The Fusarium crown rot pathogen Fusarium pseudograminearum triggers a suite of transcriptional and metabolic changes in bread wheat (Triticum aestivum L.)

Background and Aims: Fusarium crown rot caused by the fungal pathogen Fusarium pseudograminearum is a disease of wheat and barley, bearing significant economic cost. Efforts to develop effective resistance to this disease have been hampered by the quantitative nature of resistance and a lack of understanding of the factors associated with resistance and susceptibility. Here, we aimed to dissect transcriptional responses triggered in wheat by F. pseudograminearum infection. Methods: We used an RNA-seq approach to analyse host responses during a compatible interaction and identified >2700 wheat genes differentially regulated after inoculation with F. pseudograminearum. The production of a few key metabolites and plant hormones in the host during the interaction was also analysed. Key Results: Analysis of gene ontology enrichment showed that a disproportionate number of genes involved in primary and secondary metabolism, signalling and transport were differentially expressed in infected seedlings. A number of genes encoding pathogen-responsive uridine-diphosphate glycosyltransferases (UGTs) potentially involved in detoxification of the Fusarium mycotoxin deoxynivalenol (DON) were differentially expressed. Using a F. pseudograminearum DON-non-producing mutant, DON was shown to play an important role in virulence during Fusarium crown rot. An over-representation of genes involved in the phenylalanine, tryptophan and tyrosine biosynthesis pathways was observed. This was confirmed through metabolite analyses that demonstrated tryptamine and serotonin levels are induced after F. pseudograminearum inoculation. Conclusions: Overall, the observed host response in bread wheat to F. pseudograminearum during early infection exhibited enrichment of processes related to pathogen perception, defence signalling, transport and metabolism and deployment of chemical and enzymatic defences. Additional functional analyses of candidate genes should reveal their roles in disease resistance or susceptibility. Better understanding of host responses contributing to resistance and/or susceptibility will aid the development of future disease improvement strategies against this important plant pathogen

Using Microsatellites to Understand the Physical Distribution of Recombination on Soybean Chromosomes

Soybean is a major crop that is an important source of oil and proteins. A number of genetic linkage maps have been developed in soybean. Specifically, hundreds of simple sequence repeat (SSR) markers have been developed and mapped. Recent sequencing of the soybean genome resulted in the generation of vast amounts of genetic information. The objectives of this investigation were to use SSR markers in developing a connection between genetic and physical maps and to determine the physical distribution of recombination on soybean chromosomes. A total of 2,188 SSRs were used for sequence-based physical localization on soybean chromosomes. Linkage information was used from different maps to create an integrated genetic map. Comparison of the integrated genetic linkage maps and sequence based physical maps revealed that the distal 25% of each chromosome was the most marker-dense, containing an average of 47.4% of the SSR markers and 50.2% of the genes. The proximal 25% of each chromosome contained only 7.4% of the markers and 6.7% of the genes. At the whole genome level, the marker density and gene density showed a high correlation (R2) of 0.64 and 0.83, respectively with the physical distance from the centromere. Recombination followed a similar pattern with comparisons indicating that recombination is high in telomeric regions, though the correlation between crossover frequency and distance from the centromeres is low (R2 = 0.21). Most of the centromeric regions were low in recombination. The crossover frequency for the entire soybean genome was 7.2%, with extremes much higher and lower than average. The number of recombination hotspots varied from 1 to 12 per chromosome. A high correlation of 0.83 between the distribution of SSR markers and genes suggested close association of SSRs with genes. The knowledge of distribution of recombination on chromosomes may be applied in characterizing and targeting genes

Specific patterns of gene space organisation revealed in wheat by using the combination of barley and wheat genomic resources

<p>Abstract</p> <p>Background</p> <p>Because of its size, allohexaploid nature and high repeat content, the wheat genome has always been perceived as too complex for efficient molecular studies. We recently constructed the first physical map of a wheat chromosome (3B). However gene mapping is still laborious in wheat because of high redundancy between the three homoeologous genomes. In contrast, in the closely related diploid species, barley, numerous gene-based markers have been developed. This study aims at combining the unique genomic resources developed in wheat and barley to decipher the organisation of gene space on wheat chromosome 3B.</p> <p>Results</p> <p>Three dimensional pools of the minimal tiling path of wheat chromosome 3B physical map were hybridised to a barley Agilent 15K expression microarray. This led to the fine mapping of 738 barley orthologous genes on wheat chromosome 3B. In addition, comparative analyses revealed that 68% of the genes identified were syntenic between the wheat chromosome 3B and barley chromosome 3 H and 59% between wheat chromosome 3B and rice chromosome 1, together with some wheat-specific rearrangements. Finally, it indicated an increasing gradient of gene density from the centromere to the telomeres positively correlated with the number of genes clustered in islands on wheat chromosome 3B.</p> <p>Conclusion</p> <p>Our study shows that novel structural genomics resources now available in wheat and barley can be combined efficiently to overcome specific problems of genetic anchoring of physical contigs in wheat and to perform high-resolution comparative analyses with rice for deciphering the organisation of the wheat gene space.</p

Investigation of Antibacterial Activity and Biofilm Formation of Silicones Coated With Minocycline-Rifampicin, Silver Nitrate, and Nitrofurantoin for Short-term Utilization in In Vitro Urinary System Models

PMID = 2652297

Identification of QTLs and Environmental Interactions Associated with Agronomic Traits on Chromosome 3A of Wheat

Genetic analyses of complex traits in wheat (Triticum aestivum L.) are facilitated by the availability of unique genetic tools such as chromosome substitution lines and recombinant inbred chromosome lines (RICLs) which allow the effects of genes on a single chromosomes to be studied individually. Chromosome 3A of ‘Wichita’ is known to contain alleles at quantitative trait loci (QTLs) that influence variation in grain yield and agronomic performance traits relative to alleles of ‘Cheyenne’. To determine the number, location, and environmental interactions of genes related to agronomic performance on chromosome 3A, QTL and QTL x environment analyses of 98 RICLs-3A were conducted in seven locations across Nebraska from 1999 through 2001. QTLs were detected for seven of eight agronomic traits measured and generally localized to three regions of chromosome 3A. QTL x environment interactions were detected for some QTLs and these interactions were caused by changes in magnitude and crossover interactions. Major QTLs for kernels per square meter and grain yield were associated within a 5-centimorgan (cM) interval and appeared to represent a single QTL with pleiotropic effects. This particular QTL displayed environmental interactions caused by changes in magnitude, wherein the positive effect of the Wichita QTL allele was larger in higher yielding environments

Estimates of relative yield potential and genetic improvement of wheat cultivars in the Mediterranean region

Information about changes associated with advances in crop productivity is essential for Understanding yield-limiting factors and developing new strategies for future breeding programmes. National bread wheat (Triticum aestivum L.) yields in Turkey have risen by an average of 20.8 kg/ha/year from 1925 to 2006. Annual gain in yield attributable to agronomic and genetic improvement averaged c. 11.6 kg/ha/year prior to 1975, but is now averaging c. 15.1 kg/ha/year. In the Mediterranean region, however, the wheat yield trend line (10.9 kg/ha/year) is c. 0.38 lower than that of Turkey. In order to understand whether such a trend was due to the cultivars released over the years. 16 bread Wheat cultivars, commonly grown in the region and representing 23 years of breeding. introduction and selection (from 1976 to 1999), were grown in a randomized complete block design with three replicates across 2 years. Data were collected on Maturation time, plant height. spike length, spikelet number/spike, grain number/spike, grain weight/spike. 1000 seed weight. harvest index and grain yield. None of the Measured plant traits showed ally historical cultivar patterns therefore, the increase in grain Yield Could not be attributed to a single yield component. Several physiological traits changed during two decades of cultivar releases in the Mediterranean region that led to a genetic gain in grain yield of about 0.5% per year. Years of data and the present field study in the Mediterranean region suggested that the genetic improvement in wheat seemed inadequate and should be reinforced with modern agricultural management practices as well as technological innovations.Information about changes associated with advances in crop productivity is essential for Understanding yield-limiting factors and developing new strategies for future breeding programmes. National bread wheat (Triticum aestivum L.) yields in Turkey have risen by an average of 20.8 kg/ha/year from 1925 to 2006. Annual gain in yield attributable to agronomic and genetic improvement averaged c. 11.6 kg/ha/year prior to 1975, but is now averaging c. 15.1 kg/ha/year. In the Mediterranean region, however, the wheat yield trend line (10.9 kg/ha/year) is c. 0.38 lower than that of Turkey. In order to understand whether such a trend was due to the cultivars released over the years. 16 bread Wheat cultivars, commonly grown in the region and representing 23 years of breeding. introduction and selection (from 1976 to 1999), were grown in a randomized complete block design with three replicates across 2 years. Data were collected on Maturation time, plant height. spike length, spikelet number/spike, grain number/spike, grain weight/spike. 1000 seed weight. harvest index and grain yield. None of the Measured plant traits showed ally historical cultivar patterns therefore, the increase in grain Yield Could not be attributed to a single yield component. Several physiological traits changed during two decades of cultivar releases in the Mediterranean region that led to a genetic gain in grain yield of about 0.5% per year. Years of data and the present field study in the Mediterranean region suggested that the genetic improvement in wheat seemed inadequate and should be reinforced with modern agricultural management practices as well as technological innovations.</p

Twin or narrow-row planting patterns versus conventional planting in forage maize production in the Eastern Mediterranean

Producing forage maize ( Zea mays L.) in twin-row planting pattern has been attempted in past years. This research was performed to determine effects of planting patterns and densities on yields of forage maize hybrids. We also examined other plant characteristics associated with forage yield under second crop conditions in Hatay, East Mediterranean region of Turkey, during 2003 and 2004. The experimental design was a randomized complete block design in a split-split-plot arrangement with three replications. The planting patterns of twin row (55:20 cm), conventional row (75 cm) and narrow row (50 cm) were main plots, the plant densities (80,000, 100,000 and 120,000 plants ha −1 ) were split-plots, and the hybrids (PR-1550, MAVERIK and DK-585) were split-split plots. Forage and dry matter yields were significantly affected by planting patterns, plant densities and maize hybrids. Our results revealed the advantage of twin-row planting pattern over conventional and narrow row plantings at all plant densities. Twin row planting out-yielded conventional row (16% more forage and 10.2% more dry matter yield) and narrow-row (7.9% more forage and 5.9% more dry matter yield) plantings. Twin-row planting pattern may be a profitable production technique for forage maize producers