Search Results (96)

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

Litchi chinensis Sonn. is an economically and culturally significant fruit crop in China, valued for its distinctive flavor, which arises from the combined contributions of taste and aroma metabolites. While the accumulation of sugars, organic acids, and volatile terpenes in litchi has been extensively studied, the role of nitrogenous flavor compounds, particularly free amino acids (FAAs), remains poorly characterized across diverse germplasm. To address this gap, high-performance liquid chromatography (HPLC) was employed to quantify 20 free amino acids in the pulp of 148 distinct litchi germplasm accessions. Comprehensive statistical analyses, including non-parametric tests, correlation analysis, and hierarchical clustering, were performed to elucidate compositional variations. Alanine (Ala), glutamate (Glu), and γ-aminobutyric acid (GABA) were the most abundant FAAs, contributing strongly to sweetness and umami. FAA profiles differed significantly among genomic groups, and clustering analysis identified three major chemotypes: Glu-accumulating, GABA-accumulating, and Ala-accumulating types. This study provides the first large-scale survey of FAA diversity in litchi germplasm and establishes a foundation for selecting cultivars with desirable flavor attributes and for future genomic dissection of amino acid metabolism. Full article

Litchi is an important subtropical fruit, highly valued by consumers for its vibrant color and distinctive flavor. B-box (BBX) proteins, which are zinc finger transcription factors, play a crucial role in regulating plant growth, development, and stress responses. Nevertheless, the specific function of BBX genes in the development and coloration of litchi fruit remains inadequately understood. In this study, 21 LcBBX genes (designated as LcBBX1-LcBBX21) were identified within the litchi genome. These genes were categorized into five sub-families based on phylogenetic analysis and were found to be unevenly distributed across 12 chromosomes. Promoter analysis revealed a rich presence of light-responsive elements, such as the G-box, and abscisic acid (ABA) responsive elements, including ABRE, within the promoter regions of LcBBX genes. Protein–protein interaction predictions indicated that the majority of LcBBX genes have the potential to interact with the light-responsive factor HY5. Transcriptome analysis and qRT-PCR results demonstrated that LcBBX genes exhibit tissue-specific expression patterns. Notably, most LcBBX genes were highly expressed prior to fruit coloration, whereas LcBBX4 and LcBBX10 were upregulated during the fruit coloration phase. Furthermore, LcBBX1/4/6/7/15/19 were upregulated in response to light following the removal of shading. The findings suggest that LcBBX4 may directly regulate anthocyanin biosynthesis in litchi pericarp. This study provides critical insights into the molecular mechanisms underlying litchi fruit development and coloration. Full article

Understory vegetation diversity is the key indicator of ecological outcomes in the close-to-nature transformation of plantations, with its composition revealing successional dynamics and ecosystem functionality. In response to China’s “Green and Beautiful Guangdong” Initiative, enhancing the ecological quality of plantations has been established as a critical objective for sustainable forest management. This study assessed the understory vegetation in four representative transformed plantations in Guangdong Province, China, using Multi-Response Permutation Procedure (MRPP), Indicator Species Analysis (ISA), Detrended Correspondence Analysis (DCA), and Redundancy Analysis (RDA). The results showed that: (1) Species richness was highest in the Eucalyptus L’Hér plantation (102 species), followed by Pinus massoniana Lamb (94), Acacia mangium Willd (92), and Litchi chinensis Soon plantations (85). (2) MRPP analysis revealed significant differences in species composition among plantation types (A = 0.149, p < 0.001). ISA identified 5, 7, 3, and 5 indicator species for each type, respectively, predominantly light-demanding pioneers such as Dicranopteris dichotoma (Thunb.) Bernh and Microstegium vagans (Nees ex Steud.) A. Camus. (3) DCA ordination showed clear compositional segregation among the understory communities of Eucalyptus, Pinus massoniana, and Acacia mangium plantations, whereas the Litchi chinensis plantation exhibited substantial overlap with others. RDA further demonstrated a significant negative correlation between mean diameter at breast height (DBH) and understory diversity (p < 0.01) across all plantations except Litchi chinensis. These findings offer a quantitative basis for tailored management strategies. We recommend structural adjustments through target-tree thinning to optimize light availability by regulating DBH, combined with interplanting native understory species. This integrated approach can enhance structural heterogeneity and promote more effective and sustainable plantation restoration. Full article

Litchi (Litchi chinensis Sonn.) is a popular subtropical fruit with a red pericarp that is primarily determined by the accumulation of anthocyanins. The peel color and fruit quality are also influenced by proanthocyanins (PAs), which play roles in fruit development and postharvest quality. In this study, we identified LcMYB2 as a key regulator of both anthocyanin and PA biosynthesis in litchi. Phylogenetic analysis revealed that LcMYB2 belongs to the VvMYB5 subclade. Expression analysis showed that LcMYB2 is highly expressed in the early stages of fruit development. Its expression pattern was consistent with that of LcLAR and LcANR, two key genes in the PA biosynthetic pathway. Subcellular localization and protein–protein interaction assays confirmed that LcMYB2 localizes to the nucleus and interacts with LcbHLH3. Dual-luciferase reporter assays demonstrated that the LcMYB2-LcbHLH3 complex activates the promoters of LcLAR and LcANR, supporting its role in regulating PA biosynthesis. Furthermore, overexpression of LcMYB2 in tobacco resulted in the synthesis of anthocyanins and PAs in the flower, indicating that LcMYB2 can regulate anthocyanin and PA biosynthesis. Additionally, transgenic tobacco plants with LcMYB2 overexpression exhibited delayed anther dehiscence, suggesting a broader role in plant development. These findings highlight the multifunctional nature of LcMYB2 in regulating both anthocyanin and PA biosynthesis, as well as its involvement in reproductive development. Full article

Sugars function as essential signaling molecules and metabolic substrates in plant growth, development, yield formation, and fruit quality. The aril of litchi (Litchi chinensis Sonn.) accumulates high levels of hexoses, primarily glucose and fructose; however, the molecular mechanisms underlying this process remain poorly characterized. This study aimed to systematically identify the monosaccharide transporter (MST) gene family in litchi and elucidate its role in aril sugar accumulation. Through a comprehensive analysis of the litchi genome, we identified a total of 45 LcMST genes, which were classified into seven distinct subfamilies: STP, ERD6L, PLT, INT, pGlcT, TMT, and VGT. Analysis of gene structure and conserved motifs revealed notable conservation among members within the same subfamily. Collinearity and gene duplication analyses suggested that the LcMST family expanded through both tandem and whole-genome duplication events, a process primarily governed by purifying selection. Expression profiling across diverse tissues demonstrated that LcMST genes exhibit distinct tissue-specific expression patterns. During fruit development in the hexose-dominant cultivar ‘Tianshuili’, the expression of the tonoplast monosaccharide transporter gene LcTMT1 exhibited a significant positive correlation with the accumulation of fructose, glucose, and total sugars. Heterologous functional complementation assays in yeast confirmed the ability of LcTMT1 to transport both glucose and fructose. In conclusion, this study presents the first genome-wide identification and characterization of the MST gene family in litchi, and identifies LcTMT1 as a key contributor of hexose accumulation in the aril. These findings establish a foundation for elucidating the molecular mechanisms of sugar accumulation in litchi fruit and for guiding future genetic improvement of fruit quality. Full article

Colorectal cancer (CRC) remains a leading global health challenge, and natural products are increasingly explored for their multi-targeted therapeutic potential. Litchi chinensis seed extract (LCSE) has shown promising anti-cancer activity in vitro, though its in vivo effects remain underexplored. LCSE was analyzed by colorimetric assays and HPLC to quantify the phytochemical composition. Nude mice bearing HT-29 or SW480 xenografts were orally administered LCSE (0.1 or 0.6 g/kg) daily for 14 days. Tumor volume was measured, and immunohistochemistry was used to assess EGFR, p21, p53, Ki-67, CEA, CK20, CDX2, and Bax expression. Phytochemical profiling demonstrated LCSE contains abundant phenolics and flavonoids, with gallic acid as a predominant constituent, underscoring the potential bioactive properties. LCSE significantly inhibited tumor growth in HT-29 xenografts and dose-dependently reduced EGFR, p21, p53, cell cycle proteins and proliferation/differentiation markers. In SW480 tumors, inhibitory effects were evident primarily at the higher dose, with limited reduction in p53 expression. Bax levels remained unchanged in both models, indicating a non-apoptotic mechanism. No systemic toxicity was observed in treated mice. LCSE exhibits dose-dependent anti-tumor activity in CRC xenografts, likely mediated through suppression of proliferation and modulation of key regulatory proteins rather than apoptosis. These findings support LCSE as a safe, multi-target botanical candidate for CRC intervention and justify further mechanistic and translational studies. Full article

The efficiency of in vitro regeneration in litchi (Litchi chinensis Sonn.) is highly influenced by the type and concentration of plant growth regulators (PGRs), particularly auxins. This study evaluated the effects of phenylacetic acid (PAA) and its derivatives—4-chlorophenylacetic acid (CPA) and 4-iodophenylacetic acid (IPA)—on callus proliferation, somatic embryogenesis, and plantlet regeneration in ‘Feizixiao’ litchi, as well as to establish an efficient regeneration protocol. The inclusion of CPA or IPA in callus proliferation medium significantly enhanced the proliferation rate, with 20 mg·L⁻¹ CPA being the most effective. The highest number of somatic embryos per gram of fresh embryonic callus weight (gFW⁻¹) (1131 embryos·gFW⁻¹) was observed with 40 mg·L⁻¹ PAA in proliferation medium. The addition of 10 mg·L⁻¹ IPA to the proliferation medium yielded the highest plantlet regeneration rate (50 plantlets·gFW⁻¹). Supplementing the somatic embryo induction medium with 5 mg·L⁻¹ PAA resulted in 460 somatic embryos·gFW⁻¹ and 86 regenerated plantlets·gFW⁻¹. These findings indicate that PAA and its derivatives are effective PGRs for the in vitro regeneration of litchi, providing a valuable protocol for the propagation of elite cultivars. Full article

As a globally significant fruit crop, litchi (Litchi chinensis Sonn.) exhibits substantial variation in seed size, which is a key determinant of fruit quality. However, the lack of molecular markers closely associated with seed-related traits has hindered targeted breeding efforts. In this study, we systematically evaluated six critical traits—single fruit weight, seed weight, seed length, seed width, edible rate, and seed-to-fruit weight ratio—across 131 early-maturing litchi accessions. Hierarchical clustering analysis (HCA) and principal component analysis (PCA) revealed a clear bifurcation of these accessions into two distinct groups based on seed size-related traits. Using bulked segregant analysis sequencing (BSA-seq), we identified a candidate genomic region (24.93–25.69 Mb) on chromosome 5, potentially regulating litchi seed size. Within this region, 1600 single-nucleotide polymorphisms (SNPs) and 314 insertion/deletion mutations (InDels) exhibited significant divergences between the extreme pools. To validate these findings, we performed PCR-based screening on 87 litchi accessions. Two InDel markers demonstrated strong phenotypic associations: Chr5_25610680_InDel showed highly significant correlations with seed weight, edible rate, seed length, seed width, and seed-to-fruit weight ratio, explaining 22.60–35.54% of phenotypic variation. Meanwhile, Chr5_25585686_InDel was significantly associated with seed weight and edible rate, accounting for 18.66% and 18.94% of the phenotypic variation, respectively. These findings provide valuable molecular markers for marker-assisted breeding of litchi seed size, offering a promising avenue to advance precision breeding in this economically important crop. Full article

Litchi (Litchi chinensis Sonn.) is a kind of evergreen fruit tree with good flavor and taste which has high economic value. Sufficiently low temperature in winter is essential for the successful flower formation of litchi. Therefore, in the context of global warming, litchi often experiences unstable flower formation, ultimately resulting in a decrease in litchi production. Our previous research has highlighted the pivotal role of the LcFT1 gene in regulating the flower formation of litchi and identified two AP1 homologous genes associated with LcFT1 (named LcAP1-1 and LcAP1-2) based on RNA-Seq and weight gene co-expression network analysis (WGCNA). In this study, the functions of the two AP1 homologous genes in regulating flowering time were investigated. Result showed that LcAP1-1 and LcAP1-2 were expressed in all litchi tissues. LcAP1-1 was more highly expressed in mature leaves compared to other tissues, while the LcAP1-2 has the highest expression level in flower buds. Both of them exhibited upregulation in the terminal bud of litchi under low temperature. The expression of LcAP1-1 and LcAP1-2 was highly correlated with the initiation of flower buds and the development of flower organs. They increased gradually during the floral initiation but decreased gradually during flower bud development. The transgenic tobacco of LcAP1-2 flowered about 55 days earlier than wild-type, while tobacco overexpressing the LcAP1-1 gene had no significant changes in flowering time compared to the wild-type. These results indicate that the two genes have divergent regulatory functions, and that the LcAP1-2 gene may be involved in the regulation of flower transformation and flower organ development in litchi. Our research will further reveal the molecular regulatory mechanisms of flower formation in litchi and will also provide theoretical guidance for the molecular breeding of litchi. Full article

Sulfur fumigation (SF), acid dipping (HCl treatment, HAT), and their combination (SF+HAT) are common methods for long-term preservation and color protection of litchi. However, their effects on the metabolic profile of the litchi pericarp have not been investigated. SF resulted in a yellowish-green pericarp by up-regulating lightness (L*), b*, C*, and h° but down-regulating total anthocyanin content (TAC) and a*, while HAT resulted in a reddish coloration by up-regulating a*, b*, and C* but down-regulating L*, h°, and TAC. SF+HAT recovered reddish color with similar L*, C* to SF but a*, b*, h°, and TAC between SF and HAT. Differential accumulated metabolites (DAMs) detected in HAT (vs. control) were more than those in SF (vs. control), but similar to those in SF+HAT (vs. control). SF specifically down-regulated the content of cyanidin-3-O-rutinoside, sinapinaldehyde, salicylic acid, and tyrosol, but up-regulated 6 flavonoids (luteolin, kaempferol-3-O-(6″-malonyl)galactoside, hesperetin-7-O-glucoside, etc.). Five pathways (biosynthesis of phenylpropanoids, flavonoid biosynthesis, biosynthesis of secondary metabolites, glutathione metabolism, and cysteine and methionine metabolism) were commonly enriched among the three treatments, which significantly up-regulated sulfur-containing metabolites (mainly glutathione, methionine, and homocystine) and down-regulated substrates for browning (mainly procyanidin B2, C1, and coniferyl alcohol). These results provide metabolic evidence for the effect of three treatments on coloration and storability of litchi. Full article

The use of unmanned aerial vehicle (UAV) pesticide spraying technology in precision agriculture is becoming increasingly important. However, traditional spraying methods struggle to address the precision application need caused by the canopy differences of fruit trees in orchards. This study proposes a UAV orchard variable-rate spraying method based on canopy volume. A DJI M300 drone equipped with LiDAR was used to capture high-precision 3D point cloud data of tree canopies. An improved progressive TIN densification (IPTD) filtering algorithm and a region-growing algorithm were applied to segment the point cloud of fruit trees, construct a canopy volume-based classification model, and generate a differentiated prescription map for spraying. A distributed multi-point spraying strategy was employed to optimize droplet deposition performance. Field experiments were conducted in a citrus (Citrus reticulata Blanco) orchard (73 trees) and a litchi (Litchi chinensis Sonn.) orchard (82 trees). Data analysis showed that variable-rate treatment in the litchi area achieved a maximum canopy coverage of 14.47% for large canopies, reducing ground deposition by 90.4% compared to the continuous spraying treatment; variable-rate treatment in the citrus area reached a maximum coverage of 9.68%, with ground deposition reduced by approximately 64.1% compared to the continuous spraying treatment. By matching spray volume to canopy demand, variable-rate spraying significantly improved droplet deposition targeting, validating the feasibility of the proposed method in reducing pesticide waste and environmental pollution and providing a scalable technical path for precision plant protection in orchards. Full article

Previous studies have shown that foliar spraying with a 0.3% CaCl₂ + 0.3% MgCl₂ solution can mitigate the “sugar receding” phenomenon in fruit pulp, partly by regulating sugar conversion in the pulp of ‘Feizixiao’ litchi (Litchi chinensis Sonn.). Given that calcium-dependent protein kinases (CDPKs) in plants regulate sugar metabolism by modulating the activity of key sugar conversion enzymes, this study investigated the expression response of CDPK genes in ‘Feizixiao’ litchi pulp to foliar calcium–magnesium nutrient treatment and their regulatory characteristics on sugar conversion. After the fruit set, ‘Feizixiao’ litchi trees were subjected to three consecutive foliar spray applications of 0.3% CaCl₂ + 0.3% MgCl₂, with water spraying as the control. The dynamic changes in peel h values and soluble sugar and monosaccharides, water-soluble calcium (Ca²⁺) and magnesium (Mg²⁺), plant hormones, and the concentration of CDPKs in the pulp were compared throughout fruit development. Key differentially expressed members of the CDPK gene family were screened through real-time quantitative PCR analysis. The results showed that the peel color transition occurred earlier in the control (CK) than in the treatment (T), but the coloration process accelerated in the treated fruit, leading to no significant difference in peel h values between the groups at 76 days after anthesis (DAA), when both reached the lowest levels. The total of soluble sugar in the pulp peaked at 70 DAA in both groups, but while the CK exhibited a significant decline thereafter, T maintained stable sugar levels, thereby mitigating the “sugar receding” phenomenon. Water-soluble calcium and water magnesium levels were significantly higher in the T at 42 and 63 DAA, with water calcium remaining significantly higher at 70 DAA. Furthermore, sucrose, glucose, fructose, abscisic acid (ABA) contents, and CDPK concentration were significantly higher in the T at 70 and 76 DAA. The CDPK gene family members LcCDPK1, LcCDPK2, LcCDPK3, LcCDPK4, LcCDPK5, LcCDPK9, LcCDPK15, and LcCDPK17 were upregulated in response to T. Among them, LcCDPK1, LcCDPK4, LcCDPK5, LcCDPK9, and LcCDPK17 were identified as key structural genes due to their significant correlation with soluble sugar content and CDPK concentration, as well as their differential expression between T and CK. In conclusion, foliar calcium–magnesium nutrient treatment upregulates the expression of these five CDPK gene family members by increasing the ABA levels in the pulp, leading to more CDPK accumulation. This accumulation inhibits sugar conversion and promotes sucrose and fructose accumulation, thereby mitigating the “sugar receding” phenomenon in ‘Feizixiao’ litchi pulp. Full article