Powdery Mildew of Xanthium strumarium Caused by Podosphaera xanthii in central China.

Xanthium strumarium, known as cocklebur, is an annual herb and has been used in traditional Chinese medicine. In October 2020, powdery mildew-like disease signs and symptoms were observed on X. strumarium grown in a crop field, Xinxiang city, Henan Province, China (35.36076° N, 113.93467° E). The specimen (PX-XS2023) was stored in Xinxiang Key Laboratory of Plant Stress Biology. White colonies in irregular or coalesced circular shaped-lesions were abundant on both ad- and abaxial surfaces of leaves and covered up to 99 % of the leaf area. Some of the infected leaves were senesced. More than 70 % of plants (n = 130) exhibited these signs and symptoms. Conidiophores were straight or slightly curved, 55 to 160 × 11 to 13 µm composed of foot-cells, shorter cells and conidia. Conidia were ellipsoid to oval, 29 to 40 × 14 to 20 µm (n = 50), with a length/width ration of 2.0 to 2.5, containing fibrosin bodies. Dark brown to black chasmothecia were found on infected leaves. The appendages were mycelium-shaped and at the base of scattered or gregarious chasmothecia (n = 50, 70 to 120 µm in diameter). Asci were 55 to 80 × 50 to 65 µm (n=30). These morphological characteristics were consistent with those of Podosphaera xanthii (Braun and Cook 2012). The internal transcribed spacer (ITS) region and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) region of the fungus (PX-XS2023) were amplified and sequenced with primers ITS1/ITS4 (White et al. 1990) and GAPDH1/GAPDH3R (Bradshaw et al. 2022) according to a previously reported method (Zhu et al. 2022). The resulting sequences were respectively deposited into GenBank (Accession No. MW300956 and PP236083). BLASTn analysis indicated that the sequences were respectively 99.82 % (564/565) and 100% (272/272) identical to P. xanthii (MT260063 and ON075658). The phylogenetic analysis indicated that the strain PX-XS2023 and P. xanthii were clustered into a same branch. Therefore, the causal agent of powdery mildew on X. strumarium was P. xanthii. To conduct pathogenicity assays, mature leaves of five healthy X. strumarium (height in 50 centimeters) were inoculated with fungal conidia by gently pressing surfaces of infested leaves onto leaves of healthy plants (Zhu et al. 2020). Five untreated plants served as controls. The controls and inoculated plants were separately maintained in greenhouses (humidity, 60%; light/dark, 16 h/8 h; temperature, 18°C). Eight days post-inoculation, signs of powdery mildew were detectable on inoculated plants, however, the controls were asymptomatic. Thus, the fungal pathogen was morphologically and molecularly identified and confirmed as P. xanthii. This powdery mildew caused by P. xanthii was previously reported on X. strumarium in Korea, Russia and India (Farr and Rossman, 2021). In addition, P. xanthii was recorded on X. strumarium in Xinjiang Province, China (Tai 1979). However, this is the first report of P. xanthii on X. strumarium in central China, where is around 3000 km away from Xinjiang Province with geographically differences. The sudden presence of powdery mildew caused by P. xanthii may adversely affect plant health and thus reduce medical value of X. strumarium. Therefore, the identification and confirmation of P. xanthii infecting X. strumarium enhance the knowledge on the hosts of this pathogen in China and will provide fundamental information for disease control in the future.

Prediction of land use for the next 30 years using the PLUS model's multi-scenario simulation in Guizhou Province, China.

Land use changes significantly impact the structure and functioning of ecosystems. The current research focus lies in how to utilize economic and policy instruments to regulate conflicts among stakeholders effectively. The objective is to facilitate rational planning and sustainable development of land utilization resources. The PLUS model integrates a rule-based mining method for land expansion analysis and a CA model based on multi-type stochastic seeding mechanism, which can be used to mine the driving factors of land expansion and predict the patch-level evolution of land use landscapes. Using the PLUS model, a simulation was conducted to study the future land use distribution in the research area over the next 30 years. Based on land use data from Guizhou Province in 2000, 2010, and 2020, a total of 16 driving factors were selected from three aspects: geographical environment, transportation network, and socio-economic conditions. Four scenarios, namely natural development, urban development, ecological conservation, and farmland rotection, were established. Comparative analysis of the simulated differences among the various scenarios was performed. (1) The overall accuracy of the land use simulation using the PLUS model in the study area was 0.983, with a Kappa coefficient of 0.972 and a FoM coefficient of 0.509. The research accuracy meets the simulation requirements. (2) Through the simulation of four different scenarios, the study investigated the land use changes in Guizhou Province over the next 30 years. Each scenario exhibited distinct impacts on land utilization. Comprehensive comparison of the different simulation results revealed that the farmland protection scenario aligns with the sustainable development goals of the research area. Currently, there is a relative scarcity of research on land use simulation, particularly in model application, for Guizhou Province. This study aims to provide a reference for the rational planning of land resources and high-quality urban construction in Guizhou, promoting the high-quality economic development in tandem with advanced ecological and environmental protection.

Podosphaera xanthii Causing Powdery Mildew on Salvia farinacea in Central China.

Salvia farinacea, commonly referred as mealycup sage, is a perennial herbaceous plant belonging to the Salvia genus of the Lamiaceae family. It originates from the Mediterranean region, North America, and Europe and is globally cultivated due to its appealing and captivating flowers. Moreover, mealycup sage is utilized as traditional Chinese medicinal plant for treatment of cardiovascular diseases (Li et al. 2018). In October 2023, powdery mildew-like symptoms were observed on Salvia farinacea plants cultivated in a garden located in Xinxiang City, Henan Province, China (113.93, 35.29). The leaves were covered with white and thin masses of mycelia, conidiophores and conidia of the fungus. About 100 plants were checked and 90 % were infected. There were a large number of white colonies with irregular or continuous round lesions on the adaxial and abaxial surfaces of the leaves, covering approximately 80% of the leaf area. The slightly or straight curved conidiophores (n = 30) were 46 to 145× 8 to 11 µm in size and consisted of foot cells, shorter cells and conidia. The ellipsoidal to oval conidia (n = 30), containing fibrosin bodies, were 24 to 35 × 12 to 19 µm in size and had a length/width ratio of 1.8 to 2.1. No chasmothecia were observed on leaves. These morphological features were consistent with those of Podosphaera xanthii (Braun and Cook 2012). Following the previously described method (White et al. 1990; Bradshaw et al. 2022; Zhu et al. 2022a), the sequences of ITS and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) regions were amplified with specific primers ITS1/ITS4 (ITS1 5'-TCCGTAGGTGAACCTGCGG-3' ; ITS4 5'-TCCTCCGCTTATTGATATGC-3') and PMGAPDH1/PMGAPDH3R (PMGAPDH1 5'-GGAATGGCTATGCGTGTACC-3'; PMGAPDH3R 5'-CCCCATTCGTTGTCGTACCATG-3'), and the resulting sequences were uploaded in GenBank (Accession No. OR761885 and PP236082, respectively). BLASTn analysis showed that the sequence shared 560/565 (99%) and 272/272 (100%) homology with P. xanthii (MW301281) on Impatiens balsamina (Zhu et al. 2022b) and with P. xanthii (ON075658) on Cucumis melo (Bradshaw et al. 2022), respectively. The phylogenetic analysis clearly illustrated that the collected isolate of P. xanthii clustered in the same clade. The pathogenicity was tested according to the method previously described (Zhu et al. 2021). The fungus was inoculated onto the leaf surfaces of three healthy plants by blowing conidia from infected leaves with pressurized air. Non-inoculated plants were treated as control. Both the control and inoculated plants were separately placed in growth chambers under 60% humidity; light/dark, 16 h/8 h; and a temperature of 18°C. After a period of 12-15 days, the leaves of the inoculated plants exhibited signs of powdery mildew, whereas the control group remained unaffected. Therefore, the fungal pathogen was identified and confirmed as P. xanthii (isolate PXSF202310). Previously, P. xanthii was reported on Impatiens balsamina and S. farinacea from China and Korea (Zhu et al. 2021; Choi et al. 2022). As far as we know, this is the first documentation of P. xanthii on S. farinacea in central China. The presence of P. xanthii can lead to a deterioration in plant health and stunted growth, thereby negatively impacting both the decorative and medicinal value of S. farinacea. The recognition of P. xanthii on S. farinacea enhances our comprehension of this pathogen hosts and provides fundamental information for forthcoming disease control studies.

Low-cost and versatile integration of microwire electrodes and optical waveguides into silicone elastomeric devices using modified xurographic methods.

Microelectrodes are used in microfluidic devices for a variety of purposes such as heating, applying electric fields, and electrochemical sensing. However, they are still manufactured by expensive deposition techniques such as sputtering or evaporation and patterned using photolithography methods. More recently, alternate methods including nanoparticle sintering and use of liquid metal flowing through microchannels have been used to fabricate microelectrodes. These methods are limited in the material choices or require post processing to be integrated into microchannels. Here we developed a low-cost and versatile method to integrate high-quality metal microwires into polydimethylsiloxane (PDMS) using xurography. The microwire integration process includes cutting slit pattern on PDMS substrate and subsequent writing metal microwires into the slit pattern using a specialized tip. Then the microwire-integrated PDMS was sealed/bonded using uncured PDMS prepolymer. This method enables integration of metal microwires of diameter as small as 15 µm into PDMS devices. Integration of multiple microwires with minimum spacing of 150 µm has also been demonstrated. The versatility of this method is demonstrated by the fabrication of metal microwire suspended in the middle of the microchannel, which is difficult to achieve using conventional electrode fabrication methods. This low-cost method avoids expensive clean room fabrication yet producing high-quality electrodes and can be used in a variety of microfluidic and MEMS applications.