Search Results
-like plasmid from coinfecting vancomycin-resistant enterococci [ 12 ]. The transfer of this plasmid requires the presence of a pSK41-like plasmid in recipient S. aureus [ 49 ]. In our study, however, the only VRSA isolate neither contains vanA nor
6. Robert-Gangneux F , Meroni V , Dupont D , Botterel F , Garcia JMA , Brenier-Pinchart MP , Toxoplasmosis in transplant recipients, Europe, 2010–2014 . Emerg Infect Dis . 2018 ; 24 ( 8 ): 1497 – 504 . https://doi.org/10
parasitic infection dose down to one T. gondii cyst per recipient animal only. Depending on the virulence of the respective T. gondii strain and the age and sex of the susceptible mice [ 3 ], an accidental increase in cyst number might result in a much
Cytomixis has been described in many plant species, but not in Thinopyrum . The present study reports spontaneous cytomixis during microsporogenesis in Thinopyrum intermedium (2n = 42), Thinopyrum ponticum (2n = 70), and their F 1 hybrids with wheat. Cytomixis frequently occurred in early prophase I but very rarely in meiosis II. The type of cytomixis that occurred most often was where chromatins migrate from one nucleus into an adjacent cel1. Migration from one nucleus into two or more cells or from two or more nuclei into one cel1 was also observed. After a donor cell transferred chromatin to a recipient cell, the recipient cell would sometimes pass the chromatin on to another cell. Migration did not necessarily occur between cells in the same stage. Cytomixis in Th. ponticum and its hybrids with wheat was more complex than that in Th. intermedium . The possible causes, cytological consequences and genetic significance of cytomixis are discussed.
Compared to the known method of conjugation the frequency of transposon mutagenesis following conjugation was enhanced 11-fold by two hours of pre-incubation of recipient Pseudomonas viridiflava 1 on conjugation media. The increased frequency was ƒ = 1.3 × 10 −4 . In other species of Pseudomonas, Pectobacteira and Xanthomonas high rates of transposon mutants were similarly obtained; however, in these strains the increased frequency was less than 5-fold.
The relatively copper-tolerant wheat variety Chinese Spring (recipient), the copper-sensitive variety Cappelle Desprez (donor) and their substitution lines were screened for copper tolerance in a soil pot experiment under artificial growth conditions. Chromosomes 5A, 5B, 5D and 7D of Cappelle Desprez significantly decreased the copper tolerance of the recipient variety to varying extents. By contrast, the 6B and 3D chromosomes significantly increased the copper tolerance of Chinese Spring, suggesting that a wide range of allelic differences could be expected between wheat genotypes for this character. The significant role of homologous group 5 in copper tolerance was confirmed by testing wheat-rye substitution lines. The substitution of rye chromosome 5R (5R/5A substitution line) into a wheat genetic background significantly increased the copper tolerance of the recipient wheat genotype. The results suggest that chromosomes 5R and 5A probably carry major genes or gene complexes responsible for copper tolerance, and that the copper tolerance of wheat can be improved through the substitution of a single chromosome carrying the responsible genes. At the same time, it is also possible that the effect of homologous group 5 is not specific to copper tolerance, but that the genes located on these chromosomes belong to a general stress adaptation (frost, cold, vernalisation requirements, etc.) complex, which has already been detected on this chromosome. To answer this question further studies are needed to determine the real effect of these chromosome regions and loci on copper tolerance.
Although significant progress has been made on Agrobacterium -mediated wheat transformation, the current methodologies use immature embryos as recipient tissues, a process which is labor intensive, time consuming and expensive. In this study, we have managed to develop an Agrobacterium -based transformation scheme using explants derived from mature embryos. Based on transient expression of β -glucuronidase (GUS) marker, mature embryo halves prepared from freshly imbibed seeds were generally most susceptible to Agrobacterium -mediated T-DNA transfer. According to the results of callus induction and shoot production, Yumai 66 and Lunxuan 208 showed higher selection and regeneration efficiency than Bobwhite. In line with this finding, fertile T 0 transgenic plants were most readily obtained for both spring and winter wheat when mature embryo halves were used for co-inoculation by Agrobacterium cells. The presence of the antibiotic selection marker ( nptII , encoding neomycin phosphotransferase II) in the T 0 plants was revealed by both genomic PCR amplification and the enzyme-linked immunosorbent assay (ELISA). Additional analysis showed that the transgene was stably inherited from the two different generations and segregated normally among the T 1 progenies. Further development along this line will raise the efficiency of wheat transformation and increase the use of this approach in the molecular breeding of wheat crop.
In order to locate QTLs controlling the phenotypic stability and drought tolerance of yield and yield components in barley, seven disomic addition lines were sown together with their parents (donor and recipient) in a randomized complete block design with three replications under four rainfed and irrigated conditions. The descriptive diagram of yield and yield components exhibited a genotype (G) × environment (E) interaction and moderate variability over different environments, indicating the possibility of selection for stable and drought-tolerant entries. The AMMI stability value (ASV) and yield stability index (YSI) discriminated addition lines 2H and 4H as the most stable and droughttolerant.Path analysis revealed that the relative contribution of the number of seeds per plant (NSPP) (0.71) to grain yield (GY) was higher than that of the number of seeds per spike (SPS) (−0.44) and of thousand-seed weight (TSW) (−0.14). Therefore, the contribution of NSPP to the stability of GY over different environments was higher than that of other yield components. In other words, the instability of GY was caused by TSW and SPS in different environments. Path analysis on the drought susceptibility index revealed that most of the QTLs controlling drought tolerance and drought susceptibility in barley are located on chromosomes 3H and 6H, respectively.
In order to locate QTLs controlling field and laboratory indicators of drought tolerance, chromosome addition lines of Agropyron elongatum (donor) in the genetic background of Chinese Spring (recipient) were tested in the field and laboratory of the College of Agriculture, Razi university, Kermanshah, Iran. The plant genetic material was cultivated in the field and laboratory under two different water regimes (irrigated and non-irrigated). High significant differences were found for promptness index (PI), coleoptile length (CL) and root length (RL) under stress and non-stress conditions, indicating the presence of genetic variation and the possibility of selection for these traits. High correlation coefficients were found between PI, germination stress index (GSI) and stress tolerance index (STI), displaying a high association between the indices of field and laboratory predictors of drought tolerance. Field and laboratory predictors of drought tolerance showed that most of the QTLs controlling drought tolerance criteria in Agropyron are located on chromosomes 3E, 5E and 7E, which collectively constitute 84.3% of the additive genetic variance.
Two monosomic alien substitution lines (MAS lines, 2n=41=40+5R) of wheat Triticum aestivum L. cv. ‘Saratovskaya 29’ were used as recipients in the development of inter-varietal substitution lines for chromosomes 5A and 5D. In the MAS lines, chromosomes 5A or 5D of ‘Saratovskaya 29’ were replaced by homoeologous univalent chromosome 5R of rye Secale cereale L. cv. ‘Onokhoiskaya’, which bears the Hp marker gene coding for hairy peduncle. The donors included 18 spring and winter wheat varieties. The MAS lines were developed by crossing monosomic lines of ‘Saratovskaya 29’ for chromosomes 5A and 5D to a wheat-rye substitution line of ‘Saratovskaya 29’ 5R(5D) followed by cytological and morphological selection of plants with chromosome configuration 20II +5RI in metaphase I of pollen mother cells from F 1 and F 2 plants with slightly hairy peduncles. It was shown that MAS lines could be maintained during long-term propagation (18 generations). Use of MAS lines with the Hp marker gene allows acceleration and abbreviation of cytological analysis and elimination of the probability of ‘univalent switch’ in the course of the development of substitution lines. The method was applied to the development of 22 ‘Saratovskaya 29’ lines with inter-varietal substitution for chromosomes 5A and 5D. Fourteen and thirteen microsatellite markers located in chromosomes 5A and 5D, respectively, were used to prove the authenticity of the inter-varietal substitution lines. According to these markers, 21 substitution lines from 22 studied were correct.
