bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of tolerant breeding lines of tomato, Lycopersicon esculentum, originating from three different sources (L. peruvianum, L. pimpinellifolium and L. chilense) to early controlled inoculation by tomato yellow leaf curl virus (TYLCV)
Authors: Vidavsky F. , Leviatov S. , Milo J. , Rabinowitch H. D. , Kedar N. , Czosnek H.
Published: April 2006

Selection of tomato plants supposedly tolerant to tomato yellow leaf curl virus (TYLCV), based solely on the absence of symptoms in an infested field can be misleading. An inoculation routine was therefore established to avoid escapes and to overcome difficulties associated with the age of the plant at the time of infection. The inoculation routine was applied to a selection of resistant/tolerant individuals generated through a diallel F1 cross and to F2 segregating populations originating from three wild tomato species described as tolerant to TYLCV: Lycopersicon peruvianum EC 104395, Lycopersicon pimpinellifolium Hirsute and Lycopersicon chilense LA 1969. Clear differences were observed between susceptible symptomatic and tolerant symptomless tomato genotypes, indicating that the uncertainty resulting from escapes, from different levels of inoculum, and from the time of inoculation, can be eliminated. The genes involved in tolerance provided different levels of protection; combinations of various tolerant sources and levels in a single genotype gave a higher level of tolerance. Differences in level of protection were found between genes from the same source and between sources; none of the sources tested had complete dominance. The results obtained with the F2 segregating population showed that tolerance from L. pimpinellifolium is controlled by one major gene, that from L. chilense by two genes, and that from L. peruvianum by three genes with no dominant effect. The combination of sources for resistance can thus have positive or negative synergistic effects, or no effect. We suggest that a maximal level of tolerance can be obtained by the additive effect of the partly dominant genes from L. pimpinellifolium and L. chilense.
Genetic analysis of low‐temperature tolerance during germination in tomato, Lycopersicon esculentum Mill.
Authors: Foolad M. R. , Lin G. Y.
Published: April 2006

The genetic basis of low‐temperature tolerance during germination of tomato seed was investigated using two approaches. First, a cold‐tolerant (PI 120256) and a cold‐sensitive tomato cultivar (UCT5) and their reciprocal F2, F3 and BC1 progeny (total of 10 generations) were evaluated for germination at a low (11 ± 0.5°C) and a high (control) temperature 20 ±0.5° C) Weighted least‐square regression analysis indicated that in the low‐temperature treatment most of the variation resulted from additive genetic effects, and dominance and epistatic interactions were nonsignificant. Partitioning of the total genetic variance into those attributable to the effects of embryo, endosperm, testa and the cytoplasm indicated that additive effects of endosperm and embryo could individually account for 80% and 77% of the total variance, respectively. In the control treatment, greater than 60% of the variation could be explained by individual additive effects of endosperm or embryo and ≅ 27% of the variation could be explained by embryo dominance effects. Across generations, there was a positive correlation (r = 0.78, P < 0.01) between germination in the control and low‐temperature treatments and there were no significant genotype × temperature interactions. The results indicate the presence of similar or identical genes with predominantly additive effects on germination under both low and high temperatures. In the second approach, the effectiveness of directional phenotypic selection to improve tomato cold tolerance during germination was evaluated by selecting (in an F2 population of the same cross) the fastest germinating seeds under low temperature and comparing the germination of the selected F3 progeny with germination of an unselected F3 population. The results indicated that selection was highly effective and significantly improved germination performance of the progeny; a realized heritability of 0.74 was obtained for low‐temperature tolerance during germination. It is concluded that in these tomato lines germination under low temperature is genetically controlled, with additivity being the major genetic component, and thus the trait can be improved by phenotypic selection.
Development of synthetic maize populations for resistance to Striga hermonthica
Authors: Kim S. K. , Fajemisin J. M. , Thé C. , Adepoju A. , Kling J. , Badu‐Apraku B. , Versteeg M. , Carsky R. , Lagoke S. T. O.
Published: April 2006

The parasitic witchweed, Striga hermonthica (Del.) Benth, is the greatest biological constraint for cereal crop production by resource‐poor farmers in sub‐Saharan Africa. Maize, Zea mays L., is a widely grown cereal crop in this region (22 × 106 ha). Striga‐resistant maize populations were produced and tested as half‐sib families in West and Central Africa. Three populations with white (W), yellow (Y), or mixed (Y/W) grain colour were formed by: (1) intercrossing Striga resistant maize inbred lines followed by two generations of random mating; (2) testing far under artificially induced S. hermonthica infestations in Nigeria, Cameroon, and Ivory Coast and selection of resistant families; (3) two generations of random mating; and (4) two years of testing for resistance. Striga‐resistant synthetic W, Y and Y/W populations were produced by compositing resistant half‐sib families. Outstanding performance in grain yields and host plant resistance was observed. Maize damage ratings and number of harvested ears were highly correlated with grain yield. High variation was observed for Striga emergence counts. The populations have combined resistance to Striga, maize streak virus (MSV), and other major biotic constraints for maize cultivation in Africa, thus providing the opportunity for improved sustainable maize production under stress environments. Breeder's seed of these synthetic varieties are being multiplied for distribution to national programmes.
Production of doubled haploids in triticale (×Triticosecale Wittm.) by means of crosses with maize (Zea mays L.) using picloram and dicamba
Authors: Wȩdzony M. , Marcińska I. , Ponitka A. , ŚLusarkiewicz‐Jarzina A. , Woźna J.
Published: April 2006

The aim of the present study of triticale × maize crosses was to find an appropriate growth regulator treatment to improve the yield of triticale haploids and the subsequent production of doubled haploids. The growth effect in unpollinated ovaries of triticale was examined after treatment with 1000 mg/1 indole‐3‐acetic acid (IAA) or 100 mg/1 solutions of the following auxin analogues: 2,4‐dichlorophenoxyacetic acid (2,4‐D), 3,6‐dichloro‐o‐anisic acid (dicamba), 4‐chloro‐o‐tolyloxyacetic acid (MCPA), phenylacetic acid (PAA), 4‐amino‐3,5,6‐trichloropicolinic acid (picloram) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐ T), respectively. Dicamba stimulated growth of the ovaries significantly more than picloram and both stimulated more growth than the other growth regulators tested. Neither dicamba nor picloram induced embryo development in unpollinated pistils. Dicamba and picloram solutions, at concentrations of 25, 50, 75 and 100 mg/1, were subsequently applied to pistils of triticale pollinated with maize. On average, between 17.1 and 21.5 embryos/100 fiorets were excised after treatment with 75 or 100 mg/1 solutions of picloram or dicamba but the concentrations of 20 and 50 mg were less effective. The frequencies of excised embryos did not differ between genotypes. Seventy‐six green haploids were obtained from 100 embryos rescued in vitro on the 190–2 and modified B5 media, the first medium being superior. The plants were subjected to colchicine treatment at the 3–4 tiller stage. Out of 68 plants brought to maturity, 25 exhibited fertile sectors. In comparison with previous studies, picloram and dicamba significantly improved the efficiency of the triticale × maize crossing. The low dependence on the mother germplasm makes triticale × maize crossing an efficient alternative to the androgenetic methods of doubled haploid production in triticale.
Classification of Brazilian wheat cultivars for aluminium toxicity in acid soils
Authors: De Sousa C. N. A.
Published: April 2006

Aluminium (Al) toxicity is an important limiting factor for wheat Triticum aestivum L. adaptation to acid soils in different regions of Brazil. The purpose of this research was to classify the reaction of recommended wheat cultivars in Brazil in relation to Al toxicity. Seventy‐five cultivars were tested from 3 to 15 years under field conditions from 1980 to 1995 in Passo Fundo, Brazil. Soils with pH between 4.2 and 4.9 contained from 2.50 to 4.27 cmol Al/1. The resistance to aluminium in acid soil was evaluated visually before heading time in some years and at maturity in all years in three replications, using a score ranging from 0.5 (highly resistant) to 5 (highly susceptible). Using the over‐years mean index, 19 cultivars were classified as resistant, 33 as moderately resistant, 17 as moderately susceptible, and six as susceptible. The cultivars ‘BH 1146’, ‘Embrapa 15’, ‘Embrapa 24’, ‘Embrapa 49’, ‘IAC 5‐Maringá’, ‘IAC 18‐Xavantes’, ‘IAC 27‐Pantaneiro’, ‘IAPAR 46’, ‘IAPAR 53’, ‘RS 8‐Westphalen’, Trigo BR 15’, ‘Trigo BR 20‐Guató’, ‘Trigo BR 25’, ‘Trigo BR 35’, and ‘Trigo BR 41‐Ofaié’ were the most Al resistant of the 75 tested. It is highly probable that all Brazihan Altolerant cultivars have a major gene known to be on the long arm of chromosome 4D. Aluminium tolerance was traced by pedigree analysis to a small number of landraces introduced and grown in Brazil in the early twentieth century. Breeding for resistance to Al is required because soil amehoration by liming is effective only in the upper root zone and susceptible or moderately susceptible cultivars do not develop extensive root systems and suffer under drought or heat stress.
Genetic variability in foxtail millet, Setaria italica (L.) P. Beauv. ‐ RFLP using a heterologous rDNA probe
Authors: Schontz D. , Rether B.
Published: April 2006

Ribosomal DNA was surveyed in a world collection (43 lines) of Setaria italica for variation in repeat unit length and restriction enzyme site variability using a non‐radioactive wheat rDNA probe. Only two lengths of repeat units of about 7.9 or 7.6 kb were observed. The fact that these two repeat unit lengths were not randomly dispersed throughout the world collection suggests the existence of three genetic groups. The central European lines and most western European accessions have only the 7.6 kb repeat unit and most Asiatic lines have a 7.9 kb repeat unit. Lines originating from the north or the south of Asia showed different numbers of Bam HI fragments. The fact that the difference between the Asiatic and European pool is not continuous (7.9 or 7.6 kb) excludes the hypothesis of domestication being based on the spread of an initial population over Eurasia.
Genetic variation within eight populations of perennial forage grasses
Authors: Casler M. D.
Published: April 2006

Information on both mean performance and genetic variation is important in determining the value of germplasm for breeding via recurrent selection. The objectives of this experiment were to evaluate different methods of controlling spatial variation for forage yield, and to estimate genetic variances and heritability in eight perennial forage grass populations. Polycross families of two populations of smooth bromegrass (Bromus inermis Leyss.), two populations of hybrid wheatgrass (Elytrigia×muctonata (Opiz ex. Bercht.) Prokud.), and four populations of orchardgrass (Dactylis glomerata L.) were field tested for 2 years. Spatial variation was present in all three progeny tests, but was well accounted for by either the incomplete block design or a nearest neighbour analysis (NNA) of yield potentials. Low rank correlations between adjusted family means for the incomplete block design vs. the NNA created the unanswered question of which would provide a more appropriate estimate of family mean performance. Genetic variation was detected in six out of eight populations for forage yield, four out of six populations for ground cover, all four orchardgrass populations for maturity and one of four orchardgrass populations for leafspot reaction (caused by Drechslera spp.). Excessive year‐family interactions prevented detection of genetic variation for leafspot reaction in the other populations. Heritability estimates ranged from 0.30 to 0.42 for forage yield. In all three species, there was a trend toward a negative relationship between population mean and genetic variance, suggesting that less elite populations may need to contribute other traits to be useful in the short term.
In vitro rescue of zygotic embryos of sour orange, Citrus aurantium L., and their detection based on RFLP analysis
Authors: Carimi F. , De Pasquale F. , Puglia A. M.
Published: April 2006

Embryo development in vivo has been studied in four Citrus aurantium L. polyembryonic genotypes. Seeds were collected 65, 85, 105, 125 and 220 days after pollination (DAP). None of the immature seeds harvested 65 and 85 DAP contained visible embryos. A single embryo at a more advanced developmental stage was observed in the central position at the micropylar apex of the embryo sac in about 74% of seeds harvested at 105 DAP, while at 125 and 220 DAP the majority of seeds had two or more embryos at the same developmental stage crowded together. Restriction fragment length polymorphism (RFLP) analysis of lowand high‐copy‐number nuclear DNA was used to distinguish zygotic from nucellar seedlings. Analysis of plantlets derived from in vitro culture of the bigger embryos, located in the central position at the micropylar apex of the embryo sac of seeds harvested at 105 DAP, established that the frequencies of zygotic embryos ranged from 82 to 88%. Media for immature embryo germination in vitro were based on the nutrients and vitamins of Murashige and Skoog (MS) and Murashige and Tucker (MT) media supplemented with various concentrations of sucrose and growth regulators. A total of 76% of globular stage embryos (<0.3mm) germinated on MT medium containing 150 mM sucrose and 14.4 μM gibberellic acid. Heart stage embryos (0.3‐0.8 mm) germinated at 95% on MT medium supplemented with 150 mM sucrose and 2.9 μM gibberellic acid. The addition of 500 mg/l malt extract to MS medium increased the germination of early cotyledon stage (0.8‐2.0mm) embryos to 98%. The optimum sucrose concentration for embryo rescue was 150 mM for the three embryo developmental stages. The ability to form plants in vitro strongly increased with increasing embryo developmental stage.
Identification of five physiological races of blackspot, Diplocarpon rosae, Wolf on roses
Authors: Debener T. , Drewes‐Alvarez R. , Rockstroh K.
Published: April 2006

Differentiation into physiological races of Diplocarpon rosae, which causes blackspot on wild and cultivated roses, was investigated with single conidial isolates of the pathogen. Infection experiments with a simple excised leaf assay demonstrated differential interactions between single isolates and a set of 10 test rose genotypes. Differential reactions could be observed among rose varieties as well as between and within a wild rose species. Accordingly, five different physiological races can be identified among the 15 isolates tested. A breeding line and one genotype of the wild species Rosa wichuraiana were found to be resistant against all isolates tested. These data will be employed in further investigations on the genetics of blackspot resistance in roses and for resistance breeding programmes.
Second cycle gynogenesis in onion, Allium cepa L., and genetic analysis of the plants
Authors: Javornik B. , Bohanec B. , Campion B.
Published: April 2006

Haploid induction in onion via gynogenesis provides inbred lines that can be used in production of hybrid cultivars. Despite several successful reports, the gynogenic induction rate is still relatively low, ranging mainly from 0.5 to six embryos per 100 cultured flowers. In the present study, gynogenesis was induced in selfed progeny of three genetically homozygous and stable fertile doubled haploid lines previously obtained through in vitro gynogenesis. The aims were to acquire information on whether the gynogenic responsiveness of a particular heterozygous cultivar is correlated with higher or lower gynogenic capacity in the second cycle of gynogenesis, to evaluate the non‐genetic component of the variability, and to monitor by random amplified polymorphic DNA (RAPD) analysis the onset of eventual gametoclonal variation induced during the gynogenic processes. The results from the gynogenic induction of 9708 flowers showed significant differences among three lines, one of them being extremely responsive, showing a mean yield of 118.3 haploid embryos per 100 cultured flowers (118.3%). The high embryo yield of this line was determined by the line's particular genotype. However, the induction rate of gynogenic embryos obtained within 24 genetically uniform donor plants of this responsive line varied from 67 to 196% and this variation can be attributed to uncontrolled environmental conditions. A total of 157 plants sampled from two lines and obtained through a first (RI) and a second (SCG) cycle of gynogenesis, was analysed by RAPDs. The single band profiles were compared either between or within the RI and SCG plants of each line. A total number of 4600 RAPD fragments were scored and no variation was found in the highly responsive line, while in the less responsive one, minor changes were detected for the presence/absence of two RAPD bands. These results indicate high genetic stability of onion homozygous lines passed through two cycles of gynogenesis.
Reproductive behaviour and broomrape resistance in interspecific hybrids of sunflower
Authors: Sukno S. , Jan C. C. , Melero‐Vara J. M. , Fernandez‐Martinez J. M.
Published: April 2006

Interspecific hybrids and backcross generations between the wild perennial species Helianthus resinosus, Helianthus paucifiorus, Helianthus laevigatus, Helianthus nuttallii ssp. nuttallii T. & G. and Helianthus giganteus, resistant to broomrape (Orobanche cernua) and susceptible inbred lines were obtained to study crossability to cultivated sunflower and the transmission and expression of resistance to this parasitic weed. Conventional crosses with all the species tested were successful except for the crosses with diploid H. giganteus, for which embryo rescue techniques were needed to overcome hybrid incompatibility. Pollen viability and seed set were highest for F1 hybrids with hexaploid species and lowest for those with the diploid H. giganteus. We evaluated F1, BC1F1, some BC2F1 plants and the wild and cultivated parents. The wild species and interspecific hybrids were resistant to broomrape infection except for H. nuttallii, which showed segregation, indicating that the resistance is dominant. The crossability and resistance of F1, and back‐cross generations of species with different ploidy levels indicate that the transfer of broomrape resistance to cultivated sunflower is feasible.
Random amplified polymorphic DNA variation among German and Dutch asparagus cultivars
Authors: Jaag T. , Langsdorf A. , Snowdon R. J. , Köhler W. , Hartmann H. D.
Published: April 2006

DNA polymorphism among nine cultivars of Asparagus officinalis L. was measured using random amplified polymorphic DNA (RAPD). Of 69 reproducible amplification products from 12 arbitrary decamer primers, 49 RAPD markers were polymorphic and could be used to distinguish six German and three Dutch asparagus cultivars. Even with very small sample sizes, genetic similarity measurements based on the RAPD data allowed accurate grouping of the nine cultivars into distinct clusters, with the exception of two individuals which clustered to closely related varieties. Two German cultivars showed high genetic similarity and were distinct from the remaining German varieties. The German and Dutch cultivars were clearly separated by a relatively large genetic distance.
Inheritance of Russian wheat aphid resistance in PI 140207 spring wheat
Authors: McIntosh R. A. , Porter D. R. , Baker C. A. , Webster J. A.
Published: April 2006

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), has become a serious, perennial pest of wheat (Triticum aestivum L.) in many areas of the world. This study was initiated to determine the inheritance of RWA resistance in PI 140207 (a RWA‐resistant spring wheat) and to determine its allelic relationship with a previously reported RWA resistance gene. Crosses were made between PI 140207 and ‘Pavon’ (a RWA‐susceptible spring wheat). Genetic analysis was performed on the parents, F1, F2, backcross (BC) population and F2‐derived F3 families. Analyses of segregation patterns of plants in the F1, F2, and BC populations, and F2‐derived F3 families indicated single dominant gene control of RWA resistance in PI 140207. Results of the allelism test indicated that the resistance gene in PI 140207, while conferring distinctly different seedling reactions to RWA feeding, is the same as Dn 1, the resistance gene in PI 137739.
Genetic variation in testcrosses of European maize inbreds for resistance to the European corn borer and relations to line per se performance
Authors: Kreps R. C. , Gumber R. K. , Schulz B. , Klein D. , Melchinger A. E.
Published: April 2006

The European com borer (ECB) Ostrinia nubilalis H. is a major pest in World maize Zea mays L. production. Objectives of this study were to (1) investigate the genotypic variance and covariance in testcrosses of European flint and dent inbreds for ECB resistance and agronomic traits, and (2) estimate the correlation between line per se and testcross performance for ECB resistance traits. A total of 16 flint and 24 dent inbreds and their testcrosses with two testers from the opposite germplasm pool were evaluated in four and three German environments, respectively. Using artificial infestation with ECB larvae, resistance was assessed by damage rating of stalks, tunnel length in dissected stalks, and relative yield of infested plots compared with protected plots. Yield losses due to ECB damage in testcross hybrids amounted to 40%. Significant genotypic variances between flint and dent lines and high heritabilities were found for damage rating of stalks for both line per se and testcross performance. Heritabilities were low or intermediate for tunnel length and relative grain yield. Correlations between line per se and testcross performance were tight for the damage rating of stalks and moderate for tunnel length and relative yield in both flint and dent germplasm. For damage rating of stalks, per se performance of lines tested in a few environments can be used to predict their testcross performance. In contrast, assessment of testcross performance for tunnel length and relative yield requires evaluating testcrosses with several testers in multi‐environment trials.
Polymorphism of waxy proteins in Iberian hexaploid wheats
Authors: Rodriguez‐Quijano M. , Nieto‐Taladriz M. T. , Carrillo J. M.
Published: April 2006

A collection of 130 cultivars of bread wheat, 332 landraces of bread wheat and 144 spelt wheats was analysed for waxy proteins in the grain. The electrophoretic patterns showed very low polymorphism and most of the hexaploid wheats had the Wx‐Ala, Wx‐D1a and Wx‐B1 alleles of ‘Chinese Spring’. Two alleles were detected at Wx‐A1 (Wx‐A1a, and Wx‐A1b (null)), the latter was present in only 5.1% of the bread wheat landraces and 7.6% ofthe spelt wheats. No allelic variation was found at the Wx‐D1 locus and all the hexaploid wheats had the Wx‐D1a allele. Wx‐B1 was the most polymorphic locus, with three alleles detected: Wx‐B1a, Wx‐B1b (null) and Wx‐Blc coding for a Wx‐B1 protein with a slightly different mobility from Wx‐B1a. The null Wx‐B1b allele was found in 10.8% of the bread wheat cultivars, 21.4% of the bread wheat landraces and 12.5% of the spelt wheats. Among the 604 hexaploid wheats analysed, only two bread wheat landraces (0.6%) and two spelt wheats (1.4%) had the null allele at both Wx‐A1 and Wx‐B1 loci.
Comparison of intra‐ and inter‐pool crosses in faba beans (Vicia faba L.). II. Genetic effects estimated from generation means in Mediterranean and German environments
Authors: Schill B. , Melchinger A. E. , Gumber R. K. , Link W.
Published: April 2006

Genetic diversity between parents is important for hybrid breeding and for maximum usefulness of a cross in pure line breeding. However, wide crosses may suffer from poor adaptation in the target environments and recombination losses owing to disruption of favourable epistatic gene combinations. In this study we investigated the importance of various gene effects for different traits in the parents and generations F1 to F5 derived from 99 intra‐ and inter‐pool crosses among 20 lines of the Minor, Major, and Mediterranean germplasm pools of faba bean in Mediterranean and German environments. Yield performance of parental inbreds and progenies of crosses in different selfing generations was high in the region of adaptation of the respective germplasm pool. Heterosis for yield was greatest in interpool crosses of Minor × Mediterranean germplasm, amounting to 106% in Mediterranean and 72% in German environments. Interpool crosses exhibited significantly greater heterosis compared with intrapool crosses in both mega‐environments. Generation means analysis revealed the importance of additive gene effects and dominance × dominance epistasis in Mediterranean and German environments. Dominance effects and additive × additive epistasis for yield were negligible in most crossing groups. Since intrapool crosses of Mediterranean germplasm in Mediterranean environments and crosses of Minor and Major germplasm in the German environments were most promising, we suggest crosses among adapted germplasm for hybrid breeding and for establishing new base material in line breeding in faba bean.
The influence of auxin type on the array of somaclonal variants generated from somatic embryogenesis of eggplant, Solanum melongena L.
Authors: Hitomi A. , Amagai H. , Ezura H.
Published: April 2006

Somaclonal variation is a possible source of variation in plant breeding. To apply this approach to eggplant breeding, somaclonal variations were observed among plants regenerated through somatic embryogenesis induced by 1‐naphthaleneacetic acid (NAA) or 2,4‐dichlorophenoxyacetic acid (2,4‐D). Variations including leaf shape, plant height, flower number per cluster, fruit shape, anther number per flower and pollen fertility were compared among ≅ 300 plants (R0). Although these variations were confirmed among plants regenerated using both auxins, the frequencies of somaclonal variations in leaf shape, plant height, fruit shape and pollen fertility in the NAA experiment were higher than those in the 2,4‐D experiment. Variations in flower number and anther number were also confirmed among plants from both experiments, although no significant differences in their frequency were observed. Subsequently, the inheritance of variations (leaf shape, fruit shape, and flower number) observed in R0 was investigated from generation to generation (R1). Variations in leaf shape and fruit shape were inherited while those in flower number were not. From these results we concluded that, although a high frequency of somaclonal variations were observed among plants from both methods, embryogenesis with NAA was more efficient than 2,4‐D in eggplant.
Pollen storage at low temperature as a procedure for the improvement of cold tolerance in spring rape, Brassica napus L.
Authors: Lyakh V. A. , Soroka A. I. , Kalinova M. G.
Published: April 2006

The possibility of selecting spring rape for cold tolerance at the mature pollen grain stage was studied by investigating the effects of pollen storage at low temperatures on the quality of pollen grains and on the cold tolerance of the plants generated from them. Pollen treatments of F1 hybrids affected fertilization ability much more than viability and even after 10 days storage at 3 or 10°C the pollen germination percentage was reasonably high. Pollen storage for 7 or 10 days at 3 or 10°C significantly increased the cold tolerance of F2 seed germination, with 3°C being more effective. Pollen storage for a shorter time had no effect upon the number of resulting genotypes tolerant to low temperature. This approach may be successfully applied in plant breeding to enrich segregating plant populations with cold‐tolerant genotypes.
AMMI analysis of rainfed lowland rice (Oryza sativa) trials in Nigeria
Authors: Abamu F. J. , Alluri K.
Published: April 2006

The additive main effects and multiplicative interaction (AMMI) model is used to analyse the grain yield data of 13 rice genotypes grown in 12 rainfed lowland rice environments. The trials were organized by the International Network for Genetic Evaluation of Rice in Africa (INGER‐Africa) and conducted in Nigeria. Main effects due to environments (E), genotypes (G) and G × E interaction were found to be significant (P = 0.001). Cross validation analysis suggested that an AMMI model with one interaction principal component axis (IPCA) was most useful predictively, whereas Gollobs’ test declared two components, IPCA1 and IPCA2, statistically significant (P = 0.01). The IPCAl, however, accounted for most (47.8%) of the G × E sum of squares. Correlation and regression analysis, and relative scatter of genotype and environment points on the AMMI biplot suggest that the interaction partitioned in IPCA1 resulted from differences in the days to flowering among the genotypes. The paper discusses these in relation to the occurrence of Fe toxicity at the test sites and varietal tolerance to the stress.
Tetralocular mustard, Brassica juncea: New promising variability through interspecific hybridization
Authors: Katiyar R. K. , Chamola R. , Chopra V. L.
Published: April 2006

Lines of Brassica juncea with tetralocular (four‐valved) pods were produced by interspecific hybridization between dilocular (two‐valved) B. juncea var. Pusa Barani and tetralocular yellow‐seeded turnip rape (Brassica rapa ssp. trilocularis) var. YID‐1. Some selected lines were significantly superior to their parents for some agronomic traits, including seed yield and harvest index. Line 11 was the best among these and recorded 70% yield advantage in plot yield.
Genetic mapping of sedimentation volume across environments using recombinant inbred lines of durum wheat
Authors: Blanco A. , Bellomo M. P. , Lotti C. , Maniglio T. , Pasqualone A. , Simeone R. , Troccoli A. , Di Fonzo N.
Published: April 2006

SDS‐sedimentation volume (SV) is a biochemical index widely used to evaluate flour quality in durum and bread wheats. Significant association between SV and endosperm proteins (gliadin, high‐molecular‐weight‐ and low‐molecular‐weight‐glutenin subunits) have been reported. Protein loci, however, account for only a portion of the total genetic variability. The objective of this study was to identify and locate quantitative trait loci (QTLs) associated with SV in a set of recombinant inbred (RI) lines, derived from a cross between the cv.‘Messapia’ of durum wheat and the accession MG4343 of the var. dicoccoides, and characterized for 259 genetic and molecular (RFLP) markers. Significant differences were detected for the quality index in the six environments examined, while the pattern of variability was that of a quantitative trait. Regression analysis of marker loci and sedimentation volume indicated, as expected, that chromosome 1B, on which are located the Gli‐B 1/Glu‐B 3 loci for some gliadin and glutenin subunits, is important for wheat quality. Two additional regions located on chromosomes 6AL and 7BS, and four regions on 1AL, 3AS, 3BL and 5AL, were shown to have single‐factor effects on sedimentation volume at P < 0.001 and P < 0.01, respectively. Positive effects were contributed by both parents. A multiple linear regression model consisting of seven significant loci on different chromosomes explained 62–91% of the genotypic variation of the trait. The availability of linked markers to QTLs may facilitate the genetic dissection of quantitative traits and the early selection in wheat breeding programmes.
Genetic variation of β‐amylase thermostability among varieties of barley, Hordeum vulgare L., and relation to malting quality
Authors: Kihara M. , Kaneko T. , Ito K.
Published: April 2006

To investigate variation in the thermostability of β‐amylase among varieties of barley, Hordeum vulgare L., crude enzyme was extracted from the seeds, and the relative remaining activity was calculated after heat treatment. Our results indicated that the varieties tested were divided into three groups (types A, B and C). All the latest Japanese malting varieties showed high themostability (type A), while European, North American and Australian varieties showed intermediate (type B) or low thermostability (type C). Isoelectric focusing (IEF) of β‐amylase was also investigated. Type B varieties divided into two subtypes (types B1 and B2) based on two different IEF patterns (types I and II), whereas those of types A and C showed only one IEF pattern (type II). We also examined their thermostability in the varieties based on the pedigrees of the Japanese malting barley. Our results indicated that the thermostability of β‐amylase had a close relationship to fermentability for the production of beer. This fact suggests that the thermostability of β‐amylase has a significant influence on the malting quality of barley.
Genotypic variation for in vitro criteria and relationships with in vivo digestibility in forage maize hybrids
Authors: Argillier O. , Barrière Y. , Dardenne P. , Emile J. C. , Hébert Y.
Published: April 2006

The aim of this work was to study the genotypic variation for in vitro digestibility and composition traits within maize elite hybrids, and their relationships with in vivo digestibility traits. Experiments using 58 maize hybrids were carried out in four French environments in 1995. Near‐infrared reflectance spectroscopy (NIRS) was used to determine in vitro digestibility (whole‐plant and cell‐wall digestibility) and biochemical composition (starch, soluble carbohydrates, neutral detergent fibre, acid detergent lignin, protein and ash contents). The 58 hybrids were also studied at INRA, Lusignan, France, within a long‐term experiment to determine their in vivo digestibility of organic matter and of crude fibre using standard sheep. Genotypic variation was studied and relationships between hybrid mean values for in vitro parameters and in vivo digestibilities were examined. For evaluation and breeding purposes, it is possible to discriminate maize elite hybrids according to their digestibility, especially for discarding low‐value genotypes. in vitro parameters, such as in vitro whole‐plant digestibility and cell‐wall digestibility associated with cell‐wall content, can be routinely investigated with NIRS. Accurate criteria that are satisfactorily relevant to reference data of in vivo digestibility evaluated with standard sheep can be obtained to explain about 60% of the variation.
Anther culture response of wild Oryza species
Authors: Tang K. , Sun X. , He Y. , Zhang Z.
Published: April 2006

Thirteen different wild species of the genus Oryza were investigated for their response to anther culture and plant regeneration. Callus induction from microspores of anthers was found to be strongly dependent on the species. Although large numbers of anthers from wild Oryza species, including O. barthii, O. latifolia, O. australiensis, O. minuta, O. nivara, O. paraguagensis and O. eichingeri, were cultured, no calli could be obtained. However, calli were produced from anthers of O. punctata, O. perennis, O. alta, O. ridleyi and O. rufipogon, although the frequency of callus induction was different. Similar species‐dependence was observed in plant regeneration from microspore‐derived calli. In total, 62 plants were derived from anther culture, including 47 albino and 15 green plants (of which 26.7% were haploids) from O. perennis; for the first time, six albino plants were obtained from O. ridleyi. Phytohormone combinations in the callus induction medium were found to influence callus induction and different wild Oryza species exhibited their own preferred phytohormone combinations for anther culture. In general, NK medium containing suitable concentrations of auxin and cytokinin may be successfully applied for anther culture of selected wild Oryza species.
Genomic structure of androgenic progeny of pentaploid hybrids, Festuca arundinacea × Lolium multiflorum
Authors: Zwierzykowski Z. , Lukaszewski A. J. , Lesniewska A. , Naganowska B.
Published: April 2006

To assess the usefulness of the doubled haploid (DH) method in the breeding of forage grasses, a sample of anther‐derived progeny of pentaploid F1 hybrids of Festuca arundinacea × Lolium multifiorum was karyotyped using genomic in situ hybridization (GISH). The technique allowed scoring of the total number of chromosomes, the number of chromosomes contributed by each parent, and the number and positions of the Festuca‐Lolium translocation breakpoints. Among 27 plants analysed, 13 belonged to three clones, effectively reducing the number of different progeny karyotyped to 17. These included 10 haploids, five doubled haploids and two plants for which the origins could not be explained. In all plants analysed, a mixture of chromosomes of both parents was present, including an average of 1.88 intergeneric translocations per plant. The translocation breakpoints were distributed along almost the entire length of the chromosome arms. Chromosome variation among androgenic progeny appeared much wider than that in the conventional backcross but low vigour and high mortality suggest that this additional variation may be difficult to exploit directly in breeding. However, a change in the pattern of recombination makes the entire genome accessible to manipulation.
High frequency of plant regeneration from anther culture in flax, Linum usitatissimum L.
Authors: Chen Y. , Kenaschuk E. , Dribnenki P.
Published: April 2006

The effects of induction medium compositions on flax anther culture were investigated in order to improve the efficiency of callus induction and plant regeneration. Anthers were inoculated onto the modified MS medium supplemented with five different combinations of plant growth regulators. The medium containing the combination of 2mg/l 2,4‐ dichlorophenoxy‐acetic acid (2,4‐D) and 1 mg/1 6‐benzylaminopurine (BAP) produced a significantly higher number of calli forming shoots/100 responded anthers and a significant increase in overall efficiency of regeneration than the same basal medium containing 1 mg/1 a‐naphthalene‐acetic acid (NAA) and 2 mg/1 BAP (CK). Among the five levels of thiamin hydrochloride tested, the modified MS medium containing 10 mg/1 thiamin hydrochloride significantly increased the number of calli forming shoots/100 responded anthers and the overall efficiency of regeneration compared with the same basal medium containing 0.1 mg/1 thiamin hydrochloride. Maltose concentration had a significant effect on the percentage of anthers producing call, the number of calli forming shoots/100 responded anthers and the overall efficiency of regeneration. The medium containing 6% or 9% maltose produced the highest overall efficiency of regeneration among the five levels of maltose evaluated. Sucrose concentration significantly affected the number of calli forming shoots/100 responded anthers and the overall efficiency of regeneration, and dramatically affected the frequency of microspore‐derived plants and the frequency of spontaneous chromosome doubling in microspore‐derived plants. The efficiency of doubled haploid line production obtained in this study appears adequate for applied breeding programmes.
Multiple changes in tobacco mitochondrial DNA populations during tissue culture
Authors: KANAZAWA A.
Published: April 2006

Changes in the composition of mitochondrial DNA (mtDNA) in tobacco during the processes of long‐term tissue culture and regeneration were detected by DNA gel blot analyses using several mtDNA fragments as probes. The changes in mtDNA were identified by differential accumulations of mtDNA fragments in cultured cells that were hybridized with probes atp6, cob, and nad3‐rpsl2. The changes detected by each probe did not appear to be linked, since they were different with each probe and in different subcultures of calli. Based on the current results and previous detailed analyses of the changes detected by atp6, a possible model that explains the alterations in mtDNA during tissue culture is presented. In this model, the changes are attributed to multiple shifts in the equilibrium that was maintained between different subgenomic mtDNA molecules.
Genetic diversity in mung bean germplasm revealed by RAPD markers
Authors: SANTALLA M. , POWER J. B. , DAVEY M. R.
Published: April 2006

Knowledge of the genetic relationships among landraces is useful to gene bank managers because it permits a better organization of the crop's gene pool management, more efficient sampling of the available germplasm resources and better access to useful genetic variation for breeders. Genetic diversity of 19 landraces of the cultivated mung bean, Vigna radiate, and three weedy and wild relatives including Vigna mungo, Vigna luteola and Vigna radiate var. sublobata, was investigated at the DNA level with the random amplified polymorphic DNA (RAPD) procedure. Sixty random decamer primers were employed in amplification reactions; 28 of these were informative and yielded 246 bands, of which 229 were polymorphic with a mean of 8.2 bands per primer. A genetic distance matrix based on Nei and Li coefficient was converted to a dendrogram and a two‐dimensional plot using multidimensional scaling (MDS). The accessions studied were separated into three main clusters, which included V. radiate landraces, V. mungo and V. luteola, respectively. The variation of this cluster supports the view that the genetic distance of V. mungo and V. luteola varies considerably from the accession VO2955 (V. radiata). The multidimensional scaling plot confirmed that V. mungo, V. luteola and most of the accessions of V. radiata formed distinct clusters with no overlap, and two mung bean accessions (PI177493 and VO4134–1 from Turkey and India, respectively) were genetically distant from other V. radiata landraces. V. radiata and V. mungo are positioned in separate botanical species and V. radiata var. sublobata is classified within other V. radiata landraces. Based on the limited range of accessions tested, the approach holds promise for the classification of mung bean germplasm, identification of mung bean landraces and applications of molecular markers to mung bean breeding.
Production of diploid and triploid interspecific hybrids between Lilium concolor and L. longiflorum by in vitro ovary slice culture
Authors: Arzate‐Fernández A.‐M. , Nakazaki T. , Tanisaka T.
Published: April 2006

Successful hybridization between Lilium concolor and Lilium longiflorum has not been reported but ovary slice culture technique, after cut‐style pollination has now been used to produce diploid and triploid interspecific hybrids between these species. Reciprocal crosses between diploid cultivars (2n= 2x= 24) were conducted. 5, 10, 15, 20, 25, 30, 35, 40, and 45 days after pollination (DAP), ovaries were sliced and cultured on a modified Murashige and Skoog (MS) medium without growth regulators and NH4NO3, supplemented with 6% sucrose, 50 mg/1 yeast extract and 0.25% gelrite at pH 6.3. For the L. concolor × L. longiflorum cross, embryo germination was found to be best at 20 DAP, while for the L. longiflorum × L. concolor at 25 DAP. After transfer to a MS (half‐strength) medium supplemented with 1.5% sucrose, 0.25% gelrite and 0.2% active charcoal at pH 5.8, diploid and triploid hybrid plants were developed. All regenerated plants were identified as hybrids on the basis of karyotype and isozyme analyses. Ovary slice culture technique as a method of producing polyploids is discussed.
Production of haploids in bread wheat, durum wheat and hexaploid triticale crossed with pearl millet
Authors: Inagaki M. N. , Hash C. T.
Published: April 2006

Pearl millet is an efficient alternative to maize as a pollen source for haploid production in bread wheat. To compare haploid production frequencies in other Triticeae species, the crossabilities of two genotypes each of bread wheat, durum wheat and hexaploid triticale with four pearl millet genotypes and a maize control were examined. Embryos were obtained from crosses of all three species with both pearl millet and maize. However, significant differences in crossability were found among the three species (10.5–79.8% seed development and 1.4–15.8% embryo formation), as well as among genotypes of durum wheat (7.2–23.7% and 2.1–6.4%) and hexaploid triticale (0.3–20.6% and 0.1–2.7%). Crossability of bread wheat with pearl millet was relatively high. Haploid plants were regenerated from crosses of all three species with pearl millet. As in the case of maize crosses, low crossabilities of durum wheat and hexaploid triticale with pearl millet can be attributed to the absence of D‐genome chromosomes.
Morphological characteristics of hybrids between white clover, Trifolium repens L., and Caucasian clover, Trifolium ambiguum M. Bieb
Authors: Abberton M. T. , Michaelson‐Yeates T. P. T. , Marshall A. H. , Holdbrook‐Smith K. , Rhodes I.
Published: April 2006

Hybrids between the stoloniferous Trifolium repens (2n = 4x = 32) and the rhizomatous Trifolium ambiguum (2n = 4x = 32) have been produced using T. repens as the recurrent parent. Morphological characteristics of the parent species and the F1, BC1, BC2 and BC3 hybrids were examined in a glasshouse experiment. Leaflet ratios and general plant shape indicated that the BC3 hybrid was similar to T. repens. Separation of plants into components of above‐ and below‐ground growth showed that T. repens had a greater total plant dry weight than T. ambiguum but 24% of its dry weight was in roots compared with 22% in roots and 44% in rhizomes in T. ambiguum. The BC3 generation contained plants that were predominantly T. repens‐like with stolons, but also had a small proportion of their total dry weight (3%) as rhizome, confirming the potential to produce plants that combine stoloniferous and rhizomatous growth. The proportions of rhizome and stolon varied within the BC3 generation, enabling farther selection and plant breeding. The BC3 hybrids produced similar numbers of inflorescences to T. repens however, fertility was lower, although there was some variation within the BC3 for both characters.
Fusarium vascular wilt in lentil: Inheritance and identification of DNA markers for resistance
Authors: Eujayl I. , Erskine W. , Bayaa B. , Baum M. , Pehu E.
Published: April 2006

The inheritance of resistance to lentil (Lens culinaris Medik.) vascular wilt caused by Fusarium oxysporum f.sp. lentis was investigated in a cross between resistant (ILL5588) and susceptible (L692–16‐l(s)) lines. F2:4 progenies and F6:8, F6:9 recombinant inbred line (RIL) populations were assessed for their wilt reaction for three seasons in a well‐established wilt‐sick plot. Resistance to wilt was conditioned by a single dominant gene in the populations studied. The map location of the Fw locus was identified for the first time through linkage to a random amplified polymorphic DNA (RAPD) marker (OPK‐15900) at 10.8 cM. Two other RAPD markers (OP‐BH800 and OP‐DI5500) identified by bulked segregant analysis were associated in the coupling phase with the resistance trait, and another marker (OP‐C04650) was associated with repulsion. The DNA markers reported here will provide a starting point in marker‐assisted selection for vascular wilt resistance in lentil.