Molecular Pathogens 2024, Vol.15, No.4, 189-199 http://microbescipublisher.com/index.php/mp 191 2.3 Economic and agricultural impact of viral infections The economic and agricultural impacts of rice viral infections are profound, leading to significant yield losses and threatening food security. For example, SRBSDV has been shown to cause widespread vulnerability in rice cultivars, with high susceptibility observed in both conventional and hybrid varieties, leading to characteristic disease symptoms and substantial yield reductions. The presence of rice reoviruses in insect vectors further exacerbates the threat to rice production stability in Asia (Wei and Li, 2016). The emergence of new viral pathogens like RTIV from native plants underscores the ongoing risk of viral spillover into cultivated rice, potentially leading to new disease outbreaks and further economic losses. The global dimensions of plant virus diseases highlight the need for integrated, smart, and eco-friendly strategies to manage these threats and ensure sustainable rice production (Jones and Naidu, 2019). 3 Emerging Viral Threats 3.1 New rice viruses identified in recent years Recent advancements in metagenomic and metatranscriptomic sequencing have led to the identification of several new rice viruses. For instance, the rice tiller inhibition virus (RTIV), a novel RNA virus, was discovered in colonies of Asian wild rice (O. rufipogon) and has been shown to cause low-tillering disease in cultivated rice varieties (Figure 2) (Yan et al., 2022). High-throughput sequencing has revealed the presence of eight novel virus species in rice plants, transmitted by the brown planthopper, which significantly impacts rice yield by causing sterile characteristics in infected plants (Chao et al., 2021). These discoveries underscore the importance of continuous surveillance and advanced diagnostic tools to detect and manage emerging viral threats to rice cultivation. The discovery of the RTIV virus, along with its detailed genomic, structural, and functional analyses, has provided a new perspective for rice virus research. By using molecular biology techniques to validate its infection status and phylogenetic relationships, researchers can better understand the pathogenic mechanisms of this virus in rice. Future research will need to explore effective control measures against the RTIV virus and its impact on rice production, while further harnessing the potential of metagenomics and metatranscriptomics sequencing technologies to uncover more potential plant viruses. 3.2 Genomic evolution and mutation rates of emerging viruses The genomic evolution and mutation rates of rice viruses are critical factors that influence their emergence and pathogenicity. For example, the evolutionary analysis of the 2019-nCoV, a coronavirus, demonstrated significant clustering with bat SARS-like coronaviruses, highlighting the role of mutations in the spike glycoprotein and nucleocapsid proteins in its ability to infect humans (Benvenuto et al., 2020). Similarly, the genetic diversity of begomoviruses, as revealed by high-throughput sequencing, indicates that these viruses undergo rapid evolution, which can lead to the emergence of new strains capable of infecting a wide range of plant species (Rodríguez-Negrete et al., 2019). Understanding these evolutionary dynamics is essential for developing effective strategies to mitigate the impact of emerging rice viruses. 3.3 Regional outbreaks and their global significance Regional outbreaks of rice viruses have significant implications for global food security. For instance, the southern rice black-streaked dwarf virus (SRBSDV) and rice black-streaked dwarf virus (RBSDV) have caused devastating epidemics in Asian countries, posing a major threat to rice production (Wang et al., 2022; Wu et al., 2022). These viruses are transmitted by insect vectors, and their outbreaks are often exacerbated by climate change and globalization, which facilitate the spread of viral pathogens across regions (Kreuze et al., 2023). The emergence of rice yellow mottle virus (RYMV) in Africa and rice stripe necrosis virus (RSNV) in America further illustrates the global significance of regional viral outbreaks. Effective management of these outbreaks requires international collaboration and the implementation of advanced surveillance and diagnostic technologies to prevent the spread of these viral threats.
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