Resistance risk assessment of mefentrifluconazole in Corynespora cassiicola and the control of cucumber target spot by a two-way mixture of mefentrifluconazole and prochloraz.

The cucumber target spot, caused by Corynespora cassiicola, is a major cucumber disease in China. Mefentrifluconazole, a new triazole fungicide, exhibits remarkable efficacy in controlling cucumber target spot. However, the resistance risk and mechanism remain unclear. In this study, the inhibitory activity of mefentrifluconazole against 101 C. cassiicola isolates was determined, and the results indicated that the EC50 values ranged between 0.15 and 12.85 µg/mL, with a mean of 4.76 µg/mL. Fourteen mefentrifluconazole-resistant mutants of C. cassiicola were generated from six parental isolates in the laboratory through fungicide adaptation or UV irradiation. The resistance was relatively stable after ten consecutive transfers on a fungicide-free medium. No cross-resistance was observed between mefentrifluconazole and pyraclostrobin, fluopyram, prochloraz, mancozeb, or difenoconazole. Investigations into the biological characteristics of the resistant mutants revealed that six resistant mutants exhibited an enhanced compound fitness index (CFI) compared to the parental isolates, while others displayed a reduced or comparable CFI. The overexpression of CcCYP51A and CcCYP51B was detected in the resistant mutants, regardless of the presence or absence of mefentrifluconazole. Additionally, a two-way mixture of mefentrifluconazole and prochloraz at a concentration of 7:3 demonstrated superior control efficacy against the cucumber target spot, achieving a protection rate of 80%. In conclusion, this study suggests that the risk of C. cassiicola developing resistance to mefentrifluconazole is medium, and the overexpression of CcCYP51A and CcCYP51B might be associated with mefentrifluconazole resistance in C. cassiicola. The mefentrifluconazole and prochloraz two-way mixture presented promising control efficacy against the cucumber target spot.

Resistance to the DMI fungicide mefentrifluconazole in Monilinia fructicola: risk assessment and resistance basis analysis.

BACKGROUND: Brown rot disease, caused by Monilinia fructicola, poses a significant challenge to peach production in China. The efficacy of mefentrifluconazole, a new triazole fungicide, in controlling brown rot in peaches has been remarkable. However, the resistance risk and mechanism associated with this fungicide remain unclear. This study was designed to assess the resistance risk of M. fructicola to mefentrifluconazole and reveal the potential resistance mechanism. RESULTS: The mean median effective concentration (EC50 ) of 101 M. fructicola isolates to mefentrifluconazole was 0.003 µg mL-1 , and the sensitivity exhibited a unimodal distribution. Seven mefentrifluconazole-resistant mutants were generated from three parental isolates in the laboratory through fungicide adaption. The biological characteristics of the resistant mutants revealed that three of them exhibited enhanced survival fitness compared to the parental isolates, whereas the remaining four mutants displayed reduced survival fitness. Mefentrifluconazole showed strong positive cross-resistance with fenbuconazole, whereas no cross-resistance was observed with pyrimethanil, procymidone or pydiflumetofen. No overexpression of MfCYP51 gene was detected in the resistant mutants. Multiple sequence alignment revealed that three resistant mutants (MXSB2-2, Mf12-1 and Mf12-2) had a point mutation (G461S) in MfCYP51 protein. Molecular docking techniques confirmed the contribution of this point mutation to mefentrifluconazole resistance. CONCLUSION: The risk of M. fructicola developing resistance to mefentrifluconazole is relatively low-to-medium and point mutation G461S in MfCYP51 could confer mefentrifluconazole resistance in M. fructicola. This study provided essential data for monitoring the emergence of resistance and developing resistance management strategies for mefentrifluconazole. © 2023 Society of Chemical Industry.

High-efficiency uranium extraction from seawater by low-cost natural protein hydrogel.

Utilization of uranium resource in seawater are highly possible to meet the growth demands for the sustainable development of nuclear energy industry. Bio-adsorbents exhibit high performance in terms of adsorption selectivity, equilibrium speed, and environmental friendliness, while the high fabrication cost hinders their practical application. In this study, a low-cost soy protein isolate (SPI) is used to fabricate adsorbent named SPI hydrogel for uranium extraction. This is the first report on applying bio-adsorbents derived from low-cost natural proteins for uranium extraction. The SPI hydrogel showed high uranium adsorption capacity of 53.94 mg g-1 in simulated nuclear wastewater and 5.29 mg g-1 is achieved in natural seawater, which is higher than all currently available adsorbents based on non-modified natural biomolecules. The amino and oxygen-containing groups are identified as the functional groups for uranyl binding by providing four oxygen and two nitrogen atoms to form equatorial coordination with uranyl, which guarantees the high binding selectivity and affinity to uranyl ions. The low cost for accessing the raw material together with the environmental friendliness, high salt tolerance, high uranium adsorption ability, and high selectivity to uranium, make SPI hydrogel a promising adsorbent for uranium extraction from seawater and nuclear wastewater.

Gas Particle Partitioning of PAHs Emissions from Typical Solid Fuel Combustions as Well as Their Health Risk Assessment in Rural Guanzhong Plain, China.

Air pollutants from the incomplete combustion of rural solid fuels are seriously harmful to both air quality and human health. To quantify the health effects of different fuel-stove combinations, gas and particle partitioning of twenty-nine species of polycyclic aromatic hydrocarbons (PAHs) emitted from seven fuel-stove combinations were examined in this study, and the benzo (a) pyrene toxicity equivalent (BaPeq) and cancer risks were estimated accordingly. The results showed that the gas phase PAHs (accounting for 68-78% of the total PAHs) had higher emission factors (EFs) than particulate ones. For all combustion combinations, pPAHs accounted for the highest proportion (84.5% to 99.3%) in both the gas and particulate phases, followed by aPAHs (0.63-14.7%), while the proportions of nPAHs and oPAHs were much lower (2-4 orders of magnitude) than pPAHs. For BaPeq, particulate phase PAHs dominated the BaPeq rather than gas ones, which may be due to the greater abundance of 5-ring particle PAHs. Gas and particle pPAHs were both predominant in the BaPeq, with proportions of 95.2-98.6% for all combustion combinations. Cancer risk results showed a descending order of bituminous coal combustion (0.003-0.05), biomass burning (0.002-0.01), and clean briquette coal combustion (10-5-0.001), indicating that local residents caused a severe health threat by solid fuel combustion (the threshold: 10-4). The results also highlighted that clean briquette coal could reduce cancer risks by 1-2 orders of magnitude compared to bulk coal and biomass. For oPAH, BcdPQ (6H-benzo(c,d)pyrene-6-one) had the highest cancer risk, ranging from 4.83 × 10-5 to 2.45 × 10-4, which were even higher than the total of aPAHs and nPAHs. The dramatically high toxicity and cancer risk of PAHs from solid fuel combustion strengthened the necessity and urgency of clean heating innovation in Guanzhong Plain and in similar places.

Resistance assessment of pyraoxystrobin in Magnaporthe oryzae and the detection of a point mutation in cyt b that confers resistance.

Pyraoxystrobin is a new QoI fungicide developed in China. The present study was aimed at determining the baseline sensitivity of M. oryzae to pyraoxystrobin and investigating the potential resistance risk and resistance mechanism of pyraoxystrobin in M. oryzae. The results showed that the mean EC50 of 109 M. oryzae isolates to pyraoxystrobin was 0.0094 µg/mL and the sensitivity exhibited a unimodal distribution. The established baseline sensitivity could provide critical data for monitoring sensitivity changes of M. oryzae to pyraoxystrobin in rice fields. The potential resistance risk was assessed by investigating the biological characteristics of the resistant mutants obtained by fungicide adaptation. The results indicated that the resistance risk of pyraoxystrobin in M. oryzae was medium to high with positive cross-resistance between pyraoxystrobin and azoxystrobin, but without cross resistance between pyraoxystrobin and carbendazim, isoprothiolane, and prochloraz. Further investigation revealed that the pyraoxystrobin-resistant mutants had a G143S mutation in the cyt b protein. Molecular docking confirmed that the G143S substitution conferred high resistance to pyraoxystrobin in M. oryzae. Collectively, the results of this study provided essential data for monitoring the emergence of resistance and developing resistance management strategies for pyraoxystrobin.

Low-cost whole slide imaging system with single-shot autofocusing based on color-multiplexed illumination and deep learning.

Recent research on whole slide imaging (WSI) has greatly promoted the development of digital pathology. However, accurate autofocusing is still the main challenge for WSI acquisition and automated digital microscope. To address this problem, this paper describes a low cost WSI system and proposes a fast, robust autofocusing method based on deep learning. We use a programmable LED array for sample illumination. Before the brightfield image acquisition, we turn on a red and a green LED, and capture a color-multiplexed image, which is fed into a neural network for defocus distance estimation. After the focus tracking process, we employ a low-cost DIY adaptor to digitally adjust the photographic lens instead of the mechanical stage to perform axial position adjustment, and acquire the in-focus image under brightfield illumination. To ensure the calculation speed and image quality, we build a network model based on a 'light weight' backbone network architecture-MobileNetV3. Since the color-multiplexed coherent illuminated images contain abundant information about the defocus orientation, the proposed method enables high performance of autofocusing. Experimental results show that the proposed method can accurately predict the defocus distance of various types of samples and has good generalization ability for new types of samples. In the case of using GPU, the processing time for autofocusing is less than 0.1 second for each field of view, indicating that our method can further speed up the acquisition of whole slide images.

Resistance assessment for SYP-14288 in Phytophthora capsici and changes in mitochondria electric potential-associated respiration and ATP production confers resistance.

BACKGROUND: Phytophthora capsici is a destructive plant oomycete pathogen that could lead to devastating losses in food production. Fungicide application is the main way to control plant disease caused by P. capsici. SYP-14288, a novel fungicide with a unique mode of action, could be used to control a broad range of plant diseases. Here, the potential for SYP-14288 resistance in P. capsici and the resistance mechanism involved were evaluated. RESULTS: Baseline sensitivities of 133 isolates to SYP-14288 were determined and found to conform to a unimodal curve with a mean half-maximal effective concentration (EC50 ) of 0.625 µg mL-1 . In total, 21 stable SYP-14288-resistant mutants were generated by fungicide adaptation in three sensitive isolates. The fitness of all the mutants was found to be lower than that of the parental isolates. Otherwise, downregulation of various ATPases may confer different resistance levels in P. capsici. Finally, multiple biochemical studies strongly suggest that both ATP content and electric potential were reduced in SYP-14288-resistant mutants, and as a compensatory mechanism, respiration was facilitated to make up for the energy defect in mutants. CONCLUSION: The low fitness of SYP-14288-resistant mutants suggests that the resistance risk of P. capsici to SYP-14288 is low. Resistance may be led by a permeability change in the mitochondrial inner membrane in SYP-14288-resistant isolates, and lower ATP consumption lifestyles may be key to the SYP-14288 resistance generated in P. capsici. The current study could benefit the registration and application of the novel fungicide SYP-14288. © 2020 Society of Chemical Industry.

Risk assessment for human health in a seleniferous area, Shuang'an, China.

Shuang'an in Ziyang is a typical high-selenium (Se) area in China, where human selenium (Se) poisoning was reported 30 years ago. To assess the risk of Se poisoning in the area, the Se content in agricultural soil, plant, and water in Naore, Shuang Hekou, and Lin Benhe villages of Ziyang was systematically investigated. The probable daily intake (PDI) was calculated on the basis of Se contents in food, water, and dietary habits to evaluate the risk of selenosis. Se content in hair from local habitants (32 men and 34 women) was determined to further verify the risk. Results showed that Se content in the soil ranged from 0.21 to 36.07 mg/kg, with a geometric means of 3.02 ± 5.16 mg/kg, respectively. Approximately 60% of soil reached the Se toxicity threshold (>3 mg/kg). The Se content in plants ranged from 0.02 to 17 mg/kg, with an average of 0.76 ± 2.51 mg/kg. Approximately 40% of the plant reached the toxicity standard (1 mg/kg). Se content in soil and plant of Naore village was significantly higher than that from two adjacent villages. The Se content in vegetables (on fresh weight basis) was higher than that in cereals. Se contents were 3.73 ± 9.08 and 1.32 ± 3.50 mg/kg in eggplant and pepper, respectively. The Se content in drinking water was 7.85 ± 6.04 µg/L, lower than the upper tolerable limit (40 µg/L) set by WHO. The Se content in stream water (18.5 µg/L) was significantly higher than that in drinking water because of soil erosion. The calculated PDI of habitants in Naore village (1801 µg/day) was significantly higher than that in Lin Benhe (666 µg/day) and Shuang Hekou (686 µg/day), all of which was higher than the tolerable upper Se intake (400 µg/day) set by WHO. The calculated blood Se content was relatively high, especially for habitants of Naore village (2783-2824 µg/L). Moreover, the Se content in the hair of local habitants reached as high as 12.72 ± 13.81 mg/kg, and 78.79% exceeded hair Se toxicity threshold (>3 mg/kg), which further verified the potential selenosis risk. Our study provides significant implications of the potential Se intoxication of local residents. Therefore, governments and other institutions should implement various measures to reduce the daily Se intake and to mitigate the associated health risks.

Assessment of bioavailability of selenium in different plant-soil systems by diffusive gradients in thin-films (DGT).

Uptake of selenium (Se) by plants largely depend on the availability of Se in soil. Soils and plants were sampled four times within 8 weeks of plant growth in pot experiments using four plant species. Sequential extraction and diffusive gradients in thin-films (DGT) method were employed to measure Se concentrations in potted soils in selenite- or selenate-amended soils. Results showed that DGT-measured Se concentrations (CDGT-Se) were generally several folds higher for selenate than selenite amended soils, which were obviously affected by the plant species and the duration of their growth. For example, the folds in soil planted with mustard were 1.49-3.47 and those in soils planted with purple cabbage and broccoli, which grew for 3 and 4 weeks after sowing, were 1.06-2.14 and only 0.15-0.62 after 6 weeks of growth. The selenate-amended soil planted with wheat showed an extremely high CDGT-Se compared with selenite-amended soil, except the last harvest. Furthermore, minimal changes in CDGT-Se and soluble Se(IV) were found in selenite-amended soils during plant growth, whereas significant changes were observed in selenate-amended soils (p < 0.05). Additionally, Se distribution in various fractions of soil remarkably changed; the soils planted with purple cabbage and broccoli showed the most obvious change followed by wheat and mustard. Soluble Se(VI) and exchangeable Se(VI) were likely the major sources of CDGT-Se in selenate-amended soils, and soluble Se(IV) was the possible source of CDGT-Se in selenite-amended soils. In selenate-amended soils, soluble Se(VI) and exchangeable Se(VI) were significantly correlated with Se concentrations in purple cabbage, broccoli, and mustard; in wheat, Se concentration was significantly correlated only with soluble Se(VI) but not with exchangeable Se. CDGT-Se eventually became positively correlated with Se concentrations accumulated by different plants, indicating that DGT is a feasible method in predicting plant uptake of selenate but not of selenite.

[Responses of ecosystem carbon budget to increasing nitrogen deposition in differently degraded Leymus chinensis steppes in Inner Mongolia, China].

Based on a field manipulative nitrogen (N) addition experiment, the effects of atmospheric N deposition level change on the plant biomass and net primary productivity (NPP), soil respiration (Rs) and net ecosystem exchange (NEE) were investigated respectively in 2009 and 2010 in two differently degraded Leymus chinensis steppes in Inner Mongolia of China, and the difference in the response of NEE to equal amount of N addition [10 g x (M2 x a)(-1), MN] between the two steppes was also discussed. The results indicated that for the light degraded Leymus chinensis steppe (site A) , the average plant aboveground biomass (AGB) in MN treatment were 21.5% and 46.8% higher than those of CK in these two years. But for the moderate degraded Leymus chinensis steppe (site B), the N addition decreased the plant AGB and ANPP in 2009, while showed positive effects in 2010. N addition increased the belowground biomass (BGB) of the both sites and belowground NPP (BNPP) of site B in both years, but decreased the BNPP of site A in 2010. The increase of N input in the two steppes did not change the seasonal variation of Rs. The cumulative annual soil C emissions in MN treatment in site A showed an increase of about 14.6% and 25.7% of those in the CK respectively for these two years, while were decreased by about 10.4% and 11.3%, respectively in site B. The NEE of MN treatments, expressed by C, for the two steppes were 59.22 g x (m2 x a)(1) and 166.68 g x (m2 x a)(-1), as well as 83.27 g x (m2 x a)(-1) and 117.47 g x (m2 x a)(-1), respectively in these two years. The increments in NEE originated from N addition for these two years were 15.79 g x (M2 x a)(-1) and 82.94 g x (M2 x a)(-1) in site A and 74.54 g x (M2 x a)(-1) and 101.23 g x (M2 x a)(-1) in site B. The N input per unit could obtain greater C sink effect in the steppe with lower initial N level.