UV-B, an important environmental factor, has been shown to affect the yield and quality of rice (Oryza sativa) worldwide. However, the molecular mechanisms underlying the response to UV-B stress remain elusive in rice. We perform comprehensive metabolic profiling of leaves from 160 diverse rice accessions under UV-B and normal light conditions using a widely targeted metabolomics approach. Our results reveal substantial differences in metabolite accumulation between the two major rice subspecies indica and japonica, especially after UV-B treatment, implying the possible role and mechanism of metabolome changes in subspecies differentiation and the stress response. We next conduct a transcriptome analysis from four representative rice varieties under UV-B stress, revealing genes from amino acid and flavonoid pathways involved in the UV-B response. We further perform a metabolite-based genome-wide association study (mGWAS), which reveals 3307 distinct loci under UV-B stress. Identification and functional validation of candidate genes show that OsMYB44 regulates tryptamine accumulation to mediate UV-B tolerance, while OsUVR8 interacts with OsMYB110 to promote flavonoid accumulation and UV-B tolerance in a coordinated manner. Additionally, haplotype analysis suggests that natural variation of OsUVR8groupA contributes to UV-B resistance in rice. Our study reveals the complex biochemical and genetic foundations that govern the metabolite dynamics underlying the response, tolerance, and adaptive strategies of rice to UV-B stress. These findings provide new insights into the biochemical and genetic basis of the metabolome underlying the crop response, tolerance, and adaptation to UV-B stress.

Background/Objectives: The utilization of methyl-thiophanate (MT) in vegetables and fruits is widespread due to its broad efficiency, yet its potential impact on silkworm growth remains uncertain. This study aims to examine the effects of MT on the growth of silkworms. Specifically, we assessed the weights of fifth-instar larvae that were fed mulberry leaves saturated with three concentrations (2.5, 5, and 10 mg/mL) of MT, as well as the weights of a control group. Methods: TEM was used to show the status of the silkworm midgut after MT supplementation. Oxidative stress was evaluated in the presence of MT. Furthermore, a transcriptomic sequencing experiment was conducted to investigate the mechanism through which the development of silkworms is induced by MT. Results: Our findings indicate that the supplementation of MT hindered larval growth compared to the control group, suggesting a toxic effect of MT on silkworms. The transmission electron microscopy (TEM) results show that MT supplementation induced autophagy in the silkworm midgut. MT was also found to induce oxidative stress in silkworms through the activation of reactive oxygen (ROS), superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities. Subsequent transcriptomic analysis revealed 1265 significantly differentially expressed genes (DEGs) in response to MT. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that these DEGs were associated with antioxidant defense, detoxification processes, lysosome biogenesis, and metabolic pathways. Conclusions: These findings suggest that MT toxicity in silkworm larvae is mediated through the induction of oxidative stress and alterations in metabolism. This study contributes to our understanding of the impacts of MT exposure on silkworms and provides insights into potential pesticides for use in mulberry gardens.

A lobed leaf is a common trait in plants, but it is very rare in Lauraceae plants, including species of Phoebe. In the study of germplasm resources of Phoebe neurantha, we found lobed leaf variant seedlings, and the variation could be inherited stably. Studying the lobed leaf mechanism of P. neurantha var. lobophylla can offer insight into the leaf development mechanism of woody plants. RNA-seq and small RNA-seq analysis results showed that a total of 8091 differentially expressed genes (DEGs) and 16 differentially expressed miRNAs were identified in P. neurantha var. lobophylla. Considering previous research results, a leaf margin morphological development related miRNA, pne-miRNA319a, was primary identified as a candidate miRNA. Target gene prediction showed that a total of 2070 genes were predicted to be the target genes of differentially expressed miRNAs. GO enrichment analysis of differentially expressed target genes suggested that PnTCP2 is related to lobed leaf formation. The TRV-VIGS gene silencing of PnTCP2 led to lobed leaves in P. neurantha seedlings. The downregulation of PnTCP2 led to lobed leaves. The yeast two-hybrid test and bimolecular fluorescence complementation test confirmed that the PnTCP2 protein interacted with the PnLBD41 protein. Based on the expression analysis of gene-silenced leaves and RNA-seq and small RNA-seq analysis results, pne- miRNA319a and PnLBD41 might also play important roles in this process. In conclusion, PnTCP2 plays an important and vital role in the formation of the lobed leaves of P. neurantha var. lobophylla.

The silkworm, Bombyx mori, a key economic insect, has been employed as a model organism to investigate the toxicological effects and underlying mechanisms of zinc iron oxide nanoparticle exposure on its growth and development, midgut tissue structure, and physiological functions. Exposure to zinc iron oxide inhibited larval growth and development, which was accompanied by pathological alterations in the midgut, including a reduction in columnar cells, vacuolation, chromatin condensation, microvilli shedding, and disrupted tight junctions, which directly impaired the intestinal barrier integrity and nutrient absorption. Furthermore, zinc iron oxide exposure resulted in elevated reactive oxygen species levels, decreased superoxide dismutase and glutathione contents, and increased catalase activity, indicating the activation of oxidative stress. This stress-induced mitochondrial response, characterized by the observation of autophagic vesicles, suggests the potential mitophagy of activation in action to zinc iron oxide exposure, thereby preserving cellular homeostasis. This was also associated with the downregulation of most genes involved in purine metabolism, the peroxisome, the biosynthesis of amino acids, the ribosome pathway, and carbon metabolism pathways, leading to reduced protein synthesis and energy supply, ultimately resulting in larval developmental retardation. This study elucidates the intestinal-targeted toxicity of zinc iron oxide nanoparticles in lepidopteran insects, providing direct in vivo experimental evidence for evaluating the ecological risk of zinc iron oxide in sericulture environments. Furthermore, it offers a novel research avenue for developing intestinal intervention strategies aimed at mitigating the toxic effects of nanomaterials and ensuring the stability of economically important traits in silkworms.

The excessively concentrated ripening period of mulberries causes seasonal surplus. Fruit mulberry (Morus spp.) exhibits the unique trait of “simultaneous flowering and leaf flushing”, rendering budburst timing closely correlated with fruit ripening time. Thus, deciphering the molecular mechanism underlying winter bud dormancy maintenance in fruit mulberry is urgently needed. Herein, an F₁ hybrid population comprising 337 individuals, derived from Morus wittiorum (♀) and ‘322’ (♂), was utilized as research material. Through Bulked Segregant Analysis Sequencing (BSA-Seq), we successfully mapped a dormancy-associated QTL interval designated as LB (Late Burst), spanning 9,990,001–11,990,000 bp on Chromosome 13. Integrating Weighted Gene Co-expression Network Analysis (WGCNA) results, MaSVP was identified as a candidate gene within this interval. Virus-induced gene silencing (VIGS) of MaSVP in winter buds of Morus wittiorum significantly accelerated budburst compared to the control, demonstrating that MaSVP represses winter bud dormancy release and plays a crucial role in regulating dormancy maintenance in fruit mulberry. Dynamic expression profiling of dormancy-related genes revealed that the transcript levels of MaSVP, MaSAPK3, MaCASL2, and MaPYR8 were significantly downregulated (Tukey’s test, p < 0.05) as budburst approached, whereas those of MaFT and MaGA20ox1-D were significantly upregulated (Tukey’s test, p < 0.05). These results indicate that winter bud dormancy maintenance in Morus wittiorum is associated with abscisic acid (ABA) and gibberellin (GA) metabolism. Collectively, this study provides critical insights into the biological basis of winter bud dormancy maintenance in fruit mulberry and offers valuable genetic resources for breeding late-maturing cultivars.

Maintenance of winter bud dormancy is a critical agronomic trait determining the fruit ripening period in mulberry (Morus spp.); however, the underlying molecular regulatory mechanisms remain largely elusive. In this study, we utilized an F1 segregating population derived from a cross between the late-budding species Morus wittiorum and the early-budding cultivar '322'. By integrating bulked segregant analysis sequencing (BSA-Seq) with RNA-Seq, we identified a dormancy-associated quantitative trait locus (QTL) interval (LB, 9.99-11.99 Mb) on chromosome 13 and pinpointed MaBGA (a β-glucosidase gene) as a candidate gene. Functional characterization via virus-induced gene silencing (VIGS) demonstrated that MaSVP acts as a repressor of winter bud sprouting, whereas MaBGA facilitates dormancy release. Yeast one-hybrid, dual-luciferase reporter, and electrophoretic mobility shift assays (EMSA) further confirmed that MaSVP directly binds to the MaBGA promoter to repress its transcription. Consistently, MaBGA expression was significantly upregulated during bud sprouting. Here, we unveil a novel MaSVP-MaBGA regulatory module. Distinct from the classical model where SVP/DAM proteins regulate dormancy indirectly via hormone homeostasis, this module maintains winter bud dormancy through the direct molecular interaction between a transcription factor and a β-glucosidase gene, thereby expanding the molecular regulatory network of bud dormancy in perennial plants. These findings not only provide fresh insights into the dormancy mechanisms of mulberry but also offer critical genetic resources and theoretical foundations for the molecular breeding of early- and late-ripening varieties.