• A high calcium-score reduces the diagnostic accuracy in patients scanned with cardiac CT. • These patients would normally need an invasive angiogram for diagnosis. • In this prospective, multicenter study, subtraction CT, when evaluable, reduces false-positive stenosis evaluations. • Subtraction coronary CT angiography may, when evaluable, reduce excessive downstream testing.

Dutch elm disease (DED) is a vascular disease that has killed over 1 billion elm trees. The pathogen spreads throughout the xylem network triggering vessel blockage, which results in water stress, tissue dehydration and extensive leaf wilting in susceptible genotypes. We investigated the differences between four Ulmus minor Mill. clones of contrasting susceptibility to Ophiostoma novo-ulmi Brasier regarding morphological, anatomical and physiological traits affecting water transport, in order to gain a better understanding of the mechanisms underlying DED susceptibility. We analyzed the differential response to water shortage and increased air vapor pressure deficit (VPD) to investigate whether resistance to water stress might be related to DED tolerance. Sixteen plants per clone, aged 2 years, were grown inside a greenhouse under differential watering. Stomatal conductance was measured under ambient and increased VPD. Growth, bark water content and stem hydraulic and anatomical parameters were measured 22 days after starting differential watering. Vessel lumen area, lumen fraction and hydraulic conductance were highest in susceptible clones. Stomatal conductance was lowest under low VPD and decreased faster under increased VPD in resistant clones. We found a negative relationship between the decrease in stomatal conductance at increased VPD and specific hydraulic conductance, revealing a narrower hydraulic margin for sustaining transpiration in resistant clones. The effect of water shortage was greater on radial stem growth than on leaf area, which could be explained through an extensive use of capacitance water to buffer xylem water potential. Water shortage reduced stomatal conductance and vessel lumen area. Bark water content under conditions of water shortage only decreased in susceptible clones. Higher hydraulic constraints to sap flow in resistant clones may determine higher stomatal sensitivity to VPD and so contribute to DED resistance by limiting pathogen expansion and reducing water loss and metabolic impairment in cells involved in fighting against infection.

• Calcium and metal artefacts are still a limitation for conventional coronary CTA • Diagnostic accuracy is improved by subtraction as compared with conventional CTA • Subtraction CTA is a promising tool to overcome limitations of conventional CTA.

The Dutch elm disease (DED) pathogens, Ophiostoma ulmi (Buisman) Nannf. and the more aggressive Ophiostoma novo-ulmi Brasier, have decimated European elm populations in the last 100 years. Today, the number of tolerant elm varieties available on the market is limited, partly due to the long breeding cycles and expensive facilities they require. Developing a low-cost technique to allow early screening of elm tolerance based on simple morphological and/or biochemical traits would considerably boost elm breeding and research. Within this general aim, we developed an in vitro plant culture system to (i) characterize stress responses to O. novo-ulmi-root inoculation in two Ulmus minor Mill. clones of contrasting susceptibility level to DED (termed ‘tolerant’ and ‘susceptible’) and (ii) compare the upward dispersal rate of the pathogen in the two clones. Constitutive xylem anatomy was similar in both clones, indicating that differences in plant responses to the pathogen are not attributable to anatomical factors (e.g., conduit size). Susceptible plantlets suffered a significant delay in apical growth and a decrease in chlorophyll content at 21 days post-inoculation (dpi). The rate of pathogen dispersal from roots to aerial tissues was similar in both clones. However, the tolerant clone showed a marked increase in lipid peroxidation at 1 dpi, while the susceptible clone showed enhanced values of lipid peroxidation during most of the experimental period (1–21 dpi). Despite wide stem colonization by the pathogen, the tolerant clone effectively regulated the oxidative stress levels and showed remarkable resilience to inoculation. These results extend current knowledge on elm defense mechanisms, and the proposed in vitro plant culture system emerges as a promising early screening method for tolerance to improve elm breeding.

No abstract