The plant homeodomain (PHD) finger constitutes a subgroup of transcription factors that contribute to the coordination of plant growth, morphogenesis, and adaptation to environmental stress mechanisms. In this study, we identified and functionally characterized the BrPHD58 gene from Brassica rapa. Using sequence analysis, subcellular localization of BrPHD58-GFP fusion proteins, and transgenic Arabidopsis thaliana lines ectopically expressing BrPHD58, we investigated its role in salt stress responses, including seedling phenotypes and expression of salt-responsive genes. Subcellular localization analysis indicated that BrPHD58 predominantly accumulates within the nuclear compartment. Ectopic expression of BrPHD58 in A. thaliana significantly reduced seedling survival rates and root lengths under varying concentrations of NaCl compared to wild-type (WT) plants. Under soil-grown conditions, transgenic lines overexpressing BrPHD58 exhibited markedly decreased tolerance to salt stress. Moreover, ectopic expression of BrPHD58 led to a down regulation of key salt-responsive genes, AtRD22, AtRD29A, and AtLEA14, under salt stress conditions. Collectively, all these findings indicate that BrPHD58 acts as a negative modulator of salt stress tolerance in transgenic plants. Further investigation involving the development and analysis of BrPHD58 loss-of-function mutants in B. rapa is necessary to fully elucidate its physiological role in salinity adaptation.

Fruit acidity, a key quality trait, is primarily determined by malic acid in many fruit crops. However, the molecular machinery governing its accumulation, particularly in response to hormonal cues like auxin, remains a "black box." Here, we systematically deconstruct the regulatory pathway controlling malic acid in litchi (Litchi chinensis). We first identify the tonoplast-localized transporter LcALMT1 as the principal channel for malate sequestration into the vacuole. We then uncover its upstream regulatory module, revealing that the R2R3-MYB transcription factor LcMYB70 directly binds the LcALMT1 promoter but lacks intrinsic transcriptional activity. Instead, LcMYB70 functions as a molecular scaffold to recruit the Auxin Response Factor LcARF10, which confers transcriptional repression upon the complex. This LcMYB70-LcARF10 repressor module is negatively regulated by auxin signaling, providing a direct molecular link between the decline in endogenous auxin during fruit maturation and the attenuation of malate accumulation. Critically, we identified a single-nucleotide polymorphism in the LcARF10 gene that governs the divergence between high- and low-acid cultivars. The functional C allele in low-acid cultivars enables the formation of the repressor complex. In contrast, the T allele in high-acid cultivars contains a premature stop codon that results in a non-functional, truncated protein, preventing complex assembly and causing the high-acid phenotype. Our study defines a complete pathway from hormone to trait and its genetic basis, revealing a novel MYB-ARF scaffold module; a definitive molecular link between auxin withdrawal and metabolic reprogramming; and the functional integrity of a corepressor as a new paradigm for trait diversification.

Organ abscission is a core developmental process that allows plants to optimize resource allocation, maximize reproductive fitness, and respond to environmental cues. In agricultural systems, however, premature fruit abscission can severely reduce yield. Here, we investigate premature fruit drop in litchi and identify the hexokinase homolog LcHXK1 as a nonglycolytic hexose sensor that suppresses abscission by activating a pedicel lignification program. LcHXK1 physically associates with and phosphorylates the WRKY transcription factor LcWRKY42, a modification that enhances its stability and transcriptional activity in inducing laccase and peroxidase genes required for lignin polymerization, promoting lignin deposition and reinforcing the pedicel to prevent organ detachment. Over expression of LcHXK1 or LcWRKY42 in litchi callus and in Arabidopsis elevates lignin content, increases laccase and peroxidase activities, and delays organ abscission, revealing a conserved sugar-responsive pathway. LcWRKY42 also upregulates LcHXK1, forming a positive feedback loop that amplifies hexose signaling. Together, these findings define a sugar-sensing regulatory module that couples carbon status to pedicel lignification, providing a mechanistic framework for improving fruit retention in crops.

Camellia oleifera is a commercially important woody edible oil tree species in China. Yet, heavy premature fruit drop causes substantial yield losses and significantly limits the economic potential of the oil tea industry. Ethylene is well recognized as a promoter of organ abscission in plant, and the APETALA2/Ethylene Responsive Factor (AP2/ERF) family plays critical roles in response to ethylene. However, the AP2/ERF gene family in Camellia oleifera remains largely unexplored. Enhanced fruit abscission in Camellia oleifera was associated with increased accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, in fruit pedicels. Compared with the high-yield Camellia oleifera cultivar ‘1712’, the low-yield cultivar ‘143’ exhibited significantly higher fruit abscission rates (e.g., 9.4

Plant specialized metabolites include a wide variety of bioactive substances that affect plant development, environmental acclimatization, and ecological relationships [...]

Calcium plays a crucial role in fruit development and quality formation, yet the regulatory mechanisms underlying calcium distribution and oxalic acid metabolism in litchi remain poorly understood. In this study, the effects of exogenous calcium on calcium accumulation, fruit quality, and oxalic acid metabolism in litchi were investigated through stem infusion experiments using calcium chloride (CaCl2) and ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) treatments. The results demonstrated that exogenous CaCl2 application significantly enhanced calcium accumulation in pedicel tissues, particularly in the pith, phloem, and xylem, whereas EGTA treatment chelated endogenous calcium ions (Ca2+) and inhibited this accumulation. Notably, despite increased calcium levels in the pericarp, exogenous CaCl2 and EGTA applications did not affect fruit quality parameters, including appearance, weight, seed weight, pericarp weight, color, or total soluble solids content. Furthermore, CaCl2 treatment promoted the formation of insoluble calcium oxalate crystals in both fruit pedicels and pericarp without significantly altering soluble oxalic acid content, suggesting a homeostatic maintenance of oxalic acid levels. Through bioinformatic analysis and enzymatic assays, acyl-activating enzyme 3 (LcAAE3), an oxalyl-CoA synthetase that catalyzes the initial step of oxalic acid degradation, was identified and characterized. LcAAE3 exhibited specific catalytic activity toward oxalic acid and LcAAE3 gene showed markedly higher expression levels than its paralog LcAAE3-1 across litchi tissues. Exogenous CaCl2 suppressed LcAAE3 expression, while EGTA treatment induced its expression. Virus-induced gene silencing of LcAAE3 in fruit pedicels resulted in significant accumulation of both oxalic acid and calcium oxalate in pedicels and pericarp. In contrast, overexpression of LcAAE3 in tobacco significantly inhibited the accumulation of calcium oxalate and oxalic acid, confirming its role in promoting oxalic acid degradation. These findings reveal that exogenous calcium enhances tissue-specific calcium accumulation and calcium oxalate formation without compromising fruit quality, and establish LcAAE3 as a key regulator of oxalate homeostasis in litchi. This study provides insights into calcium-mediated oxalic acid metabolism and offers a theoretical basis for improving litchi fruit quality through calcium management.

Zinc finger proteins (ZFPs) are a diverse group of plant transcription factors essential for regulating development, signaling, and stress responses. In this study, we performed a genome-wide identification and integrative analysis of 140 C3H-type zinc finger transcription factor genes in the soybean genome, exhibiting an uneven distribution across all 20 chromosomes. These C3H-ZFPs contained one (37), two (58), three (19), four (7), five (17), or six (2) C3H domains and were classified into 14 subsets based on their domain architecture. All C3H genes encoding proteins harbored the conserved C3H-ZFP domain and displayed various physicochemical characteristics. Phylogenetic analysis grouped them into 10 clades, closely related to other species like Arabidopsis, rice and alfalfa. Promoter analysis revealed cis-elements associated with stress response (~39.1%), light response (~37.3%), phytohormones (~18.5%), and development (~4.97%). Duplication analysis revealed 78 pairs of segmental and eight tandem duplication events, with purifying selection indicated by Ka/Ks (nonsynonymous/synonymous) ratios, indicating that these C3H-ZFP duplicates were largely maintained under purifying selection. A total of 388 miRNAs from 196 gene families were predicted to target 140 C3H-ZFP genes, with most enriched miRNAs targeting C3H-ZFP genes, including the miR156, miR395, and miR396 families. Transcription factor binding sites for MYB, AP2, MIKC_MADS, BBR-BPC, ERF, C2H2, and Dof were found upstream of most C3H-ZFP genes. RNA-Seq and qRT-PCR analyses showed tissue-specific expression and stress-responsive expression patterns, with several C3H-ZFP genes, especially GmC3H1, GmC3H63, GmC3H124, and GmC3H127, being significantly upregulated under abiotic stress conditions. Together, these results provide a comprehensive overview of soybean C3H-ZFP genes and identify promising candidates for future functional studies on development and abiotic stress adaptation.

Propiconazole reveals a BraBZR1-BraGRP5 transcriptional module that promotes leaf growth via cell expansion in Flowering Chinese cabbage. Flowering Chinese cabbage, also known as Caixin (Brassica rapa ssp. chinensis var. parachinensis), plays a significant and industrial role, particularly in South China. Propiconazole (PCZ), a triazole fungicide, is widely used in leafy vegetable production as a brassinosteroid (BR) biosynthesis inhibitor to improve plant architecture and marketability. However, the molecular mechanism by which PCZ regulates leaf growth in Flowering Chinese cabbage remains poorly understood. Through transcriptome analysis of PCZ-treated plants, we identified a glycine-rich protein 5 (BraGRP5). BraGRP5 expression was highest in cotyledons, leaves, flowers, and siliques, and was induced by BR application. Functional studies demonstrated that BraGRP5 acts as a positive regulator of leaf growth, as overexpression (OE) lines developed larger leaves, while RNA interference (RNAi) and virus-induced gene silencing (VIGS) lines had smaller leaves. RNA-seq analysis of BraGRP5-overexpressing lines identified differentially expressed genes (DEGs) enriched in hormone signaling and cell wall remodeling pathways. Furthermore, we established that the transcription factor (TF) BRASSINAZOLE-RESISTANT 1 (BraBZR1) directly binds to the BraGRP5 promoter and activates its transcription, forming a BraBZR1-BraGRP5 transcriptional module. Our findings demonstrate that BraGRP5 promotes leaf growth by stimulating cell expansion and define a key BR-mediated regulatory pathway in B. rapa, with PCZ serving as the critical experimental catalyst that enabled the discovery of this novel molecular module.

Dwarfism is a significant and desirable trait in the cultivation of horticultural crops. However, the regulatory mechanisms underlying dwarfism in perennial fruit trees remain poorly understood. In this study, we investigated the role of SRS genes in regulating plant height in Sapindaceae fruit trees, specifically litchi and longan. A total of five litchi SHORT INTERNODES (SHI)-related sequence genes (LcSRS) and four longan DlSRS genes were identified. Expression profile analysis in different tissues demonstrated that LcSRS1-LcSRS5 and DlSRS4 genes exhibited distinct expression patterns, with some genes showing tissue-specific expression. qRT-PCR analysis revealed that LcSRS5 and DlSRS4 genes had higher expression levels in the dwarf litchi ('Ziniangxi') and longan ('Shizi19') cultivars, respectively. Overexpression of the litchi LcSRS5 and the longan DlSRS4 in tobacco resulted in transgenic plants displaying a dwarf phenotype. Subcellular localization studies indicated that both LcSRS5 and DlSRS4 are localized in the nucleus of the cell. Hormone testing analysis indicated that the contents of auxin, cytokinin, and gibberellin varied among different cultivars of litchi and longan. GA3 treatment can promote the elongation of shoots in both litchi and longan. Additionally, silencing the LcSRS5 in litchi buds effectively promotes shoot growth, increases internode length, and significantly suppresses the expression of LcGA2ox1, LcGA2ox2, and LcGA2ox3 genes. Further studies confirmed that the LcSRS5 binds to the promoter of LcGA2ox3 to activate its expression. This study provides a foundation for further analysis of the functions of SRS genes in tropical fruit trees.

The seed development is a crucial step in ensuring a healthy fruit set, and the ultimate seed size is a significant quality feature in fruit crops. Litchi seed development is a fascinating process because of its remarkable plasticity. Previous study has indicated that the partial seed abortion phenotype of litchi cv. ‘Guiwei’ is induced by thermo-sensitive sterility and self-sterility. The comprehension of how genetic background and temperature influence the litchi seed development is limited. Here, we target LcASHR1, a putative histone-lysine N-methyltransferase gene, and LcEMF2, an EMBRYONIC FLOWER 2 gene, that were shown to be more highly expressed in the large seed cultivar ‘Huaizhi’ than in the small seed cultivar ‘Guiwei’. In addition, they were found to be enhanced in response to low temperatures, a condition flavoring the seed development of ‘Guiwei’ seeds. Among them, only the knockdown of LcASHR1 in litchi resulted in tiny seeds and a higher level of seed abortion rate. Conversely, overexpression of LcASHR1 in Arabidopsis lines led to the production of larger seeds. Furthermore, LcTRB1, a putative telomere repeats binding protein, was identified as a upstream transact factor of LcASHR1 by binding to the telo-boxes in the promoter. LcTRB1 expression pattern largely corresponded to litchi seed size. Consistent with previous findings on LcASHR1, it has been observed that LcTRB1 positively affects seed development in both litchi and arabidopsis. Overall, our results indicated that LcTRB1 is linked with litchi seed development probably by modulating the expression of LcASHR1.

l-quebrachitol, also known as 2-O-methyl-l-chiro-inositol, is a common form of methylated cyclitol found in Litchi chinensis, accounting for more than half of the soluble sugars. Nonetheless, the biological function of l-quebrachitol is somewhat restricted. Herein, we target an inositol methyltransferase (LcIMT1) gene that generates d-bornesitol (1-O-methyl-myo-inositol), an intermediate of l-quebrachitol biosynthesis, in litchi. Litchi plants confronted with drought stress showed a substantial increase in methyl inositol (d-bornesitol and l-quebrachitol) levels and LcIMT1 expression in roots and leaves relative to control plants. Additionally, overexpressing LcIMT1 in arabidopsis, tomato, and tobacco resulted in an enormous increase in d-bornesitol production compared to the wild-type (WT). Furthermore, the transgenic tomato lines displayed higher drought resistance as reflected by less wilt, lower relative electrolyte leakage, enhanced Fv/Fm, and higher CO2 assimilation mainly due to higher stomatal conductance compared to the wild-type when underwent drought conditions. Better drought resistance in transgenic tomato lines might be associated with the accumulation of d-bornesitol which assists in maintaining cell turgor by reducing cell water potential and cellular homeostasis of reactive oxidant species (ROS). Reduced oxidative damage, as evidenced by diminished MDA levels and lower concentrations of superoxide and hydrogen peroxide, may stem from the heightened energy consumption by the photosynthetic apparatus for CO2 fixation and the reactive oxygen species scavenging capability of d-borneistol in the leaves of LcIMT1 overexpressed lines. The findings of this study indicate that LcIMT1 overexpression facilitates d-bornesitol biosynthesis, which functions as an osmotic regulator and free radical scavenger, thereby enhancing the drought resistance of tomatoes. Future research could investigate the exogenous application of myo-inositol methyl ether as a potential approach for mitigating dryness in plants. This research avenue possesses significant commercial prospects for agricultural applications, especially in water-scarce settings.

Accurate measurement of key phenotypic traits, including the horizontal and vertical diameters, the weights of both fruit and pit, is essential for the selection of elite litchi cultivars and the advancement of breeding research. Manual measurement, however, is laborious, inefficient, and subjective, highlighting the urgent need for automated and precise phenotyping tools. Unlike apples, mangoes, and grapes, litchi combines a spiny, highly variable pericarp (heterogeneous areoles/tubercles across cultivars) with diverse seed morphology (including irregular, wrinkled aborted seeds), thereby increasing the difficulty of semantic segmentation and biasing diameters and weight estimation. This study presents LitchiPhenoNet, a multimodal learning framework for litchi phenotypic analysis that employs a dual-branch architecture integrating RGB (color/texture) and depth (spatial/structural) information. Experiments were conducted on an RGB–D dataset comprising 1,198 image pairs (1280 × 720) across 10 cultivars, using a stratified train/test split of 958/240 pairs by cultivar. To address inherent semantic and scale inconsistencies between modalities, the framework incorporates the RD-Fusion module for precise cross-modal feature extraction, improving robustness under complex and variable pericarp surfaces. Comparative experiments show that LitchiPhenoNet consistently outperforms leading YOLO-based models, achieving millimeter-level diameter estimation with coefficients of determination approaching 0.98 and mean errors within 2 mm. For weight estimation, gram-level precision is attained across whole fruit, pit, and pulp, with coefficients of determination up to 0.98 and mean errors comparable to repeated manual measurements. By handling fine-scale surface relief and cross-cultivar variability, the framework is readily extensible to other textured fruits and scalable for high-throughput phenotyping in breeding programs. Collectively, these results demonstrate that LitchiPhenoNet provides an efficient, reliable, and accurate solution for quantifying litchi phenotypic traits, substantially advancing the objectivity and efficiency of phenotypic analysis and breeding selection.

Protein phosphorylation plays a crucial role in regulating numerous vital cellular and physiological functions in plants. Nevertheless, the molecular mechanisms that control bud dormancy in evergreen fruit trees are not well understood, particularly concerning protein post-translational modifications. this study, a thorough quantitative phosphoproteomic analysis was performed for litchi terminal buds at different stages to explore the protein phosphorylation dynamics throughout bud development. A total of 6,785 phosphorylation modification sites were identified spanning 2,795 phosphoproteins. Additionally, 492 differentially regulated phosphoproteins (DRPs) (253 upregulated and 239 downregulated) were found in the comparison of bud break stage (S2) vs dormancy stage (S1). Two-hundred and eighty four DRPs (147 upregulated and 137 downregulated) were found the fast growth stage (S3) vs dormancy stage (S1). The comparison between the bud break stage (S2) and the growth cessation stage (S4) (S2 vs S4) revealed 374 DRPs (183 upregulated and 191 downregulated), while in S3 vs S4, 186 DRPs (87 upregulated and 99 downregulated) were identified. Gene ontology analysis indicated that most of the DRPs were involved in the protein phosphorylation process, while KEGG pathway analysis revealed that the DRPs were predominantly enriched in metabolism and genetic information processing pathways. Based on the expression patterns, the DRPs at various stages could categorized into six clusters. An intersection analysis of proteins associated with different functional pathways further highlighted the significant regulatory role of protein kinases in the dormancy removal of litchi terminal buds. Further analysis indicated that the modification levels and expression abundances DRPs, including CDPK, MAPK, MYB, and zinc proteins, were significantly higher during the growth periods (S2 and S3) compared to the bud growth cessation and dormancy periods (S1 and S4). qRT-PCR results demonstrated that the genes encoding the randomly selected DRPs exhibited notable differential expression patterns across different stages of litchi terminal buds, and some gene expression levels were consistent with the expression abundance levels their encoded DRPs. This study provides a comprehensive characterization of bud dormancy regulation during the development of shoot terminals in litchi, laying a foundation for further investigation into the regulatory mechanisms of bud dormancy in tropical fruit trees.

Volatile organic compounds (VOCs), classified as secondary or specialized metabolites, are essential for plant health [...]

KNOTTED1-like homeobox (KNOX) family transcription factors (TFs) are important regulatory factors in plant growth and development, participating in various aspects of developmental regulation. In this study, we demonstrate that the citrus KNOX gene 6 (CiKN6) regulates shoot branch development. Overexpression of CiKN6 in citrus plants resulted in a significant phenotype characterized by increased branching and shortened shoots. Expression analysis revealed that CiKN6 was predominantly expressed in the stems. Protein interaction studies showed that CiKN6 interacted with Homeobox-leucine zipper 14 (CiHOX14). Furthermore, we discovered that CiHOX14 specifically binds to the BLADE-ON-PETIOLE 2 (CiBOP2) promoter and enhances its expression. Overexpression of CiBOP2 led to increased branching and shortened shoots in Arabidopsis and citrus, while suppression of CiBOP2 expression resulted in increased plant height in citrus. Additionally, we identified a TEOSINTE BRANCHED1/CYCLOIDEA/PCF TF, CiTCP15, that promotes CiBOP2 expression by binding to its promoter. Lastly, qRT-PCR assays demonstrate that the expression of CiKN6 and CiHOX14 was upregulated by CiBOP2 through feedback regulation. These findings suggest that the CiKN6-CiHOX14 complex, along with CiBOP2, interact to regulate shoot development and branching in citrus, providing new insights into the roles of homeobox proteins in citrus.

Although extensively studied in various plants, the roles of aquaporin proteins in litchi remain unclear. In this study, low moisture content was observed in the dormant terminal buds of litchi. Transcriptome analysis revealed that two aquaporin genes, PLASMA MEMBRANE INTRINSIC PROTEIN 1;4 (LcPIP1;4) and LcPIP1;5, could be remarkably inhibited by exogenous ethylene (ETH), which also reduced the moisture content of litchi buds. Quantitative real-time polymerase chain reaction assays indicated that LcPIP1;4 expression was relatively elevated in the dormancy stage of litchi terminal buds. Inhibition of LcPIP1;4 in the buds of litchi during the growth stage delayed the onset of dormancy, resulting in a significantly reduced dormancy rate and increased moisture content. Further study indicated that LcPIP1;4 interacts with LcPIP1;4a, and they are capable of self-interaction. Silencing of LcPIP1;4a in litchi buds resulted in a phenotype consistent with silencing of LcPIP1;4. Additionally, simultaneous silencing of both LcPIP1;4 and LcPIP1;4a resulted in a more severe bud dormancy phenotype. Moreover, LcPIP1;4 was directly upregulated by LcRAP2.4. Silencing of LcRAP2.4 also delayed the onset of dormancy in litchi terminal buds, which is regulated by LcSVP2. ETH treatment at 1000 mg/l significantly downregulated the expression of LcPIP1;4 and LcRAP2.4, but had no significant effect on LcPIP1;4a. In contrast, abscisic acid (ABA) treatment at 200 mg/l significantly upregulated the expression of LcPIP1;4, LcPIP1;4a, and LcRAP2.4. Combined treatment with ETH and ABA exerted a stronger inhibitory effect on the bud break and upregulated LcPIP1;4 and LcRAP2.4 to lower degrees than ABA alone, suggesting that ABA reversed the inhibitory effect of ETH on the expression of LcPIP1;4 and LcRAP2.4. ABA treatment and combined treatment with ETH and ABA effectively reduced the moisture content of the terminal buds. These results demonstrate that LcRAP2.4, LcPIP1;4, and LcPIP1;4a play a vital role in dormancy onset of litchi terminal buds by regulating moisture levels.

Monosaccharide transporters (MSTs) are important plant glucose transporters that play roles in carbon allocation, growth, development, and stress regulation. However, research on MST regulatory genes in soybeans remains unexplored. In this study, we identified 110 MST-like candidate genes in the Glycine max L. (soybean) genome. The MST genes were distributed throughout 20 chromosomes, with many undergoing segmental duplication. The majority of MST group proteins exhibit significant preservation in Arabidopsis and soybean, and phylogenetic analysis reveals seven main categories. The promoters of the GmMST genes comprise cis-acting elements associated with plant responses to abscisic acid, auxin signaling, methyl jasmonate, low temperatures, and abiotic stresses. The RNA-seq data demonstrated diverse expression levels of MST genes across various tissues or organs, categorizing them into 11 primary clusters. The co-expression study of the network complex indicated that the GmMST genes encode proteins that interact with many essential genes associated with gibberellin, which are pivotal in seed and stamen development. A qPCR study validated the expression patterns of seven MST genes with exposure to copper (Cu) and cadmium (Cd) stress. Certain MST genes were notably stimulated by both Cu and Cd stress treatments, suggesting their involvement in defense responsiveness. Therefore, we provide a comprehensive analysis of the MST genes in soybeans and emphasize their substantial role in plant development and tolerance to metal ion stressors.

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.

Seed development is one of the most important agricultural traits, determining both the crop yield and quality of fleshy fruits. A typically abortive litchi cultivar, Guiwei, exhibits heterogeneity in seed size across production areas, years, and individual trees. Previous studies have shown that 'Guiwei' seed development failure is associated with endosperm arrest and chilling conditions. Herein, we identified a cysteine proteinase inhibitor (LcCPI5) and defensin-like protein (LcDEFL) as key genes in determining 'Guiwei' seed development through combined analysis of 'Guiwei' and 'Huaizhi' endosperm single-nucleus RNA-sequence and transcriptome data of 'Guiwei' seed subjected to different temperature treatments. LcCPI5 was exclusively expressed in the endosperm sample of 'Guiwei' at 25 days post-anthesis, and its expression decreased in response to chilling. The silencing of LcCPI5 led to significantly larger seeds, whereas employing the cysteine proteinase inhibitor E-64 resulted in smaller seeds in the cultivar 'Guiwei'. Unlike LcCPI5, LcDEFL promotes litchi seed development. The large seed cultivar 'Huaizhi' had substantially higher expression of LcDEFL than the partly abortive cultivar 'Guiwei'. LcDEFL silencing led to a notable reduction in the size of litchi seeds. These findings point to the post-translational modulation of cysteine proteinase and the critical role of cysteine-rich proteins in litchi seed development.

Auxin is a phytohormone that is critical for plant growth and development. The molecular mechanisms underlying auxin biosynthesis, transport, and signaling are well understood. However, the complex mechanism by which auxin regulates plant volatile biosynthesis has seldom been studied. A growing array of unique auxin-related plant volatiles have recently been discovered. This study comprehensively reviews recent findings on auxin and auxin-related genes and their roles in the formation of plant volatiles. This study highlights the implications of exogenous auxin application, genes involved in auxin signaling transduction, and hormonal crosstalk during volatile compound biosynthesis in plants. Plant hormones facilitate the integration of multiple volatile signals to enable specific and appropriate responses to environmental changes. This will improve our overall understanding of the role of auxins in plant volatile compound metabolic pathways. Recent studies have delineated the considerable advancements in elucidating the intricate methods by which plants employ auxin regulatory pathways to modulate the release of volatile chemicals during development and growth, along with prospective research paths.