bluuebunny/crossref_metadata_2025 huggingface dataset:
Restriction analysis of the mitochondrial DNA of male‐sterile and maintainer lines of pearl millet, Pennisetum americanum L.
Authors: Munjal S. V. , Narayan R. K. J.
Published: April 2006

Mitochondrial DNA from two pairs of cytoplasmic male‐sterile (cms) and maintainer lines of pearl millet was investigated by restriction‐enzyme analysis and Southern‐blot hybridization using three mitochondrial gene probes. Each pair of male‐sterile and maintainer lines was of a different nuclear origin. The objective was to distinguish differences in the DNA base‐sequence organization of the mitochondrial genomes of cms and maintainer lines from the two sources. Restriction‐enzyme analysis revealed differences between the different cms and maintainer lines. Southern‐blot hybridization experiments using cloned mitochondrial gene probes further distinguished differences between different lines. It is expected that the restriction‐fragment‐length polymorphisms revealed in the Southern‐blot‐hybridization experiments will be useful in distinguishing and classifying cms and maintainer lines obtained from different nuclear backgrounds.
Genetic variation in tannin‐related characters of faba‐bean seeds (Vicia faba L.) and their relationship to seed‐coat colour
Authors: Duc G. , Brun N. , Merghem R. , Jay M.
Published: April 2006

Tannin content and tanning power on haemoglobin were evaluated in a collection of faba‐bean genotypes differing in seed and flower colour. All tannin‐related measurements gave near‐zero values for white‐flowered genotypes; they showed intermediate values in brown and green‐seeded genotypes, brown being lower in tannin values than green. Genetic analysis in the F3 of a half‐diallel design confirmed the strong link between brown and green testa colour and intermediate tanning activities.
Genetic variability in plants regenerated from in vitro culture of sunflower (Helianthus annum L.)
Authors: Barotti S. , Fambrini M. , Pugliesi C. , Lenzi A.
Published: April 2006

In vitro regenerated sunflower (Helianthus annuus L.) plants (R1) were self‐fertilized and the R2 generation was evaluated for qualitative traits. A broad range of phenotypic variation was observed and mutation frequencies were calculated. Some in vitro induced variant phenotypes were similar to known spontaneous or induced mutations in sunflower, while others were new. Chlorophyll and carotenoid deficiencies, chimaerical variegation, fasciated stem and capitulum, abnormal shoot development, and other morphological variations, were noted. Substitution of anthers with petaloid structures in a disk‐floret mutant indicates a possible homeotic mutation induced by in vitro tissue culture.
Inheritance of resistance to fusarium wilt in chickpea
Authors: Gumber R. K. , Kumar J. , Hanaware M. P.
Published: April 2006

This preliminary study indicated that the resistance to race 2 of fusarium wilt is controlled by two genes, the first of which must be present in the homozygous recessive form, and the other in the dominant form, whether homozygous or heterozygous for complete resistance. Early wilting results if the other gene is homozygous recessive. Late wilting occurs if both loci are dominant. The existence of differences among chickpea cultivars in the time taken to express the initial symptoms of fusarium wilt were observed.
Relationship between electrophoretic pattern of storage proteins and gluten strength in durum wheat landraces from Turkey
Authors: Turchetta T. , Ciaffi M. , Porceddu E. , Lafiandra D.
Published: April 2006

A collection of 180 Triticum durum lines from Turkey and 22 Italian cultivars were investigated by electrophoretic techniques and evaluated for grain parameters such as protein content and sodium dodecyl sulphate (SDS)‐sedimentation test. A total of 14 different patterns were observed for high‐molecular‐weight (HMW) glutenin subunits resulting from the combination of three alleles from the A genome and seven from the B genome. Three new allelic variants, one at Glu‐A1 and two at Glu‐B1, were found. Five different alleles were detected at the Glu‐B1 locus. Genotypes with the same allelic variant at Gli‐B1 showed inconsistency of composition in B group of low‐molecular‐weight (LMW) glutenin subunits. A total of 11 different B‐subunit patterns were identified in the material analysed. A substantial proportion (78%) of the variation in gluten properties could be explained in terms of protein composition, with the LMW glutenin subunits making the largest contribution (54%). Results indicate that, in addition to Glu‐B3 encoded proteins, variation at other loci coding for some intermediate and fastest B subunits might also influence rheological properties.
A new cytoplasmic‐nuclear male sterility system in pearl millet
Authors: Rai K. N.
Published: April 2006

Among the cytoplasmic‐nuclear male sterility (CMS) systems reported in pearl millet, Pennisetum glaucum (L.) R. Br., the Am= A4 system produces the highest frequency of male‐sterile hybrids. A CMS source identified in a large‐seeded gene pool (LSGP) was compared with the A4 system. Seven diverse restorer lines of the A4 system produced hybrids with 81A4 that were all fertile (pollen‐shedding score 4 and 68–89% selfed seedset). In contrast, all the hybrids of these inbreds made with the isonuclear line with the LSGP cytoplasm were sterile (pollen‐shedding score 1 and 0–3% selfed seedset). Topcross hybrids of four diverse composites made with 81A4 had 10–35% plants that had good fertility (> 50% selfed seedset). In comparison, no plant of any topcross hybrid with the isonuclear line having LSGP cytoplasm exceeded 20% selfed seedset, and it was rare for a plant to exceed even 10% selfed seedset. These differential fertility restoration patterns of hybrids indicate that the LSGP cytoplasm represents a CMS system that is different from the A4 and, by implication, from all those reported to date. This new CMS system is designated A5.
Isolation of induced mutants in Ethiopian mustard (Brassica carinata Braun) with low levels of erucic acid
Authors: Velasco L. , Fernández‐Martínez J. , De Haro A.
Published: April 2006

Ethiopian mustard (Brassica carinata Braun) is a potential oil crop for the rain‐fed Mediterranean area. However, its usage is limited by the high erucic and high glucosinolate content of the oil and meal, respectively. In the course of a mutagenesis programme, an agronomically good line of Ethiopian mustard was treated with EMS in order to widen the natural variability of nutritional traits in this species. As a result of this programme several low erucic mutants were isolated; two of these mutants showed erucic acid values in the M4 generation in the range 5–10% of total fatty acids. Near‐infrared reflectance spectroscopy (N1RS) was successfully applied as a rapid screening method for erucic acid in this breeding programme.
Estimating the pleiotropic effect of the jointless‐2 gene on the processing and agronomic traits of tomato by using near‐isogenic lines
Authors: Boiteux L. S. , Giordano L. de B. , Furumoto O. , Aragão F. A. S.
Published: April 2006

Two near‐isogenic lines of the processing tomato cv. ‘IPA‐5’, pheno‐typically distinct from each other only in terms of the presence or absence of a jointless fruit pedicel, were used to estimate pleiotropic effects of the recessive gene j‐2 on 15 processing and agronomic parameters. Total yield, total yield of mature fruit, total yield of green fruit, total number of fruit, total number of mature fruit, total number of green fruit, mean weight of mature fruit, mean weight of green fruit, mean weight of mature plus green fruit, soluble solids, fruit colour, pH, titratable acidity, sugar: acid ratio, and fruit firmness were compared in jointed (J‐2/J‐2) and jointless pedicel (J‐2/J‐2) lines. Statistically significant differences were detected between both isolines for the following parameters: total number of fruit, total yield, total yield of green fruit, and total number of green fruit. In all cases, smaller values were observed in the isoline with the genetic constitution J‐2/J‐2. These data reinforce the view that they j‐2 gene may cause, in some specific tomato backgrounds, significant yield constraints. Furthermore, it was demonstrated that this gene cannot exert any important pleiotropic influence on any of the processing characteristics evaluated.
Estimation of variance components and heritability of bunch yield and yield components in the oil palm (Elaeis guineensis Jacq.)
Authors: Okwuagwu C. O. , Tai G. C. C.
Published: April 2006

In an experiment involving 24 single‐cross progenies of oil palm conducted at the Nigerian Institute for Oil Palm Research, 9‐year data of fresh‐fruit yield and its two components, annual bunch number and single‐bunch weight, were recorded. Means of progenies of each of the three traits obtained from 1–9‐year records were used in analyses of variance according to a repeated‐measures design. The results were then used to estimate variance components due to progenies and progeny × year interactions. These estimates were then used to estimate heritability for yield and yield components based on progeny means, which were assumed to be calculated from 1–9 years of harvests. The results revealed that heritability estimates of fresh‐fruit yield and its two yield components were not reliable based on the first‐year harvest data. The single‐bunch weight had a slower rate of improvement than the other two traits when more years were used for the estimation. Heritability can be expected to be over 80% for fresh‐fruit yield and bunch number based on 1‐, 3‐, and 4‐year means, respectively. Six‐year data are required for single‐bunch weight to reach the same heritability measure.
The viability and storage of strawberry pollen
Authors: ŽEbrowska J.
Published: April 2006

Investigations were carried out in 1990 and 1991 to estimate the pollen viability of five strawberry genotypes and their suitability for storage. Pollen viability was assessed by acetocarmine staining, in vitro germination, and in vivo assays. Pollen was stored in darkness at −18°C for 1 year, and pollen viability was estimated every 4 months during storage.

The highest percentage of stained and in vitro germinated pollen grains, respectively, was shown by fresh pollen of cv. ‘Dukat’ (91 and 45%). The lowest values of these characteristics were observed in pollen of cv. ‘Paula’ (48% and 20%, respectively). The best response to storage at −18°C occurred in pollen of the breeding clone ‘B‐302’ and the cv. ‘Redgauntlet’. ‘Paula’ pollen responded least favourably to this. Pollen of the cvs. ‘Dukaf’. ‘Senga Sengana’, and clone ‘B‐302’ after storage for 4 months, still had sufficient capacity for fruit set after cross‐pollinations.
Genetics of adult plant stripe rust resistance in four Australian wheats and the French cultivar ‘Hybride‐de‐Bersée’
Authors: Bariana H. S. , McIntosh R. A.
Published: April 2006

Long‐term resistance to rust diseases depends on the identification and use of durable resistance sources or on the continuing use of new resistances and combinations of genes for specific resistance. These studies include four Australian wheats with intermediate, but inadequate levels of resistance and a French wheat ‘Hybride‐de‐Bersée’ (‘Bersee’), with reputed durable resistance to stripe rust. Studies of F2 and F3 populations from crosses with the susceptible ‘Avocet’ indicated that intermediate levels of adult plant stripe rust resistance in cultivars ‘Harrier’, ‘Flinders’ and ‘M2435’ were inherited monogenically, whereas King possessed two genes for resistance. Cultivars Harrier and M2435 possessed the same gene. Similarly, cvs. King and Flinders carried a gene in common. Like ‘Harrier’ and ‘M2435’, ‘King’ and ‘Flinders’ share common parents. The higher level of resistance in ‘Bersee’ was controlled by four genes. This conclusion was based on conventional genetic analysis, tests on F2‐derived F7 single‐seed descent lines and testcross progenies.
Cell selection as a possible reason for the specificity of somaclonal variation in pea
Authors: Ezhova T. A. , Bagrova A. M. , Gostimski S. A.
Published: April 2006

A study of regenerants obtained from long‐term callus cultures of different pea (Pisum sativum L.) genotypes revealed specificity of in vitro mutagenesis. The specificity was displayed in the preferential generation of the somaclonal variations affecting quantitative and developmental characters. About 60% of regenerated lines obtained from the cultivar Ranny Zeleny carried mutations in the Lf and Sn loci, which control initiation of flowering. An in vitro study of isogenic lines differing at the Lf and Sn loci illustrates the growth advantages of mutant genotypes in tissue culture. These experiments suggest that mutations affecting developmental characters (e.g. mutations in loci which control flowering behaviour) may be expressed in tissue culture and may cause increased adaptation in mutant cells to the in vitro conditions. Rapid propagation of mutant cells during in vitro culture may lead to a higher proportion of quantitative mutations among the regenerated plants.
Inheritance of resistance to Tilletia indica (Mitra) in synthetic hexaploid wheat ×Triticum aestivum crosses
Authors: Villareal R. L. , Fuentes‐Davila G. , Mujeeb‐Kazi A. , Rajaram S.
Published: April 2006

Inheritance of resistance to Karnal bunt was investigated in the crosses of four resistant synthetic hexaploid wheats (SH; Triticum turgidum×T. tauschii) and two susceptible T. aestivum cultivars. The resistance was dominant or partly dominant over susceptibility. The SH cultivars Chen/T. tauschii (205) and Chen/T. tauschii (224) have single dominant resistance genes which could be allelic to each other. ‘Altar 84’/T. tauschii (219) appeared to have two dominant genes for resistance. ‘Duergand’T. tauschii (214) possessed two complementary dominant genes for resistance. The work is being extended to involve diverse Karnal bunt‐resistant SH and bread wheat cultivars.
Recurrent selection for downy‐mildew resistance in pearl millet
Authors: Weltzien R. E. , King S. B.
Published: April 2006

One population of pearl millet (Pennisetum glaucum (L.) R. Br.) highly susceptible to downy mildew (Sclerospora graminicola (Sacc.) Schroet.) was subjected to two cycles of recurrent selection for downy mildew resistance using a modified greenhouse screening method. The response to selection was evaluated under greenhouse and field conditions using 50 random S1 progenies and 50 random full‐sib progenies from each cycle bulk. Significant progress over cycles of selection was observed in all evaluation trials. These results demonstrated that, in a susceptible population, recurrent selection effectively increased the level of resistance to downy mildew. The modified greenhouse method for assessing resistance to downy mildew effectively differentiated genotypes and had the advantages of greater rapidity and suitability for use throughout the year, independent of season.

A rapid decline of genotypic variance was observed in advanced cycles of selection, indicating that a small number of genes controls downy‐mildew resistance in this population. The comparison of genotypic and error variance components from S1 progenies and full‐sib progenies suggested that full‐sib progenies can be used successfully in recurrent selection for increased downy‐mildew resistance.
Analysis of protoplast‐derived plants of Saintpaulia ionantha H. Wendl
Authors: Winkelmann T. , Grunewaldt J.
Published: April 2006

Of 3272 plants regenerated from protoplasts of 10 Saintpaulia ionantha genotypes, 98.4% survived transfer to the greenhouse. The frequency of regenerants with chlorophyll deficiencies, i.e. variegated leaves or albinos, was low (1.5%). There was a higher number of polyploid, in most cases tetraploid plants, regenerated from protoplasts (16%) which were identified by their altered morphology. Measurements of stomatal length and counting the number of chloroplasts per guard cell also allowed a clear differentiation between diploid and polyploid plants. The classification was confirmed by DNA content determination using flow cytometry.

Mechanisms leading to polyploidization included spontaneous protoplast fusion as well as chromosome doubling during callus growth and shoot regeneration. Two genotypes with instabilities in flower colour showed completely altered flower colours in plants regenerated from protoplasts as well as in plants regenerated on leaf explants in vitro.
Somaclonal variation as a source of resistance to eyespot disease of sugarcane
Authors: Leal M. Ramos , Maribona R. H. , Ruiz A. , Korneva S. , Canales E. , Dinkova T. D. , Izquierdo F. , Goto O. , Rizo D.
Published: April 2006

After 10 years of evaluation in different locations with high levels of incidence of disease, a group of sugarcane somaclones derived from callus tissues was selected for eyespot resistance. Resistance evaluations of four somaclones were performed under field and laboratory conditions. The results confirmed the superiority of two somaclones, one resistant and one tolerant to eyespot disease. Restriction analysis of mitochondrial DN A revealed that the two somaclones had a different DNA organization which distinguished them both from each other and from the donor plant; the restriction profile was similar however to that of the resistant control done. Restriction patterns of a third somaclone, also resistant, were similar to those of the donor plant. Differences among the somaclones were also evident when using a maize ribosomal DNA probe.
Genetics of resistance to Puccinia recondita in two wheat crosses
Authors: Sudhakar Y. , Joshi A. K.
Published: April 2006

Leaf rust resistance genes were identified in the common wheat variety ‘HUW 206’ and line HUWL 39 by inoculating their seedlings with 20 pathotypes of diverse avirulence–virulence combinations. The inheritance patterns and allelic relationships were studied by crossing these wheats with ‘Agra Local1 and a set of Thacher’ near‐isogenic lines with genes for resistance. Seedling resistance studies revealed the presence of genes Lr1, Lr10 and Lr26 in ‘HUW 206’ and genes Lr10 and Lr26 in HUWL 39. The presence of genes Lr1 and Lr10 was confirmed indirectly by testing for the linked genes Sr31 and Yr9. An F1 test for progressive necrosis in crosses of the lines with ‘Spica’ revealed the absence of Lr13.
Characterization of Brassica nigra chromosomes and of blackleg resistance in B. napus–B. nigra addition lines
Authors: Chevre A. M. , Eber F. , This P. , Barret P. , Tanguy X. , Brun H. , Delseny M. , Renard M.
Published: April 2006

Brassica napus‐B. nigra addition lines were previously created using the variety ‘Darmor’ as the oilseed rape genetic background. Two isozyme loci and 46 RAPD markers were added on five different B. nigra chromosomes. The oilseed rape variety used was highly susceptible to blackleg at the cotyledon stage and only the addition of chromosome 4 gave the same level of blackleg resistance as B. nigra. This resistance was efficient whatever the isolates used. A significant effect on the development of stem canker under field conditions was observed only for the line carrying chromosome 4 which was more resistant than the susceptible control. The potential effects of two other chromosomes have to be confirmed. F1 hybrids obtained by crosses between two highly susceptible lines and the monosomic addition line carrying chromosome 4 were examined under field conditions. No effect of the oilseed rape genetic background on the expression of resistance was detected. The introduction of this resistance and mapping of the gene(s) into oilseed rape varieties are discussed.
Induced mutations for reduced tuber glycoalkaloid content in potatoes
Authors: Love S. L. , Baker T. P. , Thompson‐Johns A. , Werner B. K.
Published: April 2006

Mutation breeding was used to produce mutants of the potato breeding selection NDA1725‐1 with reduced levels of tuber glycoalkaloids. Excised tuber eye‐pieces were exposed to 35 Gy of gamma rays from a 60Co source. In the M1V1, leaf tissue was screened using high‐performance thin layer chromatography and each plant given a relative score based on a subjective rating of band intensity. Tubers were harvested from all plants that produced leaves with relatively low levels of glycoalkaloids. Tuber glycoalkaloids were quantified in the M1V2 and M1V3 using high‐performance liquid chromatography, and 35% and 23% of clones with the lowest glycoalkaloid content were selected for further evaluation in each generation, respectively. In the M1V4, M1V5 and M1V6, selection was based on statistically significant differences between the mutant clones and the controls for glycoalkaloid content, as determined using a gravimetric quantification method, as well as on agronomic and quality characteristics. At the end of six clonal generations three selections exhibited acceptable levels of tuber glycoalkaloids and retained enough of the parent clone's exceptional traits to have potential in the commercial potato chip (crisp) industry.
Genetic diversity in apricot, Prunus armeniaca, aimed at improving resistance to plum pox virus
Authors: Badenes M. L. , Asíns M. J. , Carbonell E. A. , Glácer G.
Published: April 2006

Plum Pox Virus, a non‐persistent virus transmitted by aphids, causes serious damage to stone fruits. The apricot tree is very sensitive and in order to breed apricot cultivars resistant to Plum Pox Virus and establish breeding strategies, genetic diversity based on 10 enzymatic systems, six of which were polymorphic, has been studied. The plant material studied, 94 accessions, included the most important apricot cultivars grown in PPV‐affected areas. Genetic diversity is high and showed important differences between the three geographical groups studied (North African, European and North American). The North American group was very diverse and allozymes can be used to identify three subgroups. Some North American PPV‐resistant cultivars were very distant from the rest of the cultivars, mainly due to the presence of rare alleles found in an Asian apricot related species. These results support the hypothesis that Asian‐related species might be the origin of PPV resistance within the North American cultivars. Three North American cultivars have been considered as putative donors of PPV resistance to the European cultivars because of their agronomic behaviour, chilling requirements and distance from European cultivars. However, to increase the genetic variability of the European group and thereby to favour recombination, the study of Asian apricot resources is also recommended.
Interspecific hybridization between Cyclamen persicum Mill, and C. purpurascens Mill.
Authors: Ewald A.
Published: April 2006

In order to introduce valuable traits from wild species of Cyclamen into C. persicum cultivars, crosses were made between C. persicum‘Reinweiß’and C. purpurascens. Crossing barriers between C. persicum‘Reinweiß’and C. purpurascens were due to late‐acting incompatibility reactions. Interspecific hybrids were obtained by using ovary culture. The highest number of embryos was achieved from placentas excised 21 days and 35 days after pollination and transferred to Murashige‐Skoog (M.S.)–medium containing 6% sucrose and 1% agar. The hybrids showed a habit and a chromosome number intermediate between the parents. The fragrant flowers were pale red‐purple. The chromosome number in root tips was determined as 2n= 41 while in C. persicum it is 2n= 48 and in C. purpurascens 2n= 34. Due to the different parental chromosome sizes, chromosomes of distinct size were still observed in the hybrid. Pollen viability varied between 0.3 and 34.0%. Parents and interspecific hybrids also showed differences in the DNA content of leaf tissue. Flow cytometric analyses were useful in the early identification of hybrids.
Phenylacetic acid stimulation of direct shoot formation in anther and somatic tissue cultures of rice (Oryza saliva L.)
Authors: Zhuo L. S. , Si H. M. , Cheng S. H. , Sun Z. X.
Published: April 2006

The effect of phenylacetic acid (PAA) on rice (Oryza saliva L.) anther culture was investigated with six genotypes, using 2,4‐D as control. In the two‐step culture protocol, replacing 2, 4‐D with PAA in the induction medium did not influence callus induction but significantly improved the shoot differentiation from callus, particularly in the indica cultivar Teqing. The anther‐derived calli of all genotypes regenerated shoots directly on the callus induction medium containing PAA. Most of the directly‐regenerated plantlets had well‐developed root systems and were therefore readily transplanted into soil. The improved shoot differentiation potential and the frequency of direct regeneration depended on genotype, basal medium and PAA concentration. The one‐step green shoot regeneration frequencies obtained were 1.98% with the indica cultivar ‘129’, 1.5% with the indica × japonica hybrid ‘Teqing/02428’ (F1), and 1.98% with the indica × indica hybrid ‘Waiyin 2/C.B.’ (F1). The PAA‐based one‐step method was most effective on the anther culture of indica genotypes. Three DH populations have been constructed from hybrids (F1) via one‐step culture. PAA also enhanced the one‐step plantlet formation in rice somatic tissue culture.
N‐banded karyotype of Aegilops ovata and chromosomal constitution of its amphiploid with Triticum aestivum
Authors: Landgeva S. , Ganeva G.
Published: April 2006

The N‐banded karyotype of an Aegilops ovata (2n = 4x = 28) accession was produced, and the chromosomal constitution of its partial amphiploid with bread wheat Triticum aestivum‘Chinese Spring’ was established. All A. ovata chromosomes showed specific N‐banding patterns and can easily be distinguished from each other. As a result of irregular meiotic behaviour of the chromosomes in the amphiploid, some structural rearrangements have probably occurred in most of the A. ovata chromosomes. The wheat chromosomes remained unmodified in their morphology and the N‐banding patterns.
Genetic diversity of Cannabis sativa germplasm based on RAPD markers
Authors: Faeti V. , Mandolino G. , Ranalli P.
Published: April 2006

Random amplified polymorphic DN A (RAPD) markers were generated from 13 cultivars and accessions of Cannabis sativa L. Approximately 200 fragments generated by 10 primers of arbitrary sequence were used to assess the level of DNA variation. Statistical analysis was performed using the Dice coefficient of similarity and principal coordinate analysis. The grouping of the accessions according to the cluster analysis was in good agreement with their origin and lines with common ancestors were grouped together. Principal coordinates 1 and 2 revealed a clear separation of Italian and Hungarian germplasm and a third group, including a mixture of genotypes coming from different places; the third coordinate separated the Korean group which is probably the most divergent germplasm. Variability within the two cultivars ‘Carmagnola’ and ‘Fibranova1’ was also shown, suggesting good possibilities for long–term selection work. RAPD markers provide a powerful tool for the investigation of genetic variation in cultivars/accessions of hemp.
Inheritance of threshability in synthetic hexaploid (Triticum turgidum×T. tauschii) by T. aestivum crosses
Authors: Villareal R. L. , Mujeeb‐Kazi A. , Rajaram S.
Published: April 2006

Triticum tauschii provides breeders with a valuable source of resistance and tolerance genes. Elucidation of the inheritance of traits in this species that hinder its use in breeding programmes is therefore of interest to wheat breeders. Inheritance of threshability was investigated in the crosses of four non‐free‐threshing (NFT) synthetic hexaploids (Triticum turgidum×T. tauschii) and two free‐threshing (FT) T. aestivum cultivars during four crop seasons over 3 years at E1 Batan and Ciudad Obregon, Mexico. The parents, their F1 Hybrids and individual F2 plant‐derived F3 progenies of the crosses revealed that ‘Altar 84’/T. tauschii (219), ‘Chen’/T. tauschii (205), ‘Chen’/T. tauschii (224), and ‘Duergand’/T. tauschii (214) have independently segregating loci with two dominant alleles controlling threshability. Intercrosses among the synthetics, except ‘Altar 84’/T. tauschii (219), showed the genes to be allelic to each other. The cross between the FT cultivars showed no segregation in the F3 generation, indicating common recessive genes. Based on these findings, population sizes of the synthetic‐derived breeding materials should be increased to improve the chances of selecting FT desirable plants in the programme.
Resistance specificities to viruses in potato: Standardization of nomenclature
Authors: Valkonen J.P.T. , Jones R.A.C. , Slack S.A. , Watanabe K. N.
Published: April 2006

Potato viruses are prevalent worldwide and cause substantial economical losses in the potato crop (Solanum tuberosum L.). Therefore, various types of resistance to potato viruses identified in cultivated and wild potato species are used in potato breeding programs and are briefly reviewed in this paper. However, the current nomenclature of virus resistance specificities is confusing because it was adopted at an earlier time when several virus strain groups were believed to represent individual virus species and because it does not distinguish between strain‐specific and comprehensive resistance specificities. A consistent nomenclature is desirable to distinguish both currently known virus resistances and any novel virus resistances detected in the future. A descriptive and systematic nomenclature for resistance specificities is proposed which denotes (1) type of resistance (2) identity of virus (3) the virus strain group(s) against which the resistance is effective (4) the virus strain group(s) against which the resistance is not effective, and (5) the potato species in which the resistance is described.
Variation and covariation of agronomic traits and quality in triticale at low nitrogen input
Authors: Oettler G.
Published: April 2006

The use of high nitrogen (N) inputs is becoming restricted in many countries due to environmental and economic considerations and reliable information is needed about parameters pertinent for breeding N‐use efficient triticales (x Triticosecale Wittmack). This study reports estimates of variances, heritabilities, correlations, and regression for 36 triticales, grown at three locations for 2 years with two N regimes (zero and normal N supply). Eleven traits were assessed. A 45% mean reduction in grain yield by low N input was mainly the result of a 25% lower number of tiller‐bearing spikes per m2 and 17% fewer kernels per spike, whereas 1000‐kernel weight was little affected. Genotype‐nitrogen interaction was of importance only in some environments and for certain traits. Heritability estimates at both N levels were similar and moderate to high. Correlations between N levels were high for nearly all traits. Regression analysis for grain yield revealed only few N‐efficient triticales with lower than unity slope together with a high grain yield. Based on the genetic parameters, it is concluded that a special low input breeding programme does not appear to be necessary in triticale. The breeder can select at either of the N levels with similar response. But he should include tests in low productivity environments at some early stages in the breeding process to avoid loss of genetic variation for N‐use efficiency.
Genetic control of some polymeric glutenin fractions in hexaploid wheat (Triticum aestivum)
Authors: Haddad L. El , Sarrafi A. , Fabre J. L. , Aussenac T.
Published: April 2006

Reciprocal crosses were made between seven different hexaploid wheat genotypes. Hybrid kernels and their parents were used to determine the amount of polymeric glutenin fractions by size‐exclusion high‐performance liquid chromotography (SE‐HPLC) analysis. Quantitative aspects of the genetic control for various glutenin fractions were investigated through diallel cross analysis. The association between the potential effect on hexaploid wheat quality of various allelic types and the quantitative expression of the polymeric glutenin fractions was confirmed. Significant average heterosis effects were demonstrated for insoluble glutenin (pFi), total soluble and insoluble glutenin (pF1 + pF2 + pFi) and the ratio of soluble to insoluble glutenin, (pF1 + pF2)/pFi. Some genotypes showed significant positive or negative combining abilities and general reciprocal effects for the glutenin fractions studied. For gluten quality, ‘Qualital’ was the best combiner for determining an optimal glutenin composition (high values for pFi and pF1 + pF2 + pFi and low values for pF1/pF2 and (pF1 + pF2)/pFi, respectively). These results should be of great interest in breeding programmes aimed at improving hexaploid wheat quality.
Genetic basis of physiological traits related to salt tolerance in tomato, Lycopersicon esculentum Mill.
Authors: Foolad M. R.
Published: April 2006

Genetic relationships between salt tolerance and expression of various physiological traits during vegetative growth in tomato, Lycopersicon esculentum Mill., were investigated. Parental, F1, F2 and backcross progeny of a cross between a salt tolerant (PI174263) and a salt sensitive tomato cultivar (‘UCT5’) were evaluated in saline solutions with electrical conductivity of 0.5 (non‐stress) and 20 dS/m (salt stress). Absolute growth, relative growth, tissue ion content, leaf solute potential and the rate of ethylene evolution were measured. Growth of both parents was reduced under salt stress; however, the reduction was significantly less in PI174263 than ‘UCT5’, suggesting greater salt tolerance of the former. Under salt stress, leaves of PI174263 accumulated significantly less Na+ and Cl− and more Ca2+ than leaves of ‘UCT5’. Across parental and progeny generations, growth under salt stress was positively correlated with leaf Ca2+ content and negatively correlated with leaf Na+ content. In contrast, no correlation was observed between growth and either leaf solute potential or the rate of ethylene evolution under salt stress. Generation means analysis indicated that under salt stress both absolute and relative growth and the Na+ and Ca2+ accumulations in the leaf were genetically controlled with additivity being the major genetic component. The results indicated that the inherent genetic capabilities of PI174263 to maintain high tissue Ca2+ levels and to exclude Na+ from the shoot were essential features underlying its adaptation to salt stress and that these features were highly heritable. Thus, tissue ion concentration may be a useful selection criterion when breeding for improved salt tolerance of tomato using progeny derived from PI174263.
Inheritance of sesquiterpene lactone types within the Achillea millefolium complex (Compositae)*
Authors: Vetter S. , Franz Ch. , Giasl S. , Kastner U. , Saukel J. , Jurenitsch J.
Published: April 2006

Successful crossing experiments between tetraploid individuals of Achillea ceretanica, A. collina, A. distans ssp. styriaca, and A. pratensis (A. millefolium complex, Compositae) were carried out. Sesquiterpenes of 1013 hybrid plants obtained from 13 crossings were studied by qualitative thin layer chromatography (TLC). F1‐progenies from parent plants with guaianolides (GU‐type), as well as the offspring of a back‐cross, uniformly contained proazulenes. Diallel crosses between plants exclusively with eudesmanolides (EU‐type) resulted in a 7:1 segregation‐ratio of EU‐ and GU‐plants. Two reciprocal crossing experiments between EU‐ and GU‐parents resulted in 28.6% and 89.3% EU‐individuals, as well as GU‐offspring. According to these findings, the qualitative marker ‘proazulene’ (GU‐type) is thought to be a recessive character of the tetraploid Achillea species studied.
Resistance to Rhynchosporium secalis in six Nordic barley genotypes
Authors: Robinson J. , Jalli M. , Lindqvist H.
Published: April 2006

Six six‐row Nordic spring barley genotypes (Hordeum vulgare L.) were assessed in the field in Finland (1994 and 1995) for resistance to Rhynchosporium secalis (Oud.) J.J. Davis, the causal pathogen of scald, in artificially inoculated plots. The barleys were known not to contain major genes for resistance to scald and the purpose of these experiments was to identify quantitative differences in resistance to scald which might be exploitable in a breeding programme. Disease development was monitored, grain yield and yield components were recorded, and these data were compared with measurements taken from plants in plots kept free of disease. Data, averaged over both years, for disease development on the uppermost three leaves — areas under disease progress curves, terminal severity and apparent infection rates — indicated that ‘Verner’, ‘Pohto’ and ‘Pokko’ were symptomatically significantly more resistant to scald than ‘Arve’, ‘Loviisa’ and Jo 1599. Grain yields, thousand‐grain weights, test weights and proportions of plump grains were all significantly reduced in plots inoculated with scald compared with those kept free of disease; ‘Verner’ appeared to be the most useful genotype for use in crossing programmes to improve scald resistance in Finnish barleys.
Enhanced anther culture efficiency of indica rice (Oryza sativa L.) through modification of the culture media
Authors: Raina S. K. , Zapata F. J.
Published: April 2006

The production of microspore‐derived green plants from anther culture of indica rice is generally very low compared with japonica cultivars. A modified anther culture medium, consisting of a higher KNO3 content (31 mm) and casein hydrolysate (CH, 500 mg/1) but without ammonium salts, was tested in comparison with a medium consisting of the widely‐used N6 medium nitrogen background, using four indica × indica F1 hybrids as test materials. Green plant regeneration frequency was at least three‐fold higher in the microspore‐calli derived from the former medium than in those derived from the modified N6 medium. More than 700 microspore‐derived plants were raised in the field. Another study was carried out using indica × japonica and indica × javanica F1 hybrids. The results indicated that a medium with higher (3.5 mm) ammonium sulphate may induce a higher frequency of anthers with microspore‐calli but not necessarily lead to a larger number of green‐plant regenerating calli. Subsequently, using the indica cv. ‘IR‐43’ as the test material, use of a lower level (1.75 mm) of (NH4)2SO4, in addition to KNO3 (31 mm), was found to be better than CH (500 mg/l) for anther‐response as well as green plant regenerability of the derived microspore‐calli. Nitrate‐nitrogen or ammonium‐nitrogen alone elicited poor response. Twenty‐five media involving combinations of KNO3 (20–34 mm) and (NH4)2SO4 (1–3 mm) were tested for their effects on anther response. Combinations involving KNO3 (31–34 mM) and (NH4)2SO4 (2.0–2.5 mm) were found superior not only for achieving greater anther response but also, for subsequent green‐plant regeneration. This contrasts with the 28 mm of KNO3 and 3.5 mm of (NH4)2SO4 in the widely‐used N6 medium developed for japonica rice. Other than potassium nitrate and ammonium sulphate, and potassium phosphate to some extent, the levels of other inorganic salts tested did not make any significant difference to the process of anther response. Based on these results, modified media with three levels of ammonium sulphate were tested for anther culture efficiency of indica × japonica and indica × javanica derivatives (F3s). Microspore‐calli derived from a medium of a lower (1.75 mm) level of (NH4)2SO4 showed a higher regeneration potential overall than those derived from a higher (3.5 mm) level. A revised medium has been suggested, on the basis of these results, for the realization of improved anther culture efficiency and, consequently, improved feasibility of using doubled haploids in genetic and breeding research with indica rice.
Widespread introgression of Solatium phureja DNA in potato (S. tuberosum) dihaploids
Authors: Clulow S. A. , Rousselle‐Bourgeois F.
Published: April 2006

Dihaploids were assumed to be of parthenogenic origin but cv. ‘Pentland Crown’ dihaploids produced at the Scottish Crop Research Institute (SCRI), Dundee, Scotland, are known to contain DNA from the S. phureja dihaploid inducer. This study investigates whether inducer DNA occurs in dihaploids of cultivars ‘Aminca’, ‘Brio’, ‘Lizen’ and ‘Sirtema’, produced at INRA, Ploudaniel, France. Two microsatellite markers and five simple sequence repeat 5′‐anchored polymerase chain reaction (PCR) primers were used to generate markers. Markers originating from the dihaploid inducer were detected in 13 of the 19 INRA dihaploids and in some dihaploids from each cultivar. Greater introgression occurred in ‘Lizen’ dihaploids than in ‘Brio’ dihaploids, suggesting that the female (S. tuberosum) parent influences introgression. The percentage of INRA dihaploids containing inducer DNA was similar to that for ‘Pentland Crown’ dihaploids (c. 65%). The micro‐satellite markers provided the first evidence of the transfer of specific, potentially useful, genes from the inducer to the dihaploid offspring.

Interspecific introgression during dihaploid induction is more widespread than previously thought and researchers should be aware that it may influence the results of research using dihaploids.
Evaluation of FDR diploid and tetraploid parents in potato under two different day‐length environments
Authors: Ortiz R. , Iwanaga M. , Peloquin S. J.
Published: April 2006

Five tetraploid clones of potato were crossed to each of eight diploid first division restitution (FDR) 2n pollen producers and four tetraploid males using a line × tester mating design. A total of 59 families were obtained and evaluated under long days at Rhinelander (USA). A subset of 49 families were grown under short days at four Peruvian locations. Tuber yield (kg per plant) of 4x‐2x families was similar to, or greater than, that of 4x‐4x families in short day environments. The diploid clones had breeding values greater than or equal to those of the tetraploid clones. Only families derived from FDR 2n pollinators combined high tuber yield with stability and high dry matter content. Reciprocal recurrent selection would be the best breeding scheme, in which the diploids are testers of the tetraploids and vice‐versa. Intra‐population improvement could be achieved through phenotypic recurrent selection. The best materials from both breeding pools could then be crossed to produce tetraploid hybrids through unilateral sexual polyploidization (4x‐2x crosses).
Effect of genotype and light intensity on somatic embryogenesis and plant regeneration in melon (Cucumis melo L.)
Authors: Kintzios S. E. , Taravira N.
Published: April 2006

The efficiency of 14 commercial cultivars of melon (Cucumis melo L.) for callus induction, plant regeneration and somatic embryogenesis under different photosynthetic photon flux densities (PPFDs) (150 or 50μmol m−2 s−1) was investigated. Cotyledonal explants were cultured on a Murashige and Skoog (MS) medium supplemented either with 9.0 μM 2,4‐dichlorophenoxyacetic acid and 23.2μM kinetin or with 0.05 μM 2,4‐dichlorophenoxyacetic acid and 0.26 μM 6‐benzyladenine for the induction of somatic embryogenesis and shoots, respectively. For embryo maturation and root induction, growing callus tissues were transferred on growth regulator‐free MS medium. Both genotype and the intensity of light significantly affected the rate of somatic embryo‐genesis, embryo maturation and plant regeneration. On average, 12–47 primary globular‐stage embryos were produced per mm2 of explant surface. Fully developed, cotyledonary‐stage somatic embryos were obtained from only three cultivars. Relatively high root induction rates were observed both on the shoot induction medium (11 cultivars) and on growth regulator‐free medium (seven cultivars). In contrast, only six cultivars responded positively to the shoot induction treatment. Callus growth and somatic embryogenesis were significantly improved if cultures were incubated under higher PPFD values, although plant regeneration from all cultivars was significantly reduced under the same conditions.
Absence of a genetic relationship between salt tolerance during seed germination and vegetative growth in tomato
Authors: Foolad M. R. , Lin G. Y.
Published: April 2006

Two approaches were used to determine the relationship between salt tolerance during seed germination and vegetative growth in tomato. First, F4 progeny families of a cross between a breeding line, ‘UCT5’ (salt sensitive at all developmental stages), and a primitive cultivar, ‘PI 174263’ (salt tolerant during germination and vegetative growth), were evaluated in separate experiments for salt tolerance during germination and vegetative growth. There were significant differences among the F4 families in both the rate of seed germination and the plant growth (dry matter production) under salt stress. There was, however, no significant correlation between the ability of seeds to germinate rapidly and the ability of plants to grow under salt stress. In the second approach, selection was made for rapid germination under salt stress in an F2 population of the same cross and the selected progeny was evaluated for salt tolerance during both germination and vegetative growth. The results indicated that selection for salt tolerance during germination significantly improved germination performance under salt stress; a realized heritability estimate of 0.73 was obtained. Selection for salt tolerance during germination, however, did not affect plant salt tolerance during vegetative growth; there was no significant difference between the selected and unselected progeny based on either absolute or relative growth under salt stress. Obviously, in these genetic materials, salt tolerance during germination and vegetative growth are controlled by different mechanisms. Thus, to develop tomato cultivars with improved salt tolerance, selection protocols that include all critical developmental stages would be desirable.
Efficiency of various insects in germplasm regeneration of carrot, onion and turnip rape accessions
Authors: Schittenhelm S. , Giadis T. , Rao V. R.
Published: April 2006

Seed regeneration is one of the most important tasks in genebank work. To regenerate germplasm of allogamous, entomophilous plant species in isolation facilities, insects are often used as pollen vectors. The objective of this study was to determine the effect of pollinator species, pollinator densities, pollinator combinations, and flower preferences on the seed quantity and quality of Daucus carota, Allium cepa, and Brassica rapa. The isozyme phosphoglucoisomerase (PGI) served as genetic marker in determining outcrossing rates and pollen dispersal distances. Field plots and isolation cages without insects were used as controls. The pollinators studied consisted of the following insect species from German native fauna: red mason bees (Osmia rufa L.), hoverflies (Eristalis tenax L.), and blowflies (Calliphora sp. and Lucilia sp.). In D. carota and B. rapa, higher seed yields were achieved in isolation cages than in field plots, but in A. cepa lower seed yields were obtained in the isolation cages. Although O. rufa showed no liking for A. cepa, unintentional pollination was effected by this insect in isolation cages. Lower insect densities were necessary for O. rufa than for the various fly species.