Search Results (83)

Lychee (Litchi chinensis Sonn.) is a major subtropical fruit crop, yet the regulatory hierarchy underlying edible ratio (flesh weight/whole fruit weight, %) and juice yield (juice weight/whole fruit weight, %), the core processing-quality traits, remains unresolved. We phenotyped 301 accessions from ten origins under uniform conditions and used hierarchical regression to predict and evaluate edible ratio and juice yield based on structural and physiological fruit traits, thereby separating the contributions of structural constraints and physiological modulation. Both traits exhibited broad population variation and were significantly modulated by maturity stage, with late-maturing accessions outperforming early types. A strong positive correlation (r = 0.679, p < 0.001) supported the identification of “double-high” germplasm combining superior edible ratio and juice yield. Kernel ratio emerged as the dominant structural constraint on edible ratio (R² = 0.6699, p < 0.001), while the combined inedible fraction served as the basal limiting factor for juice yield (R² = 0.4262, p < 0.001). Critically, after controlling for structural variation, physiological traits contributed an independent 9.2% of explained variance (ΔR² = 0.092, p < 0.001). pH was identified as the primary positive physiological predictor (β = 0.322, p < 0.001), whereas soluble solids content (SSC) exhibited a weak negative effect (β = −0.064, p = 0.008), indicating that high sugar content is not a priority target for processing-oriented breeding. An Integrated Ideotype Score (IIS) was constructed to objectively rank germplasm; elite accessions including ‘10_269’, ‘Yujinqiu’ and ‘Nuomici’ combined edible ratio > 75% with juice yield > 40%. These findings establish a “structural constraint-physiological modulation” two-tier regulatory hierarchy for lychee processing quality and provide a multivariate framework for germplasm evaluation and breeding selection. Full article

Litchi (Litchi chinensis Sonn.) is an economically important tropical and subtropical fruit crop, but frequent outbreaks of diseases and pests severely threaten yield and quality. Traditional field monitoring is inefficient and cannot meet requirements for early and accurate detection over large areas. Although various sensing technologies and artificial intelligence (AI)-based methods have been developed, the literature remains fragmented and lacks systematic comparison across different monitoring scales and technological approaches. This review summarizes recent advances in intelligent detection technologies for litchi diseases and pests across scales ranging from individual fruits to entire orchards. First, biological and spectral response mechanisms of infected tissues are introduced as a theoretical basis. Then, fruit-level sensing technologies, including near-infrared spectroscopy, multispectral and hyperspectral imaging, RGB imaging, fluorescence sensing, and data fusion, are reviewed. Orchard-scale monitoring using unmanned aerial vehicles (UAVs) and Internet of Things (IoT) is further analyzed. Machine learning and deep learning methods for feature extraction, recognition, and risk prediction are also summarized. Finally, advantages, limitations, and application scenarios of different technologies are compared in terms of their advantages, limitations, and suitable application scenarios. This review highlights the transition toward multimodal and intelligent monitoring systems and discusses future directions including edge intelligence, multimodal fusion, and collaborative monitoring for precision agriculture. Full article

Although pericarp browning is a major postharvest challenge in litchi fruit, the browning behavior of the aril and seeds remains poorly understood. This study aimed to investigate tissue-specific browning and the underlying mechanisms. Mature litchi fruit were separated into pericarp, aril, and cut seed, stored at 25 °C. Browning occurred predominantly in the pericarp and seeds, while aril showed no visible browning. The pericarp exhibited greater increases in electrolyte leakage (REL) and malondialdehyde (MDA) content than the aril and seeds. The pericarp and seed were rich in total phenolics, flavonoids, and proanthocyanidins (PAs), all of which declined in both the pericarp and seed during browning, whereas PAs were nearly undetectable in aril. Notably, epicatechin (EC) content was higher in the pericarp than in the seed, while catechin (CT) was abundant in seed but absent in pericarp. Laccase (LAC) and peroxidase (POD) activities, along with transcript levels of LcLAC14-4/5, LcLAC7, and LcPOD3, were substantially higher in the pericarp than in the seed, and barely detectable in aril. The results indicate that tissue-specific browning in litchi fruit is associated with enzymatic oxidation of PA-associated phenolics in the pericarp and seeds, offering a mechanistic target for postharvest preservation. Further studies should explore the biosynthetic regulation of PAs in the pericarp and seeds. Full article

The development of functional ingredients from perishable tropical fruits supports sustainable food systems by reducing postharvest losses while retaining bioactive compounds. This study developed and optimized black lychee (Litchi chinensis Sonn.) extracted powder (BLEP) by spray drying and evaluated its physicochemical characteristics and antioxidant stability during storage. A 2² factorial design was employed to investigate the effects of maltodextrin concentration (5–30%) and inlet temperature (160–200 °C). Graphical optimization using an overlay plot identified 17.80% maltodextrin and an inlet temperature of 200 °C as the best compromise among the significant responses within the range tested. The optimized BLEP contained vanillic acid and epicatechin as the predominant phenolic compounds together with essential amino acids, including leucine. Degree of glycation (DG) and HMF were measured as indirect indicators of Maillard reaction progress. Over six months at 4, 25, 35, and 45 °C, color parameters, DG, and HMF remained stable, whereas total phenolic content (TPC) declined from 437.11 to 225–252 mg GAE/100 g db and ABTS radical scavenging activity declined progressively. TPC was strongly associated with antioxidant capacity (r = 0.914 with ABTS, p < 0.01), and its degradation followed zero-order kinetics (adjusted R² = 0.931–0.971) with a predicted half-life (L₅₀) of 199–220 days. The optimized powder therefore showed good physical and chromatic stability with partial loss of antioxidant-related compounds over time. Full article

Cognitive impairment and memory decline represent major health concerns affecting older adults worldwide, and systemic metabolic dysfunction plays a critical role in their progression. Black lychee is produced from Litchi chinensis Sonn. through postharvest thermal processing. It contains polyphenolic compounds known for their neuroprotective properties. This study investigated the cognitive-enhancing effects of black lychee in a rat model of scopolamine-induced cognitive impairment. Male rats (n = 8 per group) received scopolamine (2 mg/kg, i.p.) alone or in combination with black lychee at 100, 200, or 400 mg/kg/day for 20 days. Untargeted blood metabolites and the phytochemical composition of black lychee were identified using ¹H-NMR spectroscopy. Cognitive performance was assessed using the passive avoidance test. Phytochemical analysis confirmed that black lychee is rich in polyphenols. All black lychee-treated groups showed a significant increase in step-through latency compared with the scopolamine group. Blood metabolomic analysis revealed alterations in 26 metabolic pathways associated with oxidative stress and energy metabolism. These findings suggest that polyphenols in black lychee attenuate scopolamine-induced cognitive impairment by reducing oxidative stress and restoring key metabolites involved in energy metabolism. These results support the potential of black lychee as a functional food for mitigating age-related cognitive decline. Full article

CONSTANS-LIKE (COL) genes are pivotal regulatory components in the photoperiodic flowering pathway of plants. These genes can be regulated by both photoreceptors and the circadian clock, modulating plant flowering responses under specific day lengths by regulating florigen levels. However, the COL gene family in Litchi chinensis Sonn. has not yet been characterized. In this study, we identified eight COL family members in litchi and classified them into three subgroups based on phylogenetic analysis. The analysis of cis-regulatory elements within the promoters of LcCOLs revealed a wide distribution of elements associated with light, hormone, and stress responses. Transcript expression profiling indicated that most LcCOLs exhibited relatively high expression levels in leaf buds, leaves, and young fruits. Diurnal expression analysis under natural photoperiod conditions revealed that the expression peaks of all LcCOLs, with the exception of LcCOL1, occurred during the nighttime. The heterologous overexpression of LcCOL7 and LcCOL8, the closest homologs to AtCO, in Arabidopsis thaliana significantly delayed the flowering time under both long-day (LD) and short-day (SD) conditions, indicating that these genes act as repressors of flowering. This study provides a foundational basis for elucidating the molecular mechanisms underlying litchi flowering regulation and identifies promising candidate genes for the molecular breeding of litchi flowering-related agronomic traits. Full article

Lychee, an entomophilous fruit crop cultivated in tropical and subtropical regions, depends heavily on pollination services for optimal fruit yield and the economic sustainability of farmers. However, information on its pollinator interactions remains limited. This study was conducted over three flowering seasons to document the pollinator assemblage of lychee and examine variation in their activity under different physical conditions, including time of day, panicle height, and light–shade environments. Several insects (here, 47, including many butterflies, bees and flies) were recorded as flower visitors of lychee. The most effective pollinators were Apis cerana, Apis dorsata, Apis florea, Braunsapis mixta, and Tetragonula pagdeni. Pollinator abundance, species richness, diversity, and foraging traits (e.g., flower visitation rate and flower handling time) varied with daytime, inflorescence height, and light availability (light versus shade). Greater abundance, richness, and diversity were documented between 8:00 and 12:00 h, at mid-canopy height (2–6 m), and on well-lit inflorescences. Flower visitation rate was higher under these conditions, whereas flower handling time was lower. This study uncovered the key pollinators of lychee and demonstrated that plant–pollinator interactions vary across different physical conditions. These findings may help to improve pollinator management and enhance pollination services in lychee cultivation. Full article

Background: Lychee fruits are sweet and juicy, yet mitochondrial genomic data for this species remains scarce, limiting in-depth studies of its genetic and evolutionary characteristics. To address this gap, in this study, the abortive-seeded cultivar ‘Xianjinfeng’ (XJF) and the large-seeded cultivar ‘Xinqiumili’ (XQML) were selected for analysis. Using third-generation sequencing technology, we sequenced, assembled, and annotated their mitochondrial genomes, and compared their structural characteristics and evolutionary relationships. Results: Assembly revealed mitochondrial genome sizes of 579,270 bp for XJF and 579,261 bp for XQML, both with 45.41% GC content. The mitogenomes contain 396 repetitive sequences, including 47 tandem repeats and 165 dispersed repeats, with SSR loci primarily 10–14 bp in length. Each genome encoded 62 genes, comprising 22 tRNAs, 3 rRNAs, and 35 protein-coding genes. Further analysis revealed 15 homologous sequences originating from chloroplasts in both mitochondrial genomes, totaling 12,194 bp (2.11% of the mitochondrial genome). These included 9 tRNA genes, 4 rRNA genes, and partial protein-coding sequences. Additionally, 184 simple sequence repeats (SSRs) were identified in both cultivars, whereas 564 and 563 potential RNA editing sites were predicted by computational tools in XJF and XQML, respectively, indicating subtle genetic differences between the cultivars. This study also analyzed codon usage preferences, nucleotide diversity, and chloroplast-to-mitochondria gene transfer events. Collinearity and comparative genomics results indicate that lychee is closely related to Nephelium lappaceum L. and Xanthoceras sorbifolium Bunge within the Sapindaceae family. Conclusions: In this study, two high-quality lychee mitochondrial genomes were successfully assembled and annotated, enriching the mitochondrial genome resources of Sapindaceae plants and laying a foundation for future lychee phylogenetic and evolutionary studies of closely related species. Full article

2,4-Dichlorophenoxyacetic acid (2,4-D) is a vital exogenous auxin for the induction and proliferation of litchi embryogenic callus. At present, its molecular regulation mechanism remains unclear. In this study, transcriptome sequencing samples were selected based on different cell growth phenotypes observed in ‘Feizixiao’ litchi embryogenic callus cultured in liquid medium with or without 2,4-D. By integrating transcriptome profiling with weighted gene co-expression network analysis (WGCNA), we identified key genes and signaling pathways dynamically responsive to 2,4-D concentration changes. We identified 558 commonly differentially expressed genes (DEGs), of which 117 were up-regulated and 387 were down-regulated; functional enrichment analysis revealed significant enrichment in the “plant hormone signal transduction” and “phenylpropanoid biosynthesis” pathways. In the former pathway, genes such as AUX28, GH3.17, GH3.6, and ARR5 were up-regulated; in the latter, by comparison, β-glucosidase 47 and Peroxidase 61 exhibited increased expression levels induced by 2,4-D. Furthermore, among these DEGs, 57 transcription factors belonged to 24 families. Notably, VRN1, FEZ, and DOF5.4 were significantly and rapidly induced by 2,4-D. WGCNA results demonstrated a significant positive correlation between the yellow module and 2,4-D treatment. Small heat shock protein (sHSP) genes constituted the core hub genes in the yellow module. Through Venn analysis of DEGs and key modules, 38 cross-genes were identified, of which non-specific lipid-transfer protein-like genes (nsLTP) were found to be specifically up-regulated without 2,4-D. The transcription factors and genes identified work in synergy to ensure the formation and sustained proliferation of embryogenic callus by precisely regulating the dynamic balance of auxin and cytokinin within cells and maintaining the stability of cell structure. Our findings provide a crucial theoretical foundation for understanding the molecular mechanism of 2,4-D in regulating litchi embryogenic callus proliferation. Full article

Gibberellin 2-oxidase (GA2ox) is instrumental in gibberellin (GA) catabolism and the modulation of plant growth. In this investigation, nine LcGA2ox genes (LcGA2ox1-LcGA2ox9) were identified within the litchi (Litchi chinensis Sonn.) genome. Bioinformatics analyses revealed that the proteins encoded by these genes uniformly possess 2OG-Fe (II)_Oxy and DIOX_N domains, exhibiting a range of physicochemical properties and subcellular localizations. Phylogenetic analysis categorized these genes into three subgroups, C₁₉-GA2ox-I, C₁₉-GA2ox-II, and C₂₀-GA2ox-I, with each subgroup characterized by specific motif compositions and gene structures. These gene promoters harbor cis-regulatory elements implicated in light signaling, hormonal pathways, abiotic stress responses, and developmental processes. The LcGA2ox gene family contributes to the maintenance of GA metabolic homeostasis through interactions with GA synthases, receptors, and repressors. This gene family demonstrates distinct tissue-specific and spatiotemporal expression patterns: LcGA2ox1/6/7 are predominantly expressed in flowers, LcGA2ox8 in fruits, and LcGA2ox9 in buds. Notably, LcGA2ox6/7 are key regulators of male and female flower development in litchi, exhibiting a negative correlation with the female flower genes AGL1 and SPT. The overexpression studies conducted in Arabidopsis have demonstrated that LcGA2ox6 acts as an inhibitor of both vegetative and reproductive development. This study characterizes the LcGA2ox family, establishing a theoretical basis for understanding GA regulation in litchi reproductive development and genetic improvement. Full article

The TIFY family, known as a novel group of transcription factors unique to the plant, plays a number of roles and has been functionally characterized in numerous plant species. However, TIFY proteins remain unexplored in litchi. Here, we identified 14 TIFY genes in litchi, which were unevenly located on 8 of 15 chromosomes. All of the LcTIFY proteins were predicted to be nuclear-localized and were phylogenetically categorized into four subfamilies (TIFY, PPD, ZML, and JAZ). Duplication analysis detected no tandem duplications but identified one segmental duplication event with LcTIFY genes, suggesting that segmental duplication served as the primary driving force for the expansion of LcTIFY genes. Comparative collinear analysis revealed 12, 5, and 27 collinear gene pairs between litchi and Arabidopsis, rice, and apple, respectively, providing valuable clues for understanding the evolution of the LcTIFY genes. RNA-Seq and qRT-PCR analyses indicated tissue-preferential expression patterns among LcTIFY genes. Notably, LcPPD1 and LcJAZ5 expressions were negatively correlated with anthocyanin accumulation in the ‘Feizixiao’ variety, except that LcJAZ5 displayed a positive correlation under CPPU treatment. In contrast, LcJAZ7 expression showed a positive correlation across all treatments, implicating these genes in the regulation of pericarp pigmentation. Collectively, these findings lay the groundwork for future investigations into the functional roles of TIFY genes in litchi and offer valuable genetic resources for elucidating the mechanisms underlying litchi pigmentation, thereby providing fresh perspectives for subsequent research into the molecular mechanisms of color formation in plants. Full article

Proanthocyanidins (PAs) display antioxidant properties and can partially delay pericarp browning in postharvested litchi (Litchi chinensis Sonn.) fruits. In this study, litchi fruit was treated with 3 g/L PA and then stored at 25 °C for 10 days. Differential metabolites and differentially expressed genes were comprehensively analyzed in litchi pericarp across four stages of browning progression. A total of 630 metabolites were identified through untargeted metabolomic analysis, with 237 of them being annotated in the kyoto encyclopedia of genes and genomes (KEGG) database. The abundance of flavonoids (kaempferol), six types of anthocyanins, cyanidins, (−)-epicatechin, and (+)-catechin in the PA biosynthetic pathway was notably reduced in PA-treated pericarp compared to that of the control fruit. Transcriptomic analysis also revealed that five genes in the phenylpropanoid biosynthesis pathways and seven genes of phenoloxidase were significantly downregulated. In addition, correlation analysis revealed significant positive correlations between the browning index and genes like LcFLS (flavonol synthase), LcANS (anthocyanidin synthase), LcUFGT (UDP-glucose:anthocyanidin 3-O-glucosyltransferase), LcPPO (polyphenol oxidase), and LcLAC7 (laccase), and a significant negative correlation with PAs and (−)-epicatechin. In conclusion, PA treatment can efficiently delay pericarp browning, mainly by reducing brown substrate accumulation and oxidation, and decreasing PA oxidation and polymerization. This study delves into the regulatory mechanisms through which PA delays litchi pericarp browning. Full article

At present, fruit picking mainly relies on manual operation. Taking the litchi (litchi chinensis Sonn.)-picking robot as an example, visual perception is often affected by illumination variations, low recognition accuracy, complex maturity judgment, and occlusion, which lead to inaccurate fruit localization. This study aims to establish an embodied perception mechanism based on “perception-reasoning-execution” to enhance the visual perception and decision-making capability of the robot in complex orchard environments. First, a Y-LitchiC instance segmentation method is proposed to achieve high-precision segmentation of litchi clusters. Second, a generative artificial intelligence model is introduced to intelligently assess fruit maturity and occlusion, providing auxiliary support for automatic picking. Based on the auxiliary judgments provided by the generative AI model, two types of dynamic harvesting decisions are formulated for subsequent operations. For unoccluded main fruit-bearing branches, a skeleton thinning algorithm is applied within the segmented region to extract the skeleton line, and the midpoint of the skeleton is used to perform the first type of localization and harvesting decision. In contrast, for main fruit-bearing branches occluded by leaves, threshold-based segmentation combined with maximum connected component extraction is employed to obtain the target region, followed by skeleton thinning, thereby completing the second type of dynamic picking decision. Experimental results show that the Y-LitchiC model improves the mean average precision (mAP) by 1.6% compared with the YOLOv11s-seg model, achieving higher accuracy in litchi cluster segmentation and recognition. The generative artificial intelligence model provides higher-level reasoning and decision-making capabilities for automatic picking. Overall, the proposed embodied perception mechanism and dynamic picking strategies effectively enhance the autonomous perception and decision-making of the picking robot in complex orchard environments, providing a reliable theoretical basis and technical support for accurate fruit localization and precision picking. Full article

Litchi (Litchi chinensis Sonn.) is a pillar of the tropical agricultural economy in southern China, yet its production faces increasing instability due to climate change. Traditional agronomic models often fail to capture the complex, non-linear interactions between meteorological drivers and yield formation in perennial fruit trees. To address this challenge, the study constructed a yield prediction framework using an optimized Random Forest (RF) model integrated with interpretable machine learning (SHAP), based on a comprehensive dataset from 17 major production regions in Hainan Province (2000–2022). The model demonstrated robust predictive capability at the provincial scale (R² = 0.564, RMSE = 2.1 t/ha) and high consistency across regions (R² ranging from 0.51 to 0.94). Feature importance analysis revealed that heat accumulation (specifically growing degree days above 20 °C) is the dominant driver, explaining over 85% of yield variability. Crucially, scenario simulations uncovered asymmetric climate risks across phenological stages: while moderate warming generally enhances yield by promoting vegetative growth and ripening, it acts as a stressor during the Fruit Development stage, where temperatures exceeding 26 °C trigger yield decline. Furthermore, the yield penalty for drought during Flowering (−8.09%) far outweighed the marginal benefits of surplus rainfall, identifying this window as critically sensitive to water deficits. These findings underscore the necessity of phenology-aligned adaptation strategies—specifically, securing irrigation during flowering and deploying cooling interventions during fruit development—providing a data-driven basis for climate-smart management in tropical agriculture. Full article

Superoxide dismutase (SOD) serves as a critical enzyme that is involved in plant development and abiotic stresses by effectively detoxifying reactive oxygen species (ROS). Though the SOD gene family has been reported across various plant species, its specific members and functional roles in litchi (Litchi chinensis Sonn.) remain poorly understood. In this study, a total of seven SOD (christened LcSOD) genes were identified from the litchi genome and classified into three groups across six chromosomes. Notably, genes from the same evolutionary branch had more similar structures and motif distributions. The LcSOD genes were confirmed to have a stronger collinearity with dicotyledons than with monocotyledons. Cis-acting elements analysis indicated that the LcSOD gene family was deeply involved in orchestrating growth, development, and responses to multiple phytohormones and diverse stresses. Expression patterns of the LcSOD genes across different tissues revealed universal and specific expressions. In leaves, expression levels of the LcSOD genes were induced by cold, heat, drought, and salt stresses, and transcript levels correlated positively with concomitant changes in key physiological parameters under the same conditions. In addition, the LcSOD genes were characterized for their physicochemical properties, subcellular localizations, secondary and tertiary structures, gene ontology (GO) annotations, and protein-protein interactions. Our findings offer comprehensive insights into the LcSOD gene family, enriching genetic resources. They provide a framework for functional characterization and the development of stress-resistant cultivars, driving both basic research and applied breeding programs in litchi. Full article