MAIN CONCLUSION: Rice sheath blight research should prioritise optimising biological control approaches, identification of resistance gene mechanisms and application in genetic improvement and smart farming for early disease detection. Rice sheath blight, caused by Rhizoctonia solani AG1-1A, is one of the most devasting diseases of the crop. To move forward with effective crop protection against sheath blight, it is important to review the published information related to pathogenicity and disease management and to determine areas of research that require deeper study. While progress has been made in the identification of pathogenesis-related genes both in rice and in the pathogen, the mechanisms remain unclear. Research related to disease management practices has addressed the use of agronomic practices, chemical control, biological control and genetic improvement: Optimising nitrogen fertiliser use in conjunction with plant spacing can reduce spread of infection while smart agriculture technologies such as crop monitoring with Unmanned Aerial Systems assist in early detection and management of sheath blight disease. Replacing older fungicides with natural fungicides and use of biological agents can provide effective sheath blight control, also minimising environmental impact. Genetic approaches that show promise for the control of sheath blight include treatment with exogenous dsRNA to silence pathogen gene expression, genome editing to develop rice lines with lower susceptibility to sheath blight and development of transgenic rice lines overexpressing or silencing pathogenesis related genes. The main challenges that were identified for effective crop protection against sheath blight are the adaptive flexibility of the pathogen, lack of resistant rice varieties, abscence of single resistance genes for use in breeding and low access of farmers to awareness programmes for optimal management practices.
Multiple diseases, including brown spot (Cochliobolus miyabeanus), leaf spot (Epicoccum sorghimum), and blast (Magnaporthe oryzae), can cause spot-like symptoms on the leaves of rice. In July 2021, a disease showing symptoms like brown spot was observed in an 8-hectare field of rice, with disease incidence of >30%, in Beaumont, Texas. Lesions started as small pinhead-size blackish spots on leaf tips or from the edges of leaf blades. The spots enlarged to become irregular (most) or oval brown spots with a slight chlorotic halo. Diseased leaves were collected, washed in running tap water and cut into small pieces. Pieces of the tissue were surface sterilized with 1%NaOCl for 2 min followed by 75% ethanol for 30 s and then washed in sterile distilled water three times with each time lasting for 1 min. The disinfected tissue pieces were air dried, placed on potato dextrose agar (PDA) medium and incubated at 25℃. Initially fungal colonies were hairy in texture with light dark brown center and whitish edge and dark brown pigmentation at the reverse side. Mature colonies turned to black in the center and dark brown toward the edge, with black at the reverse side after 2 or more weeks of incubation. Conidia were oval to narrowly oblong, rounded at the ends, with 2 to 6 distoseptate, and 15 to 35 × 6 to 10 µm in size. These morphological characteristics were similar to those described for Curvularia hawaiiensis (Aslam et al. 2019; Ellis 1971; Kusai et al. 2015). For molecular identification, DNA was extracted and the two different rRNA regions internal transcribed spacer (ITS) and large subunit (LSU), and the two genes RNA Polymerase II (RPB1) and translation elongation factor 1 alpha (EF1) of the fungus were amplified using the primers of ITS1/ITS4 (Wang et al. 2014), D1/D2 domain region of LSU (Fell et al. 200), and RPB1 and EF1 (Wang et al. 2014), respectively, and sequenced. The ITS sequence (OK397200) was 98.27% identical to C. hawaiiensis (KP131943); the EF1 sequence (OK492159) was 99.78% identical to C. hawaiiensis (KC503942); the LSU sequence (OK397295) was 98.96% identical to multiple C. hawaiiensis (MN055715, MH160813, MH875853, etc.); the RPB1 sequence (OK492160) was 97.41% identical to C. hawaiiensis (JN992363). To evaluate pathogenicity, three rice plants (cv. Presidio) at the 3-leaf stage were spray inoculated with a conidial suspension of 1 x 106 conidia/ml. Another set of three plants that were sprayed with sterilized distilled water served as the controls. Treated plants were maintained in a greenhouse with temperature ranging from 25 to 30℃. After 2 weeks, typical symptoms, like those observed in the field, developed on the inoculated plants while no symptoms developed on the control plants. The same fungus was consistently re-isolated from the diseased plants. The pathogenicity test was conducted three times with similar results. To our knowledge, this is the first report of brown leaf spot caused by C. hawaiiensis in rice in the United States. Curvularia species are frequently associated with rice grain and cause blackish discoloration symptoms on grain kernels. Recently, however, C. hawaiiensis has also been reported to cause brown leaf spot in Malaysia (Kusai et al. 2015) and Pakistan (Aslam et al. 2019). This research will help identify this disease from other leaf spot-like diseases and develop effective management strategies.
At the end phase of the Global Programme to Eliminate Lymphatic Filariasis, antibody testing may have a role in decision-making for bancroftian filariasis-endemic areas. This study evaluated the diagnostic performance of BLF Rapid™, a prototype immunochromatographic IgG4-based test using BmSXP recombinant protein, for detection of bancroftian filariasis. The test was evaluated using 258 serum samples, comprising 96 samples tested at Universiti Sains Malaysia (in-house) and 162 samples tested independently at three international laboratories in the USA and India, and two laboratories in Malaysia. The independent testing involved 99 samples from Wuchereria bancrofti microfilaria or antigen positive individuals and 63 samples from people who were healthy or had other infections. The in-house evaluation showed 100% diagnostic sensitivity and specificity. The independent evaluations showed a diagnostic sensitivity of 84-100% and 100% specificity (excluding non-lymphatic filarial infections). BLF Rapid has potential as a surveillance diagnostic tool to make "Transmission Assessment Survey"-stopping decisions and conduct post-elimination surveillance.
In plants, pathogen resistance is brought about by the binding of certain transcription factor (TF) proteins to the cis-elements of certain target genes. These cis-elements are present upstream in the motif of the promoters of each gene. This ensures the binding of a specific TF to a specific promoter, therefore regulating the expression of that gene. Therefore, the study of each promoter sequence of all the rice genes would help identify the target genes of a specific TF. Rice 1 kb upstream promoter sequences of 55,986 annotated genes were analyzed using the Perl program algorithm to detect WRKY13 binding motifs (bm). The resulting genes were grouped using Gene Ontology and gene set enrichment analysis. A gene with more than 4 TF bm in their promoter was selected. Ten genes reported to have a role in rice disease resistance were selected for further analysis. Cis-acting regulatory element analysis was carried out to find the cis-elements and confirm the presence of the corresponding motifs in the promoter sequences of these genes. The 3D structure of WRKY13 TF and the corresponding ten genes were built, and the interacting residues were determined. The binding capacity of WRKY13 to the promoter of these selected genes was analyzed using docking studies. WRKY13 was considered for docking analysis based on the prior reports of autoregulation. Molecular dynamic simulations provided more details regarding the interactions. Expression data revealed the expression of the genes that helped provide the mechanism of interaction. Further co-expression network helped to characterize the interaction of these selected disease resistance-related genes with the WRKY13 TF protein. This study suggests downstream target genes that are regulated by the WRKY13 TF. The molecular mechanism involving the gene network regulated by WRKY13 TF in disease resistance against rice fungal pathogens is explored.
Free-flowing rivers (FFRs) support diverse, complex and dynamic ecosystems globally, providing important societal and economic services. Infrastructure development threatens the ecosystem processes, biodiversity and services that these rivers support. Here we assess the connectivity status of 12 million kilometres of rivers globally and identify those that remain free-flowing in their entire length. Only 37 per cent of rivers longer than 1,000 kilometres remain free-flowing over their entire length and 23 per cent flow uninterrupted to the ocean. Very long FFRs are largely restricted to remote regions of the Arctic and of the Amazon and Congo basins. In densely populated areas only few very long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and reservoirs and their up- and downstream propagation of fragmentation and flow regulation are the leading contributors to the loss of river connectivity. By applying a new method to quantify riverine connectivity and map FFRs, we provide a foundation for concerted global and national strategies to maintain or restore them.
The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of squamous cell carcinoma (SCC) of the oral cavity, larynx, oropharynx and hypopharynx was published in 2020. It was therefore decided by both the ESMO and the Korean Society of Medical Oncology (KSMO) to convene a special, virtual guidelines meeting in July 2021 to adapt the ESMO 2020 guidelines to consider the potential ethnic differences associated with the treatment of SCCs of the head and neck (SCCHN) in Asian patients. These guidelines represent the consensus opinions reached by experts in the treatment of patients with SCCHN (excluding nasopharyngeal carcinomas) representing the oncological societies of Korea (KSMO), China (CSCO), India (ISMPO), Japan (JSMO), Malaysia (MOS), Singapore (SSO) and Taiwan (TOS). The voting was based on scientific evidence and was independent of the current treatment practices and drug access restrictions in the different Asian countries. The latter was discussed when appropriate. This manuscript provides a series of expert recommendations (Clinical Practice Guidelines) which can be used to provide guidance to health care providers and clinicians for the optimisation of the diagnosis, treatment and management of patients with SCC of the oral cavity, larynx, oropharynx and hypopharynx across Asia.