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Cellulases play important roles in the shedding of plant organs; however, little is yet known about the functions of cellulase genes during the process of organ abscission. Abnormal fruitlet abscission is a serious problem in the production of litchi (Litchi chinensis), an economically important fruit widely grown in South Asia. In this study, two abscissionaccelerating treatments (carbohydrate stress and application of ethephon) were evaluated in litchi fruitlets. Cell wall degradation and cell separation were clearly observed in the abscission zones of treated fruitlets, consistent with enhanced cellulase activities and reduced cellulose contents. The expression of two cellulase genes (LcCEL2 and LcCEL8) was strongly associated with abscission. Floral organs of transgenic Arabidopsis overexpressing LcCEL2 or LcCEL8 showed remarkably precocious abscission. Electrophoretic mobility shift assays and transient expression experiments demonstrated that a novel homeodomain-leucine zipper transcription factor, LcHB2, could directly bind to and activate HD-binding cis-elements in the LcCEL2 and LcCEL8 promoters. Our results provide new information regarding the transcriptional regulation of the cellulase genes responsible for cell wall degradation and cell separation during plant organ shedding, and raise the possibility of future manipulation of litchi fruitlet abscission by modulation of the activities of these two cellulases.

Unmanned aerial vehicles (UAV) provide an unprecedented capacity to monitor the development and dynamics of tree growth and structure through time. It is generally thought that the pruning of tree crops encourages new growth, has a positive effect on fruiting, makes fruit-picking easier, and may increase yield, as it increases light interception and tree crown surface area. To establish the response of pruning in an orchard of lychee trees, an assessment of changes in tree structure, i.e., tree crown perimeter, width, height, area and Plant Projective Cover (PPC), was undertaken using multi-spectral UAV imagery collected before and after a pruning event. While tree crown perimeter, width and area could be derived directly from the delineated tree crowns, height was estimated from a produced canopy height model and PPC was most accurately predicted based on the NIR band. Pre- and post-pruning results showed significant differences in all measured tree structural parameters, including an average decrease in tree crown perimeter of 1.94 m, tree crown width of 0.57 m, tree crown height of 0.62 m, tree crown area of 3.5 m2, and PPC of 14.8%. In order to provide guidance on data collection protocols for orchard management, the impact of flying height variations was also examined, offering some insight into the influence of scale and the scalability of this UAV-based approach for larger orchards. The different flying heights (i.e., 30, 50 and 70 m) produced similar measurements of tree crown width and PPC, while tree crown perimeter, area and height measurements decreased with increasing flying height. Overall, these results illustrate that routine collection of multi-spectral UAV imagery can provide a means of assessing pruning effects on changes in tree structure in commercial orchards, and highlight the importance of collecting imagery with consistent flight configurations, as varying flying heights may cause changes to tree structural measurements.

DREB/ERF transcription factors play pivotal roles in plant development; however, their structural characteristics, DNA‐binding preferences, and functional roles in highly heterozygous woody plants remain insufficiently understood. Using lychee ( Litchi chinensis ) as a model, we identified 95 DREB/ERF genes subdivided into ten phylogenetic groups. DNA affinity purification sequencing (DAP‐seq) of 45 representative members uncovered 65 194 binding sites with subfamily‐specific motifs: C(G/A)CCG(A/C)C for DREB and CGCCG(C/T)C for ERF subfamilies. Each group exhibited unique binding motif preferences, aligning with their protein structures and essential peptide positions. Notably, LITCHI017494 directly regulated terpenoid biosynthesis and aroma formation by activating tandemly repeated LcTPS genes. Furthermore, single nucleotide polymorphisms (SNPs) in LITCHI017494's binding sites altered the binding efficiency of two flowering‐related genes ( LcSVP and LcVOZ ) in early‐ and late‐maturing haplotypes, revealing a mechanism underlying flowering and fruit maturation period. Overall, with experimental evidence, this study provides a comprehensive binding profile of the DREB/ERF family in lychee, revealing intricate transcriptional regulatory networks and serving as a crucial resource for transcription factor research within complex genomic contexts, especially in the DREB/ERF gene family.

Amyloid-β (Aβ) is commonly recognized as the most important factor that results in neuronal cell death and accelerates the progression of Alzheimer’s disease (AD). Increasing evidence suggests that microglia activated by Aβ release an amount of neurotoxic inflammatory cytokines that contribute to neuron death and aggravate AD pathology. In our previous studies, we found that lychee seed fraction (LSF), an active fraction derived from the lychee seed, could significantly improve the cognitive function of AD rats and inhibit Aβ-induced neuroinflammation in vitro, and decrease neuronal injuries in vivo and in vitro. In the current study, we aimed to isolate and identify the specific components in LSF that were responsible for the anti-neuroinflammation effect using preparative high performance liquid chromatography (pre-HPLC), liquid chromatography-mass spectrometry (LC-MS), and nuclear magnetic resonance (NMR) methods. To this end, we confirmed two polyphenols including catechin and procyanidin A2 that could improve the morphological status of BV-2 cells and suppress the release, mRNA levels, and protein expression of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) through downregulating the nuclear factor-κB (NF-κB) signaling pathway using ELISA, RT-PCR, and Western blotting methods. Furthermore, catechin and procyanidin A2 could inhibit Aβ-induced apoptosis in BV-2 cells by upregulating Bcl-2 and downregulating Bax protein expression. Therefore, the current study illustrated the active substances in lychee seed, and first reported that catechin and procyanidin A2 could suppress neuroinflammation in Aβ-induced BV-2 cells, which provides detailed insights into the molecular mechanism of catechin and procyanidin A2 in the neuroprotective effect, and their further validations of anti-neuroinflammation in vivo is also essential in future research.

This report presents the development of a highly effective method employing high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) to investigate chlorantraniliprole’s dissipation, risk assessment, and residue distribution in whole lychee fruit and its pulp. Mean recoveries of the samples ranged from 80 to 105%, exhibiting a relative standard deviation (RSD) of below 8%. The limits of quantification (LOQ) for lychee and pulp were determined as 0.001 mg/kg, and half-lives (t1/2) ranged from 8.0 to 12.2 days. Terminal residue concentrations in whole litchi and pulp were determined as 0.008–0.45 mg/kg and ≤0.001 mg/kg. These residues were treated twice and thrice at two different dosage levels with pre-harvest intervals (PHIs) of 7, 14, and 21 days. The potential chronic risk posed by chlorantraniliprole to humans was non-negligible, as indicated by the risk quotient (RQ) value not exceeding 1. Therefore, this study provides significant fresh data about the safe application of chlorantraniliprole in the production of lychee, which will help China develop maximum residual limits (MRLs).

Due to the change of illumination environment and overlapping conditions caused by the neighboring fruits and other background objects, the simple application of the traditional machine vision method limits the detection accuracy of lychee fruits in natural orchard environments. Therefore, this research presented a detection method based on monocular machine vision to detect lychee fruits growing in overlapped conditions. Specifically, a combination of contrast limited adaptive histogram equalization (CLAHE), red/blue chromatic mapping, Otsu thresholding and morphology operations were adopted to segment the foreground regions of the lychees. A stepwise method was proposed for extracting individual lychee fruit from the lychee foreground region. The first step in this process was based on the relative position relation of the Hough circle and an equivalent area circle (equal to the area of the potential lychee foreground region) and was designed to distinguish lychee fruits growing in isolated or overlapped states. Then, a process based on the three-point definite circle theorem was performed to extract individual lychee fruits from the foreground regions of overlapped lychee fruit clusters. Finally, to enhance the robustness of the detection method, a local binary pattern support vector machine (LBP-SVM) was adopted to filter out the false positive detections generated by background chaff interferences. The performance of the presented method was evaluated using 485 images captured in a natural lychee orchard in Conghua (Area), Guangzhou. The detection results showed that the recall rate was 86.66%, the precision rate was greater than 87% and the F1-score was 87.07%.

We introduce YOLO-Lychee-advanced, a lightweight and high-precision detector for lychee stem-borer damage on fruit surfaces. Built on YOLOv11, the model incorporates (i) a C2f module with dual-branch residual connections to capture fine-grained features of pest holes ≤2 mm, (ii) a CBAM channel-spatial attention block to suppress complex peel-texture interference, and (iii) CIoU loss to tighten bounding-box regression. To mitigate illumination variance, we augment the original 3,061-image dataset to 9,183 samples by simulating direct/back-lighting and adopt a “pest-hole only” annotation strategy, which improves mAP50–95 by 18% over baseline. Experiments conducted on an RTX 3060 with a batch size of 32 and an input size of 416 × 416 pixels show YOLO-Lychee-advanced achieves 92.2% precision, 85.4% recall, 91.7% mAP50, and 61.6% mAP50-95, surpassing YOLOv9t and YOLOv10n by 3.4% and 1.7%, respectively, while maintaining 37 FPS real-time speed. Compared with the recent YOLOv9t and YOLOv10n baselines on the same lychee test set, YOLO-Lychee-advanced raises mAP50–95 by 3.4% and 1.7%, respectively. Post-processing optimization further boosts precision to 95.5%. A publicly available dataset and PyQt5 visualization tool are provided at https://github.com/Suxueping/Lychee-Pest-Damage-images.git .

Açaí, lychee, mamey, passion fruit and jackfruit are some lesser-consumed tropical fruits due to their low commercial production. In 2018, approximately 6.8 million tons of these fruits were harvested, representing about 6.35% of the total world production of tropical fruits. The present work reviews the nutritional content, profile of bioactive compounds, antioxidant and anti-inflammatory capacity of these fruits and their by-products, and their ability to modulate oxidative stress due to the content of phenolic compounds, carotenoids and dietary fiber. Açaí pulp is an excellent source of anthocyanins (587 mg cyanidin-3-glucoside equivalents/100 g dry weight, dw), mamey pulp is rich in carotenoids (36.12 mg β-carotene/100 g fresh weight, fw), passion fruit peel is rich in dietary fiber (61.16 g/100 dw). At the same time, jackfruit contains unique compounds such as moracin C, artocarpesin, norartocarpetin and oxyresveratrol. These molecules play an important role in the regulation of inflammation via activation of mitogen-activated protein kinases (including p38, ERK and JNK) and nuclear factor κB pathways. The properties of the bioactive compounds found in these fruits make them a good source for use as food ingredients for nutritional purposes or alternative therapies. Research is needed to confirm their health benefits that can increase their marketability, which can benefit the primary producers, processing industries (particularly smaller ones) and the final consumer, while an integral use of their by-products will allow their incorporation into the circular bioeconomy.

Neuronal apoptosis plays a critical role in the pathogenesis of Alzheimer’s disease (AD). Previous studies have shown that lychee seed saponins (LSS), isolated and extracted from traditional Chinese medicine lychee seeds, possess many beneficial activities including anti-oxidation, anti-diabetes, anti-AD, etc. In the present study, we established an in vitro neuronal apoptotic model of PC12 cells induced by Aβ25-35 and studied the effect of LSS on apoptosis by the methods of Hoechst 33342/propidium iodide (PI) fluorescence double staining, Annexin V/PI double staining, and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL). We also investigated the effects of LSS on mitochondria membrane potential, the expressions of Bcl-2 and Bax proteins, and the mRNA expression and the nuclear translocation of NF-κBp65 in PC12 cells. The results showed that LSS markedly inhibited apoptosis, improved the mitochondria membrane potentials, upregulated the expression of Bcl-2 protein, downregulated the expression of Bax protein, and decreased the mRNA expression and nuclear translocation of NF-κBp65 in PC12 cells. The study demonstrated that LSS significantly inhibited apoptosis induced by Aβ25-35 via regulation of the apoptotic and NF-κB pathways in PC12 cells. Therefore, LSS has the potential to be developed as a novel agent or nutrient supplement for the prevention and/or treatment of AD.

Cold stress poses a significant threat to the quality and productivity of lychee ( Litchi chinensis Sonn . ). While previous research has extensively explored the genomic and transcriptomic responses to cold stress in lychee, the translatome has not been thoroughly investigated. This study delves into the translatomic landscape of the 'Xiangjinfeng' cultivar under both control and low-temperature conditions using RNA sequencing and ribosome profiling. We uncovered a significant divergence between the transcriptomic and translatomic responses to cold exposure. Additionally, bioinformatics analyses underscored the crucial role of codon occupancy in lychee's cold tolerance mechanisms. Our findings reveal that the modulation of translation via codon occupancy is a vital strategy to abiotic stress. Specifically, the study identifies ribosome stalling, particularly at the E site AAU codon, as a key element of the translation machinery in lychee's response to cold stress. This work enhances our understanding of the molecular dynamics of lychee's reaction to cold stress and emphasizes the essential role of translational regulation in the plant's environmental adaptability.