bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a New Cytoplasmic Male‐Sterility System in Brassica juncea through Wide Hybridization
Authors: Rao G. U. , Batra‐Sarup Vinita , Prakash S. , Shivanna K. R.
Published: April 2006

A new cytoplasmic male‐sterility system was developed in an oilseed Brassica, viz. B. juncea var. ‘Pusa Bold’ with the cytoplasmic background of a wild species, Diplotaxis siifolia, obtained through wide hybridization. The synthetic alloploid (D. siifolia×B. juncea: 2n = 56, D3D3AABB) was repeatedly backcrossed to B. juncea to achieve cytoplasmic substitution. The CMS plants resembled the cultivar in growth and morphology. The flowers had narrow sepals and petals and short, shrivelled anthers which failed to dehisce. The meiotic process appeared to be normal. The microspores degenerated at an early stage after tetrad formation. Female fertility in the CMS plants was as good as in the cultivar. Female transmission of sterility confirmed it to be cytoplasmically encoded.
A Greenhouse Method to Assess Sunflower Resistance to Sclerotinia Root and Basal Stem Infections
Authors: Grezes‐Besset B. , Tournade G. , Arnauld O. , Urs R. , George P. , Castellanet P. , Toppan A.
Published: April 2006

A method was developed to assess sunflower resistance to sclerotinia root infections in greenhouses. Some of the genotypes were also tested in the field to validate the greenhouse testing method. Efficiency of this method was also tested in a diallel cross. The susceptibility could be assessed by the final percentage of dead plants or by the time required to reach a given threshold of attack (threshold latency parameter). The correlation coefficients between susceptibility assessed in the field and with the greenhouse method were significant. The diallel cross analysis indicated that only additive effects are important. Correlation for susceptibility to sclerotinia wilt, between parental lines and the mean of their hybrids, was significant. It is concluded that breeding programmes for increase of resistance to sclerotinia root and basal stem attacks, using the described testing method, should be effective.
Evaluation of the U.S. Cucumber Germplasm Collection for Early Flowering
Authors: Walters S. A. , Wehner T. C.
Published: April 2006

A greenhouse study was conducted to evaluate 866 cultigens (718 accessions, 38 breeding lines, and 110 new and obsolete cultivars) of cucumber (Cucumis sativus L.) for early staminate flower production. Complete data were obtained for 866 cultigens. The study was conducted on plants that were part of a root‐knot nematode experiment. Plants were grown from seeds in greenhouses in each of 3 seasons with 2 replications per season. There were significant differences for mean time of flowering over all cultigens among the 3 seasons. Days from planting to first staminate flower ranged from 26 to 45, with a mean of 35 for all cultigens. Root‐knot nematode infestation may be related to flowering, since early‐flowering cultigens had more root galling. The earliest flowering cultigen was PI 249561 (26 days to flowering); the latest was PI 470254 (45 days to flowering).
Karnal Bunt Resistance in Wheat‐Barley Addition Lines
Authors: Chauhan R. S. , Singh B. M.
Published: April 2006

Wheat‐barley addition lines 7H, 2H, 3H, 4H, 6H and 5H having barley chromosomes 1, 2, 3, 4, 6 and 7, respectively, were evaluated for resistance to karnal bunt (Neovossia indica) using syringe inoculation of sporidial suspensions of N. indica under glasshouse conditions. Addition lines 4H and 7H were rated as highly resistant and resistant, respectively, with zero and 3.22 coefficients of infection compared to ‘Chinese Spring’ which had a 23.5 coefficient of infection. All the six addition lines were found to be susceptible to specific virulences of Puccinia recondita tritici and P. striiformis.
The Effect of A Genome Substitution on the Resistance of Brassica napus to Infection by Leptosphaeria maculans
Authors: Crouch J. H. , Lewis B. G. , Mithen R. F.
Published: April 2006

Six accessions belonging to four subspecies of Brassica rapa, including three accessions of B. rapa subsp. sylvestris, were crossed with B. oleracea subsp. alboglabra in order to develop a series of synthetic B. napus lines with a common C genome but contrasting A genomes. Different A genomes had significant effects on the efficiency of B. napus resynthesis and the sexual compatibility of the synthetic lines with oilseed rape cultivars. The synthetic lines were used to investigate the effect of A genome substitution on the resistance of B. napus to infection by Leptosphaeria maculans, and to explore the potential for the use of wild forms of B. rapa in oilseed rape breeding programmes. Synthetic lines derived from two wild accessions of B. rapa, and their F1 hybrids with oilseed rape cultivars, expressed high levels of resistance to L. maculans in glasshouse experiments. One of these lines also expressed high levels of resistance in field experiments in England and Australia when exposed to a genetically diverse pathogen population. All other synthetic lines and cultivars were highly susceptible in both glasshouse and field experiments. F1 hybrids between oilseed rape cultivars and synthetic lines derived from B. rapa subsp. chinensis were significantly more susceptible than either parent.
Hardening of Some Winter Wheat (Triticum aestivum L.), Rye (Secale cereals L.), Triticale (×Triticosecale Wittmack) and Winter Barley (Hordeum vulgare L.) Cultivars During Autumn and the Final Winter Survival in Finland
Authors: Hömmö Leena Maarit
Published: April 2006

Profound hardening is the prerequisite for survival of a cultivar over winter. In the present study, hardening abilities of 13 winter wheat, 10 rye, 3 triticale and 6 winter barley cultivars were determined in field samples collected during the autumns of 1990 and 1991 by measuring the amount of ion leakage from frost‐treated leaf segments. The cultivars tested were selected from the Inter‐Nordic Winterhardiness Project, in which Field Survival Indices were determined for a total of 23 winter wheat, 13 rye, 5 triticale and 11 winter barley cultivars in order to estimate winter survival potentials under Finnish conditions. The winter survival of the materials studied correlated well with their hardening ability assessed by using the electrolyte leakage method.
Adjustment for Competition Between Genotypes in Single‐Row‐Plot Trials of Winter Wheat (Triticum aestivum)
Authors: Goldringer I. , Brabant P. , Kempton R. A.
Published: April 2006

Several statistical methods were investigated for improving yield estimation for 72 genotypes of winter wheat tested in a single‐row‐plot (SRP) trial. The different analytical models were compared using several criteria: the residual mean square fit; the standard error of differences of genotype means; the correlations of genotype means with means from six‐row‐plot (6RP) reference trial; the expected genetic gains relative to 6RP trial from selecting the 10 top yielding genotypes.

There was no significant correlation between the unadjusted genotype means for SRP and 6RP. Genotype yields were positively correlated with height in SRP, but this correlation was reversed in 6RP. Using the mean height difference of a plot with its two neighbours as a covariate to adjust for competition in SRP reduced the standard error of difference of genotype means and substantially increased their correlation with the 6RP means. The predicted selection efficiency in SRP trial increased from zero, before adjustment, to 83 % of 6RP trial. Including the difference in heading date and the effect of guards at borders as covariates in the SRP analysis improved the residual mean square fit but had no effect on correlation with 6RP means or selection efficiency. A producer‐competitor model in which individual competitor effects were estimated for each genotype gave a substantial improvement in fit over the covariate models but a much lower correlation with 6RP means and selection efficiency.

Yield selection in early generation wheat trials based on single‐row plots could be considerably strengthened by use of a plot covariate derived from height difference between neighbours.
Inheritance of Resistance to Mycosphaerella graminicola in Hexaploid Wheat
Authors: Jlibene M. , Gustafson J. P. , Rajaram S.
Published: April 2006

Septoria tritici blotch constitutes a major disease problem of wheat world‐wide. To efficiently breed wheat for resistance to this disease, an understanding is required of the inheritance of resistance. Our objective was to study the quantitative inheritance of resistance under field conditions. A nine‐parent diallel and a generation mean experiments were conducted at Toluca, México in 1986 and 1987, respectively, to investigate gene effects. General combining ability effects accounted for most of the variation although specific combining ability effects were detected in some crosses. Ias20*5/H567.71, Thornbird, and RPB709.71/Coc contributed the most to reduced disease severity. Reciprocal effects were detected in two of 36 crosses, where RPB709.71/Coc contributed additional reduced disease severity when used as female. The analysis of generation means confirmed results obtained from the diallel. Additive effects were also most important. Dominance effects and epistasis, mostly of the additive × additive type, were found in some crosses. Hence, substantial genetic progress for resistance can be expected among progeny from crosses with resistant parents. However, selection would be most effective if delayed to later generations because of dominance, and choice of the specific female parent may produce a higher level of resistance.
Triploid and Hexaploid Regenerants from Hexaploid Timothy (Phleum pratense L.) via Anther Culture
Authors: Abdullah A. A. , Pedersen S. , Andersen S. B.
Published: April 2006

Pollen embryos were obtained from eight genotypes and viable green plants were regenerated from four genotypes in an anther‐culture experiment with 165 genotypes of Phleum pratense L. Formation of proembryos inside the cultured anthers during the first 10—12 days was significantly influenced by genotypes and by the type of nutrient media. Primary embryos developed into multiple secondary embryos before regeneration of plants. Among a total of 62 plants regenerated, only 13 were albinos. Of the green regenerants, 11 were triploid while 35 were hexaploid when DNA‐content was measured by flow cytometry. Eight plants with a triploid DNA‐content did possess the triploid chromosome number of 21. Triploid and hexaploid regenerants from two different parents showed simplified isozyme (GPI and PGD) banding patterns relative to that of their parents.
Inheritance of ‘Hullability’ in Sunflowers (Helianthus annuus L.)
Authors: Denis L. , Dominguez J. , Vear F.
Published: April 2006

Improvement of the feed value of sunflower seedmeal by hulling achenes before crushing is of economic importance and varieties with good ‘hullability’ (ease of hulling) would be economically significant. Knowledge of the genetics of this characteristic is therefore necessary. Studies of heritability were made on a factorial cross of six female and six restorer lines. Hullability was measured as the ratio of hull removed by a laboratory huller against the total quantity of hull in the achene. The genotypes studied showed a wide range of hullabilities. There were considerable environmental effects but only small interactions; correlations between results in different locations were significant. Additive genetic effects predominated, although there were some interactions between parental lines. Narrow‐sense heritabilities were 0.73–0.85 for genotype means, 0.52 when calculated from individual plants, and 0.36–0.76 from parent‐progeny regressions. Early selection based on progeny means or a combination of individual and progeny values would appear to be the best method of breeding for improved hullability of sunflower achenes.
Wheat Breeding in a Water‐stressed Environment. I. Delineation of Drought Tolerance and Susceptibility
Authors: Sadiq I.I.S. , Siddiqui K. A. , Arain C. R. , Azmi A. R.
Published: April 2006

To elucidate genotypic differences expressed through the grain yield of drought‐stressed wheat, 21 commercial varieties and advanced lines were evaluated in the field under a range of soil water levels to induce varying degrees of drought stress. This paper presents data on grain yield and yield‐based indices to indicate drought tolerance and drought susceptibility. AZS‐4 was identified as drought tolerant and AZS‐17 and ‘Pavon’ as drought susceptible. High gram yield under stress can be explained in terms of high yield potential, thus grain yield proved to be the best indicator of drought tolerance.
The Transfer of Thinopyrum‐Derived Leaf‐rust Resistance from Common Wheat to Durum Wheat.
Authors: Littlejohn G. M. , Pienaar R. DeV.
Published: April 2006

The leaf rust resistance gene on chromosome 7AL of ‘Chinese Spring’ transfer no. 12 derived from Thinopyrum ponticum, was transferred to durum wheat by standard backcrossing. In ‘Agatha’ and ‘Indis’ a leaf rust resistance gene from Thinopyrum ponticum and Thinopyrum ponticum respectively, is found on a translocated segment on chromosome arm 7DL. The use of the ‘Langdon’ disomic D‐chromosome substitution lines for 7A and 7B resulted in the recovery of tetraploid leaf‐rust resistant lines from the crosses with ‘Agatha’ in the B2F1 generation. Tetraploid lines carrying the ‘Indis’ translocation segment were recovered in the B2F2 generation. The F2 segregation ratios for rust resistance after selfing or back‐crossing generally fitted a 1: 1 ratio indicating non‐transmission of the translocation segments in the male gametes. Homozygous resistant plants were not obtained. Meiotic instability was observed in 28 chromosome B2 F2 derivatives of the crosses between ‘Chinese Spring’ transfer no. 12 and durum wheat.
Nuclear Mutations Affecting Chloroplastic Pigments of Photoperiod‐insensitive Barley
Authors: Gallagher L. W. , Hafez A. A. , Goyal S. S. , Rains D. W.
Published: April 2006

Three photoperiod‐sensitive spring barley cultivars (Hordeum vulgare L.) and three independently derived, single‐gene, nuclear mutants expressing photoperiod insensitivity and extremely early heading time under short daylengths were investigated for chloroplastic pigment variation in three environments using reverse‐phase high‐performance liquid chromatography (HPLC) to account for differences in laminae colour. In a greenhouse, non‐stress environment and in a full sunlight, high‐temperature stress environment, no systematic differences were observed among pigments of the mutant‐parent pairs. However, under 12 h of daily light (600 μE m 2sec−1) and stress temperatures (20/10°C, night/day) in a growth chamber, the three mutants appeared similar to each other in chlorotic appearance and laminae pigment contents, but differed from the three non ‐chlorotic parents, which were similar to each other. The mutants had less chlorophyll a and b, β‐carotene, lutein, taraxanthin, violaxanthin, and neoxanthin but more zeaxanthin than their parents. When shaded, the mutants became less chlorotic. How phenotypic differences for heading time and perception of day‐length might be related to altered chloroplast contents remains unclear. The single‐gene mutants conferring photopenod insensitivity were more sensitive to photothermal stress than their photoperiod‐sensitive counterparts and as a result, their zeaxanthin content increased but the level of other pigments decreased.
Components of Seed and Straw Yield in Common Vetch (Vicia sativa L.)
Authors: ÇAkmakci S. , Aclikgöz E.
Published: April 2006

178 common vetch (Vicia sativa L.) strains were tested for 2 years under dryland conditions in Bursa, Turkey. Broad‐sense heritability of the traits was calculated for each trait. Phenotypic and genotypic correlation coefficients between seed and straw yield, with several morphological and reproductive traits, were obtained. Broad‐sense heritability estimates were high for 1000‐seed weight and number of seeds per pod. Heritability values for both seed and straw yield were small and insignificant. Harvest index, 1000‐seed weight and spring vigour showed significant positive correlations with seed yield, but days to flower correlated negatively with seed yield. Spring vigour, plant height and number of leaflets per leaf correlated positively, while harvest index, seeds per pod and seeds per plant correlated negatively with straw yield. Correlations between seed and straw yield were both positive and significant.
Relationship between the Origin of European Landraces and the Level of Partial Resistance to Wheat Leaf Rust
Authors: Broers L. H. M. , De Haan A. A.
Published: April 2006

The reaction to leaf rust of 33 European spring‐wheat landrace selections was assessed in the field and in the greenhouse to study the relationship between levels of partial resistance and levels of leaf rust at the origin of the landrace selections. The selections were classified into three groups according to the mean annual damage observed at the collection site. For each group of selections with high‐infection types the mean disease‐severity, area under disease progress curve and latency period were assessed. The data suggest that there is a greater likelihood of finding partial resistance in selections that come from locations with a high or intermediate mean annual damage as they displayed lower disease severity, lower area according to a disease‐progress curve and a longer latency period than the selections from locations with low mean annual damage.
Orychophragmus violaceus, a Potential Edible‐oil Crop
Authors: Luo Peng , Lan Z. Q. , Li Z. Y.
Published: April 2006

Orychophragmus violaceus, a member of the Cruciferae family, has been found to have a high oil quality with high contents of palmitic (14.3 %) and oleic (20.3 %) acids, and lower contents of linolenic (4.8 %) and erucic (0.9 %) acids. Plants of O. violaceus exhibit a high number of branches, pods per plant, and seeds per pod, which contributes to the high yield potential of this plant. Individual selection was made in the original population of O. violaceus, and a few early, disease‐tolerant and high‐yielding lines were obtained. Intergeneric hybridization was performed between B. napus and O. violaceus and several hybrid plants (F1) were obtained. After treatment with colchicine, amphidiploid plants developed. O. violaceus shows great potential for becoming an edible oil crop or being used as genetic material in a rapeseed breeding programme.
Prediction of Yield for Specific Locations in German Winter‐wheat Trials
Authors: Weber W. E. , Westermann T.
Published: April 2006

The interaction between varieties and environment can make the prediction of crop performance difficult. The farmer is obviously interested in achieving optimum production within the particular growing environment of his farm, thus, this paper investigates if crop performance predictions can be improved by making information from other locations into account. The investigation is based on yield data from winter wheat resulting from official German variety‐performance tests. The predictors are based on the single location (control), unweighted means, principal components, and weighted means, produced using regression coefficients as weights. These predictors were tested on an independent data set from another year. For the given yield data in winter wheat, the overall mean proved to be the best, which suggests that prediction for all locations should be the same, and predictors for specific locations cannot, therefore, be recommended. The main reason for this is the relatively small interaction between genotype and location, in comparison to the second‐order interaction between genotypes, locations and years.
Utilization of Asymmetric Somatic Hybridization for the Transfer of Disease Resistance from Brassica nigra to Brassica napus
Authors: Gerdemann‐Kncörck M. , Sacristan M. D. , Braatz C. , Schieder O.
Published: April 2006

Asymmetric somatic hybrid calli were produced between Brassica napus and a transgenic (Hyg R) line of B. nigra using a donor recipient fusion method for the production of cybrids. The transgenic line of B. nigra used as a donor also possessed genetic resistance to the pathogenic fungi Phoma lingam and Plasmodiophora brassicae. Using hygromycin for selection, 332 hybrid calli were obtained from which 30 produced shoots (1—‐20 per callus) which were rooted on a hormone‐free culture medium. The rooted shoots were transferred into soil and cultivated in a growth chamber where the plants were tested for resistance against the two pathogens. Out of 129 hybrid plants tested for resistance against P. brassicae, 30 (23.3 %) plants proved to be resistant and from 78 plants tested for resistance against P. lingam, 41 (52.6 %) plants remained disease‐free after infection.
Introgression of Phaseolus acutifolius A. Gray Genes into the Phaseolus vulgaris L. Genome
Authors: Pratt R. C. , Gordon S. G.
Published: April 2006

The tepary bean (Phaseolus acutifolius A. Gray) is a desirable genetic resource for incorporation of improved disease, pest, and stress resistance into common bean (P. vulgaris L.). Reproductive barriers separate the two species and the degree to which tepary genes may be introgressed into the common bean genome has not been well described. Greenhouse studies of gene introgression through recurrent back‐crossing to common bean were performed using two first backcross (BC1) and nine second backcross (BC2) populations. The truncate primary leaf characteristic of tepary bean was readily observed but the short primary leaf petiole and narrow bract tepary traits were infrequently observed in both BC1 and BC2 populations. In one BC, population high frequencies of adaxial stomata (characteristic of P. acutifolius) and the presence of a 30 kD cotyledon polypeptide from P. acutifolius were also observed; however, a diapho‐rase isozyme from P. acutifolius appeared to be eliminated from BC1 progeny at a high rate whereas 6‐phosphogluconate dehydrogenase alleles appeared to be transmitted normally. The expression of tepary primary leaf truncate morphology and bract width were correlated with decreased fertility in one of the two BC1 populations. Given suitable parental genotypes and population sizes it should be possible to transfer genes from P. acutifolius to P. vulgaris, especially in regions of the genome which are not associated with inviability or sterility. It will be difficult to transfer factors from certain regions of the tepary genome which are preferentially eliminated during introgression.
Genetic Control of Vernalization, Day‐length Response, and Earliness per se by Homoeologous Group‐3 Chromosomes in Wheat
Authors: Miura H. , WOrland A. J.
Published: April 2006

To identify homoeologous group‐3 chromosomes that carry genes for vernalization, day‐length responses, and earliness per se, a series of aneuploid lines (mono‐somics and tetrasomics) and chromosome‐substitution lines in ‘Chinese Spring’ (CS) were surveyed under different vernalization and day‐length regimes in controlled environments. The results indicated that genes on all three chromosomes of group 3 can have striking effects on ear‐emergence time. The replacement of CS 3B by its homologues in ‘Lutescens 62’ and ‘Cheyenne’ produced an increased insensitivity to vernalization, while 3B homologues from ‘Ceska Presivka’ gave CS a remarkable sensitivity to vernalization. This provided evidence for multiple allelism at a new Vrn locus on chromosome 3B. A negative association between gene dosage and day‐length response was found in CS 3D which was thought to carry a gene for promoting insensitivity to day‐length. The behaviour of CS monosomic 3A and CS (Timstein 3A), in reducing numbers of days to heading independently of environmental stimuli, suggested the presence of earliness per se genes on this chromosome.
An Assessment of Variation for Nutritional and Non‐nutritional Carbohydrates in Lentil Seeds (Lens culinaris)
Authors: Frias J. , Vidal‐Valverde C. , Bakhsh A. , Arthur A. E. , Hedley C.
Published: April 2006

The levels of the raffinose family of α‐galactosides (raffinose, stachyose, verbascose and ciceritol) and of the nutritional carbohydrates (fructose, sucrose and starch) were determined in the seed of a range of lentil lines from germplasm collections and commercial Spanish cultivars. Significant levels of variation were found for all the measured characters, and particularly for the α‐galactosides. The greatest variation was found in verbascose content, which ranged from about 1 % of the seed dry weight to undetectable amounts. The relationship between these chemical components and morphological seed characteristics was assessed. The only significant relationship between the different groups of characteristics was a positive correlation between the level of verbascose and the average seed weight for each genotype.
The Genetics and Breeding Potential of Rht12, a Dominant Dwarfing Gene in Wheat
Authors: Worland A. J. , Sayers E. J. , Börner A.
Published: April 2006

Rht12, a dominant dwarfing gene of wheat, was shown to be located distally on the long arm of chromosome 5A. Lack of recombination with the awn inhibitor B1 suggested that Rht12 is cither tightly linked to this gene or is, in this material, a pleiotropic expression of the gene. Linkage to β‐Amy‐A1 was also very tight, indicating that Rht12 is present on the segment of chromosome SAL ancestrally translocated from 4AL. The close linkage to β‐Amy‐A1 also suggests that Rht12 is not a homoeoallele of the commercially important GA‐insensitive dwarfing genes.

Analysis of near‐isogenic lines in a number of genetic backgrounds showed that Rht12 reduces height without altering ear size and significantly increases spikelet fertility. However its successful utilization in breeding programmes will require careful selection since in some backgrounds the gene reduces grain numbers and grain size. In all backgrounds, Rht12 delayed ear emergence time by around 6 days. A delay of this magnitude could, in many environments, adversely affect yield if it is not neutralized by altering the balance of other genes determining ear emergence time.
Inheritance of Total and Individual Glucosinolate Contents in Seeds of Winter Oilseed Rape (Brassica napus L.)
Authors: Rücker B. , Röbbelen G.
Published: April 2006

Genetic analyses were carried out with B. napus lines that differed in total content of individual glucosinolates (GSLs), as well as in their profile. Inheritance of total GSL content was studied with a complete F1 diallel mating of eight doubled haploid (DH) lines (5–120/μmol GSL/g dry seed) as well as with the segregating populations of two crosses between DH lines. Most of the genetic variability was caused by gca effects; heterosis was not important; heritability of GSL content was high (h2b, = 0.95, h2n= 0.87). For GSL contents below 20/μmol/g seed, heritability values reached h2b, = 0.69 and h2n, = 0.66. Low total GSL content was found to be controlled by 4–5 recessive genes with additive gene action. Alkenyl GSL profiles studied in F2 from resynthesized rapeseed lines were determined by four loci, two that are responsible for the elongation of the butenyl to pentenyl GSLs and two that are responsible for hydroxylation of alkenyl GSLs. Initial genetic studies of indolyl GSL contents from 0.1–4.5/μmol/g show that two or three genes may be involved. The frequency distribution of F2 phenotypes was virtually continuous due to both segregational and environmental variation. Genotypes with low alkenyl and low indolyl GSL contents were selected after crossing parents with low alkenyl/high indolyl and high alkenyl/low indolyl GSL content. The alkenyl GSL profiles are discussed with regard to the parental diploid species B. oleracea and B. campestris.
Efficient Production of Doubled Haploid Plants through Chromosome Doubling of Isolated Microspores in Brassica napus
Authors: Chen Z. Z. , Snyder S. , Fan Z. G. , Loh W. H.
Published: April 2006

Three methods of chromosome doubling to produce doubled haploid plants from microspore cultures of Brassica napus were compared: colchicine treatment of microspore‐derived plants, microspore‐derived embryos, and isolated microspores. In the whole plant treatment, 53% of the treated plants set seed, but the treatment delayed plant growth and reduced seed set. When microspore‐derived embryos were treated with colchicine, the doubling frequency was 32% (compared to 15% for spontaneous doubling). Direct colchicine treatment of isolated microspores resulted in a doubling efficiency of 70 % of the whole plants. This treatment also stimulated embryogenesis in microspore culture, leading to increased plant regeneration. Thus, direct chromosome doubling of isolated microspores is efficient and more than 10 000 doubled haploid plants have been produced in this manner in the past three years in order to accelerate the plant‐breeding process.
Efficient In Vitro Shoot‐regeneration Systems in Cassava (Manihot esculenta Crantz)
Authors: Konan N. K. , Sangwan R. S. , Sangwan‐Norreel B. S.
Published: April 2006

Two different protocols for in vitro regeneration of cassava using zygotic embryos and nodal axillary meristems have been developed. In both cases, buds were regenerated directly from excised explants without an intervening callus phase after a two‐step culture procedure. In cotyledonary explants derived from zygotic embryos, prolific shoot formation occurred within 2—3 weeks on MS medium supplemented with 0.5—5 mg/1 BAP alone or in combination with 0.1 mg/1 NAA. Nodal explants with axillary meristems derived from aseptically grown seedlings or stem cuttings were used to initiate a round compact bulb‐like structure on MS medium containing 10 mg/1 BAP. These latter structures, when cultured on MS medium supplemented with 0.1 mg/1 NAA, 1 mg/1 BAP and 0.1 mg/1 GA3, produced multiple shoots. Somatic embryos isolated at the globular/torpedo stage from zygotic embryo explants were also capable of multiple shoot production on medium with 1 mg/1 BAP. Rooting of regenerated shoots exceeded 95 % in phytohormone‐free MS medium. No change in their ploidy levels was observed. Therefore, the protocols developed should be of use in the particle gun and Agrobacterium‐mediated genetic transformation of cassava.
Enhancement of RAPD Analysis by Restriction‐endonuclease Digestion of Template DNA in Wheat
Authors: Riede C.R. , Fairbanks D.J. , Andersen W.R. , Kehrer R.L. , Robison L.R.
Published: April 2006

Random amplified polymorphic DNA (RAPD) analysis has proven to be an effective procedure for molecular marker applications in plant breeding, although non‐specific amplification may limit its utility in some species. The objective of this study was to determine the effectiveness of restriction‐endonuclease digestion of template DNA for elimination of non‐specific amplification and generation of heritable RAPD markers. Restriction endonucleases digested wheat DNA to completion in amplification buffer, suggesting that the restriction endonuclease can be added directly to the reaction mixture prior to amplification. A 1‐h 37°C step was programmed into the thermal cycler for restriction‐endonuclease digestion which was followed immediately by amplification. Non‐specific amplification was reduced and DNA marker patterns were altered in digested samples when compared to undigested samples. Genetic segregation of two polymorphic markers tested in F5 inbred progeny fit expected 1:1 ratios. These results suggest that heritable DNA markers may be generated with reduction in non‐specific amplification when restriction‐endonuclease digestion of template DNA is conducted as part of the RAPD procedure.
Intergeneric Transfer (Rye to Wheat) of a Gene(s) for Russian Wheat Aphid Resistance
Authors: Marais G. F. , Horn M. , Du Torr F.
Published: April 2006

An octoploid triticale was derived from the F, of a Russian wheat aphid‐resistant rye, ‘Turkey 77’, and ‘Chinese Spring’ wheat. The alloploid was crossed to common wheat, and to ‘Imperial’ rye/‘Chinese Spring’ disomic addition lines. F2, progeny from these crosses were tested for Russian wheat aphid resistance and C‐banded. A resistance gene(s) was found to be associated with chromosome arm IRS of the ‘Turkey 77’ rye genome. A monotelosomic IRS (‘Turkey 77’) addition plant was then crossed with the wheat cultivar ‘Gamtoos’, which has the 1BL.1RS ‘Veery’ translocation. Unlike the IRS segment in ‘Gamtoos’, the ‘Turkey 77’‐derived 1 RS telosome did not express the rust resistance genes Sr31 and Ar26, which could then be used as markers. From the F, a monotelosomic 1 RS addition plant that was also heterozygous for the 1BL. 1 RS translocation was selected and testerossed with an aphid‐susceptible common wheat, ‘Inia 66’ Meiotic pairing between the rye arms resulted in the recovery of five euploid Russian‐wheat‐aphid‐resistant plants. One recombinant also retained Sr31 and Lr26 and was selfed to produce translocation homozygotes.
Analyses of Interactions of Wheat Cultivars in Tests for Resistance to Pseudocercosporella herpotrichoides
Authors: Lind V. , Züchner S. , Spanakakis A. , Thiele A.
Published: April 2006

A total of 20 cultivars of winter wheat were tested by ELISA for resistance to Pseudocercosporella herpotrichoides in six environments and three growth stages. In a three‐factor statistical analysis, the contribution of the different factors to their respective interactions was studied. The genotype × environment interactions exerted a considerable influence which could be reduced by increasing the number of test locations. Environments with a high disease level were less suited to measuring resistance than those environments with a medium level. Estimates of heritability from 0.54 to 0.78 show that successful selection may be possible using ELISA. Significant correlations of quantitative resistance at different environments were only obtained under similar environmental conditions (the same location, the same year) and with P. herpotrichoides populations of similar composition (the same inoculum). The contributions of the individual cultivars to the genotype/ environment interactions were not significantly different, except for ‘Roazon’ and ‘Rendezvous’. Due to high environmental effects in growth stage H5, the determination of quantitative resistance was more reliable in younger stages (65, 75). Nevertheless, the use of the values from that late stage did not reduce the genetic parameters (σ2, h2) if they were combined with the earlier measurements.
A New Source of Resistance to Pseudocercosporella herpotrichoides, Cause of Eyespot Disease of Wheat, Located on Chromosome 4V of Dasypyrum villosum
Authors: Murray T. D. , de la Pena R. C. , Yildirim A. , Jones S. S. , Qualset C. O.
Published: April 2006

Resistance to Pseudocercosporella herpotrichoides in five wheat cultivars, accession W6 7283 of Dasypyrum villosum, and ‘Chinese Spring’ disomic addition lines of the D. villosum chromosomes IV, 2V, 4V, 5V, 6V and 7V, was evaluated in seedlings by measuring disease progress 6 weeks after inoculation with a β—glucuronidase—transformed strain of the pathogen and by visual estimates of disease severity. D. villosum and the disomic addition line of chromosome 4V were as resistant as wheat cultivars ‘VPM—1’ and ‘Cappelle Desprez’, but less resistant than ‘Rendezvous’. Resistance of the chromosome 4V disomic addition line was equivalent to that of D. villosum.‘Chinese Spring’ and disomic addition lines of IV, 2V, 5V, 6V and 7V were all susceptible. These results confirm Sparaguee's (1936) report of resistance in D. villosum to P. herpotrichoides and establish the chromosomal location for the genes controlling resistance. The presence of chromosome 4V in the addition line and its homocology to chromosome 4 in wheat were confirmed by Southern analysis of genomic DNA using chromosome group 4‐specific clones. This genetic locus is not homoeologous with other known genes for resistance to P. herpotrichoides located on chromosome group 7, and thus represents a new source of resistance to this pathogen.
Establishing Cytoplasmic Male Sterility in Brassica napus by Mitochondrial Recombination with B. tournefortii
Authors: Stiewe G. , Röbbelen G.
Published: April 2006

Fusion experiments between B. napus and X‐ray‐treated B. tournefortii protoplasts were carried out to develop cytoplasmic male sterility (ems) in B. napus. From the regenerants, six lines containing male sterile plants were selected; five lines segregated for male sterility, but one line (25–143) was completely male‐sterile from the beginning. Molecular analyses of mitochondrial (mt) and chloroplast (cp) DNA of B. napus, B. tournefortii, B. juncea and cms juncea indicated that the original cytoplasmic donor of the cms juncea‐system in B. napus was a B. tournefortii form, while the B. napus genotype used for the fusion experiments had a B. campestris cytoplasm. By analysis (it regenerated plants, line 25–143 was identified as possessing mt‐DNA recombined between B. campestris and B. tournefortii. with the major part derived from B. campestris. No differences were detected between epDNAs from H. campestris and from line 25—143. The other five lines were similar to B. campestris with all the probes used. The low frequency of sterile lines from the fusion experiments and the inheritance of the cms in segregating progenies are both discussed.
Genetic Analysis for Partial Resistance to an Iranian Strain of Bacterial Leaf Streak (X. campestris pv. hordei) in Barley
Authors: Alizadeh A. , Benetti V. , Sarrafi A. , Barrault G. , Albertini L.
Published: April 2006

Seven barley genotypes with high genetic variability for resistance to bacterial leaf streak (Xanthomonas campestris pv. hordei) were crossed in diallel fashion to determine the inheritance of resistance to this disease. Two experiments were undertaken in a controlled growth chamber using a complete‐block design with four replicates. Each replicate consisted of a row of 20 seedlings per parent or F1 hybrid. An Iranian strain of bacterial leaf streak was used for inoculation of 12‐day‐old seedlings. Results showed that the cultivars ‘Express’ and ‘Morex’ and the Iranian pure line Iran‐3a had a high partial resistance in booth experiments. Diallel analysis showed highly significant general and specific combining abilities. ‘Morex’ and Iran‐3a were the best combiners for partial resistance to bacterial leaf streak in barley and could be successfully used for breeding purposes.
Yield Stability in Faba Bean, Vicia faba L. 1. Variation Among Inbred Lines*
Authors: Link W. , Stelling D. , Ebmeyer E.
Published: April 2006

Cultivation of faba beans (Vicia faba L.) is hampered by poor yield stability. The genetic variation at the homozygous level for yield stability in the gene pool of the small‐seeded and indeterminate European faba beans and the usefulness of auxiliary traits for the improvement of yield stability were investigated. The concept of stability, based on the regression technique, was applied. A sample of 36 faba bean lines was tested in 16 environments and a subsample of eight lines was tested in 11 additional environments. Significant differences were found between lines for yield stability parameters, but the repeatability of the results was limited. Early maturity correlated markedly (r = 0.51**) with one of the yield stability parameters (deviation from regression). Although lodging resistance was not correlated with the stability parameters, it proved to be a safety factor for performance.
An analysis of seed development in Pisum sativumL. XVI. Assessing variation for fatty‐acid content by use of a non‐destructive technique for single‐seed analysis
Authors: Jones D. A. , Barber L.M. , Arthur A. E. , Hedley C. L.
Published: April 2006

Analyses of seeds from a wide range of pea lines have revealed extensive variation for all of the major fatty acids normally found in pisum. Unlike total lipid content, this variation was not affected by the presence of mutant alleles at the r and rb loci. To allow chemically analysed seed to be used in crosses, which is of particular importance for F2 seed, a method has been developed by which individual seeds can be analysed non‐destructively. This system entails drilling a small hole in the seed, away from the embryonic axis. The small quantity of powder produced by this process can be used for the chemical analysis but does not prevent the seed from being grown to produce progeny. Reducing the sample size had no significant effect upon the compositional analysis of the fatty acids.
Prospects of breeding opium poppies (Papaver somniferum L.) as a high‐linoleic‐acid crop
Authors: Singh S. P. , Khanna K. R. , Shukla S. , Dixit B. S. , Banerji R.
Published: April 2006

Fatty‐acid composition was studied in a half diallel in opium poppies using six parents, F1 and F2. Poppy is an oleic‐linoleic‐acid type of crop with a low level of linolenic acid of up to 3% or only trace. Transgressive segregation was observed in F2 having up to 81% linoleic acid making it suitable for development as a high‐linoleic‐acid crop. This is the first report of its kind in opium poppy.
Genetic improvement in wheat yield and associated traits. A re‐examination of previous results and the latest trends
Authors: Calderini D. F. , Dreccer M. F. , Slafer G. A.
Published: April 2006

Two field experiments were carried out with seven wheat cultivars (three of them, including a commercial hybrid, released during the last 10 years) representing different eras of plant breeding, to evaluate genetic improvement over the last century in grain yield, height, biomass, harvest index and grain yield components. Plots were fertilized and irrigated, and lodging and diseases were prevented.

Main culm height was negatively correlated with the year of release of the cultivars, probably as a consequence of selection for increased lodging resistance. There was no significant association between total above‐ground biomass and year of release of the cultivars. On the other hand, grain yield increased as newer cultivars were released. Results indicate that during recent years harvest index has been kept as the main attribute responsible for increases in grain yield. In general, number of grains/m2 was associated with increases in grain yield during the century. However, the newest cultivars showed an increased grain weight. In both growing seasons, cultivars released before 1980 showed a trend towards reduced grain weight, but cultivars released after 1987 had a similar number of grains per m2 with a higher grain weight than their predecessors. This was probably because the most modern cultivars have a longer grain‐filling duration with a similar length of growth cycle.
Mapping the GA3‐insensitive dwarfing gene ct1 on chromosome 7 in rye
Authors: Plaschke J. , Korzun V. , Koebner R.M.D. , Börner A.
Published: April 2006

A gibberellic acid‐insensitive dwarfing gene in rye (ct1) was mapped in an F2 population on chromosome 7R close to the centromere. Two RFLP markers were found, which flank the gene at distances of 1 and 3 cM, respectively. A total of 11 markers were mapped on 7R of which six cluster around the centromere and show segregation distortion in the case of the codominant markers. The ct1 gene is closely linked to copies of both α‐amylase and EmBP, as is the ct2 gene on chromosome 5R. Because of the different chromosomal locations of the GA3‐insensitive dwarfing genes in rye and wheat it is concluded that these genes are not homoeologous. This is supported by further differences in their phenotypic and genotypic expressions.
Identification of powdery‐mildew‐resistance genes in common wheat (Triticum aestivum L.). VI. Wheat cultivars grown in China
Authors: Xia X. C. , Hsam S. L. K. , Stephan U. , Yang T. M. , Zeller F. J.
Published: April 2006

A total of 26 common wheat cultivars and advanced breeding lines grown in China were tested with a set of 11 differential powdery‐mildew isolates. Seven cultivars were susceptible. Another seven cultivars showed the response pattern of resistance gene Pm2, either individually or in combination with genes Pm3d or Pm4a. Five cultivars expressed the resistance of gene Pm4b singly or in combination with Pm6. Another four cultivars exhibited the response patterns of genes Pm5, Pm6 and Pm8, respectively. Three cultivars, which included one breeding line with a pair of substituted chromosomes from Haynaldia villosa, presumably carrying the resistance gene Pm21, showed resistance‐response patterns to all the isolates tested.
Genetic analysis of resistance to leaf‐rust (Puccinia recondita f. sp. tritici) pathotypes in the durum wheats ‘PBW 34’ and ‘DWL 5023’
Authors: Gupta S. , Saini R. G. , Gupta A. K.
Published: April 2006

Genetic analysis of leaf‐rust resistance was conducted on two durum wheats. Triticum durum cvs. ‘PBW 34’ and ‘DWL 5023’ were crossed with the leaf‐rust‐susceptible durum wheat ‘Malvi Local’. The F1, F2 and F3 generations were tested against leaf‐rust pathotypes 1, 77A and 108. In ‘PBW 34’, a single dominant gene was effective against each of the pathotypes 1 and 108, whereas two independently inherited dominant genes were effective against pathotype 77A. In ‘DWL 5023’, two independently inherited dominant genes were operative against pathotypes 1 and 77A, whereas a single dominant gene was identified as being operative against pathotype 108. Allelic tests on F2 generation and joint segregation analysis on F3 generation seedlings, suggested that two different genes in each cultivar are effective against these three leaf‐rust pathotypes. Cultivar ‘PBW 34’ has Lrd1 and Lrd2 genes whereas Lrd1 and Lrd3 genes are present in ‘DWL 5023’.
Divergent selection for sprouting resistance in spring wheat
Authors: Hucl P.
Published: April 2006

The development of sprouting‐resistant spring‐wheat (Triticum aestivum L.) cultivars is a major breeding objective in many wheat‐producing regions. Sprouting resistance is thought to be associated with delayed maturity. The primary objective of this study was to measure the reciprocal effects of selection for sprouting resistance and maturity. Two experiments were conducted over a 3–4‐year period in Saskatoon, Canada. In the first experiment, two populations of hard red spring wheat were subjected to divergent selection (k = 10%) for maturity. In the second experiment, six populations derived from crosses between two sprouting‐resistant, late‐maturing, white‐grained cultivars (‘AUS1293’ and ‘AUS1408’) and three early maturing, red–grained cultivars (‘Park’, ‘PT516’ and ‘Roblin’), were subjected to divergent selection (k = 10%) for sprouting resistance. Selection for earliness reduced sprouting resistance in one population but had no effect in the second. For both populations, earlier maturity was associated with higher test weight but lower grain yield. In the second experiment, selection for increased sprouting resistance was effective, with realized heritabilities averaging 0.74. Increased sprouting resistance was associated with a slight delay (1–2.5 days) in time to spike emergence in four out of six populations, but had little effect on time to maturity in most populations. There was a trend towards redder grain in the sprouting‐resistant selections. The recovery of sprouting‐resistant, early maturing segregants was relatively low, averaging less than 10% over the six populations. In conclusion, selection for increased sprouting resistance can result in delayed maturity, but the magnitude of that delay will vary among populations.