bluuebunny/crossref_metadata_2025 huggingface dataset:
Production and cytogenetics of tetraploid–octoploid Avena hybrids
Authors: Katsiotis A. , Forsberg R. A.
Published: April 2006

The objectives of this research were to gather hybridization information about crosses between tetraploid and synthetically derived octoploid lines of Avena and their reciprocals, and to study the cytology of the hybrids obtained. When the octoploid plants were used as females, only 2.6% of the pollinated florets set seed, while seed set increased to 39.0% in reciprocal crosses. However, germination was 95.7% for the first group of hybrids and only 18.2% for the reciprocals. These diverse results can be explained by the paternal: maternal endosperm genomic ratios and the hypothesis of polar nuclei activation. The tetraploid‐octoploid hybrids did not always contain 42 chromosomes. Octoploid lines derived indirectly from tetraploid (AABB) × hexaploid (AACCDD) crosses were found to retain their A and B genome chromosomes. Univalents in the above hybrids averaged 15.44 in 1990 and 15.15 in 1991, indicating the presence of C and D genome chromosomes inherited from the octoploid lines. Directly synthesized octoploids from diploid (AcAc) × hexaploid (AACCDD) crosses were found to form 20.44 univalents, 5.30 bivalents, and 2.69 trivalents when crossed with AABB tetraploid species. The high number of univalents indicates that chromosomes from at least three genomes, i.e. B, C, and D, remain unpaired, while trivalents are the result of homology between the A and Ac genomes. Hybrids between tetraploid and octoploid lines can be obtained at low frequencies but, regardless of the direction of the cross, these hybrids are highly sterile.
Genetic variation in the feeding efficiency of maize genotypes evaluated from experiments with dairy cows
Authors: Barrière Y. , ÉMile J.‐C. , Traineau R. , Hébert Y.
Published: April 2006

Genetic variation in the feeding efficiency of maize genotypes was evaluated from experiments with dairy cows. Maize genotypes were chosen to represent a range of digestibilities from previous experiments with standard sheep.

The variation in milk yield observed with dairy cows fed genotypes with low or high digestibilities or energy values was about 1.0–2.0 kg per animal per day. Moreover, the range of variation in body weight was about 10–30 kg during the 3 months of the experiments. Hybrids with similar energy values had a similar effect on milk yield, but the intake of each hybrid could be very different when they were fed to dairy cows, even if no difference in intake had been observed in sheep. The higher silage maize intake of ‘DK265’ was mostly converted into a body weight gain rather than an increased milk yield, probably because the milk yield potential of the animals was soon reached. It appeared that those hybrids whose predicted energy value from sheep measurements was low led to relatively low performances in cows. Dairy cow performances also appeared to be related to the enzymatic solubility values of the whole plants.

For maize breeders, the prediction of hybrid efficiency in dairy cow rearing must include digestibility and ingestibility factors. The most important challenge for maize breeders now will probably be the adjustment of a criterion for predicting intake because the stover digestibility and the starch content can be predicted reliably with the use of NIRS calibrations.
Breeding for resistance to rhizomania in sugar‐beet (Beta vulgaris L.)
Authors: Büttner G. , Märländer B. , Manthey R.
Published: April 2006

In breeding for resistance to rhizomania, breeding material was routinely examined for resistance to the rhizomania virus over several years. This study was performed in order to investigate the value of virological examination of sugarbeet breeding material in breeding for resistance to the rhizomania virus. Tests were conducted with varieties susceptible or partially resistant to rhizomania, as well as with several new and more‐resistant hybrids.

A test on young plants showed that all genotypes contained beet necrotic yellow‐vein virus (BNYVV), but that the virus content differed widely. Plants of two commercially used partially resistant varieties had, on average, only half the virus content of susceptible varieties in their roots, and plants of eight new hybrids still in the process of registration contained less than one third of that amount.

There was a significant negative correlation between the quantity of BNYVV in young plant roots and final yield under disease conditions in the field. Opportunities for further improvement in the level of the resistance to BNYVV in sugarbeet by means of conventional breeding programmes are discussed.
A rapid and simple method of producing high‐resolution zymograms from Brassica and related species on isoelectric‐focussing gels
Authors: O'Neill C. M. , Mathiasu R. J.
Published: April 2006

Isozymes are potentially valuable genetic markers in the identification of hybrid plants, the assessment of seed purity, and in molecular and conventional genetic maps. The starch gels commonly used to prepare Brassica zymograms have very low resolutions. Consequently, isoelectric‐focussing polyacrylamide‐gel electrophoresis was explored as a means of producing high‐resolution zymograms of four Brassica isozymes. Crude sap extracts were found to be unsuitable for electrophoresis. Centrifugation, passage over sepharose beads and overnight dialysis were tested as alternative means of clarifying samples. The zymograms presented here demonstrate that isoelectric focussing, following overnight sample dialysis, results in zymograms which, in comparison to their starch counterparts, have vastly improved separation and resolution.
Breeding for impact resistance in potato: use of a pendulum in progeny testing
Authors: Rousselle P. , Gravoueille J. M.
Published: April 2006

Breeding for impact resistance in potato is common at the end of a breeding scheme, where there is no more variability for it. The purpose of this study was to propose an objective progeny test using a pendulum and single‐year data. Data were recorded over a 5‐year period using 275 progenies, organized in small factorial and hierarchical designs. The variability of response of the additive variance made it impossible to generalize parental choice. However, once the crosses were made, the high degree of variability among the progenies and the high level of broad‐sense heritability in every case suggest that selection can be carried out efficiently using single‐year data.
Changes in the genetic structure of wheat germplasm accessions during seed rejuvenation
Authors: Zeuli P. L. Spagnoletti , Sergio L. , Perrino P.
Published: April 2006

Changes in the genetic structure of wheat accessions caused by interspecific competition during periodic seed rejuvenation at a gene‐bank were studied. Electrophoretic patterns (Acid‐PAGE) of gliadin storage proteins were used to discriminate bread from durum wheat and to identify bread‐wheat genotypes. Bread wheat shows high selective advantage over durum wheat and its frequency increased up to 100% after seven rejuvenation cycles. The number of bread‐wheat genotypes identified in each entry varied from five to 13, but only a few prevailed and these were different in each accession. In most cases, bread wheat was already present in the field sample collected, but at low frequency. In one case, ‘seed flow’ was thought to have occurred at a very low rate among neighbouring plots. The implication of these findings for genetic resources conservation are: 1. Mixtures of wheat species within the same germplasm accession must be avoided; 2. Only in some cases are low planting densities effective in reducing competition; and 3. The genetic structure of accessions in the gene banks must be monitored.
An EMS‐induced wheat mutant restoring fertility against photoperiod‐sensitive cytoplasmic male sterility
Authors: Murai K. , Ogihara Y. , Tsunewaki K.
Published: April 2006

Triticum aestivum cv. ‘Norin 26’ with Aegilops crassa cytoplasm shows photoperiod‐sensitive cytoplasmic male sterility (PCMS). This alloplasmic line is almost completely male‐sterile under long‐day conditions (≥ 15h), but highly male‐fertile under short‐day conditions (≤ 14.5h). To obtain male—fertile mutants against PCMS, seeds of the alloplasmic line were treated with ethyl methane sulfonate (EMS). The M3 generation was evaluated for PCMS expression, and one fertility‐restoring (FR‐mutant) line showing high male fertility under the long‐day conditions was selected. Reciprocal F, hybrids between the FR‐mutant and the alloplasmic ‘Norin 26’ showed male sterility under the long‐day conditions, and continuous segregation with respect to the degree of fertility restoration occurred in their F2 generations. These results indicate that multiple recessive mutations with minor effects, induced in the nuclear genome, are involved in the fertility restoration. In fact, no restriction‐fragment‐length polymorphisms of mitochondrial DNA between the FR‐mutant and the alloplasmic ‘Norin 26’ are found.
Polymorphism of two waxy proteins in the emmer group of tetraploid wheat, Triticum dicoccoides, T. dicoccum, and T. durum
Authors: Yamamori M. , Nakamura T. , Nagamine T.
Published: April 2006

Gel‐electrophoretic analyses detected polymorphism of two waxy (Wx) proteins, Wx‐Al and Wx‐Bl, in 334 accessions of the emmer group of tetraploid wheat, Triticum dicoccoides, T. dicoccum and T. durum. The null allele for the Wx‐Al protein (Wx‐Alb) was found in one accession of T. dicoccoides and seven of T. dicoccum, but it was not present in those T. durum accessions analysed. The null allele for the Wx‐Bl protein (Wx‐Blb) did not occur in three emmer‐wheat species. Wx‐Al and Wx‐Bl proteins showing alteration in mobility in SDS‐PAGE gel or in isoelectric points were found in five accessions and considered to be the products of new alleles, Wx‐Ald, Wx‐Ale and/or Wx‐Bld. Densitometric analysis of Wx protein bands revealed that Wx‐Al was present in smaller amounts than Wx‐B1 in almost all accessions.
Cytogenetic analysis of a long‐term Triticum timopheevii (Zhuk.) Zhuk. cell suspension culture
Authors: Zorinyants S. E. , Nosov A. V. , Badaeva E. D. , Smolenskaya I. N. , Badaev N. S.
Published: April 2006

In vitro culturing of plant cells can cause changes in karyotype. Chromosome variations following long‐term propagation in suspension culture of Triticum timopheevii (Zhuk.) Zhuk. were studied by routine staining and C‐banding. The culture was highly heterogeneous with respect to the number and structure of chromosomes. The modal class cells had a lower chromosome number than T. timopheevii (2n= 28). This data was confirmed by cytophotometric analysis of nuclear‐DNA content. Frequencies of chromosome loss varied for different homoeologous groups. At genome chromosomes tended to be preferentially eliminated in cells of different ploidy levels.

Deletions, insertions, translocations, telocentric chromosomes, isochromosomes and dicentrics and their derivatives were observed in cultured cells. Chromosomes of various homoeologous groups differed in the frequencies and spectra of re—arrangements, but most aberrations occurred in the G‐genome chromosomes. In vitro chromosome modifications did not correspond to in vivo variation. Presumably, this difference was caused by differences in the mechanisms of adaptation to the environment at the levels of the cell and the whole organism. G‐genome chromosomes were more frequently involved in this process, both in vivo and in vitro.
Chromosome doubling in Tripsacum: the production of artificial, sexual tetraploid plants
Authors: Leblanc O. , Dueñas M. , Hernández M. , Bello S. , Garcia V. , Berthaud J. , Savidan Y.
Published: April 2006

A collection of embryogenic diploid calli of Tripsacum was established and treated with colchicine to induce chromosome doubling. Sections containing duplicated cells in calli were identified using flow cytometry and ploidy level was determined in the regenerated plantlets. Tetraploid plants from several origins were obtained. In contrast to wild polyploid plants, which show apomictic development, the regenerated tetraploid plants reproduced sexually. By hybridizing these plants with wild tetraploid apomicts, various populations were established; these will allow a study of the inheritance of apomixis in Tripsacum.
Reciprocal differences for forage traits in single and three‐way crosses of maize
Authors: Seitz G. , Melchinger A. E. , Geiger H. H. , Singh I. S.
Published: April 2006

Eleven flint inbreds of maize were crossed with 11 dent inbreds according to a balanced incomplete factorial mating design to produce 66 single crosses (2W) in both reciprocal forms. Additionally, six three‐way crosses (3W) were also produced in both reciprocal forms. These hybrids were evaluated for 11 forage yield and quality traits in 1983 and 1984 at three sites in Germany. Highly significant reciprocal differences were observed for nine traits in the 2W. The respective variance component estimates amounted to 2–33% of the variance component due to crosses. On average, flint × dent 2W had lower dry‐matter content (DMC) than dent × flint 2W and a 1 % greater dry‐matter yield (DMY) of forage. Three‐way crosses produced on singles exhibited greater DMC (3%) and DMY (5%) of the ear, metabolizable energy content (MEC) of stover (1%), and DMC and DMY of forage (2%) than their reciprocal forms produced on lines. Based on this study, because of their minor importance, routine testing for reciprocal differences among 2W hybrids is not recommended.
Breeding value of base populations derived from ‘contiguous’ clusters in perennial ryegrass
Authors: Charmet G. , Debote B.
Published: April 2006

Five broad‐based breeding populations were produced by polycrossing natural populations sampled in five clusters developed by a hierarchical method with a geographic‐contiguity constraint. As a result, each of these breeding populations originates from a single region and the populations within a cluster are more likely to share the same alleles with similar frequencies. A single generation of intercrossing would therefore be sufficient to establish a panmixia equilibrium.

These populations were tested for dry‐matter yield in plots and compared to control cultivars in two locations. There were some trends of specific adaptation related to the geographic origin of populations, which, on average, compared well to controls. Their half‐sib families were evaluated as spaced plants in one location. This allowed genetic parameters and expected response to selection to be computed. Three out of five breeding populations appeared to be promising for the development of new, improved synthetic varieties.
Heterosis and combining ability in hybrids among 12 commercial varieties of sesame (Sesamum indicum L.)
Authors: Quoada P. , Layrisse A.
Published: April 2006

Heterosis and combining‐ability effects were studied in the parents and 66 F1 hybrids from a diallel cross of 12 elite sesame varieties in five different environments in Venezuela. The mean yield of the hybrids was clearly superior to the parental mean in all five locations. There were three heterotic hybrids that showed a higher yield than controls in all environments. The best hybrid in each place yielded significantly better than the best cultivar, the differences ranging from 28 to 109%. Specific combining‐ability (SCA) effects were more important than general combining‐ability (GCA) in four of the environments. A large genotypexlocation interaction was found for all traits, suggesting that hybrids should be produced for specific locations. ‘Arawaca’ and ‘Piritu’ should be chosen as parents for any sesame‐breeding programme in view of their large GCA effects.
Inheritance of resistance to Karnal bunt (Tilletia indica Mitra) in bread wheat (Triticum aestivum L.)
Authors: Fuentes‐Davila G. , Rajaram S. , Singh G.
Published: April 2006

The mode of inheritance and allelic relationships among genes conferring resistance to Karnal bunt were studied in seven bread‐wheat (six resistant and one susceptible) genotypes. The resistant genotypes originated in China (‘Shanghai#8’), Brazil (PF71131), the USA (‘Chris’), and Mexico (‘Amsel’, CMH77.308 and ‘Pigeon’). The susceptible line WL711 was from India. Evaluation of these wheat lines and all possible crosses among their F1 and F3 generations (about 100 progenies in each cross) revealed that two partially recessive genes conferred the resistance to Karnal bunt in ‘Pigeon’, whereas four partially dominant genes were present in the other genotypes. ‘Chris’, ‘Amsel’ and PF71131 carry one gene, whereas ‘Shanghai#8’ and CMH77.308 have two genes. ‘Chris’, ‘Amsel’, and PF71131 have different genes, whereas one gene was common to PF71131, CMH77.308 and ‘Shanghai#8’, and another to ‘Chris’ and CMH77.308. Gene symbols were formally designated to the resistant stocks. Resistance was incomplete and stable.
Effect of chromosome‐doubling agents on somaclonal variation in the progeny of doubled haploids of maize
Authors: Wan Y. , Widholm J. M.
Published: April 2006

This study was carried out to determine whether the treatment of anther‐culture‐derived haploid callus of maize (Zea mays) with chromosome‐doubling agents, such as colchicine or the herbicides pronamide and amiprophos‐methyl (APM), induces higher than normal levels of somaclonal variation. A total of 79 R1 families produced by diploid regenerated plants resulting from chromosome‐doubling treatments were evaluated in the field in comparison with the three parental inbreds.

Four qualitative variant phenotypes — male sterility, chlorophyll deficiency, earless plants, and short plants with narrow leaves and thin stalks —– were observed. The last phenotype (narrow leaves and thin stalks) was also found in the inbreds FR16 and H99 grown from seed, so it may not be directly related to the tissue‐culture conditions or the anti‐microtubule‐agent treatments. The frequency of R1 families segregating for the other three mutations was 3.8%, which is no higher than the somaclonal variation frequencies observed previously in tissue‐culture‐derived maize plants. Observations of three quantitative traits—–days to anthesis, days to silk emergence, and plant height—– also failed to detect any extra variation that could be related to the treatments with anti‐microtubule agents. These studies indicate that the anti‐microtubule agents APM, pronamide and colchicine can be used to induce chromosome doubling of anther‐culture‐derived callus to produce a high proportion of doubled haploid plants without causing increased rates of mutation (somaclonal variation).
Anther‐Culture ability in Secale cereale L.
Authors: Fleinghaus‐Roux T. , Deimling S. , Geiger H. H.
Published: April 2006

Success in anther culture of rye (Secale cereale L.) has mainly been restricted to genotypes whose genome is partly determined by S. vavilovii Grossh. The aim of this study was to identify true S. cereale genotypes with anther‐culture ability. The plant material used included the semi‐wild standard genotype SC35, six single crosses of the ‘Petkus’ and 10 of the ‘Carsten’ gene pool, plus a double cross between SC35 and one of the ‘Carsten’ single crosses. Three anther‐culture experiments were performed. Several single crosses within the ‘Carsten’ gene pool produced green plants. The ‘Petkus’ single crosses tested did not show anther‐culture ability. As expected, the induction and regeneration rates of SC35 were higher than those of all other genotypes tested. The performance of the double cross was intermediate between its parents. The results demonstrate for the first time that anther culture in rye is a valuable tool in plant breeding. The data also show the possibility of transferring anther‐culture ability from high‐ to low‐responding genotypes.
Comparison of predicted and observed response to selection in two breeding populations of perennial ryegrass
Authors: Ravel C. , Charmet G. , Balfourier F. , Debote B. , Vézine J. C. , Astier C.
Published: April 2006

To predict any genetic response to selection, two breeding populations of perennial ryegrass, consisting of half‐sib families, were evaluated as spaced plants from 1987 to 1989 for several agronomical traits. In each population, the best plants selected through a multitrait Smith and Hazel's index were planted in a polycross to produce the second generation half‐sib families. Both generations were evaluated together from 1991 to 1993 as spaced plants. The difference between generations was the observed genetic response, which was compared to that predicted. Rust tolerance, aftermath heading and persistence were significantly improved in both populations. In trial plots used to assess the yield, no effect of mass selection was noticed. Thus, it is concluded that mass selection failed to increase productivity but produced some improvements in disease tolerance and aftermath heading.
Powdery‐mildew‐resistance genes Mla29 and Mla32 in H. spontaneum derived winter‐barley lines
Authors: Kinizios S. , Jahoor A. , Fischbeck G.
Published: April 2006

Allelism to the highly polymorphic Mia locus was demonstrated for the powdery‐mildew resistance of two Hordeum spontaneum derived winter–barley lines, ‘110‐4 × Sonja’ and ‘142–29 × Dura’, by testing the F2 progeny of crosses between these lines and the winter‐barley cv. ‘Triton’ (Mlal3) with two appropriate isolates. The results were confirmed by RFLP analysis, using the probe MWG 1H036, which is very closely linked to the Mia locus. The designations Mla29 and Mla32 are proposed for the genes identified in the two lines.
Unreduced gamete in interspecific hybrids in the Festuca/Lolium complex
Authors: Morgan W. G. , Thomas H. , Hanumphreys M. W.
Published: April 2006

Self‐sterile interspecific hybrids between diploid Lolium perenne and either Festuca arundinacea or F. gigantea (both hexaploids) set some seeds when subjected to a heavy pollen cloud from the amphiploids derived from the hybrids. All the progeny were octoploid and were formed from the fertilization of unreduced gametes in the F1 hybrid by amphiploid pollen. The significance of the results in relation to breeding efforts within the Lolium/Festuca complex is discussed.
Selection for seed yield in Middle American versus Andean × Middle American interracial common‐bean populations
Authors: Singh S. P.
Published: April 2006

The objective of this study was to compare the seed yield, seed weight, and maturity of random lines derived from two contrasting populations of common bean (Phaseolus vulgaris L.): Middle American (TR 7790) and Andean × Middle American (TR 7791). TR 7790 involved crosses between common‐bean races of Middle American origin only (Mesoamerica and Durango), whereas TR 7791 involved crosses between races of Middle American and Andean origin (Mesoamerica and Nueva Granada). A total of 85 random lines from each of these two double‐cross, interracial populations, a bulk sample of both populations, and all parents were evaluated in a replications‐in‐set design in eight environments in Colombia between 1991 and 1993. The mean yields of parents, population bulk, and lines from TR 7790 were significantly higher (P < 0.05) than those of TR 7791. Six lines in TR 7790 and nine lines in TR 7791 yielded significantly higher (P < 0.05) than the mean of their parents. Four lines from TR 7790 out‐yielded the highest‐yielding line from TR 7791. Moreover, while three lines from TR 7790 out‐yielded its best parent, none of the lines from TR 7791 out‐yielded its highest yielding parent. Thus, substantial yield gains should be expected from interracial populations within the Middle American group of common beans, whereas selection for higher seed yield from Andean × Middle American populations would seem problematic.
Yield, biomass and yield components in dwarf, semi‐dwarf and tall isogenic lines of spring wheat under recommended and late sowing dates
Authors: Miralles D. J. , Slafer G. A.
Published: April 2006

Grain yield and some of its physiological determinants were analysed in a field study conducted over two growing seasons with standard‐height (SH), semi‐dwarf (SD) and dwarf (DD) isogenic lines of a spring wheat sown at recommended and delayed dates. The objective was to test whether the action of Rht1 and Rht2 alleles in improving grain yield depended upon sowing date.

As expected, the dwarfing genes significantly reduced plant height in both sowings and growing seasons. There was a tendency for the SD line to produce more biomass than the SH and DD lines, although the differences were mostly not significant. Harvest index was linearly and negatively related to plant height. Consequently, the SD and SH line showed the highest and lowest grain yields in all environments. The optimum height for grain yield was estimated to be c. 70 cm, and this value was not affected by sowing date. Lines carrying Rht1 and/or Rht2 alleles always showed more grains/m2 (owing to an increased number of grains per spike and spikes/m2) than the SH line. Conversely, average grain weight was negatively associated with the number of grains/m2. Because the slope of this negative relationship was smaller (less negative) than that representing complete compensation, the relationship between grain yield and number of grains/m2 was hyperbolic. Although these relationships are frequently regarded as a reflection of increased competition among grains when the number of grains/m2 is increased owing to the use of semi‐dwarf genes, two alternative hypotheses are analysed and discussed.
Genetic distance between Triticum timopheevi Zhuk., T. aramticum Jakubz. and T. aestivum L.
Authors: Farshadfar M. , Kissimon J. , Sutka J.
Published: April 2006

The genetic distances between two cultivated wheat (Triticum aestivum L.) varieties (Martonvásári 9, Martonvásári 15), a Martonvásári 9 line possessing the crossability gene krl, and 21 accessions of T. timopheevi Zhuk. and T. araraticum Jakubz. were estimated, based on agro‐morphological, physiological and biochemical analysis of data. Cluster analysis based on Mahalanobis' D2 values was applied. All 21 accessions of T. timopheevi and T. araraticum could be classified into eight clusters. Clusters I and II consisted of all the T. timopheevi, while T. araraticum was located in six clusters. Discriminant analysis was applied to test significant differences between cluster pairs. The genetic distance (GD) based on the electrophoretic data of gliadins indicated two types of electrophoregrams in T. timopheevvi, distinguished as groups A and B. T. araraticum accessions were variable as regards the spectra. Mean, minimum and maximum GD were estimated within and between different wheat groups based on acid polyacrylamide gel electrophoresis.
Agronomical and morphological differentiation among winter and spring triticales
Authors: Royo C. , Soler C. , Romagosa I.
Published: April 2006

A collection of 299 secondary hexaploid triticale cultivars and advanced breeding lines from 18 countries, which were considered a representative sample of the existing diversity, was evaluated for morphological and agronomical characters with autumn planting at Lleida, Spain, from 1988 to 1991. The entries were classified as having winter (84) or spring (215) growth habit and among this latter group were complete (73) or substituted (147) types according to CIMMYT's terminology. Winter and spring triticales were grouped by cluster and principal component analyses. Winter triticales were taller with longer growth cycles, longer spikes, and more spikelets per spike than spring types. At early stages they also had prostrate growth. Spring‐substituted types were separated from complete material. As a group, spring‐substituted triticales differed more from winter types than the spring complete genotypes, which showed intermediate characteristics. Complete types of spring habit had tendency to be taller, with longer spikes, more spikelets per spike and bigger and heavier grains than substituted triticales. Greater variation in morphological and agronomical parameters was detected among winter triticales followed by the complete‐spring group.
The Yd2 gene and enhanced resistance to barley yellow dwarf virus (BYDV) in winter barley
Authors: Delogu G. , Cattivelli L. , Snidaro M. , Stanca A. M.
Published: April 2006

A breeding programme was developed to obtain barley yellow dwarf virus (BYDV)‐resistant winter genotypes using the Yd2 gene. The aim was to incorporate the Yd2 allele into the new high‐yielding genotypes to release cultivars that allow barley cultivation in areas where BYDV is endemic.

The resistant lines were developed using pedigree selection. An ICARDA resistant line (83RCBB130) carrying the Yd2 gene was crossed with three susceptible, high‐yielding winter varieties and their F1 lines were either selfed or backcrossed to the matching susceptible parent. The best lines selected from subsequent selfing generations were evaluated in replicated trials in the presence or absence of BYDV, starting from F6 and BC1F5 to F8 and BC1F7 generations. Four genotypes with superior agronomic traits and BYDV resistance were selected.
Genetic analysis of karnal bunt resistance in 14 Mexican bread‐wheat genotypes
Authors: Singh G. , Rajaram S. , Montoya J. , Fuentes‐Davila G.
Published: April 2006

Fourteen Mexican genotypes of bread wheat (Triticum aestivum L.) with good to moderate levels of resistance to Karnal bunt (Tilletia indica (Mitra)) were crossed with the highly susceptible cultivar WL711 to determine the genetic basis of resistance. The parents, F1 F2 and backcross populations of the 14 crosses were evaluated under artificial epiphytotic conditions during the 1993–94 season for Karnal bunt resistance. The F1 data suggested that the resistance was dominant to partially dominant over susceptibility. The F2 analysis of the segregation ratios in the F2 and backcross generations indicated that the resistance in the wheat genotypes Luan, Attila, Vee #7/Bow, Star, Weaver, Milan, Sasia and Turacio/Chil is controlled by two genes. The resistance in genotypes Cettia, Irena, Turaco, Opata, Picus, and Yaco was found to be conditioned by a single dominant gene. The genotypes with two genes for resistance expressed a higher level of resistance than those with a single gene and, therefore, are better sources of resistance to Karnal bunt.
The HMW glutenin suhunit composition of bread‐wheat varieties bred in Pakistan
Authors: Tahiru M. , Hussain S. A. , Turchetta T. , Lafiandram D.
Published: April 2006

A total of 50 bread‐wheat varieties bred in Pakistan were characterized for the composition of the high‐molecular‐weight glutenin subunit (HMW‐GS). The glutenin subunits, as revealed by sodium dodecyl‐sulfate‐polyacrylamide‐gel electrophoresis (SDS‐PAGE) were numbered according to Payne's numbering system and, varieties were accordingly assigned theoretical quality scores. All varieties were found to possess either subunit 1 or 2* coded by the A genome. Subunits 17+18 and 7 + 9 of the B genome and 5+10 of the D genome were predominantly found in this set of varieties. The frequency of the appearance of Glu‐l alleles in the varieties was different from that seen in other countries, especially in terms of the absence of the ‘null’ form of the A genome and the presence of novel subunits at the Glu‐Bl and Glu‐Dl loci. The compositions of HMW‐GS were generally of good quality, with more than 50% of the varieties achieving quality scores of 9–10 with a high (8.6) average score. The results in this study indicate that wheat varieties bred in Pakistan have a narrow genetic base in terms of HMW glutenin subunits. It appears that the breeders have been selecting wheat genotypes of glutenin subunits associated with good quality without knowing the actual composition of these subunits. The database established on the basis of these results is useful for wheat‐improvement programmes aimed at varietal identification and breeding for good quality parameters.
Meiotic studies of spontaneous hybrids of Amaranthus: genome analysis
Authors: Greizerstein E. J. , Poggio L.
Published: April 2006

The meiotic behaviour of 13 spontaneous interspecific F1 hybrids of Amaranthus was studied. The hybrids between species with n= 16 chromosomes had 16 bivalents but varied considerably in pollen stainability (0–55%). These results suggest the existence of cryptic structural hybridity. The hybrids involving A. cruentus (n = 17) and species with n = 16 (A. caudatus and A. quitensis) always formed 15II+1 III with very low pollen stainability (5–7%). Further observations indicated that Amaranthus species are allotetraploids with basic numbers of x= 8 and x= 9 but exhibit x= 16 and x= 17 as secondary basic numbers, as demonstrated by (a) the frequent presence of 811 + 171 in the meiosis of the hybrid A. spinosus (n = 17) × A. hybridus (n= 16); and the occurrence of secondary associations between bivalents in MI. Genomic formulae are proposed for each species, on the basis of the meiotic behaviour of the hybrids studied.
Quantitative genetic analysis ofSphaerotheca fuligineasporulation in Cucurbit a pepo
Authors: Leibovich G. , Elkind Y. , Dinoor A. , Cohen R.
Published: April 2006

The inheritance mechanism by which summer squash (Cucurbita pepo L.) suppresses powdery mildew (caused bySphaerotheca fuliginea) sporulation was studied by analysis of the sporulation yield per colony, measured spectrophotometrically at 700 nm. The value of the optical density (LOD) was used as the criterion for the pathogen sporulation. Three breeding lines of summer squash were used: Straightneck powdery mildew resistant (SNP), Benning's Green Tint (BGT) and Sihi Lavan (SLA), each differing in its susceptibility to powdery mildew. Cultivar SNP (resistant) was crossed with SLA (susceptible) or BGT (moderately susceptible) to generate F1F2and backcross populations. Continuous distribution was observed and joint scaling effect tests indicated that the additive‐dominant model was adequate. Narrow‐and broad‐sense heritability estimates for BGT × SNP were 0.74 and 0.85, respectively, and for SLA × SNP both were 0.79. These results indicate that it should be possible to select C. pepo populations on whichS. fuligineahas low sporulation, and which consequently will exhibit quantitative resistance.
Inheritance of dwarfism in plantain (Musa spp., AAB group)
Authors: Ortiz R. , Vuylsteke D.
Published: April 2006

Plantain (Musa spp., AAB group) is a major food crop in the humid lowland tropics of Africa, the Caribbean and Latin America. Lodging, caused by strong winds occurs periodically in these areas. Therefore, development of dwarf plantain cultivars and elucidation of the inheritance of dwarfism is desirable. A heterozygous normal plantain cultivar (2n= 2x) with long false‐internodes (19.4 ± 0.9 cm) was crossed with a homozygous wild banana (2n= 2x) with short false‐internodes (6.9 ± 0.4 cm) to develop a test‐cross segregating population. A total of 74 euploids (2x, 3x and 4x) were produced. Forty‐one normal and 24 dwarf diploids were obtained, which fits a 2: 1 trisomic test‐cross segregation ratio for one locus. Dwarfism is controlled by a single recessive gene, dw. At the tetraploid level, two normal and six dwarf hybrids were produced, suggesting that the dw locus is close to the centromere and that there is a dosage effect of the dw allele at the tetraploid level.
An evaluation of the potential of intergeneric gene transfer between Brassica napus and Sinapis arvensis
Authors: Bing D. J. , Downey R. K. , Rakow G. F. W.
Published: April 2006

The possibility of gene transfer between Brassica napus and Sinapis arvensis was evaluated. Six spring‐type cultivars of B. napus and four strains of S. arvensis were reciprocally crossed through controlled crosses. No hybrid was yielded from any cross. However, one hybrid with 28 chromosomes was obtained from B. napus×S. arvensis through ovule culture. The hybrid plant was highly sterile and set no seed on open pollination. Two F2 plants, with 35 and 36 chromosomes respectively, were obtained through self‐pollination by hand. Backcross of B. napus produced 23 plants carrying some characteristics of S. arvensis, but backcross to S. arvensis failed to produce a plant. The chromosome counts of the BC1F1 plants indicated that gametes with more than nine chromosomes were favoured during the meiosis. The data demonstrated that gene transfer from S. arvensis to B. napus was very difficult under controlled cross and backcross, while to transfer genes from B. napus to S. arvensis would be extremely remote even under the most favorable conditions.
Multigenic inheritance of biotype‐E greenbug resistance in wheat
Authors: Lazar M. D. , Peterson G. L. , Hu J.
Published: April 2006

Relatively little is known about host‐plant insect‐resistance genes. Near‐isogenic lines (NILs) can be a useful tool in evaluating such genes and their mechanisms of action. Through backcrossing and single‐seed selection, NILs have been produced in wheat (Triticum aestivum L.) for resistance/susceptibility to biotype‐E greenbug, Schizaphis graminum (Rondani). Crosses among several resistant and susceptible NILs produced segregation patterns in the F2 generation that were inconsistent with simple monogenic inheritance. The simplest genetic hypothesis consistent with the data would involve two independently segregating loci, requiring complementary expression of multiple resistance alleles. F3 segregation data were also consistent with the proposed genetic hypothesis. Multiple alleles are required to account for the observed variation, although the source of the multiple alleles is unknown. Direct comparison of specific resistant/susceptible pairs of NIL's, as well as bulked segregant analysis, should permit elucidation of resistance mechanisms. Based on the segregation data presented, new designations for the resistance loci studied are proposed.
Inheritance of genes coding for gliadin proteins and glume colour introgressed into Triticum aestivum from a synthetic wheat
Authors: Pshenichnikova T. A. , Maystrenko O. I.
Published: April 2006

A synthetic hexaploid, Triticum timofeevii×T. tauschii, was used to transfer disease resistance genes to the commercial cultivar Saratovskaya 29 (S29) by backcrossing. After five backcrosses the resulting derivatives still showed some traits of the synthetic, namely brown spike glumes and several gliadin components. Genetic analysis showed that the derived forms had inherited the Gli‐D1 allele of the synthetic, which was found to be tightly linked to a gene for glume colour. Recombination percentages between these genes was estimated to be 2.5 ± 1.7%. The development of the derivatives was also accompanied by a rearrangement within the Gli‐B1 locus, resulting in the formation of a new variant of the allele in S29.
Photoperiod and vernalization response of wheat under controlled environment and field conditions
Authors: Ortiz‐Ferrara G. , Mosaad M. G. , Mahalakshmi V. , Fischer R. A.
Published: April 2006

Characterization of large numbers of breeding lines for vernalization and photoperiod response in wheat is needed to enhance adaptation. A total of 20 wheat lines were evaluated for response to vernalization and photoperiod under two controlled environments and high ambient air temperatures under field conditions. Vernalized and non‐vernalized seedlings were transplanted into pots and placed in three photoperiod (8, 12 and 16 h of light) cabinets, in the greenhouse or in growth chambers. Days to anthesis decreased with increasing photoperiod. Vernalized plants flowered earlier than non‐vernalized. There was a significant correlation between days to anthesis in the greenhouse and the growth chamber (r = 0.88, P < 0.001). Basal vegetative period, effect of vernalization and photoperiod from the two screening techniques were positively correlated with each other. Growth habit, vernalization requirement and heading date in the field were highly correlated with the main effect of vernalization in the two controlled environments. The results indicate that selection for vernalization response in a large number of genotypes can be achieved under high ambient air temperatures in the field and the selected material can subsequently be screened for photoperiod response under greenhouse conditions.
Short‐duration colchicine treatment for in vitro chromosome doubling during ovule culture of Beta vulgaris L.
Authors: Hansen A. L. , Gertz A. , Joersbo M. , Andersen S. B.
Published: April 2006

Colchicine uptake into ovules of sugar beet after 7 days of culture and its chromosome‐doubling effect on ovule‐derived plants were studied with high colchicine concentrations (0.4–6.0%) and short treatment duration (0–5 h). The best result of 4.2 diploid plants per 100 ovules was produced by treatment with 0.4% colchicine for 2.5 h. Both colchicine concentration and treatment time of ovules showed toxic effects on embryo formation, but it was stabilized at a low level with short exposure. The chromosome‐doubling effect, by contrast, was unchanged with the colchicine concentrations used, but highly affected by the duration of exposure studied. A maximum percentage of 60% diploid plants was obtained after 3–5 h of uptake, which corresponds to only 31–39% of the total capacity for colchicine uptake in the ovules. Further uptake of the drug produced mainly toxic effects. Flow‐cytometric measurements of the ploidy level in plantlets in vitro and of the same plants before flowering in soil were similar in about 80% of cases. Thus, flow‐cytometric selection of diploid plants in vitro may be an efficient tool.
Identification of PCR‐based markers linked to the powdery‐mildew‐resistance gene Pl1 from Malus robusta in cultivated apple
Authors: Markussen T. , Krüger J. , Schmidt H. , Dunemann F.
Published: April 2006

The availability of molecular markers linked to mildew resistance genes would enhance the efficiency of apple‐breeding programmes. This investigation focuses on the identification of random amplified polymorphic DNA (RAPD) markers linked to the Pl1 gene for mildew resistance, which has introgressed from Malus robusta into cultivated apples. The RAPD marker technique was combined with a modified ‘bulked seg‐regant analysis’ mapping strategy. About 850 random decamer primers used as single primers or in combinations were tested by PCR analysis on the basis of resistant and susceptible DNA pools. Selected primers producing RAPD fragments were applied in an additional selection step to M. robusta and genotypes representing intermediate breeding stages of the breeding population 93/9, for which a 1:1 segregation could be observed for the resistance trait. Seven RAPD markers, all representing introgressed DNA sequences from M. robusta, were identified and arranged with the Pl1 locus in a common linkage group. The two most tightly‐linked RAPD markers, OPAT20450 and OPD21000 were mapped with a genetic distance of 4.5 and 5 cM, respectively, from the Pl1 gene. Both markers are suitable for marker‐assisted selection in apple breeding. The polymorphic DNA fragment OPAT20450 was cloned and sequenced, and longer primers for the generation of a sequence‐characterized amplified region (SCAR) marker have been constructed; this marker was easier to score than the original RAPD marker.
Host plant resistance in some wild wheats to the Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae)
Authors: Deol G. S. , Wilde G. E. , Gill B. S.
Published: April 2006

A total of 259 accessions of wild Triticum species originating from different countries, along with 91 triticale (6×)× bread wheat true‐breeding derivatives, two bread wheat, and three triticale cultivars were screened for resistance to the Russian wheat aphid, a serious insect pest of the wheat crop. Twenty‐four entries with low damage ratings on the basis of amount of leaf rolling and leaf chlorosis were retested along with resistant and susceptible controls. On the basis of leaf roll damage ratings, eight entries including four Triticum monococcum var. boeoticum (T. boeoticum), one T. monococcum var. monococcum (T. monococcum), two T. timopheevii var. araraticum (T. araraticum), and one triticale cultivar were significantly superior to ‘Karl’ (susceptible control) wheat. Among these, four accessions — three T. boeoticum and one T. araraticum— were significantly superior to all other entries and were equal to the resistant control (PI 372129) in resistance rating based on leaf rolling and leaf chlorosis (except T. boeoticum TA 202). The leaf chlorosis damage rating of all accessions were significantly lower than that of the susceptible check.
Characterization of the interspecific cross Cicer anetinum L. ×C. judaicum (Boiss)
Authors: Verma M. M. , Ravi  , Sandhu J. S.
Published: April 2006

An interspecific cross involving Cicer anetinum L. and C. judaicum (Boiss) No. 182 was established. The F1 could be distinguished from the parents by its prostrate growth habit at the seedling stage and through isozyme patterns for peroxidases and esterases. The inheritance of PRX‐3 was found to be relatively simple and behaved as a monomer. Meiotic studies indicated the occurrence of six bivalents and four uni‐valents in about 6% of F1 PMC's at metaphase I, but normal 8–8 chromosomal distribution in anaphase I, indicating near complete homology. The F1 hybrid was characterized for three morphological and six agronomical characters. A large F2 was studied for secondary branches per plant, 100‐seed weight (g), pods per plant, and grain yield per plant (g). Distributions of F2 for pod number and grain yield displayed high C.V. and were highly skewed in a positive direction. F2 recombinants were isolated with a very large number of secondary branches and a high pod number and yield. Such wide variability is not normally encountered in intevarietal crosses.
Gain or loss of single chromosomes in wheat‐rye addition lines and in 6x triticale detected by flow cytometry
Authors: Pfosser M. , Amon A. , Lafferty J. , Heberle‐Bors E. , Lelley T.
Published: April 2006

Flow cytometric DNA analysis was used to study changes in nuclear DNA content induced by the gain or loss of chromosomes or chromosome arms in wheat‐rye addition lines and in triticale. The amount of DNA present was determined by comparison with internal reference values obtained from euploid plants. The smallest difference in the DNA level which could be detected between aneuploid and euploid plants was 1.84%. Thus, it was possible to determine aneuploidy in all cases, except when very short telocentric rye chromosomes were added to wheat (addition line 1RS). The study has proved that flow cytometry is an efficient and simple way to discriminate between euploid and aneuploid plants in wheat and triticale.
Resistance to barley yellow‐dwarf‐virus disease in derivatives of crosses between hexaploid wheat and species of Lophopyrum (Triticeae; Poaceae)
Authors: McGuire P. E. , Zhong Gan‐Y. , Qualset C. O. , Dvořak J.
Published: April 2006

Among the wheatgrasses that are possible sources of genetic resistance for wheat to barley yellow‐dwarf‐virus disease (BYD) are those that have been commonly subsumed under the name Agropyron elongatum (Host) P. Beauv. Two of these wheatgrass species are the diploid Lophopymm elongatum (Host) Á. Löve (2n = 2x = 14) and the decaploid L. ponticum (Podp.) Á. Löve (2n = 10x = 70). These two species, the addition and substitution lines of L. elongatum chromosomes in hexaploid wheat (Triticum aestivum L.), and derivatives of hybrids between hexaploid wheat and L. ponticum, were screened for resistance to BYD, as defined by visual symptoms in field‐grown plants. The two species, an amphiploid derived from L. elongatum×‘Chinese Spring’ wheat, and the derivatives involving L. ponticum chromosomes were all highly resistant. The substitution and addition lines of L. elongatum chromosomes in ‘Chinese Spring’ revealed that the genetic control of resistance in L. elongatum must be complex, with more than one critical locus involved. Chromosomes 2E and 5E are involved and there are lesser contributions to resistance from the remaining wheatgrass chromosomes. One highly resistant derivative was determined to have only three pairs of L. ponticum chromosomes. It has a wheat‐like morphology and shows promise for further characterization.