Dynamics of spatial and temporal population structure of Pyricularia oryzae in Taiwan.

BACKGROUND: To gain a better understanding of how Pyricularia oryzae population shifts is important for selecting suitable resistance genes for rice breeding programs. However, the relationships between P. oryzae pathogenic dynamics, geographic distribution, rice varieties, and timeline are not well studied. RESULTS: Resistance genes Piz-5, Pi9(t), Pi12(t), Pi20(t), Pita-2, and Pi11 showed stable resistance to the Taiwan rice blast fungus over 8 years of observations. Furthermore, 1749 rice blast isolates were collected from 2014 to 2021 and categorized into five pathotype clusters based on their correlation analysis between the geographic sources and virulence of Lijiangxintuanheigu monogenic lines. A detailed map of their distributions in Taiwan is presented. Isolates collected from the western region of Taiwan had greater pathotype diversity than those from the east region. Isolates collected from the subtropical region had greater diversity than those from the tropical region. Rice cultivars carrying Pik alleles were highly susceptible to pathotype L4. Cultivars with Piz-t were highly susceptible to pathotype L5, and those with Pish were highly susceptible to pathotype L1. The geographical distribution of each pathotype was distinct, and the population size of each pathotype fluctuated significantly each year. CONCLUSION: The regional mega cultivars significantly impact the evolution of Pyricularia oryzae in Taiwan within the span of 8 years. However, the annual fluctuation of pathotype populations likely correlate to the rising annual temperatures that selected pathotype clusters by their optimal growth temperature. The results will provide useful information for effective disease management, and enable the R-genes to prolong their function in the fields. © 2023 Society of Chemical Industry.

The relative influence of model parameters on finite element analysis simulations of intervertebral body fusion device static compression performance.

Non-clinical mechanical performance testing is a critical aspect of intervertebral body fusion device (IBFD) development and regulatory evaluation. Recently, stakeholders have begun leveraging computational modeling and simulations such as finite element analysis (FEA) in addition to traditional bench testing. FEA offers advantages such as reduced experiment time, lower costs associated with elimination of bench testing (e.g. specimen manufacture and test execution), and elucidating quantities of interest that traditional testing cannot provide (e.g. stress and strain distributions). However, best practices for FEA of IBFDs are not well defined, and modeler decision making can significantly influence simulation setup and results. Therefore, the goal of this study was to determine the relative influence of modeling parameters when using FEA to assess non-clinical mechanical performance of IBFDs. FEA was used to conduct a series of IBFD static uniaxial compression simulations. Several parameters relating to implant geometry, loading/boundary conditions, and material properties were carefully controlled to assess their relative influence on two output variables (IBFD stiffness and yield load). Results were most influenced by device geometry, while the effects of boundary conditions and material properties were more significant within IBFDs of identical or similar geometries. These results will aid stakeholders in the development of standardized best practices for using FEA to assess non-clinical mechanical performance of IBFDs.

Uncovering the Genetic of Cadmium Accumulation in the Rice 3K Panel.

Because Cadmium (Cd) is harmful to humans, and most non-smokers are exposed to Cd mainly through rice consumption, low-Cd rice breeding is urgently needed. It might not be possible to apply variation created using gene editing technology to breeding directly, so it is important to explore genetic variation in this trait in a natural population. In this study, variation in 4 genes was identified among 3024 accessions from the International Rice Research Institute 3000 Rice Genome Project (IRRI 3K-RGP) and 71 other important varieties, and the relationships between the variants and plant Cd accumulation were validated with hydroponic and pot experiments. Variants in OsNRAMP1, OsNRAMP5, OsLCD, and OsHMA3 were grouped into two, four, three, and two haplotypes, respectively. Fourteen combinations of these haplotypes, which were referred to as Cd-mobile types, were found in the collection. Of these, type 14 was shown to have the greatest potential for low-Cd accumulation, and functional markers for this type were designed. The results of this study provide an important resource for low-Cd rice breeding and highlight an effective strategy for pre-breeding programs.