) sown at two densities (48 and 96 seeds/m2 per weed species). Seedling establishment, ground cover, and seed yield for the three species were determined, as was wheat tiller number, spike number, maximum height, leaf area index, leaf orientation, and flag leaf length and size. Significant (P = 0.001) weed rate by genotype interactions involving changes in genotype rank were detected for wheat grain yield, indicating that the 16 wheat genotypes differed in competitive ability. Wheat grain yield reductions averaged over the two weed densities ranged from 45% to 59%. The highest‐yielding genotypes under weed‐free conditions were not necessarily the highest yielding under weedy conditions. Genotypes which suffered smaller yield reductions were more effective in suppressing weed growth. Although competitive genotypes were generally taller than non‐competitive genotypes, other traits such as large seedling ground cover and flag leaf length were associated with wheat yield under competitive conditions.
Sequential path analysis of grain yield and its components in maize
Authors: Agrama H. A. S.
Published: April 2006

The efficiency of a breeding programme depends mainly on the direction and magnitude of the association between yield and its components and also the relative importance of each factor involved in contributing to grain yield. The purpose of this research is to describe the application of causal path analysis to grain yield in maize (Zea mays L.) to take into account the sequential development of yield components. Causal‐admissible path analysis was performed assuming unidirectional causal relationships among yield components of eight maize populations. Sequential path analysis of the five yield components studied revealed that ears per plant had the highest direct effect on grain yield. However, the indirect effects of component traits via number of grains per ear was maximum. It was concluded that the number of kernels per ear, prolificacy, and grain size serve as potential characters in breeding for superior lines for grain yield in maize.
Comparison of intra‐ and inter‐pool crosses in faba beans (Vicia faba L.). I. Hybrid performance and heterosis in Mediterranean and German environments
Authors: Link W. , Schill B. , Barbera A. C. , Cubero J. I. , Filippetti A. , Stringi L. , Kittlitz E. von , Melchinger A. E.
Published: April 2006

Two recently detected, promising CMS systems in faba bean have opened up new possibilities in hybrid breeding. This study was conducted to determine hybrid performance and heterosis of 33 intra‐pool and 66 inter‐pool crosses from a factorial of six European small‐seeded (Minor), six European large‐seeded (Major), and eight Mediterranean faba bean lines. The parent lines and F1 crosses were evaluated at two German and seven Mediterranean environments for anthesis, maturity, yield, yield components and plant height. Yield in the Mediterranean environments was 60% of that in the German environments. European Minor lines and their intra‐pool crosses were unadapted to Mediterranean environments and yielded only 31 % compared with the Mediterranean lines and their crosses, whereas European Major genotypes yielded 58%. In German environments the European crosses yielded 107% of the Mediterranean crosses. Heterotic yield increase over the parental mean was largest for European Minor x Mediterranean inter‐pool crosses, amounting to 95% in the Mediterranean and 73% in German environments. Our results confirmed the expectation of an increased heterosis in inter‐pool over intra‐pool hybrids and poor adaptation of European genotypes in Mediterranean environments. In the latter, Mediterranean intra‐pool hybrids were the most promising, whereas in Germany inter‐pool hybrids of the European Minor × Mediterranean type were most promising.
Efficiency in the use of phosphorus, nitrogen and potassium in topless faba beans (Vicia faba L.) – variability and inheritance*
Authors: Stelling D. , Wang S.‐H. , Römer W.
Published: April 2006

In a field experiment with topless faba beans, parental inbred lines and FI hybrids of a 7 × 7‐diallel were evaluated for traits related to the P, N and K efficiency. In addition, the parental inbreds were cultivated in a pot experiment at two P levels (100 vs. 700 mg P per pot). Significant heterosis for grain yield, uptake and utilization efficiency of nutrients in the field experiment highlighted the enhancement of nutrient efficiency in the hybrids. Amongst both parental inbreds and hybrids, significant genotypic variation was found for nearly all recorded traits. In the diallel analysis, the GCA effects generally proved to be highly significant and in most cases considerably higher than the SCA effects. In the pot experiment, grain yield ranking of the parental lines at the high P level (= P700) was very similar to that in the field experiment, whereas at the low P level (= P100, – P deficiency) the ranking of the lines changed considerably. Correspondingly, the P level‐line interaction was highly significant. High tolerance towards P deficiency was found for those two parental inbreds derived from cultivars bred under Syrian conditions. At the high P supply, P efficiency was more favoured by a high P uptake, but at P deficiency by a high internal P utilization.
Identification and mapping of random amplified polymorphic DNA markers linked to a rhizomania resistance gene in sugar beet (Beta vulgaris L.) by bulked segregant analysis
Authors: Pelsy F. , Merdinoglu D.
Published: April 2006

Bulked segregant analysis was employed to identify random amplified polymorphic DNA (RAPD) markers linked to a gene that confers rhizomania resistance to a sugar beet line created from a Holly Sugar Company breeding population (USA). Polymorphism revealed with 160 arbitrary 10‐mer oligonucleotide primers was screened in two bulks produced by separately pooling the individual DNAs from the six most resistant and the six most susceptible plants of an F2 population segregating for rhizomania resistance. A study of the F2 individuals showed that 19 primers generated 44 polymorphic markers which were then grouped into nine linkage groups. By analysis of variance, 12 were shown to have a significant effect upon the level of resistance and were mapped on a segment 22.3 cM long. A quantitative trait locus (QTL) of resistance was identified and located in a 4.6cM interval between two markers. It accounted for 67.4% of the observed variation and almost all the genetic variation. These results suggest that the identified QTL corresponds to a unique major gene conditioning the Holly resistance studied, which we have named Rz‐l.
Gli‐B3/Glu‐B2 encoded prolamins do not affect selected quality properties in the durum wheat cross ‘Abadía’×‘Mexicali 75’
Authors: Ruiz M. , Carrillo J. M.
Published: April 2006

A study was made of the effects of the Gli‐B3/Glu‐B2 encoded prolamins on durum‐wheat quality. Twenty‐six F3 lines from the durum wheat cross ‘Abadia’×‘Mexicali 75’ were analysed electrophoretically for prolamin composition and for the following quality parameters: SDS sedimentation value, mixing properties, and percentage grain protein and percentage vitreous kernels. The results showed that the presence or absence of the Gli‐B3/Glu‐B2 encoded prolamins did not result in any significant difference in the quality characteristics of the F3 lines; however, as expected, the LMW glutenins encoded at Glu‐B3 showed large differences and are therefore the major prolamins influencing durum wheat gluten quality.
Short Communication Resistance to common bunt in Hordeum chilense X Triticum spp. Amphiploids
Authors: Rubiales D. , Ramírez M. C. , Martín A.
Published: April 2006

The reaction of tritordeum and its Hordeum chilense and Triticum spp. parents to common bunt incited by Tilletia tritici were determined in field experiments. H. chilense accessions were very resistant, and durum wheats exhibited high to moderate levels of resistance. Conversely, bread wheats were highly susceptible. Resistance from H. chilense was expressed in the amphiploids, although the level of resistance was partially diluted at higher ploidy levels. Hexaploid tritordeums were immune to the disease; some infection was observed among the octo‐ploids but at much lower levels than in their respective wheat parents.
Stability of fingerprints of Solanum tuberosum plants derived from conventional tubers and vitrotubers
Authors: Mandolino G. , De Marco S. , Faeti V. , Bagatta M. , Carboni A. , Ranalli P.
Published: April 2006

The restriction and amplification patterns of potato genomic DNA of eight different cultivars and breeding clones has been studied. The analysis was carried out by polyacrylamide high resolution gels, and subsequent blotting and hybridization to potato DNA probes, and by agarose gel electrophoresis of the amplification products obtained with a variety of random primers. Fingerprinting of the genotypes was possible using two enzyme‐probe combinations (Rsal‐GP35 and Rsal‐CP6) and three random primers (OPA4, OPA19 and OPG12). Based on the same techniques, a number of plants from the cvs. Monalisa and Spunta originated from the sprouting of in vitro‐induced tubers (vitrotubers) were analysed to test the reproducibility of RFLP and PCR patterns. No variations were found with RFLP analysis. Some different RAPD patterns were seen, showing putatively vitrotuber‐specific variations.
Callus induction and plant regeneration from immature and mature embryos of winter durum wheat genotypes
Authors: ÖZgen M. , Türet M. , ÖZcan S. , Sancak C.
Published: April 2006

Seven genotypes of winter durum wheat (Triticum durum Desf.) were cultured to establish an efficient method of callus formation and plant regeneration from mature embryo culture, and to compare the responses of immature and mature embryo cultures. Immature embryos were aseptically dissected from seeds and placed, with the scutellum upwards, in dishes containing Murashige and Skoog's (MS) mineral salts and 2mg 2,4‐ dichlorophenoxyacetic acid (2,4‐D) per litre. Calli and regenerated plants were maintained on 2,4‐D‐free medium. Mature embryos were moved slightly on the imbibed seeds. For callus formation, the seeds with moved embryos were placed, furrow downwards, in dishes containing 8 mg 2,4‐D per litre. The developed calli and regenerated plants were maintained on the MS medium. Plants regenerated from both embryo cultures were vernalized and grown to maturity in soil. Variability was observed among the wheat genotypes tested for various culture responses in both explant cultures. Callus induction rate and regeneration capacity of callus were independent of each other. Mature embryos have a low frequency of callus induction but a high regeneration capacity. Considering availability, rapidity and reliability, this form of mature embryo culture can be used as an alternative method for immature embryo culture.