bluuebunny/crossref_metadata_2025 huggingface dataset:
Absence of the Lhcb1 and Lhcb2 proteins of the light‐harvesting complex of photosystem II – effects on photosynthesis, grana stacking and fitness
Authors: Jenny Andersson , Mark Wentworth , Robin G. Walters , Caroline A. Howard , Alexander V. Ruban , Peter Horton , Stefan Jansson
Published: July 2003

We have constructed Arabidopsis thaliana plants that are virtually devoid of the major light‐harvesting complex, LHC II. This was accomplished by introducing the Lhcb2.1 coding region in the antisense orientation into the genome by Agrobacterium‐mediated transformation. Lhcb1 and Lhcb2 were absent, while Lhcb3, a protein present in LHC II associated with photosystem (PS) II, was retained. Plants had a pale green appearance and showed reduced chlorophyll content and an elevated chlorophyll a/b ratio. The content of PS II reaction centres was unchanged on a leaf area basis, but there was evidence for increases in the relative levels of other light harvesting proteins, notably CP26, associated with PS II, and Lhca4, associated with PS I. Electron microscopy showed the presence of grana. Photosynthetic rates at saturating irradiance were the same in wild‐type and antisense plants, but there was a 10–15% reduction in quantum yield that reflected the decrease in light absorption by the leaf. The antisense plants were not able to perform state transitions, and their capacity for non‐photochemical quenching was reduced. There was no difference in growth between wild‐type and antisense plants under controlled climate conditions, but the antisense plants performed worse compared to the wild type in the field, with decreases in seed production of up to 70%.
Target genes for OBP3, a Dof transcription factor, include novel basic helix‐loop‐helix domain proteins inducible by salicylic acid
Authors: Kang Hong‐Gu , Foley Rhonda C. , Oñate‐Sánchez Luis , Lin Chentao , Singh Karam B.
Published: July 2003

Overexpression of a salicylic‐acid (SA)‐inducible Arabidopsis DNA binding with one finger (Dof) transcription factor, called OBF‐binding protein 3 (OBP3; AtDof3.6), has previously been shown to result in growth defects. In this study, suppressive subtraction hybridization (SSH) was used to isolate genes induced in an OBP3‐overexpression line and several putative clones, called OBP3‐responsive genes (ORGs), were isolated. The link with the induced expression levels of these genes and OBP3 overexpression was confirmed by analysing additional OBP3‐overexpression lines. ORG1 through ORG4 are novel genes, while ORG5 is an extensin gene, AtExt1. While ORG4 has no similarity with other proteins in the database, ORG1 has weak similarity in different regions of the predicted protein with CDC2 and fibrillin. ORG2 and ORG3 share 80% overall identity in their deduced amino acid sequences and contain a basic helix‐loop‐helix DNA‐binding domain, suggesting that ORG2 and ORG3 may be transcription factors. The expression of the ORG1, ORG2 and ORG3 genes was co‐regulated under all conditions examined including upregulation by SA and downregulation by jasmonic acid (JA). Fifteen OBP3‐silenced lines were generated to further explore the function of OBP3. Although there were no visible phenotypic changes in any of these lines, the expression of ORG1, ORG2 and ORG3 was reduced. Among the ORG genes, ORG1, ORG2 and ORG3 contained the highest number of potential Dof‐binding sites in the promoter region, and their expression was significantly increased within 3 h after induction of OBP3 expression using an inducible promoter system, and closely reflected the expression levels of the exogenous OBP3 protein. The results from the gain‐of‐function and loss‐of‐function experiments suggest that the ORG1, ORG2 and ORG3 genes are direct target genes of OBP3.
The SPA1‐like proteins SPA3 and SPA4 repress photomorphogenesis in the light
Authors: Laubinger Sascha , Hoecker Ute
Published: July 2003

Suppressor of phyA‐105 (SPA1) is a phytochrome A‐specific signaling intermediate that acts as a light‐dependent repressor of photomorphogenesis in Arabidopsis seedlings. SPA1 is part of a small gene family comprising three genes: SPA1‐related 2 (SPA2), SPA1‐related 3 (SPA3), and SPA1‐related 4 (SPA4). Here, we investigate the functions of SPA3 and SPA4, two very closely related genes coding for proteins with 74% identical amino acids. Seedlings with mutations in SPA3 or SPA4 exhibit enhanced photomorphogenesis in the light, but show no phenotype in darkness. While there are small differences between the effects of spa3 and spa4 mutations, it is apparent that SPA3 and SPA4 function to inhibit light responses in continuous far‐red, red, and blue light. Phytochrome A is necessary for all aspects of the spa4 mutant phenotype, suggesting that SPA4, like SPA1, acts specifically in phytochrome A signaling. Enhanced photoresponsiveness of spa3 mutants is also fully dependent on phytochrome A in far‐red and blue light, but not in red light. Hence, SPA3 function in red light may be dependent on other phytochromes in addition to phytochrome A. Using yeast two‐hybrid and in vitro interaction assays, we further show that SPA3 as well as SPA4 can physically interact with the constitutive repressor of light signaling COP1. Deletion analyses suggest that SPA3 and SPA4, like SPA1, bind to the coiled‐coil domain of COP1. Taken together, our results have identified two new loci coding for negative regulators that may be involved in fine tuning of light responses by interacting with COP1.
Systemic movement of a tobamovirus requires host cell pectin methylesterase
Authors: Chen Min‐Huei , Citovsky Vitaly
Published: July 2003

Systemic movement of plant viruses through the host vasculature, one of the central events of the infection process, is essential for maximal viral accumulation and development of disease symptoms. The host plant proteins involved in this transport, however, remain unknown. Here, we examined whether or not pectin methylesterase (PME), one of the few cellular proteins known to be involved in local, cell‐to‐cell movement of tobacco mosaic virus (TMV), is also required for the systemic spread of viral infection through the plant vascular system. In a reverse genetics approach, PME levels were reduced in tobacco plants using antisense suppression. The resulting PME antisense plants displayed a significant degree of PME suppression in their vascular tissues but retained the wild‐type pattern of phloem loading and unloading of a fluorescent solute. Systemic transport of TMV in these plants, however, was substantially delayed as compared to the wild‐type tobacco, suggesting a role for PME in TMV systemic infection. Our analysis of virus distribution in the PME antisense plants suggested that TMV systemic movement may be a polar process in which the virions enter and exit the vascular system by two different mechanisms, and it is the viral exit out of the vascular system that involves PME.
Evaluation of in vitro activity of ciclopirox olamine, butenafine HCl and econazole nitrate against dermatophytes, yeasts and bacteria
Authors: Kokjohn Katrina , Bradley Mary , Griffiths Brian , Ghannoum Mahmoud
Published: July 2003

Background  In many instances, a cutaneous fungal infection may exist concomitantly with bacterial involvement. In this study we compared the in vitro activity of three antifungal agents against the dermatophytes, yeasts and bacteria recovered most commonly from cutaneous mycoses and bacterial infections.

Methods  Using a microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS), we determined the minimum inhibitory concentrations (MICs) of ciclopirox olamine, econazole nitrate and butenafine HCl against a panel of dermatophyte fungi and yeasts (n = 39) and bacterial isolates (n = 45).

Results  All three antifungals demonstrated comparable activity against the dermatophytes tested, with a MIC range of 0.03–0.25 µg/ml for ciclopirox, < 0.001–0.25 µg/ml for econazole and 0.03–0.25 µg/ml for butenafine. For yeasts, ciclopirox showed activity against all isolates, with an MIC range of 0.001–0.25 µg/ml, whereas econazole had a broader range of 0.125–> 0.5 µg/ml. Butenafine displayed limited activity against the yeast Candida albicans and no activity against Malassezia furfur. For the antibacterial activity studies, ciclopirox demonstrated activity against all isolates tested with a range of 0.06–2 µg/ml, while econazole showed activity against Gram‐positive bacteria only, with a MIC range of 0.004–0.25 µg/ml. Butenafine HCl had a limited activity against bacterial isolates tested, showing activity against β‐hemolytic Streptococcus Group A and Corynebacterium only. Neither econazole nitrate nor butenafine HCl demonstrated activity against any of the Gram‐negative strains evaluated in this study.

Conclusions   The data suggest that ciclopirox olamine has the broadest in vitro activity, in comparison to econazole and butenafine HCl, against bacteria, yeasts and bacteria. These findings may have implications in the use of these antimycotics in the treatment of mixed cutaneous infections where bacteria or yeasts are present in addition to dermatophytes.
Effect of Nitrogen Rate and Stubble Height on Dry Matter Yield, Crude Protein Content and Crude Protein Yield of a Sorghum–Sudangrass Hybrid[Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf.] in the Three‐Cutting System
Authors: Iptas S. , Brohi A. R.
Published: July 2003

In this study, the effects of nitrogen (N) rate (60, 120, 180 and 240 kg N ha−1 applied in three equal dressings at seeding and after the first and second cuttings) and stubble height (7, 14 and 21 cm) on the dry matter (DM) yield, crude protein (CP) content, and CP yield of a sorghum–sudangrass hybrid [Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf., cv. Pioneer 988] in the three‐cut system was investigated. The N rate had no significant effect in the first and third cuttings, but in the second cutting DM yields increased significantly with increase in N rate. The highest yield of 9.1 t ha−1 was obtained with 80 kg N ha−1 for the average of 2 years at the second cutting, but no significant difference was found among the 40, 60 and 80 kg N ha−1 rates. CP content and yield were not significantly affected by N rate at the first and third cuttings, but CP content and yield were significantly affected by application of N at the second cutting. Stubble height had a significant effect on CP content at the third cutting. However, it had no significant effect on CP content at the first and second cuttings. Stubble height had a significant effect on the CP yield at the first cutting, but no significant effect on CP yield at the second and third cuttings.
The Influence of Row Spacing and Seeding Rate on Seed Yield and Yield Components of Forage Turnip (Brassica rapa L.)
Authors: Bilgili U. , Sincik M. , Uzun A. , Acikgoz E.
Published: July 2003

The effects of four row spacings (17.5, 35.0, 52.5 and 70.0 cm) and five seeding rates (50, 100, 200, 400 and 800 viable seeds m−2) on seed yield and some yield components of forage turnip (Brassica rapa L.) were evaluated under rainfed conditions in Bursa, Turkey in the 1998–1999 and 1999–2000 growing seasons. Plant height, stem diameter, pods/terminal raceme, total pods/plant, seeds/pod and primary branches/plant were measured individually. The number of plants per unit area was counted and the lodging rate of the plots was scored. The seed yield and 1000‐seed weight were also determined. Row spacing and seeding rate significantly affected most yield components measured. The number of plants per unit area increased with increasing seeding rate and decreasing row spacing. Plant height was not greatly influenced by row spacing and seeding rate, but higher seeding rates reduced the number of primary branches and the stem diameter. The number of pods/main stem was affected by row spacing and but not by the seeding rate. Also, the number of seeds per pod was not affected by either the row spacing or the seeding rate. In contrast, the number of pods per plant clearly increased with increasing row spacing, but decreased with increasing seeding rate. The plots seeded at narrow row spacings and at high seeding rates were more sensitive to lodging. Seeding rate had no significant effect on seed yield in both years. Seed yield was similar at all seeding rates, averaging 1151 kg ha−1. However, row spacing was associated with seed yield. The highest seed yield (1409 kg ha−1) was obtained for the 35.0‐cm row spacing and 200 seeds m−2 seeding rate combination without serious lodging problems.
Bulbil Formation and Yield Responses of Chinese Yam to Application of Gibberellic Acid, Mepiquat Chloride and Trinexapac‐ethyl
Authors: Kim S. K. , Lee S. C. , Lee B. H. , Choi H. J. , Kim K. U. , Lee I. J.
Published: July 2003

A field experiment was conducted in three successive years at the Institute of Bioresources, Kyongbuk Provincial Agricultural Technology Administration, Andong, South Korea, to determine the effects of gibberellic acid (GA3) and the two plant growth retardants mepiquat chloride (MC) and trinexapac‐ethyl (TNE) on bulbil formation and yield, including tuber yield responses, in the Chinese yam. The most effective plant growth retardant in inducing early bulbil formation was MC in the three successive seasons. MC treatment greatly increased bulbil yield compared with the control in the three successive years. It also markedly increased the ratio of bulbil size (> 4 mm) compared with the control. Furthermore, the ratio of bulbil size (> 4 mm) was greatly increased at highest MC concentration (600 p.p.m.) to 65.4 %. Tuber yield per hectare was significantly increased by GA application compared with the control. GA application at the highest concentration (600 p.p.m.) was most effective in increasing tuber size in Chinese yam.
RFLP diversity within and between major groups of barley in Europe
Authors: Backes G. , Hatz B. , Jahoor A. , Fischbeck G.
Published: July 2003

Restriction fragment length polymorphism (RFLP) diversity has been determined and analyzed as expressed by 33 single‐ or low‐copy clone/ enzyme combinations at 32 loci distributed over all chromosomes of the barley genome within a sample of 223 European barley accessions comprised of pure line (single‐head progenies) genotypes. The accessions have been selected to include landraces and widely grown cultivars derived from crossbreeding during the 20th century in North‐, West‐ and Central European countries. Genetic diversity obtained from 83 alleles across all accessions is characterized by the diversity index H = 0.385. The diversity indices determined for landraces and cultivars were almost equal, with the difference between spring (H = 0.260) and winter (H = 0.415) barley approaching statistical significance, while comparisons of other groupings only revealed statistically insignificant trends. A more detailed analysis based on differences in allele frequency distributions at each locus (clone/enzyme combinations resp.) revealed very clear differences related to the existence, continuity and dynamics of changes in group‐specific RFLP profiles. With the majority (69%) of RFLP alleles at 23 out of 32 loci on all barley chromosomes involved, contributions from chromosomes 1H, 3H, 4H and 5H seem to be of special importance. Differences in the overall average of abundance indicate higher levels of genetic diversity within both groups of winter barley compared with both groups of spring barley, from which the most frequent alleles at 15 (2‐rowed spring barley) and 17 (6‐rowed spring barley) RFLP loci approach fixation. The results of this study are discussed in relation to the history of barley cultivation and barley breeding in Europe, and possible explanations for group‐specific differences in the RFLP profiles of landraces and cultivars as well as for the high levels of (nearly) fixed alleles of both subsets of spring barley, and with respect to progress in barley breeding that it has been possible to obtain within the rather narrow RFLP profiles.
Associations of simple sequence repeats with quantitative trait variation including biotic and abiotic stress tolerance in Hordeum spontaneum
Authors: Ivandic V. , Thomas W. T. B. , Nevo E. , Zhang Z. , Forster B. P.
Published: July 2003

abstract

A total of 33 simple sequence repeats (SSRs) was analyzed in 52 genotypes of Hordeum spontaneum originally collected from two different soil types (Terra rossa and Basalt) at Tabigha in Israel. Data on the performance of developmental, morphological, and yield‐related traits under well‐watered control and water‐stress conditions were available from previous experimentation, and powdery mildew susceptibility was scored. Regression analyses based on SSR allele class differences were performed. Highly significant associations were detected at the SSR loci Bmac181 (on chromosome 4H) and Bmac316 (6H) for water ‐stress tolerance and powdery mildew resistance, respectively. The study shows that association mapping using SSRs and genetically diverse germplasm provides an effective means of relating genotypes to complex quantitative phenotypes.
Clonal selection in ‘Uzunmusa’ hazelnut
Authors: İ Slam A.
Published: July 2003

Clonal selection was practised in ‘Uzunmusa’ hazelnut over the past 3 years (1999‐2001) to select the highest quality types. Based on an initial assessment of a total of 102 types, 45 were selected for further study. The best types were selection numbers (SN) 397 and 570. The two selected clones have very good characteristics and seem to be superior to the standard clone. The clones had a higher kernel percentage (62.72%), a higher number of nuts per cluster (5.5), thinner shells (0.75 mm) and heavier nuts (2.34 g). On the other hand, the clones seem to be very suitable for the nut industry because of their oil content and size. These types have very thin shells which are suitable for in‐shell market.
Reciprocal effects in true potato seed breeding in short‐day length environments
Authors: Golmirzaie A. M. , Ortiz R.
Published: July 2003

Reciprocal crosses may have significantly distinct performances regarding tuber characteristics in potato, suggesting the importance of cytoplasmic effects in this crop. The selection of parents for true potato seed breeding therefore needs to consider this potential effect when determining the direction of a cross. The aim of this research was to determine whether a broad‐based true potato seed breeding population, developed at the Centro Internacional de la Papa, could be affected by cytoplasmic effects in the short‐day length environments of the tropics. Two random sets of reciprocal biparental crosses were included in the first set of experiments, which were grown in two contrasting Peruvian locations. Only one out of 14 reciprocal crosses showed significantly distinct performance for tuber yield and tuber set. In the second set, only one of each of the 12 reciprocal crosses had distinct performance for vine earliness, days to flowering and flowering intensity, but four of the reciprocal crosses in the second set showed distinct pollen production. The results suggest that cytoplasmic effects in this breeding population are more important for reproductive characteristics such as pollen production than for tuber yield. This finding is not surprising because male sterility in potato results from the interaction between sensitive cytoplasm and dominant nuclear genes.
Molecular and agronomic evaluation of wheat doubled haploid lines obtained through maize pollination and anther culture methods
Authors: Guzy‐Wrobelska J. , Szarejko I.
Published: July 2003

Although maize pollination (MP) and anther culture (AC) are alternative techniques widely used for wheat doubled haploid (DH) production, there is only limited information on the attributes of the plant materials produced through both methods. This study was conducted to evaluate genetic fidelity, transmission of parental gametes, and to compare field performance of DH populations produced by the MP and AC methods from the F1s of two crosses between spring bread wheat cultivars. The DH populations were compared to single seed descent (SSD) lines created from the same crosses. In total, 76 MP and 122 AC lines of the cross between cultivars of divergent origin were subjected to RAPD and AFLP analysis. Only changes in AFLP banding patterns, at similarly low frequencies, 0.18% (MP) and 0.21% (AC), were detected. The frequency of the DH lines affected by the variation, 14.5% (MP) and 14.8% (AC), was similar in both populations. For most of the DH lines, variation in 1‐2 loci only, out of several hundreds scored, was observed. A total of 14.3% (MP) and 22.2% (AC) marker loci showed the significant segregation distortion from the expected 1 : 1 ratio, but in at least one polymorphic locus the within‐cultivar variation was responsible for the skewed segregation. The field performance of the corresponding MP and AC lines derived from two crosses confirmed the equivalency of both DH populations. In most of the traits analyzed, the MP and AC lines performed the same as the SSD populations created from the same crosses. No, or very small differences in means and ranges, were observed when the best 10% of the lines from all three methods were compared. Moreover, the best 10 % of the lines of the cross between Polish wheat cultivars adapted to the local environment performed significantly better for some traits than different groups of checks used in the study.
Assessment of genetic diversity in clover species from Sardinia, Italy, using AFLP analysis
Authors: Bennett S. J. , Mathews A.
Published: July 2003

Two species,Trifolium glomeratumandT. nigrescens, from Sardinia, Italy, were analysed for genetic diversity using amplified fragment length polymorphism (AFLP). Variation between and within populations was compared between the inbreeder,T. glomeratum, and the outbreeder,T. nigrescens.Four AFLP primer combinations resulted in a total of 292 loci, of which 75% were polymorphic inT. glomeratumand 85% in Trifolium nigrescens. Variation was highest between populations in both species, but the difference between populations was greater inT. glomeratum(Fst = 0.17), compared withT. nigrescens(Fst = 0.02). Cluster analysis and principal coordinates analysis were used to verify the relationships found. The high level of genetic variation within populations in both species is attributed to the movement of sheep between paddocks, the existence of both species in Sardinia for thousands of years and the persistence of a long‐lived seedbank due to the production of large numbers of small seeds with high levels of hard seededness.
Modification of tomato taste in transgenic plants carrying a thaumatin gene from Thaumatococcus daniellii Benth
Authors: Bartoszewski G. , Niedziela A. , Szwacka M. , Niemirowicz‐Szczytt K.
Published: July 2003

Fruit taste is an important component of fruit quality, but its genetic basis is complex, making it difficult to alter by plant breeding. Thaumatin is a sweet‐tasting, flavour‐enhancing protein produced by fruits of the African plant Thaumatococcus daniellii Benth. Agrobac‐terium‐mediated transformation was used to produce two transgenic tomato lines expressing biologically active thaumatin in fruits. Transgenic tomato fruits from the T2 plant generation were sweeter than the controls and possessed a specific aftertaste as determined by sensory evaluation. These results demonstrate that transgenic expression of thaumatin could be useful for modifying tomato fruit taste, especially in breeding lines possessing poor fruit taste, such as those carrying a non‐ripening (nor) mutation.
Long‐term conservation of embryogenic competence by induction and disorganization of somatic embryos in carrot
Authors: Nomura K.
Published: July 2003

A simple procedure was established to maintain the rate of somatic embryogenesis in carrot cell strains. Secondary cell strains were induced by the disorganization of heart‐shaped somatic embryos by transferring them into a medium containing 2,4‐dichlorophenoxyacetic acid and the rate of somatic embryogenesis was restored to the original level. It was possible to keep the original rate of embryogenesis by repeated induction and disorganization of somatic embryos, as the restored rate of embryogenesis decreased gradually during subcultures. In the carrot cell suspension culture used in this work, it was possible to keep high rates of somatic embryogenesis for at least 3 years by using this method at every 50th subculture. The method presented here should be useful to maintain regeneration competence in certain important cell strains.
Effect of parental genotypes and colchicine treatment on the androgenic response of wheat F1 hybrids
Authors: Zamani I. , Gouli‐Vavdinoudi E. , Kovacs G. , Xynias I. , Roupakias D. , Barnabas B.
Published: July 2003

The effect of the parental genotypes and colchicine treatment on the androgenic response of wheat (Triticum aestivum L.) F1 hybrids was studied. For this, anthers from three F1 hybrids and their parents were cultured on W14 initiation medium and W14 supplemented with 0.03% colchicine. The number of responding anthers, microspore‐derived structures/100 anthers, green plants/embryos cultured, green plants/100 anthers and albino plants/100 anthers were recorded. It was observed that embryo formation and plant regeneration ability were genetically controlled and genotype dependent. In both treatments the variety Kavkaz had a significantly higher percentage of responding anthers, microspore‐derived structures and green plants/100 anthers than the other genotypes. On the other hand, the variety Myconos also demonstrated high microspore‐derived structure production and green plant regeneration when treated with colchicine. The good response observed in these two varieties indicates the importance of colchicine treatment only for certain genotypes. Green plant production capacity of the hybrids was intermediate to that of the parental varieties. As one parent with a high or even an intermediate response to anther culture could lead to the production of sufficient (for breeding purposes) green plants from the F1 hybrids, it was concluded that screening the inbred lines for the response to anther culture with and without colchicine treatment could contribute to utilization of breeding material with a low response to anther culture via the proper hybrid combinations.
Improvement of maize populations for resistance to downy mildew
Authors: Ajala S. O. , Kling J. G. , Kim S. K. , Obajimi A. O.
Published: July 2003

Upgrading levels of disease resistance are a primary objective of maize breeding programmes. Efficacy of S1 recurrent selection in improving levels of resistance to downy mildew (DM) infection was assessed in Nigeria from 1997 to 2000 in six maize populations. Improvement procedures consisted of evaluating S1 progenies under artificial infection with DM spores and in disease‐free environments and using a selection index to combine selection for reduced DM infection with appropriate agronomic characters from more than one environment. Three to four cycles of selection were completed in each of the populations. Products from the different cycles of selection were evaluated and data collected on DM infection parameters and agronomic traits. Result obtained showed 3–4 cycles of selection were adequate to reduce DM infection levels significantly and increase grain yield. Downy mildew infection decreased by between 58 and 100% while grain yield increases ranged from 10 to 98% for the 2‐4 cycles of selection relative to the C0 (original). Selection increased grain yield with acceptable changes in plant height while maintaining maturity in disease‐free environments.
Characterization for agronomic use of cytoplasmic male‐sterility in sunflower (Helianthus annuus L.) introduced from H. resinosus Small
Authors: Echeverria M. M. , Salaberry M. T. , Rodriguez R. H.
Published: July 2003

A backcrossing programme was carried out both to assess the stability of a cytoplasmic male‐sterility (CMS) source from Helianthus resinosus, designated RES1, and to incorporate it into inbred sunflower lines (HA89, RHA271, RHA801). All the progenies, grown in different environments, were completely male‐sterile. This suggests that the expression of this cytoplasm is stable. Female‐fertility of lines HA89, RHA271 and RHA801 carrying CMS RES1 were compared with those of the corresponding fertile inbred lines. There were no differences in the number of seeds per head. This indicates that female‐fertility is not affected by RES1 cytoplasm. Cytological studies showed that meiosis proceeds normally until the tetrad stage; consequently, the absence of pollen is caused by alterations that take place during postmeiotic stages. With the aim of identifying male‐fertility restorer genotypes, crosses were made between HA89 (CMS RES1) plants and different annual diploid and perennial hexaploid Helianthus species. All the diploid germplasm evaluated behaved as a CMS RES1 maintainer. However, the hexaploid species, H. resinosus, H. x laetiflorus, H. pauciflorus and H. tuberosus, restored pollen fertility in CMS RES1 plants.
Cytological screening of rice TGMS lines
Authors: Kalaiyarasi R. , Vaidyanathan P.
Published: July 2003

An investigation was undertaken to develop new stable thermo‐sensitive genic male sterility (TGMS) rice lines in intermated progenies (IMPs) of TGMS lines by using an anther clearing technique. The results indicate that both pre‐ and post‐meiotic genetic systems operate during anther development for the expression of sterility in TGMS lines. In all the TGMS lines, sterile anthers were small with empty pollen grains of irregular shape, except for TS 16, which showed pollen‐free anthers. This indicates that the sensitive stage of TS 16 is around stage IV (stamen and pistil primordia) of panicle development. Distinct differences were observed between sterile and fertile phases with respect to anther size, shape and colour of the pollen grains in TS 18 and TS 29. The pollen grains at the sterile phase were small and irregular in shape while in the fertile phase they were plump and larger with a yellow colour, establishing that the occurrence of sterility in TS 18 and TS 29 is post‐meiotic. Three distinct classes of pollen fertility percentage viz. <20%, 50‐70% and >90% were observed in IMPs. Anther clearing in IMPs showed distinct developmental patterns of pollen production with respect to distinct classes of pollen fertility. Less than 20% pollen fertility was observed in hybrids such as TS 15 × TS 16, TS 15 × Co 47, TS 18 × TS 16 and TS 18 × Co 47 which hold promise for developing new TGMS lines with a good plant type and acceptable quality.
Heterosis and combining ability for grain yield and other agronomic traits in winter triticale
Authors: Oettler G. , Burger H. , Melchinger A. E.
Published: July 2003

Hybrid breeding is a widely discussed alternative for triticale. Heterosis as well as general (GCA) and specific combining ability (SCA) effects were estimated for eight agronomic traits. The experiment comprised 24 F1 hybrids, produced by a chemical hybridizing agent, together with their six female and four male parents, grown in drilled plots in two locations. In comparison with the mid‐parent values, hybrids averaged a 6.4 dt/ha (10.1%) higher grain yield, 8.4% more kernels per spike, a 6.8% higher 1000‐kernel weight, 9.7% lower falling number (FN) and 4.4% greater plant height. SCA effects for grain yield were significant and ranged from 4.5 to 6.9 dt/ha for grain yield. Together with GCA x location interactions, they explained most of the variation. For 1000‐kernel weight, GCA effects were predominant. SCA and interactions with location accounted for most of the variation in FN, whereas interactions were negligible for plant height. Correlations between mid‐parent and hybrid performance and between GCA and per se performance of parents were tight for all traits except grain yield, which allows for pre‐selection of parental lines. Although the amount of heterosis in triticale at present is closer to wheat than to rye, by selecting parents for combining ability and identifying heterotic patterns, grain yield heterosis of up to 20% appears sufficiently encouraging to embark on hybrid breeding.
AFLP analysis of Solanum phureja DNA introgressed into potato dihaploids
Authors: Straadt I. K. , Rasmussen O. S.
Published: July 2003

Introgression of Solanum phureja DNA into S. tuberosum dihaploids was analysed by the use of amplified fragment length polymorphism (AFLP) markers. Five dihaploids, derived from crosses between S. tuberosum cv. Pentland Crown and two different S. phureja pollinators (IVP48 and EC90) were investigated by use of 17 AFLP primer pairs. Also 30 dihaploids, derived from pollination of five different S. tuberosum seed parents with S. phureja IVP101, were investigated for the presence of S. phureja‐specific markers. In total approximately 680 and 850 AFLP products were detected in the diploid S. phureja clones and in the tetraploid S. tuberosum genotypes, respectively. A total of 68 S. phureja IVP48‐specific markers were detected, while the total number of S. phureja IVP101‐specific markers was in the range of 72‐96, depending on the S. tuberosum seed parent. Introgression of DNA in the S. tuberosum cv. Pentland Crown dihaploids, after pollination with S. phureja IVP48 and S. phureja EC90, was demonstrated by the detection of 14 of 68 IPV48‐specific markers in the dihaploids. However, no DNA introgression was found in any of the 30 S. tuberosum dihaploids derived from S. phureja IVP101. Hence, S. phureja IVP101 is regarded as an excellent pollinator in the production of S. tuberosum dihaploids in potato breeding programmes because of the high yield of dihaploids per 100 berries, and because no introgression of DNA into the S. tuberosum dihaploids was evidenced.
Inheritance and mapping of a yellow leaf mutant of carrot (Daucus carota)
Authors: Nothnagel T. , Straka P.
Published: July 2003

A yellow leaf mutant at a locus named YEL was selected in a population of the cultivated carrot. Genetic analysis of segregating F2 progenies and corresponding F3 families, indicates that the phenotype expressed is controlled by a single recessive nuclear gene. The mutant is stably inherited and is associated with a reduced leaf‐biomass of approximately 30% compared with the wild‐type. Amplified fragment length polymorphism markers were developed and used in bulked segregant analysis. Seventeen marker candidates were detected by using 45 primer pairs. Ten of these could be linked with the YEL locus and mapped in a linkage group with a total length of 33.2 cM. Application of the yellow leaf mutant in carrot research is discussed.
Concentration of moniliformin produced by Fusarium species in grains of transgenic Bt maize hybrids compared to their isogenic counterparts and commercial varieties under European corn borer pressure
Authors: Magg T. , Bohn M. , Klein D. , Merditaj V. , Melchinger A. E.
Published: July 2003

The European corn borer (ECB), Ostrinia nubilalis Hb., is a major pest of maize in Central Europe and is suspected to promote infection of maize with Fusarium species. The objectives of this study were to (1) determine moniliformin (MON) concentration in early maturing European Bt maize hybrids, their isogenic counterparts, commercial cultivars and experimental hybrids, (2) evaluate the association between MON concentration and ECB resistance and (3) correlate MON concentration with concentrations of other mycotoxins determined from the same plant materials. The field experiments were performed at five locations in Germany. MON concentration was significantly higher with manual infestation of ECB larvae (296 μg/kg) than under insecticide protection (66 μg/kg). Bt hybrids showed significantly lower MON concentrations and higher grain yields under manual ECB infestation than their corresponding isogenic counterparts, as well as commercial and experimental hybrids. All ECB resistance traits and grain yield under ECB infestation were significantly correlated with MON concentration. Correlations between concentrations of MON and other Fusarium mycotoxins were not significant. The use of Bt maize hybrids or insecticides to control ECB reduces the contamination of maize grains with MON in Central Europe. The presence of resistance genes against Fusarium species in the current elite maize germplasm was indicated by ECB susceptible non‐Bt hybrids with low‐MON concentrations.
Development of RAPD markers associated with common bunt resistance to race T1 (Tilletia tritici) in spelt wheat
Authors: He C. , Hughes G. R.
Published: July 2003

Common bunt caused by Tilletia tritici and T. laevis has occurred worldwide and reduces yield and quality in common and durum wheats. The development of DNA markers linked to bunt resistance to race T1 in the cross, ‘Laura’(S) ×‘RL5407’ (R), was carried out in this study based on the single head derived F4:5 and single seed derived F4:6 populations. Bulked segregant analysis was used to identify two random amplified polymorphic DNA (RAPD) markers linked to the gene for resistance to race T1 in the spelt wheat ‘RL5407′. The two markers identified, UBC548590 and UBC274988, flanked the resistance gene with a map distance of 9.1 and 18.2 cM, respectively. The former was linked in repulsion phase to bunt resistance while the later was in coupling phase. The two RAPD markers and the common bunt‐resistance gene all segregated in Mendelian fashion. Use of these two RAPD markers together could assist in incorporating the bunt‐resistance gene from spelt wheat into common wheat cultivars by means of marker‐assisted selection.
Embryo‐Maternal Communication in Bovine – Strategies for Deciphering a Complex Cross‐Talk
Authors: Wolf E , Arnold GJ , Bauersachs S , Beier HM , Blum H , Einspanier R , Fröhlich T , Herrler A , Hiendleder S , Kölle S , Prelle K , Reichenbach H‐D , Stojkovic M , Wenigerkind H , Sinowatz F
Published: July 2003

Contents

Early embryonic development, implantation and maintenance of a pregnancy are critically dependent on an intact embryo‐maternal communication. So far, only few signals involved in this dialogue have been identified. In bovine and other ruminants, interferon tau is the predominant embryonic pregnancy recognition signal, exhibiting antiluteolytic activity. However, this is just one aspect of the complex process of embryo‐maternal signalling, and a number of other systems are more likely to be involved. To gain a more comprehensive understanding of these important mechanisms, integrated projects involving specialists in embryology, reproductive biotechnology and functional genome research are necessary to perform a systematic analysis of interactions between pre‐implantation stage embryos and oviduct or uterine epithelial cells, respectively. State‐of‐the‐art transcriptomic and proteomic technologies will identify reciprocal signals between embryos and their maternal environment and the respective downstream reaction cascades. Forin vivostudies, the use of monozygotic twins as recipient animals provides elegant model systems, thus eliminating genetic variability as a cause of differential gene expression. In addition, suitable systems for the co‐culture of oviduct epithelial or endometrium cells with the respective embryonic stages need to be established for functional validation of candidate genes potentially involved in the dialogue between embryos and their maternal environment. The knowledge of these mechanisms should help to increase the pregnancy rate following embryo transfer and to avoid embryonic losses. Candidate genes involved in embryo‐maternal communication will also be used to define new quality criteria for the selection of embryos for transfer to recipients. Another application is the supplementation of embryotrophic factors or components of embryo‐maternal signalling in optimized formulations, such as bioartificial matrices. As a long‐term goal, signalling mechanisms identified in bovine will also be functionally evaluated in other species, including the human.
Laboratory Semen Assessment and Prediction of Fertility: still Utopia?*
Authors: Rodríguez‐Martínez H
Published: July 2003

Contents

Finding a laboratory test reliable enough to predict the potential fertility of a given semen sample or a given sire for artificial insemination (AI) is still considered utopian, as indicated by the modest correlations seen between results obtained in vitro and field fertility. Male fertility is complex, and depends upon a heterogeneous population of spermatozoa interacting at various levels of the female genital tract, the vestments of the oocyte, and the oocyte itself. For this reason, laboratory assessment of semen must include the testing of most sperm attributes relevant for fertilization and embryo development, not only in individual spermatozoa but within a large sperm population as well. Strategies for the discovery of in vitro predictors of semen fertility require evaluations of low sperm doses for AI, so that differences in innate in vivo fertility can be accurately detected.
Oocyte and Embryo Quality: Effect of Origin, Culture Conditions and Gene Expression Patterns
Authors: Lonergan P , Rizos D , Gutierrez‐Adan A , Fair T , Boland MP
Published: July 2003

Contents

In general, the majority of immature bovine oocytes fail to develop to the blastocyst stage following maturation, fertilization and culture in vitro. The evidence suggests that while culture conditions during in vitro embryo production can impact on the developmental potential of the early embryo, the intrinsic quality of the oocyte is the key factor determining the proportion of oocytes developing to the blastocyst stage. In addition, evidence suggests that the period of post‐fertilization embryo culture is the most critical in determining blastocyst quality. This paper reviews the current literature, with emphasis on the bovine model, demonstrating evidence for an effect of oocyte origin and/or in vitro maturation conditions on the developmental capacity and gene expression patterns in the oocyte. Furthermore, the well‐documented effects of post‐fertilization culture environment on embryo gene expression and quality are highlighted.
Characteristics of Ovarian Follicle Development in Domestic Animals
Authors: Evans ACO
Published: July 2003

Contents

In most domestic animals the later stages of follicle development occurs in a wave‐like pattern during oestrous cycles (cattle, sheep, goats, horses and buffalo) or periods of reproductive activity (llamas and camels). A follicle wave is the organized development of a cohort of gonadotrophin‐dependent follicles all of which initially increase in size, but most of which subsequently regress and die by atresia (subordinate follicles). The number of remaining (dominant) follicles is specific to the species and is indicative of litter size. Follicle waves develop during both luteal and follicular phases and it is the dominant follicle(s) of the last follicular wave that ovulates. However, there are cases where dominant follicles from the last two follicle waves can ovulate (sheep and goats). There are exceptions to the organized wave‐like pattern of follicle growth where follicle development is apparently continuous (pigs and chickens). In these animals many follicles develop to intermediate diameters and at specific times follicles that are destined to ovulate are selected from this pool and continue growing to ovulation. Understanding the pattern of follicle development in different species is increasingly important for designing improved methods to manipulate reproduction in domestic animals.
The Insulin‐like Growth Factor System: a Key Determinant Role in the Growth and Selection of Ovarian Follicles? A Comparative Species Study
Authors: Mazerbourg S , Bondy CA , Zhou J , Monget P
Published: July 2003

Contents

The aim of the present paper is to make a comparative study of the expression of the elements of the insulin‐like growth factor (IGF) system in different mammalian species and thus illuminate their potential role in the process of ovarian folliculogenesis in mammals. In most mammalian species, IGFs and IGFBPs (in particular IGFBP‐2 and IGFBP‐4) are considered, respectively, as stimulators and inhibitors of follicular growth and maturation. In mammalian species, IGFs might play a key role in sensitizing ovarian granulosa cells to FSH action during terminal follicular growth. Concentrations of IGFBP‐2 and IGFBP‐4 in follicular fluid strongly decrease and increase during follicular growth and atresia, respectively, leading to an increase and a decrease in IGF bioavailability, respectively. The decrease in these IGFBPs is because of a decrease in mRNA expression (IGFBP‐2) and an increase in proteolytic degradation by PAPP‐A in follicular fluid (IGFBP‐2, IGFBP‐4 and IGFBP‐5), and likely participates in the selection of dominant follicles. In contrast, levels and/or sites of expression of IGF‐I, IGF‐II, IGFBP‐4, IGFBP‐5 and type II receptor in follicular cells strongly differ between mammalian species, suggesting that these phenomena might play species‐specific or secondary roles in ovarian folliculogenesis.
Manipulation of Domestic Animal Embryos and Implications for Development
Authors: McEvoy TG
Published: July 2003

Contents

Assisted reproductive technologies, as applied to domestic animals, can exert both novel and wide‐ranging influences on the development, viability and welfare of offspring. Some of the changes are evident immediately or soon after the time at which a manipulative procedure is carried out, while other changes may not be evident until later in development or, perhaps, may remain undetected throughout an animal's lifetime. The present review explores some of the consequences – in terms of foetal, placental, neonatal and post‐natal effects – of exposing embryos of cattle, sheep and other species to in vitro culture per se or, during culture, to physically invasive technologies including gene injection and nuclear transfer. The innate sensitivity of oocytes and recently fertilized eggs to their in vitro environment is illustrated by an examination of the later developmental repercussions resulting from apparently innocuous choices related to in vitro culture medium formulations. In contrast, an inherent resilience and paradoxical readiness to resume development following the traumas of nuclear transfer procedures is also in evidence. The extent to which assisted reproductive technologies will succeed, where relevant, in the domestic animal sector will be influenced by our appreciation of embryo requirements, for both short‐ and long‐term developmental fitness, during their earliest developmental stages. Evidence of species‐specific needs is testimony to the challenges ahead. Ultimately, our ability and inclination to resolve the limitations associated with current procedures will probably be greatly enhanced if predictive indicators (genetic, epigenetic or functional markers) of later developmental fitness can be identified.