Momordica saponins have diverse biological activities and are widely used to improve obesity. Here, we investigated the alleviation of fat accumulation and mechanism of action of the saponin-enriched ethanol extract from Momordica charantia (MSE) in Caenorhabditis elegans (C. elegans). First, MSE had a strong fat-reduction capacity in normal and high-fat worms. Second, MSE significantly increased the proportion of small lipid droplets and reduced the average particle size in ZXW618. Meanwhile, it improved lifespan and healthspan and physiological functions, such as age pigmentation and neuroprotection. Furthermore, MSE mediated fat reduction gets involved neither in energy intake nor in energy expenditure. Finally, MSE might down-regulate sbp-1 and nhr-49 via mdt-15, and up regulate age-1 via daf-2. And these targets genes together down-regulated the expression of fat-5, fat-6 and fat-7 to decrease fat accumulation. Our results provided new insights into the inhibition of fat accumulation and underlying mechanisms of Momordica saponins in C. elegans, which might be developed into a nutraceutical to ameliorate obesity.

Titanium dioxide nanoparticles (nTiO₂) are widely used as fertilizers in agricultural production because they promote photosynthesis and strong adhesion. Low pollination and fertilization due to rainy weather during the litchi plant’s flowering phase result in poor fruit quality and output. nTiO₂ would affect litchi during the flowering and fruiting stages. This study considers how nTiO₂ affects litchi’s fruit quality and pollen viability during the flowering stage. The effects of nTiO₂ treatment on pollen vigor, yield, and fruit quality were investigated. nTiO₂ effectively improved the pollen germination rate and pollen tube length of litchi male flowers. The germination rate reached 22.31 ± 1.70%, and the pollen tube reached 237.66 μm in the 450 mg/L reagent-treated group. Spraying with 150 mg/L of nTiO₂ increased the germination rate of pollen by 2.67% and 3.67% for two types of male flowers (M1 and M2) of anthesis, respectively. After nTiO₂ spraying, the fruit set rates of ‘Guiwei’ and ‘Nomici’ were 46.68% and 30.33%, respectively, higher than those of the boric acid treatment group and the control group. The edibility rate, titration calculation, and vitamin C of nTiO₂ treatment were significantly higher than those of the control. The nTiO₂-treated litchi fruit was more vividly colored. Meanwhile, the adhesion of nTiO₂ to leaves was effectively optimized by using ATP and BCS to form nTiO₂ carriers and configuring nTiO₂ complex reagents. These results set the foundation for future applications of titanium dioxide nanoparticles as fertilizers for agriculture and guide their application to flowers and fruits.

Prolonged exposure to cold temperatures often results in a relatively low flowering rate in litchi (Litchi chinensis Sonn.) trees with younger leaves. This study aimed to verify the impact of stem girdling on litchi flowering by identifying and characterizing the induced metabolic changes. After a 60 day exposure to cold treatment at 15 °C/10 °C (12 h/12 h), the flowering rate of the girdled trees was 100%, while that of the non-girdled trees was 20%, indicating that girdling improved litchi flowering at its turning stage. The metabolic profiles of litchi leaves with and without stem girdling during floral induction were compared and 505 metabolites potentially associated with litchi flowering were detected. Most metabolites were involved in the metabolism of starch and sucrose, fatty acid, and phenylpyruvic acid. The metabolic pathways concerned with the biosynthesis of epinephrine, sucrose, and d-maltose were induced in leaves after girdling treatment. The level of galactitol, phenylpyruvic acid, acetyl-CoA, linoleic acid, alpha-linolenic acid, and 13-HPOT biosynthesis remained stable in the leaves from girdled trees but changed drastically in the leaves from non-girdled trees. In addition, 379 metabolites concerning flowering rate were characterized. Metabolism pathways of starch and sucrose, galactose, and linoleic acid are of great significance to the flowering of litchi. Linoleic acid exhibited the most significant variations between girdled trees and non-girdled trees with fold changes of up to 13.62. These results contribute to understanding the biological mechanism of litchi floral induction and the metabolic changes after stem girdling.

Litchi (Litchi chinensis Sonn.) arils are predominantly white or cream-colored, with yellow-pigmented cultivars being rare and poorly characterized. The ‘JJHN’ cultivar exhibits a distinctive yellow aril that progressively attenuation during fruit development, providing an ideal model to investigate the biochemical and molecular basis of yellow pigmentation in litchi. In this study, we integrated phenotypic evaluation, widely targeted and carotenoid-targeted metabolomics, and transcriptomic analyses at ‘JJHN’ arils across fruit development. The color shift from orange-yellow to pale yellow during ripening, as indicated by declining CIE b* values, was accompanied by significant reductions in total flavonoid and carotenoid contents. Widely targeted metabolomics profiling revealed that aurones (e.g., aureusidin 4,6-diglucoside) and chalcones (e.g., naringin chalcone) were the primary yellow pigments. Targeted carotenoid analysis identified violaxanthin as the predominant carotenoid during early development, accounting for 62.4% of total carotenoids at stage Y2, but decreasing sharply and becoming undetectable at maturity. Transcriptomic data showed coordinated downregulation of structural genes involved in flavonoid (e.g., CHS, CHR, CHI) and carotenoid (e.g., ZEP, AAO3) biosynthesis, aligning with the observed pigment depletion. Weighted gene co-expression network analysis (WGCNA) identified a “turquoise” module positively correlated with flavonoid content, comprising transcription factors from MYB, bHLH, bZIP, NAC, and DOF families that possessed predicted binding sites in pigment-related gene promoters. Collectively, these findings demonstrate that the yellow aril phenotype of cv. ‘JJHN’ is regulated by a dual pigment system—aurones/chalcones and violaxanthin—whose developmental depletion is transcriptionally controlled by a complex TF network. This study provides novel insights into the regulation of fruit pigmentation and lays a foundation for breeding litchi cultivars with yellow arils.

Many litchi flowers are discarded in China every year. The litchi flower is rich in volatile compounds and exhibits strong anti-obesity activity. Litchi flower essential oil (LFEO) was extracted by the continuous phase transformation device (CPTD) independently developed by our research group to recycle the precious material resources in litchi flowers. However, its fat-reducing effect and mechanism remain unclear. Employing Caenorhabditis elegans as a model, we found that LFEO significantly reduced fat storage and triglyceride (TG) content in normal, glucose-feeding, and high-fat conditions. LFEO significantly reduced body width in worms and significantly decreased both the size and number of lipid droplets in ZXW618. LFEO treatment did not affect energy intake but increased energy consumption by enhancing the average speed of worms. Further, LFEO might balance the fat metabolism in worms by regulating the DAF-2/IIS, sbp-1/mdt-15, and nhr-49/mdt-15 pathways. Moreover, LFEO might inhibit the expression of the acs-2 gene through nhr-49 and reduce β-oxidation activity. Our study presents new insights into the role of LFEO in alleviating fat accumulation and provides references for the large-scale production of LFEO to promote the development of the litchi circular economy.

The canopy of perennial evergreen fruit trees in southern China has a unique Bidirectional Reflectance Factor (BRF) due to its complex multi-branch structure and density changes. This study aimed to address the lack of clarity regarding the changes in BRF of evergreen fruit trees in southern China. Litchi, a typical fruit tree in this region, was chosen as the subject for establishing a three-dimensional (3D) real structure model. The canopy BRF of litchi was simulated under different leaf components, illumination geometry, observed geometry, and leaf area index (LAI) using a 3D radiation transfer model. The corresponding changes in characteristics were subsequently analyzed. The findings indicate that the chlorophyll content and equivalent water thickness of leaves exert significant influences on canopy BRF, whereas the protein content exhibit relatively weak effects. Variation in illumination and observation geometry results in the displacement of hotspots, with the solar zenith angle and view zenith angle exerting significant influence on the BRF. As the LAI of the litchi orchard increases, the distribution of hotspots becomes more concentrated, and the differences in angle information are relatively smaller when observed from multiple angles. With the increase in LAI in litchi orchards, the BRF on the principal plane would be saturated, but observation at hotspots could alleviate this phenomenon. The above analysis provides a reference for quantitative inversion of vegetation parameters using remote sensing monitoring information of typical perennial evergreen fruit trees.