Effect of spore density, cultivar resistance and Phytophthora infestans isolate on tuber blight under field conditions

Survival of P. infestans in soil was limited to 5 weeks at high inoculum density. With a ten fold dilution of the infection pressure survival of P. infestans in soil was limited to two weeks. Differences between isolates concerning survival in the soil were small. From these experiments we conclude that survival of P. infestans in soil depended on spore density rather than P. infestans isolate used. Tuber blight infection rate depends on density of the sporangia in the soil, tuber blight resistance of the cultivar and to a lesser extent the P. infestans isolate used. Isolate of type EU 13 A2 was not more aggressive to tubers than IPO 428-2, regardless of the resistance level of the cultivar used. A mixture of isolates was found to be more aggressive than two single isolates tested on cultivar Bintje only. Thus measures to avoid infection of the soil with P. infestans sporangia lower the tuber blight infection risk, especially on the susceptible cultivar Bintj

Estimating annual soil carbon loss in agricultural peatland soils using a nitrogen budget approach.

Around the world, peatland degradation and soil subsidence is occurring where these soils have been converted to agriculture. Since initial drainage in the mid-1800s, continuous farming of such soils in the California Sacramento-San Joaquin Delta (the Delta) has led to subsidence of up to 8 meters in places, primarily due to soil organic matter (SOM) oxidation and physical compaction. Rice (Oryza sativa) production has been proposed as an alternative cropping system to limit SOM oxidation. Preliminary research on these soils revealed high N uptake by rice in N fertilizer omission plots, which we hypothesized was the result of SOM oxidation releasing N. Testing this hypothesis, we developed a novel N budgeting approach to assess annual soil C and N loss based on plant N uptake and fallow season N mineralization. Through field experiments examining N dynamics during growing season and winter fallow periods, a complete annual N budget was developed. Soil C loss was calculated from SOM-N mineralization using the soil C:N ratio. Surface water and crop residue were negligible in the total N uptake budget (3 - 4 % combined). Shallow groundwater contributed 24 - 33 %, likely representing subsurface SOM-N mineralization. Assuming 6 and 25 kg N ha-1 from atmospheric deposition and biological N2 fixation, respectively, our results suggest 77 - 81 % of plant N uptake (129 - 149 kg N ha-1) was supplied by SOM mineralization. Considering a range of N uptake efficiency from 50 - 70 %, estimated net C loss ranged from 1149 - 2473 kg C ha-1. These findings suggest that rice systems, as currently managed, reduce the rate of C loss from organic delta soils relative to other agricultural practices

Experimental control strategies reducing the fungicide input at a practical scale

Phytophthora infestans is the most devastating disease in potato cultivation. Chemical control is necessary to ensure a healthy crop. At the same time Dutch governmental policy asks for a reduction of the environmental impact of potato late blight control by 75% in 2012 as compared to 1996-1998. The aim of the experiments was to compare Decision Support Systems with different approaches to blight risk management for their ability to reduce the fungicide input without compromising control efficacy. Considerable savings, up to 81% when compared to weekly, full dose rate, spray schedules, can be achieved by using information on cultivar resistance, length of the critical period and disease pressure to decide whether or not to spray. The subroutine calculating the potential for viable transport of spores is only effective on resistant varieties as the threshold was exceeded with every critical period on less resistant cultivars. Implications of the experimental control strategies for agricultural practise are discusse

Evaluation of carbon isotope discrimination as selection criteria for yield and water use efficiency in lentil

Non-Peer Reviewe

Use of carbon isotope discrimination to indirectly select for improved seed yield in lentil

Non-Peer ReviewedCarbon isotope discrimination (CID) has been proposed as a secondary trait to indirectly select for improved water use efficiency and seed yield. To determine the effectiveness of CID to indirectly select for seed yield, ten diverse lentil (Lens culinaris Medikus) cultivars were grown at four locations in Saskatchewan in 1992 and 1993. Variability for CID was present among these lentil cultivars and no crossover interactions were observed. The phenotypic correlation between seed yield and CID of leaves at early flowering (CIDLF) was 0.82** (df=8). However, this highly significant relationship resulted from the extreme early maturity of PI 244026. Previous research has shown that CID values decrease with maturity and PI 244026 flowers about 15 days earlier than the other lentil lines. When PI 244026 lentil was removed, variability in CID was greatly reduced and the correlation between CIDLF and seed yield approached zero (r = 0.22, df=7). These results suggest that CIDLF cannot be used to indirectly select for seed yield in lentil

Effect of wheat distillers dried grains with solubles or sugar beet pulp on prevalence of Salmonella enterica Typhimurium in weaned pigs

Salmonella enterica Typhimurium (ST) is of concern in the swine industry with relevance for animal health and consumer safety. Nutritional strategies might help to reduce ST infection and transmission. This study examined the potential of wheat (Triticum aestivum) distillers dried grains with solubles (DDGS) and sugar beet (Beta vulgaris) pulp (SBP) to alter intestinal microbial communities and ST shedding using a Trojan model. Weaned pigs (n = 105; 28.5 ± 3.5 d of age) were separated into 3 treatment groups (7 pigs/pen) and fed a wheat-based control diet or the control diet formulated with 15% wheat DDGS or 6% SBP inclusion. Following 12 d of diet adaptation, 2 pigs/pen were inoculated with 2 x 109 cfu ST, resistant to novobiocin and nalidixic acid. Fecal swabs were taken from infected pigs and pen-mates (contact pigs) for 9 d following challenge, enriched in nutrient broth for 24 h, and plated on selective media to determine prevalence of ST. The ranges of prevalence of ST in feces were from 90 to 100% in challenged pigs and 74 to 78% in contact pigs. No influence of treatment on rectal temperature and prevalence of ST in contact pigs were observed. Fifteen contact pigs were euthanized per treatment group on 9 and 10 d postchallenge to enumerate in intestinal contents (ileum, cecum, and proximal colon), Lactobacillus spp., Enterobacteriaceae, and Clostridium clusters I, VI, and XVIa by quantitative PCR (qPCR) and to determine ST prevalence by selective culture. No significant effects of diet were observed with respect to ST prevalence in feces, ileum, cecum, colon, and lymph nodes of contact pigs. Compared with the control diet, DGGS and SBP diets showed a trend towards increased (P < 0.1) number of Lactobacillus species in the cecum and colon. Although both wheat DGGS and SBP tended to increase the Lactobacillus spp. neither of the feed ingredients affected ST prevalence

CRISPR/Cas9-induced (CTG⋅CAG)n repeat instability in the myotonic dystrophy type 1 locus: implications for therapeutic genome editing

Myotonic dystrophy type 1 (DM1) is caused by (CTG⋅CAG)n-repeat expansion within the DMPK gene and thought to be mediated by a toxic RNA gain of function. Current attempts to develop therapy for this disease mainly aim at destroying or blocking abnormal properties of mutant DMPK (CUG)n RNA. Here, we explored a DNA-directed strategy and demonstrate that single clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-cleavage in either its 5′ or 3′ unique flank promotes uncontrollable deletion of large segments from the expanded trinucleotide repeat, rather than formation of short indels usually seen after double-strand break repair. Complete and precise excision of the repeat tract from normal and large expanded DMPK alleles in myoblasts from unaffected individuals, DM1 patients, and a DM1 mouse model could be achieved at high frequency by dual CRISPR/Cas9-cleavage at either side of the (CTG⋅CAG)n sequence. Importantly, removal of the repeat appeared to have no detrimental effects on the expression of genes in the DM1 locus. Moreover, myogenic capacity, nucleocytoplasmic distribution, and abnormal RNP-binding behavior of transcripts from the edited DMPK gene were normalized. Dual sgRNA-guided excision of the (CTG⋅CAG)n tract by CRISPR/Cas9 technology is applicable for developing isogenic cell lines for research and may provide new therapeutic opportunities for patients with DM1

Effective Prolonged Therapy with Voriconazole in a Lung Transplant Recipient with Spondylodiscitis Induced by Scedosporium apiospermum

Scedosporium/Pseudallescheria species are frequently seen in cystic fibrosis patients. However, disseminated forms after lung transplantation in these patients are rarely seen, but often with poor outcome. In this case report we describe a lung transplant recipient with cystic fibrosis who developed a spondylodiscitis that was caused by Scedosporium apiospermum. The patient was treated with anti-fungal treatment by voriconazole for over three years with a clinical good response and without the need for surgical intervention. To our opinion this is the first anti-fungal treated case of invasive disease caused by Scedosporium/Pseudallescheria in a cystic fibrosis (CF) patient who underwent lung transplantation that survived