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41.
Marker assisted selection (MAS) may improve the efficiency of breeding downy mildew resistant cucumber cultivars. A study
was conducted to identify random amplified polymorphic DNA (RAPD) markers linked to the downy mildew resistance gene (dm) which would be suitable for MAS. A total of 145 F3 families from two populations (55 from the WI 1983G × Straight 8 population and 90 from the Zudm1 × Straight 8 population)
were evaluated over five locations in North America and Europe. Resistant and susceptible F3 families were identified and mean family resistance ratings were used to type individual F2 plants. No evidence for race differences in the pathogen (Psuedoperonospora cubensis (Berk. & Curt.) Rostow) between North America and Europe was found. Phenotypic correlations between locations ranged from
0.3 to 0.7. Of the 135 polymorphic RAPD markers identified from 960 primers, five were linked to dm - G14800, X151100, AS5800, BC5191100, and BC5261000. In the WI 1983G × Straight 8 population, G14800 was linked to dm at 16.5 cm, AS5800 at 32.8 cm, BC5191100 at 9.9 cm, and BC5261000 at 19.2 cm. In the Zudm1 ×Straight 8 population, G14800 was linked at 20.9 cm, X151100at 14.8 cm, AS5800 at 24.8 cm, and BC526_1000 at 32.9 cm. MarkersG14800 and BC5191100 were linked in repulsion to the dm allele, and X151100, AS5800, and BC5261000 were linked in coupling phase. These genetic markers may be exploited to develop an efficient MAS strategy for breeding resistant
cucumber cultivars.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
42.
The hallmark of rheumatoid arthritis (RA) is specific destruction of the synovial joints. In a mouse line that spontaneously develops a disorder with many of the features of human RA, disease is initiated by T cell recognition of a ubiquitously expressed self-antigen; once initiated, pathology is driven almost entirely by immunoglobulins. In this study, the target of both the initiating T cells and pathogenic immunoglobulins was identified as glucose-6-phosphate isomerase, a glycolytic enzyme. Thus, some forms of RA or related arthritides may develop by a mechanism fundamentally different from the currently popular paradigm of a joint-specific T cell response. 相似文献
43.
44.
Hubèrt van Hees Dominiek Maes Sam Millet Leo den Hartog Theo van Kempen Geert Janssens 《Journal of animal physiology and animal nutrition》2021,105(2):260-271
Dietary fibre (DF) is implicated in gastrointestinal health of weaned piglets, either through its physiochemical properties, through modulation of gut microbiota and (or) improved gut integrity. We aimed to study the effect of DF enriched supplemental diets fed to suckling piglets (‘creep feed’) on health and performance after weaning when challenged with an enterotoxigenic E. coli (ETEC). Seventy-two piglets originating from 28 litters had been fed four creep diets, that is a low-fibre control (CON); a diet containing 2% long-chain arabinoxylans from wheat (lc-AXOS) or 5% purified cellulose (CELL) or a diet containing the high fermentable and the low-fermentable fibre source (i.e. 2% lc-AXOS and 5% CELL). Upon weaning, piglets were individually housed and all fed the same diet. On days 7, 8 and 9, animals received an oral dose of ETEC (5 ml containing 107 to 108 CFU/ml). Besides growth performance, faecal and skin scores were recorded daily. Gut permeability was assessed by urinary excretion of Co-EDTA prior and post-ETEC challenge. Repeated measures in time were statistically evaluated with generalized linear mixed models. We used a binominal distribution for evaluating the faecal and skin scores. Feed intake and body weight gain did not differ between treatments (p > .05). Piglets on CELL decreased gain:feed ratio in week 2 + 3 week compared to CON (p = .035). Prior to ETEC challenge, gut permeability tended to increase for lc-AXOS (p = .092). Moreover, lc-AXOS as main effect increased intestinal permeability before ETEC challenge (p = .013), whereas the low-fermentable fibre lead to elevated intestinal permeability after ETEC challenge (p = .014). The incidence of diarrhoea was higher for lc-AXOS + CELL compared with lc-AXOS (p = .036), while skin condition was unaffected. In conclusion, neither the high fermentable nor the low-fermentable fibre source improved post-weaning growth or gastrointestinal health of the piglets. 相似文献
45.
Genetic variation among 155 U.S. modern and heirloom cultivars was assessed from assays of 21 polymorphic isozyme loci. Four loci (Fdp-1, Mdh-1, Mpi-1 and Pgd-1) were monomorphic. Multivariate analyses partitioned cultivars into two distinct groups: those released before 1968, and those released after 1968. Cluster analysis produced a dendrogram with 14 nodes and 28 groups. Modern U.S. and European cultivars released after 1968 differed in isozyme frequencies. Isozymic profiles clearly discriminated some cultivars with unique attributes and/or pedigrees [e.g., Windermoor Wonder (USA), Gergana (The Netherlands), Seiram (The Netherlands), Fancy Pak (USA), Dasher 2 (USA), and WI 2757 (USA)]. 相似文献
46.
47.
A synthetic amphidiploid species Cucumis hyriviis Chen & Kirkbride (2n = 4x = 38; genome designated as HHCC) has recently been created from an interspecific mating between C. sativus L. (2n = 2x = 14: genome designated as CC) and C. hystrx. Chakr. (2n = 2x = 24; genome designated as HH). This amphidiploid is resistant to root knot nematode, tolerant to low irradiance, and has higher nutritional value than standard processing cucumber cultivars. An allotriploid (2n = 3x = 26; HCC) was derived from a cross between C. sativus L. and C. hytivus Chen & Kirkbride. Diploid meiotic behaviour in C. sativus and C. hystrix involves the development of seven and 12 metaphase bivalents respectively. In the derived allotriploid. univalents. bivalents, and trivalents (at relatively low frequency) were observed at metaphase I indicating that some homeologues from the C and H genomes can synapse. Based on a comparative karyotype analysis of cucumber (i.e. chromosome size and pairing behaviour) and aliotriploid plants, the seven bivalents observed at metaphase I were ascertained to be cucumber homologues, while the 12 univalents were of C. hystrix origin thus confirming the allotriploid karyotypic constitution to be HCC. On average, the frequency of trivalents was 0.24 at diakinesis and 0.22 in 100 meiocytes at metaphase I. indicating the possibility of genetic exchange due to the homoeology between the C and H genomes. After simultaneous cytokinesis, only polyads were observed in pollen mother cells (PMCs) at telophase II, which led to the production of sterile pollen grains. Multi‐polarization of chromosomes was dominant at anaphase II. However. in about 20% PMCs. chromosomes separated to form a 7C + 1‐2H complement, suggesting a possible method for the production of alien addition cucumber‐C hystrix lines through further backcrossing of the allotriploid to diploid cucumber. 相似文献
48.
A set of 155 SSR (107) and SCAR (48) markers were used to evaluate 53 cucumber (Cucumis sativus L.) accessions of diverse origin to characterize genetic relationships and to define a standard marker array that was most effective in detecting genetic differences in this germplasm array. A multivariate marker‐based analysis of diverse germplasm using this standard marker array (17 SSR and 5 SCAR markers) was compared with results from a set of 70 previously reported RAPD markers, and then used to explore the potential value of these genetic markers for plant variety protection (PVP) and the establishment of essential derivation (ED) threshold values in this species using elite lines and hybrids and backcross progeny. Diversity analysis allowed identification of distinctly different lines that were used for the construction of three sets of backcross families (BC1‐BC3). While general genetic relationships among accessions were similar in SSR/SCAR analyses (rs= 0.65) using two genetic distance (GD) estimators, differences in accession relationships were detected between RAPD and SSR/SCAR marker evaluations regardless of the estimator used. The GDs among elite germplasm with known pedigrees were relatively small (0.06‐0.23 for any pairwise comparison). GD values decreased and degree of fixation (at three to seven loci depending on the mating) increased with increased backcrossing such that recurrent parent allelic fixation occurred in least one family of each of the BC3 families. In many instances the degree of fixation of loci was not uniformly achieved in the BC3. Although the level of genetic polymorphisms will likely restrict the use of molecular markers for PVP and the establishment of ED values, the use of single nucleotide differences will likely provide opportunities to define specific functional distances that have potential for PVP in cucumber. Nevertheless, without an expanded, genetically robust standard marker array (e.g. 50 codominant markers), ED threshold values will be difficult to define in this species, and perhaps will require the appraisal of single nucleotide polymorphisms as discriminators of difference in this species. 相似文献
49.
Studies on the reproduction and cytogenetic characterization of a primary amphidiploid Cucumis species C. hytivus Chen and Kirkbride (2n = 4x = 38) indicated that a more comprehensive cytogenetic analysis of this species and its first selfed progeny would increase its potential utility in cucumber improvement. With tendrils used as source materials for mitotic analysis, chromosome numbers in all selfed progenies were 2n = 38, confirming chromosomal stability in this synthetic amphidiploid species. Detailed meiotic processes were described by comparing the primary and the selfed amphidiploids.Meiotic abnormalities, such as chromosome lagging, unequal separation, chromosome multi-polarization and polyads were observed frequently in all amphidiploid plants except for the selfed no.8, in which meiosis was arrested prior to metaphase I. Generally, the frequency of multivalents was higher and the configurations were more complex in the selfed progenies, demonstrating a more extensive genetic exchange between cucumber and C. hystrix Chakr. Genome separation between cucumber and C. hystrix was observed through prophase ! to anaphase I in both generations of the amphidiploids. Consequently, in addition to n = 19, a new gamete with n = 7 was produced, which was confirmed by the chromosome counts 2n = 14 in the backcrossing progenies from cucumber × amphidiploid mating. Fertility varied among the selfed amphidiploid plants. The selfed plant no. 1 was found to have an improved fertility (e.g., pollen staining ability 40.8% and 25.6 seeds per fruit) and then was used as source germplasm in further introgression and gene exchange experiments. 相似文献
50.
James O’Shaughnessy Bernadette Earley John F. Mee Michael L. Doherty Paul Crosson Damien Barrett Theo de Waal 《Irish veterinary journal》2015,68(1)