bluuebunny/crossref_metadata_2025 huggingface dataset:
The kinetics of NADH oxidation by complex I of isolated plant mitochondria
Authors: Sooie Kathleen L. , Dry Ian B. , James Alan T. , Wiskich Joseph T.
Published: April 2006

The oxidation of matrix NADH in the presence and absence of rotenone was investigated in submitochondrial particles prepared from purified beetroot (Beta vulgaris L.) mitochondria. The submitochondrial particles oxidised NADH using oxygen and artificial electron acceptors such as ferricyanide (FeCN) and short‐chain analogues of ubiquinone(UQ)‐10, although the NADH‐FeCN reductase activity was not inhibited by rotenone. NADH‐oxygen reductase activity in the presence and absence of rotenone displayed different affinities for NADH (145 ± 37 and 24 ± 9 μM, respectively). However, in the presence of 0.15 mM UQ‐1 where any contribution from non‐specific sites of UQ‐reduction was minimal, the rotenone‐insensitive oxygen uptake was stimulated dramatically and the Km(NADH) decreased from 167 ± 55 μM to 11 ± 1 μM; a value close to that determined for the total oxygen uptake which itself was virtually unaffected by the addition of UO‐1 [Km(NADH) of 13 ± 3 μM).

The similar affinity of NADH‐oxygen reductase for NADH when UQ‐1 was present in both the presence and absence of rotenone, suggested that there may be only one NADH binding site involved in the two activities. A quantitative two‐stage model for Complex I is postulated with one NADH binding site and two sites of UQ‐reduction (one of which is insensitive to rotenone) with a common intermediate ‘P’ whose level of reduction can influence the NADH binding site. The poor affinity that rotenone‐insensitive NADH‐oxygen reductase activity displayed for NADH results from a limitation on the interaction of its UQ‐reduction site with UQ‐10 in the membrane; possibly from a low concentration of UQ‐10 around this site or from steric hindrance restricting the access of UQ‐10 to this reduction site.
Genotypic Variation for Cold Tolerance among Twelve Maize (Zea mays L.) Populations
Authors: Pozzi G. L. , Gentinetta E. , Salamini F. , Motto M.
Published: April 2006

The objectives of this study were (1) to ascertain the genetic differences for cold‐tolerance traits in a series of diallel crosses among 12 maize populations grown in field experiments, and (2) to compare, in controlled environment rooms, the modification of various metabolic parameters of two sets of four F1 variety crosses which, according to the field experiments, differed largely in seedling early vigour (cold‐tolerant [Ct] vs cold‐sensitive [Cs] Fl sets). Under field conditions, cold‐tolerance adaptability, as monitored by shoot dry matter accumulation, appeared genetically controlled; moreover, considerable differences existed among genotypes. Field data suggested that shoot dry weight was a good indicator of plant adaptability to periods of unfavorable cool conditions. The growth‐chamber experiments showed that shoot dry weights of the two sets of hybrids (Ct vs Cs), were more uniform at the highest temperature regimes than under suboptimal temperatures. Moreover, the laboratory study indicated that the interval of time of attain a specific stage of development provided a meaningful and useful criterion for differentiating the capacity of maize plants to grow at low temperatures. Although a clear association between a particular metabolite and the capacity of plants to grow at low temperatures was not observed, it was of interest to note that the total N concentration in the shoot was significantly higher in the Ct plants compared to the Cs ones.
Screening of Barley Varieties for Drought Resistance
Authors: Sinha N. C. , Patil B. D.
Published: April 2006

Barley varieties were screened for their efficient drought enduring ability and associated characters which may be useful in breeding programmes. The characters studied were: relative water content, content of proline, chlorophyll stability index (CSI), and percentage grain loss per plant due to water stress subjected to 10 days from jointing to boot stage. Proline and chlorophyll stability index were greatly associated with drought response (r =+0.54; ‐0.49), flag leaf area (r =+0.69; ‐0.51) and, to a certain extent, with leaf number (r = ‐0.35 and +0.34). Among the studied 19 varieties of barley, only three (DL 192, DL 36, DL 3) showed high enduring ability, of these the former two fall in the early, and the last one in the late flowering group. Morphological architecture of DL 192 had gathering type tiller (narrow tiller angle), wider and floppy leaves and it also bears physiological characters (high proline and high relative water content, and low value of chlorophyll stability index) necessary for drought resistance. DL 3 and DL 36 had dispersing type tiller (wider tiller angle) and erect leaf with good leaf area/plant, but unit leaf area was low in DL 3 (relates with shading behaviour reducing water loss). Other relations of drought resistance are briefly discussed in the text. An appraisal of the various traits revealed that high proline content, and low CSI (biochemical characters), earliness, larger flag leaf area and fewer leaves per plant (morphological characters) were directly correlated with productivity of the cultivars under drought conditions. These characters could be used as a guideline for breeding drought resistant cultivars of barley.
Evaluation of Near Infra‐red Reflectance Spectroscopy for Predicting Grain and Stover Quality Traits in Maize
Authors: Melchinger A. E. , Schmidt G. A. , Geiger H. H.
Published: April 2006

The prediction of grain and stover quality parameters in maize {Zea mays L.) by near infra‐red reflectance spectroscopy (NIRS) was studied. A total of 110 grain and 135 stover samples originating from different genotypes and environments were assayed. Calibration equations for content of crude protein (CP), crude fat (CF), starch (ST), and water soluble carbohydrates (WSC) in grain were obtained by multiple linear regression of known manual values on NIRS data from the odd numbered samples. Calibrations for CP, acid detergent fibre (ADF), in vitro digestible organic matter according to the Tilley & Terry (IVDOM‐T & T) and the gas production (IVDOM‐Gp) method, respectively, and metabolizable energy (ME) in stover were developed analogously. Equations were validated with the evennumbered .samples and for ME additionally with the 1584 stover samples from an experiment with 66 F1 hybrids tested in six environments. The coefficients of multiple determination (R2) of the prediction equations ranged from 0.80 for IVDOM‐Gp and ME in stover to 0.94 for CP in grain. Standard errors of calibration (SEC) and prediction (SEP) were in most cases not higher than commonly reported for conventional manual assays. With regard to the correct ranking of hybrids, prediction equations for ME applied well to stover samples from other environments with one exception. We concluded that NIRS can evaluate the quality traits investigated to a similar degree to that of conventional methods of analysis. Since NIRS is simple and safe to operate and allows rapid screening of several quality traits simultaneously, it should be particularly attractive for breeding purposes.
Electrophoretic Investigations on Nematode Resistant Sugar Beets
Authors: Jung C. , Wehling P. , Löptien H.
Published: April 2006

Hybridizations were made between beta vulgaris and three wild species of the patellares section being resistant to the best cyst nematode {heterodera schachtii). Monosomic addition lines (2 n = 19) with full nematode resistance were investigated together with wild beets by means of electrophoretical techniques. One alkaline esterase band and a complex of several acidic esterase bands were localized on the resistance‐carrying B. procumbens chromosome. The alkaline esterase marker also appeared in B. patellaris addition lines. An aconitase double band was visible in two of four B. webbiana addition lines. One resistant monotelosomic addition line with a small B. procumbens fragment had lost the esterase gene. Evidence is given that more than one chromosome is carrying genes for nematode resistance. The use of electrophoretic screening together with a nematode testing program is discussed.
Influence of Tetracycline on the Expression of Cytoplasmic Male Sterility (cms) in Chives (Allium schoenoprasum L.)
Authors: Tatlioglu T.
Published: April 2006

To influence the expression of cytoplasmic male sterility (cms), different clone members of male sterile genotypes of chives were treated with different chemicals, especially antibiotics which are known to act as protein synthesis inhibitors. A remarkable number of male sterile plants turned to partial or full male fertility after the treatment with tetracycline HCl and tetracycline base. Pollen grains produced by tetracycline on male sterile plants were viable and able to fertilize the egg cells. By using the perennial nature of Allium schoenoprasum L. it could be shown that the fertility induced on male sterile plants by tetracycline is reversible. This could be of practical importance for the multiplication of male sterile parents in hybrid breeding. None of the chemicals had any effect on the fertility of male fertile plants. Differences in reaction indicated that genetic differences exist between male sterile plants responding to tetracycline and those which do not.

The results are discussed in view of the influence of tetracycline on the mitochondrial protein biosynthesis.
Comparative Value of Androgenetic Doubled Haploid and Conventionally Selected Spring Barley Lines
Authors: Friedt W. , Breun J. , Züchner S. , Foroughi‐Wehr B.
Published: April 2006

Androgenetic doubled haploid spring barley lines (DH‐lines) were compared in field experiments with their pedigree‐selected sister lines (PD‐lines). The PD‐lines resemble a selected proportion of 1 % (10−2) or less of the original complete F2‐population. By comparison, an average of 10 DH‐lines were recovered from 10,000 anthers X > 1,000 microspores, i.e. at least 107 microspores per cross. The average success rate was therefore approximately 10−6.

Both PD‐ and DH‐families showed similar levels of performance with regard to all the characters studied, although no conscious selection had been applied in deriving doubled haploid progeny. Therefore, it is concluded that the regenerated microspore‐progenies may be the result of unconscious selection among the large numbers of microspores cultured.
Plant Regeneration from in vitro Cultured Anthers of Black Mustard (Brassica nigra Koch)
Authors: Govil S. , Babbar S. B. , Gupta S. C.
Published: April 2006

Anthers of Brassica nigra, excised from fresh as well as cold‐pretreated (3 days at 3 ± 2°C) buds cultivated on modified B5 medium (Gamborg et al. 1968) containing sucrose level varying from 2 % to 10 %, along with 1O−6M BAP (benzylaminopurine) and 9 × 10−6M 2,4‐D (2,4‐dichlorophenoxyacetic acid), developed calli and/or embryos. The latter response was observed only in anthers reared on media containing 6 % or higher levels of sucrose. On media containing two or four per cent sucrose, the anthers produced calli, exclusively. The growth of embryos was inhibited or else they started callusing if left on the media containing higher levels of sucrose. However, on transfer to MS medium (Murashige and Skoog 1962), containing 2 % sucrose, embryos started callusing and subsequently a few secondary embryos differentiated. Such embryos were sub‐cultured on MS + 5 × 10−6M BAP + 2 % sucrose, wherein numerous shoots developed from embryos. The shoots were rooted by transferring to a medium containing 5 × 10−6M NAA (naphthalene acetic acid). Within two months of culture, some of these plants started flowering in vitro.
Characterization of Somatic Brassies napus Hybrids by Polyacrylamide Gel Electrophoresis
Authors: Schenck H. R. , Uolf G.
Published: April 2006

Three somatic hybrids obtained by fusion of protoplasts from Brassica oleracea and B. campestris were analyzed by gel electrophoresis and compared with their respective parental species. By comparing multiple forms of esterases and phosphorylases it could be demonstrated that in all cases the hybrid plants contained one or more enzymes from each parent.
Selection for Oil Content in East Indian Lemongrass
Authors: Kulkarni R. N. , Rajagopal K. , Ramesh S.
Published: April 2006

The response of oil content to phenotypic selection was studied in a population of lemongrass raised from seeds of a clonally propagated variety SD‐68. During November‐December 1982, 400 plants were evaluated for oil content. Five per cent of the evaluated plants were selected for high and low oil content and were separately intermated in isolated polycross (PC) blocks in November 1983‐February 1984. The populations derived from high and low oil PC blocks were evaluated, along with the unselected parental population and OD‐19, a variety used as a local check, in a randomized complete block design, during October 1984, January and May 1985 for leaf yield, oil content and citral content in oil. The high oil PC population had a significantly higher oil content than the unselected parental population and the local check OD‐19, during all the three seasons. The low oil PC population had a significantly lower oil content than the unselected parental population in January and May 1985. Over seasons, the high oil PC population had 0.15 per cent higher oil content than the unselected parent population. Realized heritabilities for high and low oil content were 0.52 and 0.50, respectively. No significant differences were observed between the different populations for leaf yield in all the three seasons and for citral content in October 1984. In January and May 1985, the differences in citral content were not related to the differences in oil content.
Evaluation of Early Generation Testing in Chickpea1)
Authors: Rahman M. A. , Bahl P. N.
Published: April 2006

Inter‐generation correlations between F2‐F3, F2‐F4 and F3‐F4 in six crosses of chickpea were calculated by using individual plant/progeny means. In general, correlation values in case of plant height, seeds per pod and 100‐seed weight were higher between F3 and F4 than those between F2 and F3 and F2 and F4. However, inter‐generation correlations were mostly non‐significant in case of pods per plant and grain yield. These results clearly show that selection in F3 can be fruitful for seeds per pod and 100‐seed weight. However, selection for pods per plant and grain yield in early generations may not show any relationship with later generation performance for these traits.
Development of Strains with Yellow Seedcoat in Indian Mustard (Brassies juncea Czern. & Coss.)
Authors: Abraham V. , Bhatia C. R.
Published: April 2006

A mutant with yellow seedcoat colour was isolated by Nayar (1968) in the mustard variety‘Rai‐5′. This mutant was crossed to the national check cultivar ‘Varuna’ in order to develop improved strains with yellow seedcoat. Four such strains with yellow seeds were evaluated for their seed yield, yield components and percent oil. Two strains TM‐9 and TM‐17 were more productive than ‘Varuna’ in seed yield. All the yellow seeded strains showed higher oil percentage as compared to ‘Varuna’. The seedcoat in the yellow seeded strains accounts for 14‐15% of the seed weight as compared to 18% in the black seeded ‘Varuna’. The higher proportion of the cotyledons and embryo accounts for the increased oil percentage in the yellow seeded types.
Origin and Fate of Aneusomaty in Sunflower (Helianthus annuus L.)
Authors: Uremonini R. , Cavallini A.
Published: April 2006

Chromosomal variability in Helianthus annuus was studied during the ontogenetic cycle of the plant. Aneusomaty originates during embryo development, progressively decreases in the course of plant growth and disappears at pre‐meiosis.

A number of aberrant mitoses with lagging chromosomes were found in all embryonic stages examined; by contrast, mitoses never showed aberrations in the shoot apices of plants.
Hybrid Variegation in Crosses between Pelargonium zonale (L.) l'Herit. ex Ait. and Pelargonium inquinans (L.) l'Herit. ex Ait.
Authors: Pohlheim F.
Published: April 2006

In reciprocal crosses between Pelargonium zonale and Pelargonium inquinans uniformly green, uniformly bleached and variegated plants occurred among the F1 progeny. The effect has been described as hybrid variegation and also as hybrid bleaching. Because of the differences among the reciprocal crosses, it is assumed that the zonale‐plastids undergo normal development in hybrids, while the plastids of Pelargonium inquinans do not develop normally due to their interaction with the nucleus of the hybrid. Using the results obtained in the experiments, the development of zonale‐hybrids from Pelargonium is discussed.
The Tolerance to Aluminum of Triticum N‐Genome Amphiploids
Authors: Berzonsky W. A. , Kimber G.
Published: April 2006

Aluminum limits wheat (Triticum aestivum L.) yields on acid soils. An aluminum‐tolerant, N‐genome Triticum species was used to produce amphiploids, which were tested lor tolerance to 0.44 mM aluminum in solution, to assess the possibility of transferring tolerance to bread wheat. Two types of amphiploids, having the N‐genomc (Triticum uniaristatum) in common, were produced by treating three different Triticum ventricosum (DDNN) ×Triticum turgidum (AABB) hybrids and a single Triticum ventricosun×Triticum timopheevii (AABB) hybrid with colchicine. It would appear that the N‐genome amphiploids can be utilized to transfer tolerance to aluminum to cultivated Triticum species and to study the genetics of tolerance in the N genome.
Heritability and Interrelationships of Pod Length and Seed Weight in Guar
Authors: Stafford R. E. , Barker G. L.
Published: April 2006

This study was undertaken to estimate heritability of pod length and seed weight in guar, Cyamopsis tetragonoloba (L.) Taub., and to determine genetic relationships between the two traits. Narrow‐sense heritability (h2) estimates ranged from 0.63 to 0.68 for pod length and from 0.54 to 0.57 for seed weight. An additive‐dominance model was adequate to explain gene action involved in the inheritance of both traits. Estimates indicate a minimum of 5 loci or chromosome segments control pod length and 2 control seed weight. Phenotypic correlations between pod length and seed weight were highly significant and positive. Genotypic correlations between the two traits were low and positive. Moderate to high heritability values for the two traits indicate that selection for improvement in either trait should be fairly rapid. Low genotypic correlations between the traits should not pose a significant barrier in developing large seed, grain‐type cultivars.
Identification of Genes Controlling Pod Length in Spring Rapeseed, Brassica napus L., and their Utilization for Yield Improvement
Authors: Chay Patricia , Thurling N.
Published: April 2006

Experiments were undertaken to determine the inheritance of pod length in a cross with spring rapesecd, Brassica napus, and to assess the value of pod length as a criterion of selection for high seed yield.

Analyses of patterns of variation in F2; and backcross populations derived from a cross between a short‐pod line TB42 and long‐pod line CA553 indicated that much of the variation in pod length could be attributed to two major genes interacting in a complementary manner. Short‐pods were produced when cither one or both genes were homozygous for the recessive allele. Analyses of F3 progenies of selected F2 and inbred‐backcross lines derived from the same cross supported the two‐gene hypothesis but also indicated that the effects of the major genes on pod length were possibly modified by genes of minor effect.

Field testing of families derived from random intermating between F2, plants of the TB42 × CA553 cross showed that number of pods per plant varied independently of pod length, but seed weight per pod tended to increase with increasing pod length. As a result, families with the longest pods generally had significantly higher yields than those with short pods.

It was concluded that yield improvement in B. napus could be achieved through introgression of long‐pod genes into cultivars with an appropriate genetic background to ensure that selection for the long‐pod character would be accompanied by an increase in seed weight per pod with little or no reduction in number of pods per plant.
Genetic Analysis of Production Characters in Lolium
Authors: Devey F. D. , Hayward M. D. , Kearsey M. J. , McAdam N. J. , Eggleston M. P.
Published: April 2006

A Triple Test Cross and basic generations (i.e. inbred parents, F1′s, F2′s and backcrosses) have been used to investigate the genetics of dry matter yield in a population of Lolium perenne. Two trial designs, short, individual plant drills and larger sown plots were used at each of two sites in the U.K., at Aberystwyth and Birmingham. The families studied correspond to those raised as spaced plants and reported in the first paper in this series. In contrast to the spaced plants trial, the drill trial resulted in considerable epistasis as well as additivity and dominance variation whilst the plot trial failed to identify any significant genetic variation. There was considerable G × E interaction over sites and harvests, particularly in the amount of dominance. The latter showed a clear linear relationship with mean performance at both sites, the dominance ratio being higher in the poorest environments. This is largely due to the additive variance decreasing in the poor environments rather than the dominance being higher. The implications of these results to grass breeding are discussed.
Die Nutzung der Antherenkulturmethode im Zuchtprozeß von Winterweizen
Authors: Müller G. , Vahl U. , Wiberg A.
Published: April 2006

The use of anther culture in breeding winter wheat.

II. Production of new doubled haploid lines of winter wheat with 1AL—1RS‐translocation

A total of 4472 anhers was cultured from 8 F1 populations of winter wheat with the 1AL—1RS wheat‐rye translocation cultivar ‘Amigo’ as one of the crossing arents. When averaged over all populations a frequency of embruoid formation of 10% and of regeneration efficiency of green plants of 1% were observed. In addition to the 45 green regenerated plants, 93 albinos were obtained. 44% of the green plantlets had 21 chromosome in root tips and 29% were spontaneous diploids. Multiple peroxidases were used a biochemical markers in the subsequent characterization of the homogeneous breeding material. The electrophoretic patterns showed that 16 doubled haploids without rye chromosome segments were produced. In addition the features of dh0‐ plants showed, that several of the new 1AL—1RS‐translocation lines were awnless.
Inheritance of Resistance to Pseudomonas solanacearum E. F. Smith in Tetraploid Potato
Authors: Tung P. X. , Th. Hermsen J. G. , Vander Zaag P. , Schmiediche P. E.
Published: April 2006

Inheritance of bacterial wilt resistance in tetraploid potato was investigated in segregating progenies of parent clones with resistance derived from different specific sources and different types of adaptation. A race 1 and a race 3 isolate of Pseudomonas solanacearum were used to test the resistance under warm temperatures. Results obtained indicated partial dominance of resistance. Significant general and specific combining abilities showed that both additive and non‐additive gene actions are important in conditioning resistance expression. There was evidence that epistasis is an important component of the non‐additive gene action in the inheritance of resistance. Other aspects of the resistance and implications for breeding are discussed.
Efficiency of Recurrent Selection Methods to Improve the Line Value of a Population
Authors: Gallais A.
Published: April 2006

Five breedings methods have been studied for their efficiency in improving the line value of a population, i.e. the value of all lines that can be derived from the population. These methods are: half‐sib family recurrent selection (HSF‐RS), full‐sib family recurrent selection (FSF‐RS), half‐sib progeny recurrent selection (HSP‐RS), recurrent selection (S1‐RS) and the single‐doubled‐haploid descent recurrent selection (SDH‐RS). All breeding methods are compared on the basis of the genetic advance per unit of time, with the constraint of the same effective size after the first cycle of selection. Two modalities of SDH‐RS are considered for an annual plant without an off‐season generation: one with a cycle in four years (SDH1‐RS) and the other with a cycle in five years (SDH2‐RS). For all methods the possibility of one off‐season generation for intercrossing is considered. Fields of efficiency of the best methods are determined considering five main parameters, the heritability, the importance of additive variance, the correlation QL between the additive effect for line value and the additive effect for the per se value, the length of the cycle for SDH‐RS and the selection intensities. SDH‐RS is the best method when the heritability is low, with a low proportion of additive variance and with a relatively low correlation QL between additive effects for per se and line values. Without off‐season generation, S1‐RS is the best method among the remaining realistic situations; with one off‐season generation for intercrossing it is FSF‐RS. The use of an off‐season generation reduces the domain of efficiency of SDH‐RS while an increase in the selection intensity increases this domain. With a selection intensity for SDH‐RS equal to that for S1‐RS, SDH‐RS is the best in a large range of realistic situations except for SDH2 with one offseason generation and medium to high correlation QL.
Prolamin Analysis of Progenies from Androgenetic Plants of Triticale
Authors: González J. M. , López L. A. , Bernard S. , Jouve N.
Published: April 2006

The present work reports results of the analysis of variability of prolamins in five breeding lines of triticale and 61 androgenetic progenies obtained from them by in vitro culture of the anthers. The phenotypic analysis of the prolamins showed heterogeneity even between seeds harvested from the same plant regenerated by in vitro culture. The variability of prolamins in this material could be, perhaps, explained under different hypotheses: unreduced microspores, embryo fusion. The percentage of androgenetic plants which generated uniform progenies for the prolamins was 14.7. The plants obtained by in vitro culture showed a significant increase of the phenotypic variability for both specific bands and patterns of prolamins as compared with the parental materials. Some plants showed missing groups of prolamins in their electrophoretic profiles, which completely affected specific regions of the proteinogram. This could be explained by gametoclonal variation based on either structural rearrangements, or aneuploidy affecting chromosomes carrying genes involved in the expression of prolamins.
Natural Genes and Mechanisms for Resistance to Viruses in Cultivated and Wild Potato Species (Solanum spp.)
Authors: Vaikonen Jari P. T.
Published: April 2006

The types of resistance to viruses in potato are immunity, extreme resistance coded for by the R genes and hypersensitivity coded for by the N genes. Immunity prevents the establishment of virus infection, whereas extreme resistance is expressed as an extremely low virus titre resulting from restricted virus multiplication or localization of virus infection in the plant without obvious necrotic reactions. Expression of the N genes can also lead to localization of the virus infection followed by necrosis at the infection site. Tolerance to virus infection and resistance to inoculation and virus vectors are useful components of field resistance. Virus or virus strain specific resistance genes have been identified in cultivated and wild potato species and transferred to cultivated potato. However, combining resistance to the three globally most important viruses PLRV, PVY and PVX has proved difficult, and new sources of broad spectrum resistance to viruses are required for potato breeding. New molecular techniques will enhance the isolation of the natural resistance genes and studies of gene regulation.
Falling Number and Alpha‐Amylase Activity in Developing Grain of Alloplasmic Hexaploid Wheat
Authors: Oettler Gitta , Mares D. J.
Published: April 2006

Twelve fertile alloplasmic wheat lines, produced by substituting four nuclear genomes of Triticum aestivum into the cytoplasms of T. timococcum Kostoff, T. timopheevi Zhuk., and Aegilops ventricosa Tausch, were examined for cytoplasmic effects on falling number and α‐amylase activity during grain development in different environments. Nuclear genome, cytoplasm and environment were important sources of variation for falling number. In one environment, where the plants were exposed to very hot, dry conditions, the levels and patterns of change in α‐amylase activity were also significantly affected by the cytoplasm. The data indicated that alien wheat cytoplasms might result in useful additional variation in specific environments where sprouting is a problem.
Effect of Sugars in Wheat Anther Culture Media
Authors: Navarro‐Alvarez W. , Baenziger P. S. , Eskridge K. M. , Shelton D. R. , Gustafson V. D. , Hugo M.
Published: April 2006

Sugars are critical components in bread wheat (Triticum aestivum L.) anther culture media for successful somatic embryo initiation and plant regeneration. In this experiment, anthers from three wheat genotypes were cultured on a modified Liang's 85D12 initiation medium with seven sugar combinations (I‐sugars: galactose, mannose, maltose, fructose, sucrose, glucose, maltose + glucose) at 0.26 M, and 2,4‐dichlorophenoxyacetic acid (2 mg/L), 1‐naphthalene acetic acid (1 mg/L), and glutamine (254 mg/L). Wheat starch (5 % W/V), a potential source of sugars, was used as the medium gelling agent. No previous research has studied the effect of different sugars with wheat starch. A split‐plot experimental design with 42 replications was used with genotypes as whole plots and sugar combinations as subplots. Galactose and mannose did not support embryoid initiation and were dropped from the analysis. Averaged over the three genotypes, maltose was the best sugar (105 embryoids/100 anthers), followed by glucose (47 embryoids/100 anthers) and maltose + glucose (37 embryoids/100 anthers). These three sugar combinations were superior to the standard medium sugar, sucrose (24 embryoids/100 anthers), and to fructose (12 embryoids/100 anthers). The embryoids were divided into two groups for plant regeneration. The first group was transferred to regeneration medium (Liang 85D12 salts, sugars at 0.06 M, and wheat starch at 7 % w/v as gelling agent) with the same sugar (R‐sugar) used as in initiation. The second group was transferred to regeneration media with sucrose. I+R‐maltose (0.55)
Resistance to Karnal Bunt (Tilletia indica Mitra) in Synthetic Hexaploid Wheats Derived from Triticum turgidum×T. tauschii
Authors: Villareal R. L. , Mujeeb‐Kazi A. , Fuentes‐Davila G. , Rajaram S. , Del Toro E.
Published: April 2006

Synthetic hexaploids (SH) developed at the International Maize and Wheat Improvement Center (CIMMYT), involving four Triticum turgidum and nine T. tauschii parents, were evaluated for resistance to Karnal bunt (KB) (Tilletia indica Mitra) during three crop seasons over three years at Ciudad Obregon, Sonora, Mexico. Ten tillers of each SH at boot stage, taken at random, were injected with a suspension of sporidia in water (10,000 spores/ml of water). At maturity the inoculated spikes were threshed individually and evaluated for the percentage KB‐infected grains. Based on the mean KB score of each entry for three seasons, 49 % of the SH were immune (0 % infection) to KB. Highly resistant expressions characterized the SH which appeared to be influenced by the resistance of their T. turgidum and/or T. tauschii parents. The overall mean infection of the SH wheats was 0.24 % compared to 56.14 % in the susceptible bread wheat check cultivat ‘WL711’. Transfer of KB resistance genes from SH wheats into bread wheat is currently underway at CIMMYT.
Main Factors Affecting Cucumber (Cucumis sativus L.) Haploid Embryo Development and Haploid Plant Characteristics
Authors: Przyborowski J. , Nlemirowicz‐Szgzytt K.
Published: April 2006

This report gives the first detailed analysis of cucumber haploid plants and the first evaluation of genotype and season effects on haploid embryo development. Female flowers of four F1 varieties and two inbred lines were pollinated with 300 Gy‐treated pollen and three‐week old embryos were cultured in vitro on E20A medium. The variety ‘Polan’ produced the greatest number of embryos (1.34 per 100 seeds), 51 % of which were capable of further development. The number of embryos able to develop was four times higher in summer than in spring. All the plants obtained, except one, were haploids or aneuhaploids. Haploid plants grew slowly and were sterile, although they occasionally set seedless fruits. The length of the stems, leaves and guard cells was smaller than those of diploids.
Heritability, and Intra‐ and Inter‐Generation Associations Between Tuber Yield and its Components in Potato (Solanum tuberosum L.)
Authors: Gopal Jai , Gaur P. C. , Rana M. S.
Published: April 2006

The relative importance of the components of tuber yield in selection in early generations of a potato‐breeding programme was studied. In seedling generation the number of tubers were more important than average tuber weight, whereas in clonal generations the average tuber weight was more important. Correlation coefficients between number of tubers and tuber yield varied from generation to generation whereas those of average tuber weight and tuber yield were more or less constant. Unlike the number of tubers, the average tuber weight of a genotype in a generation influenced its tuber yield in subsequent generations. The average tuber weight had higher heritability than the number of tubers and tuber yield.
Regeneration of dihaploid chicory (Cichorium intybus L. var. foliosum Hegi) via microspore culture
Authors: Theiler‐Hedtrich R. , Hunter C. S.
Published: April 2006

In order to develop fully inbred chicory plants, dihaploid plants were raised from callus derived from microspores of three selected Witloof, Robin and Treviso types. Microspores were isolated from florets containing pollen at the uninuclear state and cultured in a modified MS medium plus 0.5mg/l 2,4‐D, 0.5mg/l IAA and 2.0mg/l zeatin. During culture periods of up to 6 months, gametoplasts emerged from pollen grains, divided and started to form colonies and calli. These were subcultured on the same basal medium supplemented with 0.5mg/l BA and 0.5mg/l IAA. Shoot growth was enhanced on a low salt‐containing medium supplemented with 0.4mg/l kinetin and 0.2mg/l IAA. Shoots were rooted on a half‐strength Lepoivre medium plus 0.2mg/l IBA and finally transferred to soil. Florets were excised from 34 capitula, but only microspores from four of them developed into plants via callus. More than 450 plants were raised in the greenhouse and the field. Leaves from these plants were subjected to DNA fluorescence analysis via flow cytometry: a range of ploidy levels was detected. The cell composition of 44 of these plants was predominantly haploid, with a diploid background. Regenerant plant phenotypes were compared with the parent genotypes. The value of such haploids in commercial chicory breeding is discussed.
Endopeptidase polymorphism and linkage of the Ep‐D1c null allele with the Lrl9 leaf‐rust‐resistance gene in hexaploid wheat
Authors: Winzeler M. , Winzeler H. , Keller B.
Published: April 2006

The aim of this study was to test whether the null allele Ep‐D1c of the endopeptidase Ep‐D1 can be used as a marker for the Lrl9 leaf rust resistance gene. The frequency of Ep‐D1c was determined in 1134 winter wheat, spring wheat and spelt breeding lines and varieties. Only eight lines were found to carry Ep‐D1c. Six of these lines originated from crosses with RL6040, the gene donor for Lrl9. The other two lines were leaf‐rust susceptible in the seedling stage and therefore did not carry Lr19. The genetic distance between Ep‐D1c and Lr19 was determined in a reciprocal cross between the lines FAP75184 (Ep‐D1c, Lr19) and FAP75106 (Ep‐D1a, leaf‐rust susceptible in the seedling stage). Out of 840 F2 seedlings screened, 162 were homozygous for Ep‐D1c. From 150 of these F2 plants, F3 seedlings were screened for segregation for leaf‐rust resistance with isolates avirulent on Lr19. Only one F2 plant produced susceptible F3 progeny indicating a recombination event between Ep‐D1c and Lr19. From these data, a genetic distance of 0.33 ± 0.33cM between Ep‐D1c and Lr19 was calculated. The results show that Ep‐D1c is a useful marker for a practical breeding programme allowing the rapid identification of plants homozygous for Lrl9.
Comparison of doubled haploid lines and F2 bulks for the improvement of barley in the dry areas of North Syria
Authors: Mayer M. , Gland A. , Ceccarelli S. , Geiger H. H.
Published: April 2006

Drought stress is the main factor limiting barley yields in West Asia and North Africa. This study compares the utility of doubled haploid lines (DHLs) and conventional F2 plant‐derived bulks (F2Bs) in improving barley in stress environments. Double crosses were made, DHLs were developed by anther culture from double‐cross F1 plants, and F2Bs were produced by bulking the offspring of F2 plants. Field tests were conducted in three drought‐stressed environments. No major differences were observed in the mean performance of DHLs and F2Bs. For most traits, both the genotypic and the genotype × location interaction variances were higher in the DHL group, whereas heritabilities were similar. Higher gains from selection were predicted for the DHL group. Regression analysis of yield stability indicated a lower predictability of the DHL performance. The haploid technique can improve breeding populations from which varieties with stable yields can be developed. The costs involved are determined by the DHL production rate, which needs to be improved in many developing countries.
Effects of plot type on detection of quantitative‐trait‐locus effects in barley (Hordeum vulgare L.)
Authors: Iyamabo O. E. , Hayes P. M.
Published: April 2006

Hill plots offer advantages in testing large germplasm arrays with limited area and seed. However, the relationship of trait expression between hill vs. row plots remains in question. The development of quantitative‐trait‐locus (QTL) analysis offers alternative methods of testing hypotheses regarding levels of coincident gene effects in divergent plots. The objective of this study was to compare hill and row plots in terms of QTL detection, number of common QTLs and plot‐type‐specific QTLs for various characters in barley. Assessments were based on sets of 100 F1‐derived doubled haploid progeny from two environments of hill‐plot data and two sets of multiple‐environment row‐plot data. Common large‐effect QTLs for height, heading date, and 1000‐kernel weight were detected in both plot types. Fewer QTLs were detected in the hill‐plot data, with only one QTL detected for grain yield. There were no hill‐plot‐specific QTL effects. Hill plots appear to be best suited to highly heritable characters such as height, heading date, and 1000‐kernel weight. Evaluation of grain yield is best deferred until larger experimental units can be employed.
Studies of the intraspecific competition and performance of chance‐hybrids in Lotium multiflorum Lam.1
Authors: Stelling U.
Published: April 2006

In order to study the effects of competition on the genotypic composition of chance‐hybrids in Loliuni multiflorum, eight chance‐hybrids were produced according to Burton (1948). Inbred lines and cultivars were used as parents. The proportions of parental and hybrid components in the seeds and growing‐field stands of the chance‐hybrids were determined over three cuts using gel electrophoresis. The realized hybrid proportions in the seeds, at a maximum of 38.3%, were considerably lower than the theoretically expected 50%. In the field stands, the hybrid proportions of the chance‐hybrids derived from inbred lines increased considerably and continously over cuts, whereas those of the chance‐hybrids produced from cultivars increased only slightly. A maximum hybrid tiller proportion of 76.8% was found at the third cut. Correspondingly, the total yield of the chance‐hybrids produced from cultivars was only slightly higher than that of the parents. The production of chance‐hybrids, therefore, proved to be sensible only if inbred lines had been used as parents.
Tapetal behaviour, gene action and breeding value in male‐sterile peas
Authors: Nirmala C. , Kaul M. L. H.
Published: April 2006

Eight non‐allelic male‐sterile mutants controlled by a single recessive gene were induced in garden pea (Pisum sativum) after EMS, DES and gamma‐ray‐mutagen treatments singly and in combination. These mutants differ in the time and type of tapetal development due to differential action of male‐sterile (ms) genes over the sporogenous and non‐sporogenous anther tissue. In the msg1 mutant, the sporogenous tissue breaks down during premeiosis, followed by tapetal degeneration. In msg2, sporogenous tissue and tapetal tissue exhibit anomalies at early and late prophase 1, respectively. Although in msg3 and msg5 the ms gene action over sporogenous tissue initiates during early and late prophase, respectively, the tapetal tissue breaks down during post‐meiosis. In msg6, anomalies in the sporogenous tissue appear during prophase II, but the tapetum degenerates during the mononucleate stage. Although both the tapetal and sporogenous tissue anomalies appear simultaneously at pachytene in msg4, the tapetal breakdown is delayed until the microspore stage. In msg7 and msg8, anomalies in both these tissues occur simultaneously during the tetrad and post‐meiotic stages, respectively. Despite differences in the timing of tapetal and sporogenous tissue breakdown, tapetal development is normal in msg1, msg5, msg6, msg7 and nisg8 but abnormal in msg2, msg3 and msg4. The ms gene action is dual in msg2, msg3 and msg4 but single in msg1, msg5, msg6, msg7 and msg8. In all these mutants, the time of tapetal anomaly exhibits no correlation with the time of ms gene action. The gene for open flower found in one male‐sterile mutant needs to be introduced into fertile peas for commercial hybrid‐pea breeding.
Chromosomal location of genes affecting tissue‐culture response in wheat
Authors: Amer I. M. Ben , Worland A. J. , Börner A.
Published: April 2006

Six ‘Chinese Spring/Triticum spelta’ substitution lines for chromosomes 1A, 1D (duplicates), 3D (duplicates), 6D, and one ‘Chinese Spring/ Marquis’ substitution line for chromosome 2B were studied for tissue‐culture response (TCR). The results reported here indicate that chromosomes 2B and 6D are critical for TCR, whereas chromosome ID affects callus weight only. Chromosomes 1A and 3D were not found to be critical, however, these chromosomes may carry genes with minor effects.
Identification and cytological analysis of 2n‐pollen producers in Lotus tennis Wald. et Kit.
Authors: Negri V. , Lorenzetti S. , Lemmi G.
Published: April 2006

Two meiotic mutants of L. tennis (2n = 2x = 12) producing unreduced pollen are described. When crossed to male sterile L. corniculatus (2n = 4x = 24) plants, all progeny plants were morphologically similar to L. corniculatus, had 2n = 24 chromosomes, and in the cross, were fully compatible with L. corniculatus, indicating that the male parent plants were 2n‐pollen producers. One of them also had ‘giant’ pollen grains. In metaphase II of both genotypes, there were parallel and tripolar spindles leading to dyad and triad formation, the latter being found most frequently. Since both the above‐mentioned mechanisms result in first‐division restitution‐type microspores, the genotypes examined could be useful in breeding Lotus.
Field evaluation of transgenic Brassica napus lines carrying a seed‐specific chimeric 2S albumin gene
Authors: Denis M. , van Vliet A. , Leyns F. , Krebbers E. , Renard M.
Published: April 2006

The agronomic performance of transgenic Brassica napus lines carrying chimeric 2S albumin seed protein genes was studied under field conditions. A total of 37 transgenic lines were compared to non‐transformed lines. Plant development, morphological characteristics, yield parameters and seed composition were considered. Only a few transgenic lines differed from the control, and then only for particular parameters: four lines had altered leaf morphology, two differed in germination efficiency, one differed in yield, and three differed in some parameters of seed composition. These differences were not correlated with the presence or expression of the transgene and, thus, were more probably linked to cell‐ or tissue‐culture effects, or to residual variation present in cv. ‘Drakkar’. A statistical interaction between variations in a limited number of seed composition parameters and cell haploid culture was observed.

While the expression of the chimeric 2S albumin gene was not as high as hoped, this study demonstrates that transgenic lines can be isolated in which the intrinsic morphological and agronomic properties of the original lines are maintained.
Effect of powdery mildew (Erysiphe graminis f.sp. hordei) on photosynthesis and grain yield of partially resistant genotypes of spring barley (Hordeum vulgare L.)
Authors: Balkema‐Boomstra A. G. , Mastebroek H. D.
Published: April 2006

The effect of powdery mildew on the photosynthesis and grain yield of partially resistant spring barley was investigated. The effect of powdery mildew on the CO2 exchange rate (CER) of inoculated and non‐inoculated leaves was measured in several glasshouse experiments. Grain yield reduction by powdery mildew was determined in three field experiments. The CER of the inoculated leaves was reduced by infection but that of the non‐inoculated leaves was not significantly different from that of the corresponding leaves of the control plants. The reduction in CER of the different genotypes was closely related to the percentage leaf area infected with powdery mildew.

The correlation between degree of mildew infection and grain yield reduction varied between r = 0.84 (significant at P = 0.01) and r = 0.41 (not significant). Differences in greenness of the crop were correlated better with grain yield reduction (r = 0.66, P = 0.01) than powdery‐mildew infection itself. Low percentages of powdery‐mildew infection did not lead to significant reduction in grain yield. Partial resistance to powdery mildew could thus be a valuable attribute of future barley varieties.
Effects of selection and opportunities for recombination in doubled‐haploid populations of barley (Hordeum vulgareL.)
Authors: Iyamabo O. E. , Hayes P. M.
Published: April 2006

Doubled‐haploid breeding systems are typically based on sampling gametes from F1plants. However, in the case of repulsion linkages, additional recombination could be advantageous. Pre‐selection of gamete donors might also shift progeny performance in a desired direction. The objectives of this study were to quantify the effects of an additional round of recombination and assess the effectiveness of pre‐anthesis selection in the production of barley doubled haploids. Assessments were conducted on: 1. 100 F1‐derived lines representing a subset of lines used in previous genome‐mapping studies; 2. 100 random F2‐derived lines; and 3. 50 F2‐derived lines from gamete donors selected for early heading. An additional round of recombination had only a modest effect on generating more favourable genotypes. Pre‐anthesis selection was ineffective in generating an earlier heading population. According to published quantitative‐trait locus (QTL) analyses based on the F1‐derived population, there are few repulsion linkages between QTL determining the traits measured in this experiment. Any advantages to be gained from postponing the generation of derivation of doubled haploids must be weighed against the delay and additional cost.