First Report of Pseudomonas oryzihabitans Causing Walnut Leaf Spot Disease in China.

China ranks first in the production and harvest area of walnut (Juglans regia L.) worldwide. Currently, the poor health and low yield of walnut caused by pathogen infection is of concern. In 2022, severe walnut leaf spot disease was observed on the seedlings of four walnut nurseries (0.08 to 0.23 ha) in Liaocheng, Shandong, China, with an average incidence of 48.6% (from 34.6% to 65.3% on the cultivar Xiangling). From August to October, leaf spots mainly appeared on the edges of the leaflets, and occasionally between veins. The lesions were initially soft and rotten, and then light brown, round to semi-circular. Subsequently, the adjacent lesions fused, and the edges of the leaflets and entire leaflets showed symptoms of browning and wilting. For pathogen isolation, five leaflets with representative symptoms from one of the nurseries were collected and wiped three times with sterile absorbent cotton dipped in 75% alcohol and washed with distilled water. Leaflet pieces at the junction of the lesion and healthy tissues were removed, crushed in a sterile mortar, and soaked in a small amount of distilled water for 10 min. The diseased tissue suspension was streaked on a nutrient agar medium (NA) with a sterile inoculation ring and incubated at 28°C for 24 to 72 h. The bacterial colonies obtained were further cultured on NA. The purified colonies were uniform in shape, round, and yellow, with a raised, shiny surface and smooth margin. The isolates were Gram-negative, and the electron microscope analysis showed that the pathogens were short rods (0.35 to 0.52 × 0.90 to 1.24 µm, average = 0.44 ± 0.05 × 1.08 ± 0.11 µm, n = 25). For bacterial species identification, a single-colony culture was subjected to genomic DNA extraction and gene amplification and sequencing of 16S rRNA, rpoD, and gyrB. The universal primers 27F/1492R (Lane 1991) were used to amplify the 16S rRNA gene and the specific primers 70F/70R and UP-1E/APrU (Yamamoto et al. 2000) were used to amplify the rpoD and gyrB genes, respectively. In the BLAST analysis, the 16S rRNA sequence (GenBank OR195734) of the isolate shared 99% similarity (1409/1410 bp) with Pseudomonas oryzihabitans strain IAM 1568T (AM262973.1), and the rpoD (OR709708) and gyrB (OR709707) sequences showed >98% identity to rpoD (707/717 bp; FN554494.1) and gyrB (787/801 bp; FN554210.1) of P. oryzihabitans strain LMG 7040T. Based on the above results, the isolated bacterium was identified as P. oryzihabitans. For the pathogenicity test, healthy leaflets from 10 two-year-old potted walnut seedlings (cv. Xiangling) were used as inoculation materials. The leaflets were punctured with a sterile inoculation needle of 0.4 mm, and three small holes on each leaflet at an interval of about 5 mm were covered with a piece of sterile cotton. A bacterial suspension (1 ml) at 107 CFU/ml was spread onto the cotton, and wrapped with plastic film for 24 h. Water was used as a negative control. The inoculations were performed five times. Plants were grown outdoors at a daily average temperature of 22°C with relative humidity over 45%. Two days after inoculation, the disease began to develop in the leaflets with similar symptoms to those observed in the field. In contrast, control plants remained healthy and symptomless. Bacteria were reisolated from the inoculated walnut plants, and the morphology and 16S rRNA gene sequences of the isolates were the same as those of the original strains. Since it was discovered as an opportunistic human pathogenic bacterium in the 1970s (Keikha et al. 2019), P. oryzihabitans has also been shown to cause certain plant diseases, such as panicle blight and grain discoloration on rice (Hou et al. 2020), fruit black rot on prickly ash (Liu et al. 2021), and stem and leaf rot on muskmelon (Li et al. 2021). As far as we know, this is the first report of P. oryzihabitans causing walnut leaf spot disease in China. Leaf spot caused by P. oryzihabitans may be a threat to walnut cultivation, and this report of its occurrence is the first step in determining potential spread and effective control measures.

Global trade network patterns are coupled to fisheries sustainability.

The rapid development of seafood trade networks alongside the decline in biomass of many marine populations raises important questions about the role of global trade in fisheries sustainability. Mounting empirical and theoretical evidence shows the importance of trade development on commercially exploited species. However, there is limited understanding of how the development of trade networks, such as differences in connectivity and duration, affects fisheries sustainability. In a global analysis of over 400,000 bilateral trade flows and stock status estimates for 876 exploited fish and marine invertebrates from 223 territories, we reveal patterns between seafood trade network indicators and fisheries sustainability using a dynamic panel regression analysis. We found that fragmented networks with strong connectivity within a group of countries and weaker links between those groups (modularity) are associated with higher relative biomass. From 1995 to 2015, modularity fluctuated, and the number of trade connections (degree) increased. Unlike previous studies, we found no relationship between the number or duration of trade connections and fisheries sustainability. Our results highlight the need to jointly investigate fisheries and trade. Improved coordination and partnerships between fisheries authorities and trade organizations present opportunities to foster more sustainable fisheries.

Increasing global oceanic wind speed partly counteracted water clarity management effectiveness: A case study of Hainan Island coastal waters.

A sustainable coastal "blue economy" is one of the most significant opportunities and challenges in the new era. However, the management and conservation of marine ecosystems must recognize the interdependence in the coupled human and natural systems. In this study, we employed satellite remote sensing to map the spatial and temporal distribution of Secchi disk depth (SDD) in Hainan coastal waters, China for the first time, and quantitatively revealed the impacts of environmental investments on the coastal water environment in the context of global climate change. Based on the moderate resolution imaging spectroradiometer (MODIS) in situ concurrent matchups (N = 123), a simple green band (555 nm)-based quadratic algorithm was first developed to estimate the SDD for the coastal waters of Hainan Island in China (R2 = 0.70, root mean square error (RMSE) = 1.74 m). The long time-series SDD dataset (2001-2021) for Hainan coastal waters was reconstructed from MODIS observations. Spatially, SDD showed a pattern of high water clarity in eastern and southern coastal waters and low water clarity in the western and northern coastal areas. This pattern is attributed to unbalanced distributions of bathymetry and pollution from seagoing rivers. Seasonally, the humid tropical monsoon climate drove the SDD into a general pattern of high in the wet season and low in the dry season. Annually, the SDD in Hainan coastal waters improved significantly (p < 0.1), benefiting from environmental investments over the last 20 years. However, the increasing global oceanic wind speed in recent years has exacerbated sediment resuspension and deep ocean mixing, counteracting approximately 14.14% of the remedial management's effectiveness in protecting and restoring the coastal ecosystem. This study offers ways to improve the ecological and environmental regulations under global changes and to strengthen the public service capacity for aquatic management authorities with methods that support the sustainable development of coastal areas.

Environmental and management controls of soil carbon storage in grasslands of southwestern China.

In order to predict the effects of climate change on the global carbon cycle, it is crucial to understand the environmental factors that affect soil carbon storage in grasslands. In the present study, we attempted to explain the relationships between the distribution of soil carbon storage with climate, soil types, soil properties and topographical factors across different types of grasslands with different grazing regimes. We measured soil organic carbon in 92 locations at different soil depth increments, from 0 to 100 cm in southwestern China. Among soil types, brown earth soils (Luvisols) had the highest carbon storage with 19.5 ±â€¯2.5 kg m-2, while chernozem soils had the lowest with 6.8 ±â€¯1.2 kg m-2. Mean annual temperature and precipitation, exerted a significant, but, contrasting effects on soil carbon storage. Soil carbon storage increased as mean annual temperature decreased and as mean annual precipitation increased. Across different grassland types, the mean carbon storage for the top 100 cm varied from 7.6 ±â€¯1.3 kg m-2 for temperate desert to 17.3 ±â€¯2.9 kg m-2 for alpine meadow. Grazing/cutting regimes significantly affected soil carbon storage with lowest value (7.9 ±â€¯1.5 kg m-2) recorded for cutting grass, while seasonal (11.4 ±â€¯1.3 kg m-2) and year-long (12.2 ±â€¯1.9 kg m-2) grazing increased carbon storage. The highest carbon storage was found in the completely ungrazed areas (16.7 ±â€¯2.9 kg m-2). Climatic factors, along with soil types and topographical factors, controlled soil carbon density along a soil depth in grasslands. Environmental factors alone explained about 60% of the total variation in soil carbon storage. The actual depth-wise distribution of soil carbon contents was significantly influenced by the grazing intensity and topographical factors. Overall, policy-makers should focus on reducing the grazing intensity and land conversion for the sustainable management of grasslands and C sequestration.

Tropical forest soils serve as substantial and persistent methane sinks.

Although tropical forest soils contributed substantially global soil methane uptake, observations on soil methane fluxes in tropical forests are still sparse, especially in Southeast Asia, leading to large uncertainty in the estimation of global soil methane uptake. Here, we conducted two-year (from Sep, 2016 to Sep, 2018) measurements of soil methane fluxes in a lowland tropical forest site in Hainan island, China. At this tropical forest site, soils were substantial methane sink, and average annual soil methane uptake was estimated at 2.00 kg CH4-C ha-1 yr-1. The seasonality of soil methane uptake showed strong methane uptake in the dry season (-1.00 nmol m-2 s-1) and almost neutral or weak soil methane uptake in the wet season (-0.24 nmol m-2 s-1). The peak soil methane uptake rate was observed as -1.43 nmol m-2 s-1 in February, 2018, the driest and coolest month during the past 24 months. Soil moisture was the dominant controller of methane fluxes, and could explain 94% seasonal variation of soil methane fluxes. Soil temperature could not enhance the explanation of seasonal variation of soil methane fluxes on the top of soil moisture. A positive relationship between soil methane uptake and soil respiration was also detected, which might indicate co-variation in activities of methanotroph and roots and/or microbes for soil heterotrophic respiration. Our study highlights that tropical forests in this region acted as a methane sink.

On the ratio of intercellular to ambient CO2 (c i/c a) derived from ecosystem flux.

The ratio of intercellular to ambient CO2 concentrations (c i/c a) plays a key role in ecophysiology, micrometeorology, and global climatic change. However, systematic investigation on c i/c a variation and its determinants are rare. Here, the c i/c a was derived from measuring ecosystem fluxes in an even-aged monoculture of rubber trees (Hevea brasiliensis). We tested whether c i/c a is constant across environmental gradients and if not, which dominant factors control c i/c a variations. Evidence indicates that c i/c a is not a constant. The c i/c a exhibits a clear "V"-shaped diurnal pattern and varies across the environmental gradient. Water vapor pressure deficit (D) is the dominant factor controls over the c i/c a variations. c i/c a consistently decreases with increasing D. c i/c a decreases with square root of D as predicted by the optimal stomatal model. The D-driving single-variable model could simulate c i/c a as well as that of sophisticated model. Many variables function on longer timescales than a daily cycle, such as soil water content, could improve c i/c a model prediction ability. Ecosystem flux can be effectively used to calculate c i/c a and use it to better understand various natural cycles.

[Clinical observation of axial offset after treatment by Ilizarov bone transport technology].

OBJECTIVE: To observe the incidence, causes and deviation angle of axial offset in patients with fracture ununited treated by Ilizarov bone transport technology. METHODS: From January 2007 to December 2012, 10 patients with fracture ununited were treated by Ilizarov bone transport including 8 males and 2 females with an average age of (30.3 ± 10.6) years old ranging from 18 to 49 years old. The segment of bone defect involved upper tibial in 2 cases, medial tibia in 2 cases, lower tibial in 5 cases, upper femoral in 1 case. For Paley type of bone defect, 6 cases were type B1, 4 cases were B3. The incidence and deviation angle of axial offset after Ilizarov bone transport technology were observed and evaluated on bone result by Paley assessment. RESULTS: All patients were followed up from 19 to 32 months with an average of (22.0 ± 5.6) months. Three cases were natural healed at fracture ends, the other 7 cases were healed after bone graft. The time of external fixator was 16 to 28 months. At the last follow-up, there were 3 cases occurred coronal angulation of angle 5° to 11° with an average of (8.7 ± 3.2). Sagittal angulation was in 4 cases, angle 6° to 9° with an average of (8.5 ± 2.1)°. There were 4 cases occurred axial offset. In the last follow-up, according to Paley evaluation criteria, osseous results were excellent in 7 cases, good in 3 cases; functional results were excellent in 6 cases, good in 4 cases. CONCLUSION: Axial deviation after the Ilizarov bone transport treatment is relatively common, which will result in delayed healing of bone and poor limb alignment. In order to improve the bone healing, corresponding measurements should be taken to avoid or reduce the incidence of axial deviation during and after the operation.

Effect of surface modification on photoluminescence properties of Y3Al5O12:Ce3+, Gd3+ nano-phosphors.

In this study, a series of Y(3)Al(5)O(12):Ce(3+), Gd(3+) nano-phosphors were prepared using a simply wet chemical process with polyvinyl pyrrolidone as a modifier. The crystal and bonding structures of Y(3)Al(5)O(12):Ce(3+), Gd(3+) nano-phosphors prepared with different weight percentages of polyvinyl pyrrolidone were characterized by X-ray diffractometry and infrared spectrometry. The decomposition process of dried precursor gel with adding 1.37 wt% polyvinyl pyrrolidone was investigated by differential thermal and thermogravimetric analysis. The effect of surface modification on photoluminescence properties for the samples was studied. The results show that the steric hindrance effect of polyvinyl pyrrolidone leads to high dispersion and good crystallinity of Y(3)Al(5)O(12):Ce(3+), Gd(3+) nano-phosphors prepared with adding a proper weight percentages of polyvinyl pyrrolidone. Adding polyvinyl pyrrolidone is beneficial for the photoluminescence enhancement of the samples, which is attributed to the promotion of the incorporation of Ce(3+) and Gd(3+) into the Y(3)Al(5)O(12) nanocrystal and the surface passivation of the nano-particles by the polyvinyl pyrrolidone molecules.

[Repair of the soft tissue defects of the anterior foot and the ankle with the reversed sural neurocutaneous flap].

OBJECTIVE: To investigate the operative method and effect of the reversed sural neurocutaneous flap in repairing soft tissue defects of the anterior foot and the ankle. METHODS: From March 1999 to November 2004, 19 cases (17 male, 2 female) of soft tissue defects of the anterior foot and the ankle were repaired with the reversed sural neurocutaneous flaps. The flap sizes range from 18 cm x 9 cm to 30 cm x 18 cm. RESULTS: All flaps survived well, while 1 flap had distal partial necrosis and healed after dressing change. The follow-up from 6 months to 2 years showed that all flaps were satisfactory. CONCLUSION: Sural neurocutaneous flap is easy to get and to survive. It is an effective method to repair the soft tissue defects of the anterior foot and the ankle.