Selenium (Se) is crucial for both plants and humans, with plants acting as the main source for human Se intake. In plants, moderate Se enhances growth and increases stress resistance, whereas excessive Se leads to toxicity. The physiological mechanisms by which Se influences rice seedlings’ growth are poorly understood and require additional research. In order to study the effects of selenium stress on rice seedlings, plant phenotype analysis, root scanning, metal ion content determination, physiological response index determination, hormone level determination, quantitative PCR (qPCR), and other methods were used. Our findings indicated that sodium selenite had dual effects on rice seedling growth under hydroponic conditions. At low concentrations, Se treatment promotes rice seedling growth by enhancing biomass, root length, and antioxidant capacity. Conversely, high concentrations of sodium selenite impair and damage rice, as evidenced by leaf yellowing, reduced chlorophyll content, decreased biomass, and stunted growth. Elevated Se levels also significantly affect antioxidase activities and the levels of proline, malondialdehyde, metal ions, and various phytohormones and selenium metabolism, ion transport, and antioxidant genes in rice. The adverse effects of high Se concentrations may directly disrupt protein synthesis or indirectly induce oxidative stress by altering the absorption and synthesis of other compounds. This study aims to elucidate the physiological responses of rice to Se toxicity stress and lay the groundwork for the development of Se-enriched rice varieties.

Zinc (Zn)- and iron (Fe)-regulating transport-like proteins (ZIPs) are a class of proteins crucial for metal uptake and transport in plants, particularly for Zn and Fe absorption and distribution. These proteins ensure the balance of trace elements essential for plant growth, development, and metabolic activities. However, the role of the rice (Oryza sativa) OsZIP gene family in manganese (Mn) and selenium (Se) transport remains underexplored. This research conducted an all-sided analysis of the rice OsZIPs and identified 16 OsZIP sequences. Phylogenetic analysis categorized the OsZIPs predominantly within the three subfamilies. The expression levels of OsZIPs in rice root and leaf subjected to Mn and Se toxicity stress were examined through quantitative real-time PCR (qRT–PCR). The findings revealed significant differential expression of many OsZIPs under these conditions, indicating a potential regulating effect in the response of rice to Mn and Se toxicity. This work lays a foundation for further functional studies of OsZIPs, enhancing our understanding of the response mechanisms of rice to Mn and Se toxicity and their roles in growth, development, and environmental adaptation.

Serratia marcescens is a microorganism that exhibits insecticidal activity against various insects, including the migratory fall armyworm (FAW), Spodoptera frugiperda. This article investigates the insecticidal mechanism of S. marcescens through gastric toxicity. The study involved midgut tissue sectioning, hemolymph observation, and microbiome and transcriptome analysis of both infected and uninfected FAW. The findings revealed that S. marcescens effectively disrupted the structure of the midgut, causing midgut shrinkage and rupture, as well as inducing pseudopodia formation in granulocytes. Moreover, it increased the diversity of gut microbiota. Transcriptome analysis indicated an upregulation of metabolic-related genes and tissue repair genes, while there was a downregulation of fat synthesis genes, some immune genes, hormone synthesis genes, etc. The disruption of the midgut structure negatively affects the metabolism and immune function of the FAW, potentially resulting in midgut rupture, systemic sepsis, and ultimately mortality. In conclusion, our study has elucidated the insecticidal mechanism of S. marcescens against the FAW and demonstrated its potential as a biological control agent for managing this pest.

Pesticides released into the environment are increasingly recognized as a global threat to freshwater ecosystems because of their adverse effects on non-target organisms, particularly aquatic insects and other arthropods. Superoxide dismutases (SODs) are important antioxidant enzymes that play a crucial role in protecting organisms from oxidative stress induced by harmful materials. In this study, we identified 2 cellular SODs (PxSOD1 and PxSOD2) in Protohermes xanthodes Navás (Megaloptera: Corydalidae), an freshwater predatory insect, and determined the oxidative stress induced in P. xanthodes larvae by sublethal exposure to chlorpyrifos (CPF). PxSOD1 and PxSOD2 are members of the cytoplasmic Cu/ZnSODs and mitochondrial MnSODs, respectively, and differ substantially in protein structure. Both PxSOD1 and PxSOD2 recombinant proteins demonstrated catalytic activity toward O2•− in the activity assays. After exposure to sublethal concentrations of CPF, malondialdehyde (MDA) content and SOD activities were increased in P. xanthodes larvae in a dose-dependent manner. PxSOD1 expression was decreased in the 0.42 and 4.2 μg/L CPF groups and increased in the 4.2 μg/L CPF group. PxSOD2 was upregulated by 0.42, 4.2, and 8.4 μg/L CPF treatments and the expression levels in the 4.2 and 8.4 μg/L CPF groups were significantly higher than that in the no CPF control. Our results suggest that sublethal concentrations of CPF can induce oxidative stress in P. xanthodes larvae, and the cellular SODs in P. xanthodes larvae may contribute to the protection against CPF-induced oxidative stress.