Leaf rust (Puccinia triticina Eriks.), stripe rust (Puccinia striiformis f. tritici Eriks.) and stem rust (Puccinia graminis f. sp. tritici) cause major production losses in durum wheat (Triticum ...turgidum L. var. durum). The objective of this research was to identify and map leaf, stripe and stem rust resistance loci from the French cultivar Sachem and Canadian cultivar Strongfield. A doubled haploid population from Sachem/Strongfield and parents were phenotyped for seedling reaction to leaf rust races BBG/BN and BBG/BP and adult plant response was determined in three field rust nurseries near El Batan, Obregon and Toluca, Mexico. Stripe rust response was recorded in 2009 and 2011 nurseries near Toluca and near Njoro, Kenya in 2010. Response to stem rust was recorded in field nurseries near Njoro, Kenya, in 2010 and 2011. Sachem was resistant to leaf, stripe and stem rust. A major leaf rust quantitative trait locus (QTL) was identified on chromosome 7B at Xgwm146 in Sachem. In the same region on 7B, a stripe rust QTL was identified in Strongfield. Leaf and stripe rust QTL around DArT marker wPt3451 were identified on chromosome 1B. On chromosome 2B, a significant leaf rust QTL was detected conferred by Strongfield, and at the same QTL, a Yr gene derived from Sachem conferred resistance. Significant stem rust resistance QTL were detected on chromosome 4B. Consistent interactions among loci for resistance to each rust type across nurseries were detected, especially for leaf rust QTL on 7B. Sachem and Strongfield offer useful sources of rust resistance genes for durum rust breeding.
Objectives The aim of this study was to determine the in vitro activity of lipiarmycin against drug-resistant strains of Mycobacterium tuberculosis (MTB) and to establish the resistance mechanism of ...MTB against lipiarmycin using genetic approaches. Methods MIC values were measured against a panel of drug-resistant strains of MTB using the broth microdilution method. Spontaneous lipiarmycin-resistant mutants of MTB were tested for cross-resistance to standard anti-TB drugs, and their rpoB and rpoC genes were sequenced to identify mutations. Results Lipiarmycin exhibited excellent inhibitory activity against multidrug-resistant strains of MTB with MIC values of <0.1 mg/L. Sequence analysis of the rpoB and rpoC genes from spontaneous lipiarmycin-resistant mutants of MTB revealed that missense mutations in these genes caused resistance to lipiarmycin. Although both lipiarmycin and rifampicin are known to inhibit the bacterial RNA polymerase, the sites of mutation in the rpoB gene were found to be different in MTB strains resistant to these inhibitors. Whereas all six rifampicin-resistant MTB strains tested had mutation in the 81 bp hotspot region of the rpoB gene spanning codons 507–533, 16 of 18 lipiarmycin-resistant strains exhibited mutation between codons 977 and 1150. The remaining two lipiarmycin-resistant strains had mutation in the rpoC gene. Conclusions Lipiarmycin has excellent bactericidal activity against MTB and lacks cross-resistance to standard anti-TB drugs. Furthermore, rifampicin-resistant strains remained fully susceptible to lipiarmycin, and none of the lipiarmycin-resistant MTB strains became resistant to rifampicin, highlighting the lack of cross-resistance.
Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and ...assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.
Peatland drainage depletes large carbon stocks by increasing carbon dioxide (CO2) emissions from the soil. Restoration via re‐wetting could play an important role in climate change mitigation, ...reducing CO2 emissions and increasing C storage within peatlands. However, re‐wetting leads to a biogeochemical compromise between increased CO2 uptake, and enhanced methane (CH4) release. The extent of this compromise in re‐wetted ecosystems with differing environmental conditions is uncertain. To assess re‐wetting effects, we analyzed eddy‐covariance flux measurements from a temperate bog near Vancouver, Canada, from two sites that have undergone different restoration techniques. By the end of the 1‐year study period, the actively re‐wetted, wetter site, was a weak CO2 sink (−26.1 ± 6.1 g C‐CO2 m−2), and the passively re‐wetted, drier site, was near CO2 neutral (3.8 ± 3.1 g C‐CO2 m−2). Higher CH4 emissions at the wetter site led to a larger radiative balance on 20‐ and 100‐year time horizons, implying that the strong radiative effect of CH4 can offset CO2 sink strength on shorter to medium timeframes. However, long‐term radiative forcing (RF) modeling suggests sustained CO2 uptake by the wetter site will eventually lead to a cooling effect on the climate. Furthermore, modeling results emphasize that despite both re‐wetted peatland sites having a positive RF over century timescales, the lack of restoration would have resulted in a significantly larger RF beyond the first few decades following restoration. Results highlight the importance of actively re‐wetting disturbed peatlands to mitigate climate warming and can be used to inform management decisions.
Plain Language Summary
Peatlands are important ecosystems in the global carbon cycle as their soils can store vast quantities of carbon. However, when soils in peatlands are disturbed via drainage, they dry and release carbon dioxide (CO2) into the atmosphere, contributing to global warming. Scientists have proposed re‐wetting drained peatlands to reverse this effect and promote CO uptake. This can be an issue, because wet conditions often lead to increased emissions of methane (CH4), a much more potent greenhouse gas (GHG). This study presents results comparing GHG and environmental measurements from two peatlands undergoing restoration near Vancouver, Canada—one wetter, and one drier site. Restoration of both sites has a climate benefit compared to not re‐wetting, however, results reveal that although the wetter site had higher CH4 emissions, it was a larger CO2 sink than the drier site, and therefore will eventually have a cooling effect on the climate on long timescales. These results are useful for identifying which environmental conditions in re‐wetted peatlands are most beneficial for the climate.
Key Points
Of two rewetted peatland sites, wetter conditions at one site corresponded with it being a stronger carbon dioxide sink
The wetter site was a larger methane source than the drier one, resulting in a greater radiative balance on 20‐ and 100‐year timeframes
Over century timescales, the wetter site had a lower (eventually negative) radiative forcing, and overall rewetting had climatic benefits
The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is ...14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.
Natural methyl chloride (CH3Cl) and methyl bromide (CH3Br) emissions from coastal marsh ecosystems may constitute a significant proportion of stratospheric chlorine and bromine, which catalyze ozone ...depletion. Current inventories involve substantial uncertainties associated with upscaling plot‐scale footprints (i.e., ≤1 m2). Here we present net ecosystem flux measurements of methyl halides from a brackish tidal marsh on the west coast of the United States between April 2016 and June 2017 using the relaxed eddy accumulation method. The measurement footprint encompasses a large part of the studied tidal marsh, including roughly 20 vascular plant species, open water, and soil surfaces. On the annual scale, ecosystem methyl halide emissions showed the strongest relationships to temperature and the growth cycle of halophyte vegetation, whereas on diurnal time scales, fluxes correlated the most with evapotranspiration. The maximum seasonal emissions occurred during the flowering season of Lepidium latifolium (perennial pepperweed), one of the most abundant halophytes on site. The maximum hourly emissions of 111 μg CH3Cl · m−2 s· hr−1 and 38 μg CH3Br · m−2 · hr−1 were observed during a heat wave in early June. Annually integrated emissions were 135 mg/m2 for CH3Cl and 21 mg/m2 for CH3Br, scaling up to 621 and 96 kg over the entire marsh. We provide a global salt marsh emission inventory that takes into account the spatial distribution of salt marshes in different climate zones, yielding a global salt marsh source of 31 Gg/year CH3Cl (range: 10 to 77) and 3 Gg/year CH3Br (range: 1 to 8).
Key Points
These are the first ecosystem‐scale flux measurements of methyl halides using the relaxed eddy accumulation method
Methyl halide emissions follow a seasonal pattern, controlled by temperature and the halophyte growth cycle, with episodic spikes during heat waves
The invasive perennial pepperweed (Lepidium latifolium) contributes significantly to the overall emissions
Area burned, number of fires, seasonal fire severity, and fire season length are all expected to increase in Canada, with largely unquantified
ecosystem feedbacks. However, there are few ...observational studies measuring ecosystem-scale biogeochemical (e.g., carbon dioxide exchanges) and
biophysical (e.g., energy partitioning) properties during smoke episodes and hence assessing responses of gross primary production (GPP) to changes
in incoming diffuse photosynthetically active radiation (PAR). In this study, we leveraged two long-term eddy covariance measurement sites in forest and wetland ecosystems to study four smoke episodes, which happened at different times and differed in length, over 4 different years (2015, 2017, 2018, and 2020). We found that the highest decrease in shortwave irradiance due to smoke was about 50 % in July and August but increased to about 90 % when the smoke arrived in September. When the smoke arrived in the later stage of summer, impacts on sensible and latent heat fluxes were very different than the earlier ones. Smoke generally increased the diffuse fraction (DF) from ∼ 0.30 to ∼ 0.50 and turned both sites into stronger carbon dioxide (CO2) sinks with increased GPP up to ∼ 18 % and ∼ 7 % at the forest and wetland site, respectively. However, when DF exceeded 0.80 as a result of dense smoke, both ecosystems became net CO2 sources as total PAR dropped to low values. The results suggest that this kind of natural experiment is important for validating future predictions of smoke–productivity feedbacks.
•Fuzzy cognitive mapping enabled stakeholders to formalise conceptual and causal water relationships in agriculture.•Water policy, resources management, technology uptake and knowledge translation ...identified as key areas for intervention.•Transparency and participatory stakeholder engagement needed to improve water governance and on-farm water management.
Malta faces a raft of water challenges which are negatively impacting on the sustainability of irrigated agriculture, and creating serious tensions with other sectors competing for water, including urban development, tourism and the environment. In this paper we argue for a transparent process centred on participatory stakeholder engagement to agree on the most challenging water-related risks and to identify solutions that both support the water governance framework and improve on-farm water management practices. Given Malta’s dependence on freshwater, this study focused on outdoor field-scale irrigated production. A three staged stakeholder-driven approach was developed. The first stage included Delphi analyses to identify the key constraints on water management and fuzzy cognitive mapping to enable stakeholders to analyse their mental models and formalise conceptual and causal relationships between different components impacting on Maltese agriculture. Secondly, questionnaires were used to inform understanding of national policy gaps in water management and thirdly, a “backcasting” stakeholder workshop was used to identify policy actions to achieve a more sustainable future for agriculture on the island. The study confirmed that Malta’s core challenge is tied to poor water governance and the need to define policies that are socially and environmentally acceptable and geared to tackling the complex water challenges the agricultural sector faces. Developing support for farmer training, knowledge translation, greater public awareness of the importance and value of water for high-value crop production and multi-sector collaboration to promote shared opportunities for water infrastructure investment were highlighted as potential solutions. The findings have direct relevance to other island communities where water scarcity poses serious agronomic risks to production and where agriculture underpins rural livelihoods and the economy.
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