Rice blast disease is a serious disease in rice caused by Magnaporthe oryzae (M. oryzae). Ascorbic acid (AsA), or vitamin C, is a strong antioxidant that prevents oxidative damage to cellular components and plays an essential role in plant defense response. GDP-D-mannose pyrophosphorylase (GMP or VTC1) is an enzyme that generates GDP-D-mannose for AsA, cell wall, and glycoprotein synthesis. The OsVTC1 gene has three homologs in the rice genome: OsVTC1-1, OsVTC1-3, and OsVTC1-8. Using OsVTC1-1 RNAi lines, this study investigated the role of the OsVTC1-1 gene during rice blast fungus inoculation. The OsVTC1-1 RNAi inoculated with rice blast fungus induced changes to cell wall monosaccharides, photosynthetic efficiency, reactive oxygen species (ROS) accumulation, and malondialdehyde (MDA) content. Additionally, the OsVTC1-1 RNAi lines were shown to be more resistant to rice blast fungus than the wild type. Genes and proteins related to defense response, plant hormone synthesis, and signaling pathways, especially salicylic acid and jasmonic acid, were up-regulated in the OsVTC1-1 RNAi lines after rice blast inoculation. These results suggest that the OsVTC1-1 gene regulates rice blast resistance through several defense mechanisms, including hormone synthesis and signaling pathways.

InDel markers are commonly used to assess genetic relationships among populations. In this study, we employed a whole-genome sequence comparison method to identify and develop InDel markers for the rice blast fungus Pyricularia oryzae. We analyzed 152 whole-genome sequences of P. oryzae isolates from diverse global regions, including Brazil, Burundi, China, Colombia, Côte d'Ivoire, France, Ghana, Hungary, India, Japan, Korea, Laos, Madagascar, Mali, Morocco, Nepal, the Philippines, Portugal, Spain, Suriname, Thailand, the UK, the USA, and Zambia. Our analysis identified a total of 233,595 InDel loci distributed across the seven chromosomes of P. oryzae. From these, 82 loci were selected based on their high polymorphism across the 152 genome sequences. The effectiveness of these 82 loci was assessed by analyzing the genetic diversity of 47 Thai rice blast isolates alongside two reference isolates, GUY11 (France) and KJ201 (Korea). Of the 82 InDel loci, 33 exhibited polymorphisms, with 2–4 alleles per locus and polymorphic information content (PIC) scores ranging from 0.04 to 0.67. Principal coordinate and structure analyses revealed two genetic subgroups among the Thai rice blast isolates, categorized according to host specificity. Genetic relationships highlighted disparities among rice blast populations based on their respective hosts: rice and grassy weeds. This finding suggests a correlation between genetic relatedness and the plant hosts susceptible to rice blast disease. The newly developed InDel markers provide a valuable resource for future research in this field.

Thailand is one of the most famous silk production regions, where silkworms (Bombyx mori Linn.) have been reared for sericulture for a long time. Thai silk holds the cultural importance. Several strains of silkworm have been bred and preserved by the Queen Sirikit Department of Sericulture, national administration responsible for maintaining silkworm strains in Thailand. Their efforts aim to improve the silkworm strains with desired traits and breed these traits into future generations. Therefore, the production of genetic database of silkworm reference genome, including genome annotation is crucial. This study aimed to present and annotate the polyvoltine silkworm reference genome through de novo genome sequencing of strain Nang Tui which exhibits high silk productivity and tolerance to high temperature. The estimated size of draft de novo genome assembly of strain Nang Tui was 701,413,529 bp containing 21,421 contigs. The completeness of genome assembly of Nang Tui was validated using BUSCO analysis, which revealed 90.10% single-copy BUSCOs. For gene prediction, this genome assembly harbors 337 protein-coding genes and 65 transposable elements, as predicted using the B. mori gene annotation from NCBI. Moreover, 4 rRNA and 18 tRNA-related genes were identified. The most enriched gene ontology (GO) term was plasma membrane (GO:0005886). The signaling pathway had the highest number of gene enrichments based on KEGG pathway analysis. The mononucleotide repeats were the most abundant type, with the A/T motif being the most frequent in this assembly. Moreover, genes encoding fibroin and sericin which are the main components of silk were identified. Furthermore, genes encoding serine protease inhibitors which are reported to have antimicrobial activity, were also found. Accordingly, the draft de novo genome assembly of strain Nang Tui demonstrated the high completeness and comprehensive annotation, which could serve as the novel polyvoltine silkworm reference genome and make it a valuable resource for studying the genetic diversity of various silkworm species and strains in Thailand. Furthermore, it could accelerate the understanding of molecular mechanisms for superior silk production in the future.