Capsicum frutescens is a valuable economic crop that is widely cultivated for its unique flavor and rich nutritional content. While some studies have shown differences in flavonoid content among different chili species, the mechanism by which changes in flavonoid composition lead to fruit color variations in C. frutescens remains underreported. We performed transcriptomics and widely targeted metabolome sequencing on three different growth stages of the C. frutescens fruit and analyzed the data to better understand the mechanism of color change. Based on previous research on the genes that regulate flavonoid compounds and the MBW complex, we have identified a total of 28 core genes related to flavonoid biosynthesis and 8 genes that may be related to flavonoid synthesis. Through extensive targeted metabolomic analysis, 581 differential metabolites were identified, including 43 flavonoids. Most anthocyanins, flavonols, and flavonoids were found to be more abundant during the immature fruit stage, which we presume is associated with the differential expression of genes involved in flavonoid biosynthesis and regulation. These findings provide a useful reference for understanding flavonoid synthesis and the accumulation of fruits in C. frutescens.

Pepper is a significant cash crop, and Capsicum frutescens is an exemplary variety of pepper cultivated for its distinctive flavor and substantial nutritional value. Polyploidization of plants often leads to an increase in their biomass and improved stress tolerance, and thus has important applications in plant breeding and improvement. In this study, germplasm innovation was carried out by polyploidy induction of C. frutescens by colchicine. To investigate the effects of polyploidization on C. frutescens, we conducted transcriptomic and metabolomic analyses of diploids and homotetraploids of C. frutescens to gain insights into the mechanisms of metabolite composition and molecular regulation of C. frutescens by polyploidization. Based on the analysis of metabolomics and transcriptomics data, a total of 551 differential metabolites were identified in the leaves of C. frutescens of different ploidy and 634 genes were significantly differentially expressed. In comparison, 241 differential metabolites and 454 genes were significantly differentially expressed in the mature fruits of C. frutescens of different ploidy. Analysis of KEGG enrichment of differentially expressed genes and differential metabolites revealed that both differential metabolites and differentially expressed genes were highly enriched in the phenylalanine metabolic pathway. It is worth noting that phenylpropanoids are highly correlated with capsaicin synthesis and also have an effect on fruit development. Therefore, we comprehensively analyzed the phenylalanine metabolic pathway and found that chromosome doubling significantly down-regulated the expression of genes upstream of phenylalanine (PAL, 4CL), which promoted lignin accumulation, and we suggested that this might have led to the enlargement of polyploid C. frutescens fruits. This study provides some references for further research on the phenotypic traits of different ploidy of C. frutescens, cloning of key regulatory genes, and using genetic engineering techniques in C. frutescens breeding for germplasm improvement.

Medicago sativa is one of the world’s most important forage plants, possessing strong nitrogen-fixing and regrowth capabilities. Promoting its growth not only enhances stress resistance but also reduces the use of chemical fertilizers. The value of Centella asiatica is primarily reflected in its medicinal properties. Currently, endophytic fungal resources of C. asiatica are scarce, and their potential to promote medicinal components and the underlying mechanisms remains unclear. This study employed DNA extraction techniques to isolate and identify endophytic fungi from different parts of C. asiatica. We systematically analyzed the plant growth-promoting traits of endophytic fungi. After screening for the optimal strain and inoculating it into Medicago sativa, we elucidated the mechanisms underlying its growth-promoting effect using metabolomic sequencing. Research findings: A total of 18 endophytic fungal strains were isolated, belonging to 12 genera. Among them, five indole-3-acetic acid (IAA) strains were identified, with strain J4 demonstrating the highest IAA production (17.157 mg·L⁻¹). The J4 strain has iron-transporting carrier activity, while 15 strains exhibit nitrogen-fixing activity. Inoculation with the Plectosphaerella plurivora strain significantly increases M. sativa’s germination rate, fresh weight, dry weight, and plant height. Metabolomic analysis indicates that P. plurivora may promote anthocyanin and jasmonic acid accumulation by regulating pathways such as flavonoid biosynthesis and pyrimidine metabolism, thereby promoting growth. This study reveals the mechanism by which endophytic fungi enhance M. sativa growth at the metabolomic level. This study reveals the growth-promoting mechanism of endophytic fungi in M. sativa from a metabolomic perspective, providing a theoretical basis for increasing forage yield and offering new insights into sustainable agricultural development.

Land-use change directly and indirectly affects regional carbon storage by reshaping the composition and function of terrestrial ecosystems, and understanding this process is important for guiding land-use strategies toward carbon neutrality. This study used wilderness mapping to assess wilderness quality in Pu’er City and integrated the FLUS–InVEST model to analyze spatiotemporal changes in land use and carbon storage from 2000 to 2020 and to simulate land-use and carbon-storage outcomes for 2030. Based on the wilderness-mapping results, the study area was divided into four wilderness-quality classes, and four scenarios were established: No Protection, Limited Protection, Moderate Protection, and Strict Protection. From 2000 to 2020, cropland and forestland decreased, whereas grassland, water bodies, and built-up land increased. Carbon storage first increased slightly and then declined, with an overall decrease of approximately 1.87 × 10⁶ Mg C. Relative to the harmonized five-class 2020 FLUS baseline, the 2030 simulations showed a decline of approximately 1.46 × 10⁶ Mg C under the No Protection scenario, whereas the Moderate Protection scenario produced an increase of approximately 0.21 × 10⁶ Mg C. Under the baseline carbon-density parameters, the Moderate Protection scenario yielded the highest estimated total carbon storage among the four scenarios and resulted in a larger simulated built-up land area than the Strict Protection scenario. However, the relatively small difference in estimated total carbon storage between the Moderate and Strict Protection scenarios should be interpreted with consideration of carbon-density uncertainty.

Temperature stress is a major environmental factor that limits the growth of cucumber (Cucumis sativus L.). Melatonin has been implicated in plant responses to abiotic stress; however, its transcriptional effects on cucumber under high- and low-temperature conditions remain poorly understood. In this study, cucumber seedlings were exposed to 25 °C, 40 °C, or 4 °C, with or without exogenous melatonin treatment at 75 μmol·L⁻¹, and their transcriptional responses were investigated using RNA sequencing (RNA-seq). Both high- and low-temperature treatments caused varying degrees of seedling wilting, whereas this phenotype was partially alleviated by melatonin application. Transcriptome analysis identified 7488 and 3400 differentially expressed genes in response to high and low temperatures, respectively, indicating both shared and temperature-specific transcriptional responses. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that pathways related to plant hormone signal transduction, phenylpropanoid biosynthesis, and protein processing in the endoplasmic reticulum were significantly enriched in multiple comparisons. Further analysis revealed that melatonin treatment altered the expression patterns of several hormone signaling-related genes and transcription factors, including members of the ERF, MYB, WRKY, and bHLH families. Notably, hormone signaling components exhibited distinct transcriptional responses under high- and low-temperature conditions. The expression trends of selected genes determined by quantitative real-time polymerase chain reaction (qRT-PCR) were generally consistent with the RNA-seq results. Collectively, exogenous melatonin application was associated with reduced wilting symptoms and coordinated transcriptional changes in hormone signaling pathways under temperature stress. These findings provide a basis for further elucidating the molecular mechanisms underlying melatonin-mediated temperature adaptation in cucumber seedlings.