Increased resistance to biotrophic pathogens in the Arabidopsis constitutive induced resistance 1 mutant is EDS1 and PAD4-dependent and modulated by environmental temperature

The Arabidopsis constitutive induced resistance 1 ( cir1 ) mutant displays salicylic acid (SA)-dependent constitutive expression of defence genes and enhanced resistance to biotrophic pathogens. To further characterise the role of CIR1 in plant immunity we conducted epistasis analyses with two key components of the SA-signalling branch of the defence network, ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4). We demonstrate that the constitutive defence phenotypes of cir1 require both EDS1 and PAD4, indicating that CIR1 lies upstream of the EDS1-PAD4 regulatory node in the immune signalling network. In light of this finding we examined EDS1 expression in cir1 and observed increased protein, but not mRNA levels in this mutant, suggesting that CIR1 might act as a negative regulator of EDS1 via a post-transcriptional mechanism. Finally, as environmental temperature is known to influence the outcome of plant-pathogen interactions, we analysed cir1 plants grown at 18, 22 or 25°C. We found that susceptibility to Pseudomonas syringae pv. tomato ( Pst ) DC3000 is modulated by temperature in cir1 . Greatest resistance to this pathogen (relative to PR-1:LUC control plants) was observed at 18°C, while at 25°C no difference in susceptibility between cir1 and control plants was apparent. The increase in resistance to Pst DC3000 at 18°C correlated with a stunted growth phenotype, suggesting that activation of defence responses may be enhanced at lower temperatures in the cir1 mutant

Conversion of natural forest results in a significant degradation of soil hydraulic properties in the highlands of Kenya

Land use change, especially conversion of native forests can have large impacts on water resources. Large scale conversion of native forests to agricultural land has occurred in the last few decades in the Mau Forest region. To quantify and understand landscape hydrologic responses, this study aimed at evaluating the effects of land use on soil infiltration, saturated hydraulic conductivity, bulk density, sorptivity, and soil moisture retention. A total of 136 plots representing five different land uses (native forest: n = 39, forest plantations: n = 14, tea plantations: n = 24, croplands: n = 23 and pasture: n = 36) were sampled in three catchments with similar parental material in the Mau Forest region, Western Kenya. Native forest topsoils (0–5 cm) had a bulk density of 1.0 ± 0.2 g cm−3 which was similar to values found for topsoils of forest plantations (1.1 ± 0.2 g cm−3), but significantly lower than topsoils from croplands (1.4 ± 0.2 g cm−3), tea plantation (1.3 ± 0.3 g cm−3) and pastures (1.4 ± 0.2 g cm−3). Similarly, soil infiltration rates were higher in native forest (76.1 ± 50 cm h−1) and in forest plantation (60.2 ± 47.9 cm h−1) than in croplands (40.5 ± 21.5 cm h‐1), tea plantations (43.3 ± 29.2 cm h−1) and pastures (13.8 ± 14.6 cm h−1). Native forest had the highest topsoil organic carbon contents (8.11 ± 2.42%) and field capacity (0.62 ±0.12 cm3 cm−3), while the highest permanent wilting point was recorded for pasture soils (mean of 0.41 ± 0.06 cm cm−3). The highest plant available water capacity was recorded for soils in native forest (mean of 0.27 ± 0.14 cm cm−3). Our study indicates that land use changes result in a significant degradation of soil hydraulic properties, which has likely resulted in changes of the regional water balance. Given the magnitude in which managed land use types have changed infiltration rates in our study area, we conclude that changes in land use types occurring in our study region in the last decades have already affected the hydrological regime of the landscapes and the compositions of flow components. The reduction in infiltration and hydraulic conductivity could result in increased surface run-off, erosion and frequency of flooding events

Effects of conversion of native cerrado vegetation to pasture on soil hydro-physical properties, evapotranspiration and streamflow on the Amazonian agricultural frontier

Understanding the impacts of land-use change on landscape-hydrological dynamics is one of the main challenges in the Northern Brazilian Cerrado biome, where the Amazon agricultural frontier is located. Motivated by the gap in literature assessing these impacts, we characterized the soil hydro-physical properties and quantified surface water fluxes from catchments under contrasting land-use in this region. We used data from field measurements in two headwater micro-catchments with similar physical characteristics and different land use, i.e. cerrado sensu stricto vegetation and pasture for extensive cattle ranching. We determined hydraulic and physical properties of the soils, applied ground-based remote sensing techniques to estimate evapotranspiration, and monitored streamflow from October 2012 to September 2014. Our results show significant differences in soil hydro-physical properties between the catchments, with greater bulk density and smaller total porosity in the pasture catchment. We found that evapotranspiration is smaller in the pasture (639 ± 31% mm yr-1) than in the cerrado catchment (1,004 ± 24% mm yr-1), and that streamflow from the pasture catchment is greater with runoff coefficients of 0.40 for the pasture and 0.27 for the cerrado catchment. Overall, our results confirm that conversion of cerrado vegetation to pasture causes soil hydro-physical properties deterioration, reduction in evapotranspiration reduction, and increased streamflow

Trends in reported vulval cancer in Zimbabwe, 2006-2014

Objective: To determine the trends in reported vulval cancer in Zimbabwe between the years 2006 and 2014 and to determine the age groups with the highest number of reported cases. Setting: The Zimbabwe National Cancer Registry located in Harare, Zimbabwe. Subjects: Patients with histologically confirmed vulval cancer reported to the Zimbabwe National Cancer Registry between 2006 and 2014. Main Outcome Measures: The outcome measures were the number of cases of vulval cancer that were reported between 2006 and 2014, the percentage of all the reported gynaecological cancer that they constituted and the age ranges with the highest number of reported cases. Results: Reported cases of vulval cancer rose from 16 in 2006 to 54 in 2013. In 2014 there were 46 reported cases. Vulval cancer constituted 1.8% of all reported gynaecological cancer in 2006 rising to 3.9% in 2013.In 2014 it constituted 2.8% of all reported gynaecological cancer. In 2006 the majority of the reported cases (43.8%) were aged 55 to 69 years whilst for the rest of the years the majority was aged 25 to 39 years. Conclusions: The number of reported cases of vulval cancer and the proportion of gynaecological cancer that they constituted both increased between the years 2006 and 2014. The majority of women affected by the malignancy were in the 25 to 39 years age group

Groundwater recharge rates and surface runoff response to land use and land cover changes in semi-arid environments

The effects of land use and land cover (LULC) on groundwater recharge and surface runoff and how these are affected by LULC changes are of interest for sustainable water resources management. However, there is limited quantitative evidence on how changes to LULC in semi-arid tropical and subtropical regions affect the subsurface components of the hydrologic cycle, particularly groundwater recharge. Effective water resource management in these regions requires conclusive evidence and understanding of the effects of LULC changes on groundwater recharge and surface runoff. We reviewed a total of 27 studies (2 modeling and 25 experimental), which reported on pre- and post land use change groundwater recharge or surface runoff magnitude, and thus allowed to quantify the response of groundwater recharge rates and runoff to LULC. Comparisons between initial and subsequent LULC indicate that forests have lower groundwater recharge rates and runoff than the other investigated land uses in semi-arid tropical/ subtropical regions. Restoration of bare land induces a decrease in groundwater recharge from 42% of precipitation to between 6 and 12% depending on the final LULC. If forests are cleared for rangelands, groundwater recharge increases by 7.8 ± 12.6%, while conversion to cropland or grassland results in increases of 3.4 ± 2.5 and 4.4 ± 3.3%, respectively. Rehabilitation of bare land to cropland results in surface runoff reductions of between 5.2 and 7.3%. The conversion of forest vegetation to managed LULC shows an increase in surface runoff from 1 to 14.1% depending on the final LULC. Surface runoff was reduced from 2.5 to 1.1% when grassland is converted to forest vegetation. While there is general consistency in the results from the selected case studies, we conclude that there are few experimental studies that have been conducted in tropical and subtropical semi-arid regions, despite that many people rely heavily on groundwater for their livelihoods. Therefore, there is an urgent need to increase the body of quantitative evidence given the pressure of growing human population and climate change on water resources in the region