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Chemical warfare between the host and the pathogen plays a crucial role in plant-necrotrophic pathogen interactions, but examples of its involvement in quantitative disease resistance in plants are poorly documented. In the Daucus carota-Alternaria dauci pathosystem, the novel toxin aldaulactone has been identified as a key factor in both fungal pathogenicity and the carrot’s partial resistance to the pathogen. Bioinformatic analyses have pinpointed a secondary metabolism gene cluster that harbors two polyketide synthase genes, AdPKS7 and AdPKS8 , that are likely responsible for the biosynthesis of aldaulactone. Here, we present the functional validation of AdPKS7 and AdPKS8 as genes responsible for aldaulactone production in A. dauci . We generated A. dauci knock-out mutants for AdPKS7 and AdPKS8 by replacing essential domains with a hygromycin resistance gene, marking the first reported case of genetic manipulation in A. dauci . Following transformation, the mutants were analyzed for toxin production via HPLC-UV and assessed for pathogenicity in planta . Aldaulactone production was abolished in all PKS mutants, which also exhibited significantly reduced pathogenicity on H1-susceptible carrot leaves. These findings confirm the roles of AdPKS7 and AdPKS8 in aldaulactone biosynthesis and their contribution to fungal pathogenicity.

Background Grey mould caused by Botrytis cinerea Pers. (teleomorph Botryotinia fuckeliana (de Bary) Whetzel) is one of the most destructive fungal diseases of Mediterranean crops. In Algeria, few studies have been made on the economic impact of this disease. Nevertheless, it is practically present in all tomato and strawberry greenhouses, as well as in prospected vineyards in the north and south of the country. The complexity of chemical control of this disease has led to search for Trichoderma strains that are effective in biological control. Results Fifteen isolates of Trichoderma spp. were obtained from vigorous and healthy plants (tomatoes, strawberries, and vines) rhizosphere, and from a commercial bio-compost (Bio-composte®), then identified as T. afroharzianum (four isolates), T. gamsii (four isolates), T. longibrachiatum (three isolates), T. atroviride (one isolate), T. brevicompactum (one isolate), T. breve (one isolate), and T. lixii (one isolate) on the basis of DNA sequence analysis of four genes (ITS, tef1 , rpb2 , and acl1 ). In vitro biocontrol tests revealed that four Algerian isolates of Trichoderma spp. (TAtC11, TGS7, TGS10, and TBS1) had a high antagonistic activity against B. cinerea , the mycelial growth has been reduced by 62 to 65% in dual-culture technique, by 62.31 to 64.49% in volatile compounds test, and a high inhibition of germling growth was recorded by TBS1 isolate with 90.68% in Culture filtrates test. Biocontrol tests carried out on tomato plants with T. brevicompactum (TBS1), T. atroviride (TAtC11), and T. lixii (TLiC8) against B. cinerea (BCT04) showed that TBS1 inoculation significantly reduced the incidence of disease by 64.43 and 51.35% in preventive and curative treatment, respectively. Conclusion The present study revealed the first report of T. brevicompactum , T. breve , and T. lixii in Algeria, and it also contributes to the promotion of the use of native strains of Trichoderma in biological control leading to a better preservation of soil microbial diversity.

Background MCC/eisosomes are membrane microdomains that have been proposed to participate in the plasma membrane function in particular by regulating the homeostasis of lipids, promoting the recruitment of specific proteins and acting as provider of membrane reservoirs. Results Here we showed that several potential MCC/eisosomal protein encoding genes in the necrotrophic fungus A. brassicicola were overexpressed when germinated spores were exposed to antimicrobial defence compounds, osmotic and hydric stresses, which are major constraints encountered by the fungus during the plant colonization process. Mutants deficient for key MCC/eisosome components did not exhibit any enhanced susceptibility to phytoalexins and to applied stress conditions compared to the reference strain, except for a slight hypersensitivity of the ∆∆abpil1a-abpil1b strain to 2 M sorbitol. Depending on the considered mutants, we showed that the leaf and silique colonization processes were impaired by comparison to the wild-type, and assumed that these defects in aggressiveness were probably caused by a reduced appressorium formation rate. Conclusions This is the first study on the role of MCC/eisosomes in the pathogenic process of a plant pathogenic fungus. A link between these membrane domains and the fungus ability to form functional penetration structures was shown, providing new potential directions for plant disease control strategies.

MCC/eisosomes are membrane microdomains that have been proposed to participate in the plasma membrane function in particular by regulating the homeostasis of lipids, promoting the recruitment of specific proteins and acting as provider of membrane reservoirs. Here we showed that several potential MCC/eisosomal protein encoding genes in the necrotrophic fungus A. brassicicola were overexpressed when germinated spores were exposed to antimicrobial defence compounds, osmotic and hydric stresses, which are major constraints encountered by the fungus during the plant colonization process. Mutants deficient for key MCC/eisosome components did not exhibit any enhanced susceptibility to phytoalexins and to applied stress conditions compared to the reference strain, except for a slight hypersensitivity of the [DELA][DELA]abpil1a-abpil1b strain to 2 M sorbitol. Depending on the considered mutants, we showed that the leaf and silique colonization processes were impaired by comparison to the wild-type, and assumed that these defects in aggressiveness were probably caused by a reduced appressorium formation rate. This is the first study on the role of MCC/eisosomes in the pathogenic process of a plant pathogenic fungus. A link between these membrane domains and the fungus ability to form functional penetration structures was shown, providing new potential directions for plant disease control strategies.

Purpose: Colonoscopy efficacy at preventing proximal colorectal cancer (CRC) is questioned, and little is known about efficacy in high-risk versus medium-risk populations. We investigated the relationship between colonoscopy screening, family history of colorectal cancer (FHCC), and CRC risk by site. Methods: Among 92,078 women of the E3N prospective cohort, 692 CRCs have been diagnosed after a median follow-up of 15.4 years. Cox proportional hazard models estimated adjusted hazards ratios according to subsites of cancer and FHCC. Results: A personal history of colonoscopy (PHC; n = 37,470) was associated with decreased rectal and distal colon cancer risks (hazard ratio (HR) = 0.57; 95 % Confidence Interval (CI) = 0.42–0.78 and HR = 0.37; 95 % CI = 0.26–0.52, respectively), but not proximal colon cancer risk (HR = 0.87; 95 % CI = 0.64–1.18). In women with no prior colonoscopy, those with FHCC had a 80 % higher CRC risk than those without FHCC. In women with previous colonoscopy, CRC risk was similar in women with and without FHCC (p for interaction = 0.04). Conclusions: Results showed colonoscopy ability to prevent distal cancers, but not proximal cancers in women. Colonoscopy screening also reduced the excess risk of women with FHCC to that of women with no FHCC.

Gravity is a ubiquitous component of our environment that we learnt to optimally integrate in movement control. Yet, altered gravity conditions arise in numerous applications from space exploration to rehabilitation, thereby pressing the sensorimotor system to adapt. Here, we used a robotic exoskeleton to test whether humans can quickly reoptimize their motor patterns in arbitrary gravity fields, ranging from 1g to −1g and passing through Mars- and Moon-like gravities. By comparing the motor patterns of actual arm movements with those predicted by an optimal control model, we show that our participants (N = 61) quickly and optimally adapted their motor patterns to each local gravity condition. These findings show that arbitrary gravity-like fields can be efficiently apprehended by humans, thus opening new perspectives in arm weight support training in manipulation tasks, whether it be for patients or astronauts.

The aim of this paper is to show the influence of the atmospheric boundary layer profile on the distribution of velocity in a building having two large openings. The knowledge of the flow form inside a building is useful to define a thermal environment favourable with thermal comfort and good air quality. In computational fluid dynamics, several profiles of atmospheric boundary layer can be used like logarithmic profiles or power profiles. This paper shows the impact of these profiles on the indoor airflow. Non-ventilated or ventilated parts of room are found. They show respectively ineffective ventilation and effective ventilation. A qualitative and global approach allows to observe the flows in a cubic building and to show the influence of each profile according to the external ground roughness and the incidence angle of the wind. Some zones, where occupants move, are named volumes of life. Ventilation is there observed using traditional tools in order to analyze quantitatively the ventilation of these zones.

In detailled buiding simulation models, airflow modelling and solving are still open and crucial problems, specially in the case of open buildings as encountered in tropical climates. As a consequence, wind speed conditioning indoor thermal comfort or energy needs in case of air conditionning are uneasy to predict. A first part of the problem is the lack of reliable and usable large opening elementary modelling and another one concerns the numerical solving of airflow network. This non linear pressure system is solved by numerous methods mainly based on Newton Raphson (NR) method. This paper is adressing this part of the difficulty, in our software CODYRUN. After model checks, we propose to use Picard method (known also as fixed point) to initialise zone pressures. A linear system (extracted from the non linear set of equations) is solved around 10 times at each time step and NR uses this result for initial values. Known to be uniformly but slowly convergent, this method appears to be really powerful for the building pressure system. The comparison of the methods in terms of number of iterations is illustrated using a real test case experiment.