bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining Ability for Resistance to Field Aflatoxin Accumulation in Maize Grain*
Authors: Gorman D. P. , Kang M. S. , Cleveland T. , Hutchinson R. L.
Published: April 2006

Previous genetic studies on resistance to aflatoxin production in maize (Zea mays L.) only used a limited amount of germplasm. The objective of this study was to determine general (GCA) and specific combining abilities (SCA) for resistance to prehar‐vest aflatoxin accumulation in grain, utilizing A619 Lfy syn, A632 Lfy syn, B73 Lfy syn, Hy Lfy syn, Mol7 Lfy syn, Wf9 Lfy syn, and 914 Lfy syn. We evaluated 21 F1 crosses (diallel) for aflatoxin accumulation in grain in three environments. Twenty‐one days after mid‐silk, ears were slash‐inoculated with Aspergillus parasiticus (Speare). Samples were analyzed for aflatoxins Bl B2, G1 and G2. Significant differences for aflatoxin accumulation were detected among environments, with the environment that experienced drought stress showing the highest concentration for all four aflatoxins. The GCA and crosses mean squares were not significant for any aflatoxin and the SCA mean square was significant (P = 0.1) only for aflatoxin G2. Relatively small quantities of aflatoxin accumulation on, and nonsignificant differences among the 21 F1 crosses might be indicative of their inherently high resistance levels. The SCA sums of squares constituted two thirds or more of crosses sums of squares, which indicated a preponderance of dominance and/or epistatic effects for aflatoxin accumulation. The Hy Lfy syn GCA effect tended to increase aflatoxin Bl and Wf9 Lfy syn tended to reduce aflatoxin accumulation as it showed a significant (P = 0.1), negative GCA effect for aflatoxin G1. The F1 cross Wf9 Lfy syn × 914 Lfysyn showed significant, negative SCA effect for af‐latoxins B1 and G1, whereas A619 Lfy syn × 914 Lfy syn and Mo17 Lfy syn × Wf9 Lfy syn tended to increase one or more aflatoxins. For aflatoxin Br, a significant environments (E) × crosses (C) interaction was largely due to E × GCA interaction, which, in turn, was due to an interaction of the B73 Lfy syn GCA effect with E. This interaction effect tended to reduce aflatoxin BS. The E × C interaction for aflatoxin G2 was due to both E × GCA and E × SCA interactions. B73 Lfy syn GCA × E tended to reduce aflatoxin G, and Mo17 Lfy syn GCA × E tended to increase aflatoxin G. Additive genetic correlations based on GCA effects among the four aflatoxins were significant (0.76 to 0.96), except the correlation between aflatoxins B, and G2 (0.43), suggesting that, in general, increasing resistance to one toxin may lead to resistance to the other three toxins.
Reproductive Deterioration in Buckwheat (Fagopyrum esculentum) under Summer Conditions
Authors: Guan L. M. , Adachi T.
Published: April 2006

To resolve the problem of low and unstable yield in buckwheat under unsuitable environmental conditions, five varieties were grown and compared in summer and autumn. Vegetative and reproductive growth characteristics were investigated, and embryo development was observed with Nomarski's differential interference contrast (DIG) microscopy. In summer, under high temperatures and longer day‐length, autumn‐type varieties showed faster vegetative growth and later reproductive development as compared to summer‐types. In the autumn, with generally good climatic condition for buckwheat growth in southern part of Japan, the embryo sacs and zygotes of both types developed normally. At 3 days after pollination (DAP), the embryos reached the globular stage. In summer, however, mostly abnormal embryo sacs were observed 3 DAP, leading to incomplete development, failure of fertilization or abortion of embryo. The abnormal embryo sacs were classified into 6 types. Abnormality of either type occurred in 91—100 % of the tetraploids, which is higher than in the diploids (50—77 %). The present study, conducted to clarify the factors causing low seed set in buckwheat under summer conditions, provides detailed information for further breeding of environment‐tolerant buckwheat. Di‐ploid genotypes which are less sensitive to unfavourable conditions and, thus, show more efficient fertilization in summer, should be considered for use as breeding material in buckwheat.
The Concept of Varietal Ability for Partially Allogamous Crops
Authors: Link W. , Ederer W.
Published: April 2006

General (GVA) and specific (SVA) varietal ability quantify the value of genetic stocks as components for synthetic varieties. Additionally, these parameters can be used to predict the performance of the synthetics. The concept of varietal ability is known for completely allogamous crops. It has not yet been worked out for partial allogamy with a genotype‐dependent degree of cross‐fertilization. We have developed formulae to calculate GVA and SVA referring to generation Syn 1 in this general situation. The concept of varietal ability considers the influence of the components' per se performance on the resulting synthetic variety. This influence increases with decreasing degree of cross‐fertilization. Thus, our formulae should be of special benefit to partially allogamous crops.

The formulae are illustrated by a numerical example taken from our research on Vicia faba L. To estimate the relevant parameters for Vicia fabe L., we propose to use two morphological markers (flowers and seed colour) simultaneously.
Influence of Different Cytoplasms and Nuclear Genes Involved in the cms System of Chives (Allium schoenoprasum L.) on Microsporogenesis
Authors: Ruge Brigitte , Potz Heidi , Tatlioglu T.
Published: April 2006

Microsporogenesis of different, temperature‐ and tetracycline‐sensitive cms plants, and male fertile genotypes was investigated.

The microsporogenesis of cms plants [(S)xx] and fertile plants [(N)xx or (S)X.] is similar up to the tetrade stage. During the tetrade stage, microspores of cms plants start to die off. The effect of the (S)‐cytoplasm on microsporogenesis is overcome by the restorer gene X, the temperature gene T and by tetracycline gene a. Whereas the X gene acts independently of environmental conditions, the gene T is expressed at constantly high temperature of 24 °C, and the tetracycline gene a acts after tetracycline treatment. After temperature‐ and tetracycline treatment, respectively, the sensitive genotypes need 10—14 days to change from male sterile into male fertile. This period seems to be most interesting to study the influence of the defined nuclear genes on mitochondrial transcription and translation.
Graphical Genotype of Maize Inbred B86 Revealed by RFLPs
Authors: Fahr S. , Messmer M. M. , Melchinger A. E. , Lee M. , Woodman W. L.
Published: April 2006

The objective of this study was to investigate the origin of chromosome segments of maize (Zea mays L.) inbred B86 from its parental inbreds B52 and Oh43 using RFLPS. B86 was selected to combine resistance to the first and second brood of the European corn borer with the favorable agronomic performance of Oh43. RFLP analyses of the three inbreds were performed with three restriction enzymes (EcoRI, EcoRV, HindIII) and 178 DNA probes covering all ten maize chromosomes. For two DNA probes in combination with one enzyme, B86 showed a new RFLP pattern not present in the two parents. Based on results from 119 polymorphic DNA probes, the proportion of the B86 genome contributed by B52 (51.3 %) and Oh43 (48.7 %) was almost equal.
Anther Culture‐Derived Regenerants from Hordeum vulgare × H. bulbosum Crosses
Authors: Pickering R. A. , Fautrier A. G.
Published: April 2006

Hordeum bulbosum has several desirable attributes, including disease resistance, which would be worthwhile transferring to H. vulgare. Despite homoeologous chromosome pairing in the interspecific hybrids, there have been few reports of successful gene introgression between the two species. A possible explanation for this is that recombinant male gametes are at a competitive disadvantage with normal balanced gametes during post‐pollination events. To circumvent this problem, the possibility of obtaining plants directly from immature pollen grains was investigated. Anthers from diploid, triploid and tetraploid H. vulgare × H. bulbosum hybrids were cultured on defined media. Only hybrids with dehiscent anthers in vivo responded in culture, and after transfer of calli and embryoids to regeneration medium, 36 albino and 12 green plants were obtained. Seven of the green regenerants survived, one of which contained 15 H. vulgare chromosomes (including one acrocentric chromosome) and one H. bulbosum chromosome. Another regenerant (Ac166) resembled a diploid H. vulgare × H. bulbosum hybrid but had partial anther dehiscence and a slightly modified chromosome constitution. Mostly normal H. vulgare progeny were obtained from crosses between H. vulgare cv.‘Emir’ and Ac166, but three plants involved chromosome additions and substitutions.
The Lack of a Relationship between Bitterness and Resistance of Cucurbits to Red Pumpkin Beetle (Aulacophora foveicollis)
Authors: Dhillon N. P. S.
Published: April 2006

Purified cucurbitacin B and E act as feeding stimulants for the red pumpkin beetle, but on testing three pairs of isogenic bitter (Bi) and non‐bitter (bi) lines of cucumber, no relationship was found to exist between the bitter gene and the degree of damage caused by this beetle. In summer squash, both resistant and susceptible lines contain cucurbitacin at the susceptible plant growth stage (cotyledon) but there was no correlation between the quantity of total phenols, free amino acids or reducing sugars in this material and resistance. Bitter gourd, which has cucurbitacin in the cotyledons, was not preferred by the beetle.
Fertility Improvement in Autotetraploids of Pea — Selection for Seed‐Set and Disjunction Index
Authors: Kumar H. , Mercykutty V. C. , Srivastava C. P.
Published: April 2006

Four seed‐set groups of plants, viz. unselected ‘general’ and selected ‘high’, ‘medium’ and ‘low’ were constituted in C1 generation from randomly selected autotetraploids of two pea cultivars, T 163 and 5064‐S. In C2 generation, ten plants were selected at random in each of the four groups. Two seeds each from selected autotetraploids were drawn and bulked to make 20 seeds in each of the four groups to raise C3 generation. Selection resulted in a gradual shift in seed‐set, though the magnitude and nature varied with the group and generation. Improvement in the seed‐set from C1 to C3 generation was associated with the increase in bivalents per cell, disjunction index and total chiasmata. Increase in total chiasmata was mostly due to an increase in proximal ones. Increase in seed‐set was reflected in improvement of grain yield per plant.
Chromosomal Location of Resistance to Septoria nodorum in a Synthetic Hexaploid Wheat Determined by the Study of Chromosomal Substitution Lines in ‘Chinese Spring’ Wheat
Authors: Nicholson P. , Rezanoor H. N. , Worland A. J.
Published: April 2006

Resistance to Septoria nodorum was investigated in seedlings of an amphiploid generated from Triticum dicoccum Shübl. and Aegilops squarrosa Tausch, and in a series of substitution lines of single chromosomes from this synthetic hexaploid into Triticum aestivum cv. ‘Chinese Spring’ in three tests to determine the chromosomal location of resistance. From the Ae. squarrosa parent (D genome), chromosome 5D was found to confer a high level of resistance, reducing lesion cover to near that of the amphiploid in the three tests. Chromosomes 3D, and to a lesser extent, 7D were also found to confer significant resistance to the amphiploid. Three chromosomes, 2A, 3B and 5A, from the T. dicoccum parent (AB genomes) also conferred resistance but to a lesser extent than 7D. Two chromosomes, 2B and 2D, caused a significant decrease in resistance. ‘Chinese Spring’ may thus carry genes for resistance to S. nodorum on these chromosomes which are absent in the synthetic hexaploid.
A Rapid Screening Method for Testing the Resistance of Cotyledons to Downy Mildew in Brassica napus and B. campestris
Authors: Gröuntoft M.
Published: April 2006

Several hundred breeding lines of summer and winter forms of turnip rape as well as winter rape, were sown on greenhouse tables filled with soil. A week later the cotyledons were artificially inoculated and covered with a plastic tunnel. Approximately two weeks later the average percentage of the wilted leaf area was estimated.

The method is rapid and demands little labour. It is therefore suitable for testing large numbers of breeding lines. The response to Peronospora parasitica (Pers. ex Pers.) Fr. in the rape material varied from being highly susceptible to highly resistant. Only minor differences were detected between lines with high and low glucosinolate contents. All the turnip rape material had very high resistance to P. parasitica at the cotyledonous stage.
Effects of Interspecific Competition on the Inheritance of Quantitative Traits in White Clover *)
Authors: Hill J.
Published: April 2006

Analysis of a half diallel cross among four white clover cultivars, grown as monocultures and in mixtures (duocultures) with two separate perennial rye‐grass cultivars, confirmed that for stolon and leaf number a higher proportion of the genetic variance in duocultures was non‐additive. For canopy height and dry weight, however, this proportion was less affected by inter‐specific competition. An additive‐dominance model of gene action sufficed for all four characters in monocultures, but in duocultures epis‐tasis was just one of the factors complicating the genetic picture. This, coupled with short‐term reversals in the direction of dominance, merely illustrates the complexity of breeding white clover cultivars. Possible future developments in the breeding of white clover are discussed in the light of these results.
Inbreeding Depression and Other Genetic Effects in Populations of Maize Containing Highland Tropical Germplasm
Authors: Eagles H. A. , Hardacre A. K.
Published: April 2006

A variety cross diallel of five populations of maize (Zea mays L.) was evaluated in a cool, temperate environment. Two of the parental populations were Corn Belt Dent synthetics (AS3 and BS22), one was developed from selected lines from a CIMMYT population developed for highland regions of the tropics and four Corn Belt Dent inbred lines (NZS3), and the other two had the pedigrees ‘Criollo de Toluca’× AS32 (NZS1) and ‘San Gerónimo’× BS222 (NZS2). ‘Criollo de Toluca’ is from the highlands of Mexico and ‘San Gerönimo’ is from the highlands of Peru. The objective was to study the influence of introgressing highland tropical germplasm into elite Corn Belt Dent synthetics on genetic effects, especially inbreeding depression, and to develop recommendations for the utilization of the introgressed populations.

Inbreeding depression explained the greatest proportion of the variation among entries for grain yield, days to silking and plant height, but not for grain moisture at harvest and root lodging. For grain yield, NZS1, NZS2, and NZS3 had high levels of inbreeding depression and the difference between NZS1 and AS3 was statistically significant. High levels of root lodging were associated with NZS1 and high grain moisture at harvest with NZS2. These results indicate that a recurrent selection method, such as S1 selection, which effectively reduces inbreeding depression, should be used in early cycles of selection with introgressed populations containing highland tropical germplasm.
Effect of Abscisic Acid on Pollen Germination and Tube Growth of Maize Genotypes1
Authors: Frascaroli E. , Tuberosa R.
Published: April 2006

As a preliminary step to using gametophytic selection to obtain genotypes of maize, Zea mays L., differing for abscisic acid (ABA) content and/or sensitivity, the influence of ABA on the in vitro germination and tube growth of maize pollen and the presence of genetic variability for these traits was investigated. In a first experiment, pollen samples of three genotypes were germinated on substrates containing increasing amounts of ABA. Low ABA concentration (0.5 νM) significantly increased pollen germination and tube growth, while 500 νM ABA significantly decreased both traits, thus indicating that ABA can influence the growth of maize pollen in vitro. In a second experiment, eleven inbred lines were screened for the in vitro reactivity of their microgametophytes to ABA. The lines differed significantly for the response (% of control) of tube length, but not of pollen germination to ABA.
Segregation Analysis of Isozyme Markers on Isolated Microspore‐Derived Embryos in Brassica napus L.
Authors: Foisset N. , Delourme R. , Lugas M. O. , Renard M.
Published: April 2006

The segregation of isozyme genetic markers was studied on embryos arising from isolated microspore cultures in live rapeseed F1 hybrid genotypes. Out of the ten isozyme genes considered, live (Aco‐1, Aco‐3, Lp‐1, Pgm‐3, Tpi‐1) did not segregate according to expected Mendelian ratios in at least two F1 crosses. F2 plants, generated from the same hybrids, included in the analysis, were tree of segregation distortions. Linkage analysis between each segregating enzyme locus in each progeny revealed independance between these markers.

In this paper, the results of the linkage analysis as well as the origins of the distortions are discussed. The existence of androgenic embryogenesis genes may be responsible for the abnormal segregations of the five isozyme genes.
Self‐Fertile Doubled Haploid Plants of Perennial Ryegrass (Lolium perenne L.)
Authors: Madsen S. , Olesen A. , Andersen S. B.
Published: April 2006

The self‐fertility of chromosome‐doubled haploid lines of perennial ryegrass and their first (I1) and second (I2) generation selfed offspring was studied. The overall seed set was low, 0—0.4 seeds per spike, as would be expected for chromosome‐doubled haploids of a self‐incompatible species. Nevertheless, significant genetic variation was observed for self‐fertility within three of the six lines studied. Within one line, three I2‐clones showed increased self‐fertility, while in two other lines one and three I1‐clones, respectively, showed significantly increased self‐fertility. Selection, during selfing, of rare pollen grains with mutations in the self‐incompatibility system could explain the observed changes and would lead to a general breakdown of self‐incompatibility in Lolium perenne during repeated selfing of chromosome‐doubled haploids.
Mutagenic Effects of Combined and Single Doses of Gamma Rays and EMS in Opium Poppy*
Authors: Chauhan S. P. , Patra N. K.
Published: April 2006

Mutagenic effects of gamma rays and EMS using both single and combined dosages were examined in opium poppy (Papaver somniferum L.). For inducing both macro‐ and micro‐mutations in the present study, combined mutagenic doses, especially 5 kR + 0.4 % EMS appeared to be greatly superior to all single doses of the two mutagens: gamma rays and EMS. The lowest dose of combined mutagen (5 kR + 0.2 % EMS) was about twenty times more effective than the most effective dose (15 kR) of gamma rays and twice as effective as the most effective concentration (0.4 %) of EMS. The combined dose 5 kR + 0.4 % EMS enhanced morphine content (%) to 0.98 as against 0.64 in the control. In accordance with earlier findings (GAUL 1964) the study revealed a correlation between induced macro‐ and micro‐mutations.
Genetic Variability of Rubisco in Tetraploid Wheats (Triticum turgidum)
Authors: Nicco C. , Sarrafi A. , Piquemal M. , Cavalie G.
Published: April 2006

Nineteen tetraploid wheats (Triticum turgidum), differing in their agronomical behaviour and geographic origins were grown in two experiments and analysed for the following physiological traits: soluble leaf protein content, rubisco content, initial and potential carboxylase activities of this enzyme as well as its relative content in percentage of protein, the specific activity of the enzyme and its activation state.

The results show a high genetic variability for all studied traits and more particularly for the initial carboxylase activity. High phenotypic correlation was observed between the rubisco content and its potential activities, in the first experiment. Correlation between souble leaf protein and rubisco content was significant in 9 genotypes of the second experiment.
Protein Phosphorylation and Protein Patterns in Developing Endosperms of Barley
Authors: Yupsanis T. , Shewry P. R.
Published: April 2006

The SDS‐soluble protein‐fractions of barley endosperms (2 and 3 weeks after anthesis) were compared using 1‐D SDS‐PAGE and 2‐D IEF/SDS‐PAGE. Similar procedures have been followed after in vivo phosphorylation of isolated endosperm with 32PO4.Protein patterns were similar when 1‐D SDS‐PAGE was used. On the other hand, 2‐D IEF/SDS‐PAGE revealed several major differences, the most important being the appearance of a major protein of Mr about 40,000 in the 3‐weeks old endosperm. By contrast, the patterns of phosphorylated proteins, with both methods, were relatively simple. Only two phosphorylated bands showed up in the 3‐weeks old endosperm: a highly labelled band of Mr about 65,000, and a band of about 75,000. In the case of 2‐weeks old endosperm, where the phosphorylation was more active, these and several others were also labelled, but the Mr 75,000 band was labelled more intensely.
Milling Energy Polymorphism in Hordeum spontaneum Koch in Israel and its Potential Utilization in Breeding for Malting Quality
Authors: Ellis R. P. , Nevo E. , Beiles A.
Published: April 2006

Variation for grain milling energy in Hordeum vulgare is associated with differences in grain size, shape and composition. Genetic polymorphisms within and between populations were found across the ecogeographical range of Hordeum spontaneum in Israel. Low milling energy estimates were positively correlated with and predictable by the aridity index. Milling energy in H. spontaneum, collected in Israel, ranged from the lowest values seen in making barley to twice the highest values seen in feed cultivars. It is concluded that H. spontaneum elite genotypes could be effectively identified by milling energy for use in the breeding of new cultivars.
Genetics of Panicle Exsertion in Cold‐Tolerant Rice (Oryza sativa)
Authors: Pandey D. K. , Gupta H. S.
Published: April 2006

Four cold‐tolerant rice varieties, viz. ‘Khonorullo’, ‘Namyi’, ‘Abor B’ and ‘Meghalaya‐1’ were crossed with two cold‐susceptible ones, viz. ‘Pusa 33’ and ‘Subhadra’ (DR92), in all possible combinations to study the inheritance of gene(s) governing panicle exsertion and their allelic relationship among cold‐tolerant varieties. F1 hybrids of all the crosses showed complete panicle exsertion indicating dominance of this trait. Segregation pattern of panicle exsertion in F2 and backcrosses show that all the four cold‐tolerant varieties possessed a single dominant gene designated as Ctr‐1. Absence of segregation for panicle exsertion in an F2 generation obtained from intercrosses of cold‐tolerant varieties suggests that the dominant genes in all the four cultivars are allelic.
Localization of Genes in Rye that Restore Male Fertility to Hexaploid Wheat with timopheevi Cytoplasm
Authors: Curtis C. A. , Lukaszewski A. J.
Published: April 2006

Four sets of wheat‐rye addition lines were screened to localize genes in rye that restore male fertility to hexaploid wheat with timopheevi cytoplasm. One gene, designated Rfc3, was physically located in the distal 40 % of the long arm of chromosome 6R. No allelic variation at Rfc3 was found; normal male fertility was consistently observed in all F1 hybrid combinations tested. A second gene, designated Rfc4, was located on the long arm of chromosome 4R. Variation between chromosomes 4R in the level of restoration was observed; fertility in hybrids ranged from 0 % to about 50 % of normal. Attempts to genetically map Rfc4 were inconclusive but suggested it was located 16.1 cM from the telomere of the long arm and at least 8.0 cM from the centromere. These restorers, particularly Rfc3, may have potential in hybrid wheat breeding programs and can be manipulated for production of male sterile triticale lines.
Resistance to the Barley Yellow Mosaic Virus Complex — Differential Genotypic Reactions and Genetics of BaMMV‐Resistance of Barley (Hordeum vulgare L.)
Authors: Götz R. , Friedt W.
Published: April 2006

Barley yellow mosaic disease is caused by several viruses, i.e. barley yellow mosaic virus (BaYMV), barley mild mosaic virus (BaMMV) and BaYMV‐2. The reaction of different barley germplasms to the barley mosaic viruses was studied in field and greenhouse experiments. The results show a complex situation; some varieties are resistant to all the viruses, while others are resistant to one or two of them only.

Crosses between different barley germplasms were earned out in order to test whether genetic diversity of resistance against mosaic viruses does exist, particularly, BaMMV. A total of 45 foreign barley varieties were crossed to German cultivars carrying the resistance gene ym4. In F2 of 27 crosses, no segregation could be detected, leading to the conclusion that the resistance genes of the foreign parents are allelic with ym4 e.g. Ym1 (‘Mokusekko 3’) and Ym2 (‘Mihori Hadaka 3’). A total of 18 crosses segregated in F2 indicating that foreign parents, like ‘Chikurin Ibaraki 1’, ‘Iwate Omugi 1’, and “Anson Barley”, carry resistance genes different from the gene of German cultivars, e.g. ‘Asorbia’ or ‘Franka’. By means of statistical evaluation (Chi2‐test), the observed segregation ratios were analyzed in order to obtain significant information on the heredity of resistance. All the resistance genes described here as being different from the gene ym4, act recessively. Most of the exotic varieties seem to carry only one resistance gene. In a few cases, more than one gene may be present.
Characterization of a Spontaneous Rapeseed Mutant Tolerant to Sulfonylurea and Imidazolinone Herbicides
Authors: Issaka Magha M. , Guerche P. , Bregeon M. , Renard M.
Published: April 2006

A spontaneous chlorsulfuron tolerant variant, RCS‐5, was isolated from protoplast culture of rapeseed, Brassica napus L. The tolerance level of the mutant was due to mutation of a single dominant gene resulting in an alteration of the acetolactate synthase enzyme. Seedling growth bioassays applied in vitro or after seed‐soaking treatment showed that the mutant was 250——500 more tolerant to chlorsulfuron than the sensitive control. Field tolerance was evaluated with commercial formulations of chlorsulfuron (Glean T), triasulfuron (Kéos), and metsulfuron methyl (Allié), and an imidazolinone imazamethabenz (Méganet). The results indicated that the mutant could tolerate a lower dose rate of sulfonylureas than the dose recommended for cereal culture. In contrast, the mutation provided a good protection against imazamethabenz. The possibility of using the protoplast‐derived mutation in crop rotation and F1 hybrid seed purity assessment is also discussed. However, isolated lines of the mutant were found to be less productive and one week later than the sensitive parent.
Production of Gynogenetic Plants of Onion (Allium cepa L.) after Crossing with Irradiated Pollen
Authors: Dore C. , Marie F.
Published: April 2006

The possibility of producing gynogenetic plants with pollen inactivated by irradiation was explored for the onion (Allium cepa L.). Two successive experiments included the use of cytoplasmic male sterility, recessive nuclear markers in the female plants and pollen irradiation of 150 Gy. Pollinations were achieved with the aid of flies and all seeds were harvested without the use of embryo rescue. Plantlets with recessive characters could be detected and they contained haploid and diploid cells. The development of these plantlets until flowering was observed under agronomic conditions. The use of doubled haploid (DH) plants in onion breeding is discussed.
Temperature‐Related Changes in Chlorophyll Fluorescence and Contents of Chlorophyll and Carotenoids in Andean and European Potato Clones
Authors: Kristjansdottir I. S. , Merker A.
Published: April 2006

Low‐temperature adapted Andean potato clones and low‐temperature sensitive European clones cultivated at 20/10°C were compared during stress occuring as the result of low‐temperature treatments.

The stress response of leaf tissue was assessed by measuring the decrease in chlorophyll fluorescence (Fv/Fm) in detached leaves during a period of six days. After temperature stress combined with light Fv/Fm decreased only slightly in the Andean clones, but was markedly lower than the initial values in the European clones, However, after a 2°C treatment in darkness no difference between clones of different origins was detected.

In general, chlorophyll and carotenoid contents of the Andean clones were higher than those of the European clones. They were markedly lower in all clones in treatments where low temperature was combined with light, than at 20/10°C and at 2°C in the dark. The contents of carotenoids and total chlorophylls decreased more in the European than in the Andean clones when leaves were transferred to a higher light intensity and then the lowest temperature used was combined with light. Thus carotenoids and chlorophylls in the Europeans clones were more sensitive to photo‐oxidation at low temperatures than in the Andean clones.

The changes in chlorophyll fluorescence in illuminated, detached leaves induced by a decrease in temperature were found to correlate with the low temperature performance of the genotypes. The correlation between low temperature performance and photosynthetic activity was highly significant and could be used by plant breeders to identify plants that perform well at low temperatures.
Mitochondrial DNA Restriction Fragment Length Polymorphisms in Malus Species
Authors: Kato S. , Ishikawa S. , Imakawa S. , Komori S. , Mikami T. , Shimamoto Y.
Published: April 2006

Three apple (Malus×domestica) cultivars and 11 Malus accessions have been investigated by the probe hybridization method on their mitochondrial DNA (mtDNA). The gene probes used were: coxI, coxII, atpA, atp6, and atp9. Our results revealed enough variation to characterize ten mtDNA haplotypes among the Malus genotypes examined. The taxonomic and phylogenetic implications of mtDNA polymorphism are also discussed.
Genealogical Identification of Hexaploid Tritordeum by Electrophoretic Separation of Endosperm Storage Proteins
Authors: Alvarez J. B. , Canalejo A. L. , Ballesteros J. , Rogers W. J. , Martin L. M.
Published: April 2006

Hexaploid Tritordeum (×Tritordeum Ascherson et Graebner) has been analyzed by SDS‐PAGE, to test the efficiency of the method for confirming the parents of different lines, and for unequivocally discriminating between the lines. The results clearly show that endosperm storage proteins from both parents (durum wheat ——Triticum turgidum conv. durum Desf. em. M.K. —— and Hordeum chilense Roem. et Schulz.) are expressed in the endosperm of the amphiploid between them. Although the spectra of proteins from the parental species overlap on the gel, there are sufficient number of bands with distinct electrophoretic mobilities to identify unambiguously their parental origin. Furthermore, in the six lines of tritordeum analyzed, obtained from crosses between three accessions of H. chilense and four cultivars or lines of wheat, there was sufficient polymorphism amongst the parents, particularly amongst the H. chilense accessions, to enable both aims of the project to be met, that is, to confirm the genealogy of each tritordeum, and to discriminate between different lines. This study provides the basis of future investigation on the relationship between bread‐making quality in tritordeum and the allelic composition of storage proteins.
New Isozyme Markers in Vicia faba: Inheritance and Linkage
Authors: Suso M. J. , Moreno M. T. , Cubero J. I.
Published: April 2006

Results on the inheritance of 6 enzyme systems: LDH, PGM, FDH, SKD, SOD, AAT from seeds of Vicia faba and the linkage relationships among these isozyme loci are presented. The allozymes at each one of these loci behaved in a codominant manner and segregated in the expected Mendelian ratio. Linkage tests between these loci showed that they segregate independently.
Studies on Resistance to Phoma lingam in Brassies napus‐Brassica nigra Addition Lines
Authors: Zhu J. S. , Struss D. , Röbbelen G.
Published: April 2006

B. nigra exhibits high levels of resistance to Phoma lingam. The genetic behaviour of this resistance was investigated using B. napus‐B. nigra addition lines. At least 3 different B. nigra chromosomes were found to contribute to the blackleg resistance. Thus, this resistance was suggested to be polygenic. In addition, high levels of P. lingam resistance in euploid offspring led to the assumption that translocations have taken place in early generations after hybridization between B. napus and B. nigra.
Pleiotropic Effects of Genes for Reduced Height (Rht) and Day‐Length Insensitivity (Ppd) on Yield and its Components for Wheat Grown in Middle Europe
Authors: Börner A. , Worland A. J. , Plaschke J. , Schumann Erika , Law C. N.
Published: April 2006

Under field conditions in Germany over three growing seasons the pleiotropic effects on yield and its components of four sets of near isogenic lines carrying the GA insensitive dwarfing alleles Rht1, Rht2, Rht3, Rht1+2, Rht2+3 or rht (tall) in four different genetical backgrounds were examined together with 24 single chromosome recombinant lines segregating for the GA sensitive dwarfing gene Rht8 and the gene for day‐length insensitivity Ppd1 in a ‘Cappelle‐Desprez’ background. For the GA insensitive semi‐dwarfs it was shown that in all three years a higher number of grains per ear was accompanied by a lower grain weight. Depending on the climatic conditions in a particular year, the increase in grain number was sufficient to compensate for the reduction in grain size and resulted in higher yields. For the Ppd1 allele yield advantages were found for wheats grown under environmental conditions of middle Europe.
A Monosomic Analysis of Russian Wheat Aphid Resistance in the Common Wheat PI 294994
Authors: Marais G. F. , Du Torr F.
Published: April 2006

Chromosome 7D of PI 294994 was indicated as carrying a single dominant gene for resistance to the Russian wheat aphid. The symbol Dn5 is proposed to designate the gene.
An Extended Linkage Map of Sugar Beet (Beta vulgaris L.) Including Nine Putative Lethal Genes and the Restorer Gene X
Authors: Pillen K. , Sleinrücken G. , Herrmann R. G. , Jung C.
Published: April 2006

An extended genetic map of sugar beet (Beta vulgaris L.) is presented encompassing 177 segregating markers (2 morphological traits, 7 isozymes, and 168 RFLP markers) on 9 linkage groups. The linkage map comprises 1057.3 cM equivalent to an average genetic spacing of 6.0 cM/marker. The length of individual linkage groups varies between 80.7 (group VIII) and 167.4 cM (group VIII). The number of markers per linkage group ranges between 13 and 24. No indication of duplicate regions was found, confirming the true diploid nature of B. vulgaris. Twenty‐six markers (15 %) deviated significantly (a = 0.01) from the expected segregation ratio. This distorted segregation was probably caused by linkage with lethal genes. Four such genes (designated Let Ib, Let 5b, Let 6b, Let 8) could be located at discrete positions due to their absolute linkage to skewed RFLP markers. The restorer gene X has been located terminally on linkage group ÜI, 9.6 cM distant from RFLP marker pKP1238.
An Isozyme Marker for Pollen Fertility Restoration in the Pampa cms System of Rye (Secale cereale L.)*
Authors: Wricke G. , Wilde P. , Wehling P. , Gieselmann Charis
Published: April 2006

Hybrid breeding in rye (Secale cereale L.) based on cytoplasmic male sterility requires a sufficient restoration of pollen fertility to guarantee full seed set in the hybrid variety. Therefore the selection of effective restorer lines is an important goal in the breeding process. An F2 generation tracing back to a cross of a nonrestorer line as seed parent and a restorer line, and subsequent three‐way crosses between the corresponding F1 plants and a nonrestorer line were used to find marker genes for pollen fertility restoration. A linkage between the Prx.7 isozyme locus on chromosome 1R and a putative major gene (or gene complex) for pollen fertility restoration with a recombination value of about 20 % was found. To our knowledge, this is the first case of a marker gene for this trait in rye.
A Test of the ‘Tall‐Dwarf” Hypothesis in Pearl Millet, Pennisetum glaucum (L.) R. Br.
Authors: Bidinger F. R. , Raju D. S.
Published: April 2006

Positive height‐grain yield relationships exist for many cereals, but cannot be fully used in breeding because of lodging and harvestability problems in tall cultivars. Law et al. (1978) proposed a “tall‐dwarf” hypothesis for wheat, in which the positive effects of minor height genes could be exploited by selecting for them in a major dwarfing gene background. The applicability of this hypothesis to pearl millet was tested by crossing a set of dwarf S1 progenies (from a single population) which varied in height onto two male‐sterile lines. Mean (by S1 pollinator) hybrid grain yield was closely related to mean hybrid height (r2= 0.60) over a range of mean yields of 3.0–3.9 t ha−1 and a range of mean heights of 126–165 cm. The effect of height was expressed as an increase in grain number in one cross and as an increase in grain mass in the other, indicating the importance of background genetic effects on yield‐height relationships in dwarf hybrids. The concept of “tall‐dwarfs” appears to be applicable to pearl millet.
Induction of Tetraploidy in the Tanier Cultivar ‘Inglesa’ [Xanthosoma saghtifolium (L.) Schott]
Authors: Esnard J. , Ferwarda F. , Rivera‐Amador E. , Hepperly P. R.
Published: April 2006

Induction of tetraploidy in commercial tanier was successfully achieved in vitro. Tissue cultures of a tanier [Xanthosoma sagittifolium (L.) Schott cv. ‘In‐glesa’, 2n 26] were established and maintained on modified nutrient media containing various concentrations of MURASHIGE and SKOOG basal salts, vitamins, sucrose, BA and IAA or 2,4‐D. Cultures were exposed continuously for 8 days to 0, 12.5, 25 and 50 mg/1 colchicine incorporated in the media. The colchicine‐treated tissue cultures yielded di‐ploids (2n 26), tetraploids (2n 52) and aneuploids (2n – 2 24) respectively. The diploids produced on average one leaf and 4 suckers more per plant than the tetraploids, while plant height increased at about the same rate. Continuous exposure of tanier tissue cultures tocolchicine is an effective method for the production of synthetic tetraploids that may be hybridized with non‐commercial root rot‐resistant tetraploids.
Estimation of the Response to Anther Culturing in 60 Genotypes of Different Wheat Species
Authors: Orlov P. A. , Mavrishcheva E. B. , Palilova A. N.
Published: April 2006

Sixty genotypes of different wheat species (30 cultivars of common wheat, 12 durum wheat and 18 wild wheat relatives) were estimated for response to anther culturing and capability of plant regeneration. The 4 level of responding anthers out of the total number of anthers cultured was proposed as the criterion for genotype fitness for breeding with the aid of anther culture. Among common wheat cultivars, 13 exceeded this level. Among durum wheat, none of the genotypes investigated exceeded the 4% level. Among other species, 5 cultivars of T. dicoccum as well as T. petropavlovsky and T. dicoccoides spont. exceeded the 4 value.
In vitro Selection for Tolerance to Fusarium in F1 Microspore Populations of Wheat
Authors: Fadel F. , Wenzel G.
Published: April 2006

Microspore populations of eight Fhybrids of winter wheat (Triticum aestivum L.) whose parents had different levels of resistance to Fusarium were screened in vitro, using phytotoxins of Fusarium as biochemical probe. Two selection methods were compared for the in vitro selection: either embryoids and calli were first initiated from anthers in toxin‐free medium and then grown on medium with 0.3—0.9 %Fusarium toxin; or anthers were immediately cultured in modified liquid potato‐2 medium in the presence of 1.5, 2.0 and 2.5ml Fusarium toxin per liter culture medium, a concentration which reduced the number of calli and embryoids to about 10 % compared to the toxin‐free controls. Microspores from donor hybrids which were produced from very susceptible cultivars were killed by lower toxin concentrations than micro‐spores from hybrids of less susceptible parents. From surviving calli and embryoids, originally initiated from 242,000 anthers in both procedures a total of 375 green lines could be regenerated. The results indicate that it is possible to enrich the fraction of regenerating microspores by those which contain the gene complex responsible for reduced susceptibility to Fusarium by the use of a pathotoxin.
Production of Doubled Haploids by Anther Culture and Wheat X Maize Method in a Wheat Breeding Programme
Authors: Kisana N. S. , Nkongolo K. K. , Quick J. S. , Johnson D. L.
Published: April 2006

Utilization of the doubled haploid method of breeding usually shortens the time to cultivar release, and methods of haploid production need evaluation in a breeding programme. Thirty‐eight different three‐way crosses were tested for anther culture response. On average 5.8 percent of the anthers cultured produced calli. Three crosses were found recalcitrant for callus induction. Overall, the anther culture method produced 0.6 plantlet per 100 anthers cultured. Five crosses with an average of 5.8 and 2.8 percent of anthers producing calli and plantlets, respectively, were compared using anther culture and wheat × maize crosses. Non‐responsive genotypes for callus induction and plantlet formation in the anther culture method proved to be good parental material in wheat × maize crosses. The average percentages of embryo formation and plantlet production in wheat × maize crosses were 10.3 and 4.7, respectively. Anther‐derived plants were cytologically unstable, whereas all the plants regenerated from wheat × maize crosses were haploids (n = 21 chromosomes). The chromosome numbers of the polyhaploids were doubled with a colchicine treatment. Improvement of the two haploid production methods to facilitate their efficient use in a breeding programme is discussed.
Monosomic Analyses of Yellow Rust and Leaf Rust Resistance Genes in Winter Wheat Cultivar ‘Fengkang 2’
Authors: Jiazhi Pang , Rongjin Sun , Zhigang Yang , Giuying Zhou
Published: April 2006

A set of 21 monosomics of ‘Chinese Spring’ was used to locate the rust resistance genes of Tengkang 2′, developed by the Chinese Academy of Agricultural Sciences. The resistance to yellow rust race CY25 was controlled by a dominant gene located on chromosome 5B and resistance to leaf rust race CL38 was controlled by a dominant gene located on chromosome 5A in ‘Tengkang 2’. Most likely these two genes are new.
Detection of Resistance to the Russian Wheat Aphid in Hexaploid Wheat
Authors: Porter D. R. , Webster J. A. , Baker C. A.
Published: April 2006

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), poses a serious threat to wheat (Triticum aestivum L.) production in many parts of the world. This research was initiated to evaluate wheat accessions for detection of resistance to the RWA. Over 12,000 wheat cultivars and plant introductions (PIs) from the USDA‐ARS National Small Grains Collection were evaluated for reaction to RWA feeding damage. Twenty‐nine PIs from Iran, Afghanistan, and the former Soviet Union, of various agronomic backgrounds were identified as having moderate to high levels of RWA resistance. This information is useful to wheat breeders searching for sources of resistance to the RWA to incorporate into their breeding programmes.
Potato Tuber Resistance to Phytophthora infestans and its Relation to Maturity
Authors: Swieźyński K. M. , Krusiec J. , Osiecka M. , Sieczka M. T. , Zarzycka H.
Published: April 2006

Tuber resistance to P. infestans was evaluated in the progeny of potato genotypes differing in levels of resistance and maturity. Two methods of tuber evaluation were used: testing whole tubers and testing tuber slices.

In the progeny, some genotypes were superior in resistance to the more resistant parent. This superiority was never associated with early maturity. The results of both tuber‐testing methods were positively correlated but the interaction genotypes X years was more pronounced in the reaction of tuber slices.

It is concluded that: (1) transgression in tuber resistance may be obtained, (2) a high level of tuber resistance is difficult to combine with early maturity and (3) the expression of genes for specific resistance was more pronounced in testing tuber slices than in testing whole tubers.
Internal CO2 Concentration as a Selection Criterion for Storage Respiration Rate in Sugarbeet
Authors: Campbell L. G. , Seiler G. J.
Published: April 2006

Respiration is responsible for much of the sucrose loss that occurs during sugarbeet (Beta vulgans L.) storage. Genotypes with reduced storage respiration rates would provide an efficient method for reducing sucrose losses. However, the current techniques for measuring storage respiration are not adapted easily to breeding programs. Internal CO2 concentration has been recommended as an efficient method for measuring the respiration rate of individual sugar‐beet roots in storage. This study examined the effectiveness of internal CO2 concentration as a selection criterion for reducing respiration rate of sugarbeet during storage. Lines resulting from four cycles of divergent selection for internal CO2 concentration were evaluated along with commercial hybrids and low internal CO2 germplasm lines. Selection was effective in shifting internal CO2 concentration. Relative differences in internal CO2 concentration were consistent throughout the 3‐year study. Neither the fourth‐cycle selections for low nor the fourth‐cycle selections for high internal CO2 concentration were significantly different from the original population for evolved CO2. This lack of a close relationship between internal and evolved CO2 indicated that internal CO2 concentration is not an effective selection criterion in a breeding program.
Natural Cross‐Pollination in Sesame (Sesamum indicum L.)
Authors: Pathirana R.
Published: April 2006

Three sesame genotypes with contrasting characters were grown in alternate rows to estimate the degree of natural cross‐pollination (NCP) at two locations. Capsules from the lower (first‐formed five capsules), upper (last five fully‐developed capsules) and middle portions were harvested separately and the frequency of appearance of progenies with dominant markers was used as the criterion for NCP. The degree of inter‐genotypic NCP was similar in the three genotypes and at the two locations (4.02—5.10 % NCP) when the total number of hybrid seeds per plant was considered. The lower portion of the early (1.03—1.31 % NCP) and medium (1.51—2.08%) flowering genotypes and the upper portion of the late‐flowering genotype (2.27—2.49 % NCP) recorded less NCP than the total plant. The NCP in the lower portion of the early‐flowering genotype due to pollen from the late‐flowering genotype was negligible (0—0.7 %). The results indicate the need for controlled self‐pollination for purity maintenance in sesame. However, contamination due to NCP can be reduced by sampling seeds from the lower capsules of early and medium‐flowering genotypes and from the upper capsules of late‐maturing genotypes when pollination control is not practised.