Genome editing of polyploid crops: prospects, achievements and bottlenecks.

Plant breeding aims to develop improved crop varieties. Many crops have a polyploid and often highly heterozygous genome, which may make breeding of polyploid crops a real challenge. The efficiency of traditional breeding based on crossing and selection has been improved by using marker-assisted selection (MAS), and MAS is also being applied in polyploid crops, which helps e.g. for introgression breeding. However, methods such as random mutation breeding are difficult to apply in polyploid crops because there are multiple homoeologous copies (alleles) of each gene. Genome editing technology has revolutionized mutagenesis as it enables precisely selecting targets. The genome editing tool CRISPR/Cas is especially valuable for targeted mutagenesis in polyploids, as all alleles and/or copies of a gene can be targeted at once. Even multiple genes, each with multiple alleles, may be targeted simultaneously. In addition to targeted mutagenesis, targeted replacement of undesirable alleles by desired ones may become a promising application of genome editing for the improvement of polyploid crops, in the near future. Several examples of the application of genome editing for targeted mutagenesis are described here for a range of polyploid crops, and achievements and bottlenecks are highlighted.

Oats in healthy gluten-free and regular diets: A perspective.

During the 20th century, the economic position of oats (Avena sativa L.) decreased strongly in favour of higher yielding crops including winter wheat and maize. Presently, oat represents only ~1.3% of the total world grain production, and its production system is fragmented. Nonetheless, current interest is growing because of recent knowledge on its potential benefits in food, feed and agriculture. This perspective will serve as a further impetus, with special focus on the recently valued advantages of oats in human food and health. Five approved European Food Safety Authority (EFSA) health claims apply to oats. Four relate to the oat-specific soluble fibres, the beta-glucans, and concern the maintenance and reduction of blood cholesterol, better blood glucose balance and increased faecal bulk. The fifth claim concerns the high content of unsaturated fatty acids, especially present in the endosperm, which reduces the risks of heart and vascular diseases. Furthermore, oat starch has a low glycemic index, which is favourable for weight control. Oat-specific polyphenols and avenanthramides have antioxidant and anti-inflammatory properties. Thus, oats can contribute significantly to the presently recommended whole-grain diet. Next to globulins, oats contain a small fraction of prolamin storage proteins, called 'avenins', but at a much lower quantity than gluten proteins in wheat, barley and rye. Oat avenins do not contain any of the known coeliac disease epitopes from gluten of wheat, barley and rye. Long-term food studies confirm the safety of oats for coeliac disease patients and the positive health effects of oat products in a gluten-free diet. These effects are general and independent of oat varieties. In the EU (since 2009), the USA (since 2013) and Canada (since 2015) oat products may be sold as gluten-free provided that any gluten contamination level is below 20ppm. Oats are, however, generally not gluten-free when produced in a conventional production chain, because of regular contamination with wheat, barley or rye. Therefore, establishing a separate gluten-free oat production chain requires controlling all steps in the chain; the strict conditions will be discussed. Genomic tools, including a single nucleotide polymorphism (SNP) marker array and a dense genetic map, have recently been developed and will support marker-assisted breeding. In 2015, the Oat Global initiative emerged enabling a world-wide cooperation starting with a data sharing facility on genotypic, metabolic and phenotypic characteristics. Further, the EU project TRAFOON (Traditional Food Networks) facilitated the transfer of knowledge to small- and medium-sized enterprises (SMEs) to stimulate innovations in oat production, processing, products and marketing, among others with regard to gluten-free. Finally, with focus on counteracting market fragmentation of the global oat market and production chains, interactive innovation strategies between customers (consumers) and companies through co-creation are discussed.

Ethylene and Abscisic Acid Signaling Pathways Differentially Influence Tomato Resistance to Combined Powdery Mildew and Salt Stress.

There is currently limited knowledge on the role of hormones in plants responses to combinations of abiotic and pathogen stress factors. This study focused on the response of tomato near-isogenic lines (NILs) that carry the Ol-1, ol-2, and Ol-4 loci, conferring resistance to tomato powdery mildew (PM) caused by Oidium neolycopersici, to combined PM and salt stress. These NILs were crossed with the notabilis (ABA-deficient), defenceless1 (JA-deficient), and epinastic (ET overproducer) tomato mutants to investigate possible roles of hormone signaling in response to combined stresses. In the NILs, marker genes for hormonal pathways showed differential expression patterns upon PM infection. The epinastic mutation resulted in breakdown of resistance in NIL-Ol-1 and NIL-ol-2. This was accompanied by reduced callose deposition, and was more pronounced under combined salt stress. The notabilis mutation resulted in H2O2 overproduction and reduced susceptibility to PM in NIL-Ol-1 under combined stress, but lead to higher plant growth reduction under salinity and combined stress. Resistance in NIL-ol-2 was compromised by the notabilis mutation, which was potentially caused by reduction of callose deposition. Under combined stress the compromised resistance in NIL-ol-2 was restored. PM resistance in NIL-Ol-4 remained robust across all mutant and treatment combinations. Hormone signaling is critical to the response to combined stress and PM, in terms of resistance and plant fitness. ABA appears to be at the crossroads of disease susceptibility/senescence and plant performance under combined stress These gained insights can aid in narrowing down targets for improving crop performance under stress combinations.

Gonococcal infection of human fallopian tube mucosa in organ culture: relationship of mucosal tissue TNF-alpha concentration to sloughing of ciliated cells.

BACKGROUND AND OBJECTIVES: An experimental model consisting of gonococcal infection of human fallopian tube mucosa in organ culture has proven useful in studying the molecular pathogenesis of acute gonococcal salpingitis and postsalpingitis sequelae. Gonococcal infection of human fallopian tube mucosa in organ culture results in the sloughing of ciliated epithelial cells from the mucosa. This damage to the mucosa can be quantified on fallopian tube pieces by an assay of the percent of the periphery that has ciliary activity (PPCA) remaining at specific time points after infection. Although assay of the PPCA has been quite valuable, it is labor-intensive, somewhat subjective, and requires that the observers have training and experience. A more practical assay for genital mucosal damage is desirable for further investigations that employ the fallopian tube experimental model. Gonococcal infection of fallopian tube mucosa in organ culture also results in the production of easily quantified tumor necrosis factor-alpha (TNF-alpha) by the mucosa. Furthermore, treatment of the organ cultures with recombinant human TNF-alpha (rHuTNFalpha) alone also causes sloughing of ciliated cells from the mucosa. These findings strongly suggest that TNF-alpha is a mediator of the mucosal damage that attends gonococcal infection. GOALS OF THE STUDY: To determine: (1) whether the PPCA values and the TNF-alpha concentrations in fallopian tube mucosal tissues correlate closely enough to allow prediction of the PPCA from a measurement of the mucosal tissue TNF-alpha concentration; and (2) whether the correlation of the TNF-alpha mucosal tissue concentration with the sloughing of ciliated cells (measured by the PPCA) supports the hypothesis that induction of TNF-alpha by gonococcal infection, with resultant sloughing of ciliated cells, is likely to be a major pathogenic mechanism of gonococcal salpingitis and might mediate postsalpingitis infertility and ectopic pregnancy. STUDY DESIGN: A metaanalysis was performed on studies from three research groups (two laboratories in the United States and one in the United Kingdom, using identical techniques for quantifying the PPCA, TNF-alpha, or both. RESULTS: There was a close and statistically significant correlation between the TNF-alpha mucosal tissue concentration and the proportion of ciliated cells lost from the mucosa as measured by the PPCA (r = 0.95, p < 0.001). Therefore, as the mucosal tissue concentration of endogenous TNF-alpha increased, the loss of ciliated cells from the epithelium increased proportionately. CONCLUSIONS: During gonococcal infection of human fallopian tube mucosa in organ culture, the mucosal tissue concentration of TNF-alpha can be used to predict the PPCA, and therefore, the extent of mucosal damage. This finding should facilitate studies of the molecular pathogenesis of infectious diseases involving human genital mucosa. Further, the close correlation of mucosal TNF-alpha concentration with genital mucosal damage, evaluated by the PPCA, supports the hypothesis that induction of the proinflammatory cytokine, TNF-alpha, by gonococcal infection, with resultant inflammation and sloughing of ciliated cells, is an important pathogenic mechanism of gonococcal salpingitis and may mediate postsalpingitis infertility and ectopic pregnancy as well.

Local induction of tumor necrosis factor as a molecular mechanism of mucosal damage by gonococci.

Tumor necrosis factor (TNF) is an endogenously produced cytokine that plays a critical role in mediating septic shock and multi-organ failure, but previous studies of the role TNF in disease have not examined its role in mucosal disease processes. In an experimental model of acute gonococcal salpingitis, gonococcal infection of human fallopian tube mucosa resulted in increased mucosal production of TNF. Recombinant human TNF-alpha damaged fallopian tube mucosa in a dose-response manner and produced epithelial damage with the same ultrastructural features as those observed in gonococcal infection. Blocking production of TNF during gonococcal infection diminished the extent of damage to fallopian tube mucosa. In addition to mediating systemic disease, such as septic shock, TNF is also produced locally, and can play a critical role in mediating mucosal disease processes, such as acute gonococcal salpingitis.

The immunological profile of a new immunomodulatory agent, oxamisole.

Oxamisole is a T-cell immunorestorative agent when administered by the oral (p.o.) route. It has little or no effect on the IgM or IgG responses to the T-dependent antigen, sheep erythrocytes (SRBC), in normal mice but augments antibody production in immunodeficient animals. Unlike the response to SRBC, the humoral immunocompetence of both normal and immunosuppressed animals sensitized with the T-independent antigen, trinitrophenyl-lipopolysaccharide (TNP-LPS) was unaffected by oxamisole. Oxamisole restored cellular immunocompetence, as evidenced by an increase in the in vitro proliferative response of normal murine splenocytes to T-cell mitogens, while decreasing B-cell mitogenic responses. This indicates that oxamisole may selectively restore T-cell function. However, oxamisole did not significantly modify the classical T-cell-mediated delayed hypersensitivity responses to either the protein antigen methylated bovine serum albumin or to the contact-sensitizing antigen oxazolone. When assayed in vitro, oxamisole enhanced macrophage chemotactic function but not phagocytic function, suggesting a potential stimulation of the reticuloendothelial system. In vivo studies failed to demonstrate any consistent significant activation of murine macrophage function following oral dosing with oxamisole.