Search Results (117)

Bud sport mutations are valuable sources of citrus germplasm innovation and provide an ideal system to dissect genetic regulation of specific traits. The Ponkan mandarin (Citrus reticulata Blanco cv. Ponkan) bud sport mutant “Pumpkin mandarin” displays a Pumpkin-shaped, ribbed peel protrusion phenotype with elevated soluble sugars, but its molecular basis remains unclear. Here, wild-type Ponkan (PG) and Pumpkin mandarin (NG) were compared across six developmental stages (90–240 days after flowering, DAF) for fruit appearance and internal quality, peel firmness, and tissue morphology; RNA-seq was performed on mature peel at 240 DAF. Peel protrusion was detectable as early as flowering. NG showed significantly lower mature fruit weight and consistently higher soluble sugar content throughout development. Peel firmness exhibited a stage-dependent reversal: NG exceeded PG before 180 DAF, PG exceeded NG at 180–210 DAF, and NG again exceeded PG at 240 DAF. RNA-seq generated 41.38 Gb of high-quality data and identified 580 differentially expressed genes (DEGs; 411 upregulated, 169 downregulated). DEGs were enriched in cell wall organization/modification, phenylpropanoid biosynthesis, starch and sucrose metabolism, cutin/wax biosynthesis, and photosynthesis. Expansin (EXP) and GH18 genes were upregulated, while NAM genes encoding NAC transcription factors were downregulated, suggesting an imbalance between cell wall loosening and structural maintenance in protrusion formation. Peel DEGs also included upregulated sucrose synthase (SUS) and sugar transporter (SUT) genes, indicating carbohydrate-related reprogramming in mutant peel. We propose a preliminary network in which NAM may function upstream, cell wall remodeling represents a principal effector module, and the peel carbohydrate metabolism acts as an accompanying module. Full article

Expansins are essential regulators of plant cell wall loosening, yet their roles in eggplant (Solanum melongena L.) remain poorly understood. This study performed a genome-wide analysis and identified 26 SmEXP genes, categorized into five evolutionary groups. All SmEXP proteins harbor characteristic DPBB_1 and Expansin_C domains. These genes are unevenly distributed across 10 chromosomes out of the 12 eggplant chromosomes, with Chromosome 8 identified as a major distribution hotspot. Synteny and selection pressure analyses suggest that segmental duplications and strong purifying selection have driven the family’s evolution. Promoter analysis revealed various cis-acting elements associated with light, phytohormones, and abiotic stress. Transcriptomic profiling showed that 14 SmEXP genes were significantly upregulated during the rapid fruit expansion phase (14 DAP), indicating their crucial role in fruit morphogenesis. Furthermore, some specific members (SmEXP1, 4, 10, and 13) exhibited distinct upregulation under heat stress (38 °C and 43 °C), suggesting involvement in thermotolerance. These findings identify key expansin genes controlling eggplant development and stress response, providing targets for genetic improvement. Full article

Mulberry (Morus alba) is an economically important forest tree species, yet cutting propagation is constrained by low adventitious rooting efficiency. Although ABT, a composite rooting promoter, can improve cutting survival, its molecular basis remains unclear. Here, cuttings of the cultivar Qiangsang 1 were treated with ABT, NAA, or IAA (200–1000 mg/L) and subjected to transcriptome profiling to elucidate how ABT enhances rooting. Hormone-related analyses showed that ABT upregulated GH3 (auxin-amido synthetase) at days 0 and 20, implicating auxin homeostasis. ERF1/2 (ethylene response factors) exhibited a temporal oscillation, with induction at day 10 followed by repression from days 20 to 30, consistent with a shift from developmental programs to defense-related processes. In parallel, JAZ (jasmonate ZIM-domain) genes were downregulated at day 0 and subsequently upregulated; together with CYP94C1, these changes may attenuate jasmonate-associated defense signaling. For cell remodeling and defense coordination, ABT reduced the expression of genes associated with cell-wall rigidity while inducing EXPA11 (expansin) at day 20, potentially facilitating root primordium emergence. Meanwhile, PR-1 (pathogenesis-related protein 1) was transiently upregulated at days 0, 20, and 30, and the concomitant modulation of WRKY transcription factors and RPM1 suggests enhanced defense readiness. Integrative network analysis further indicated that a GH3–ERF1/2–PR-1 module links hormonal and defense cues and may activate BAT1 (energy metabolism) and RBOHB (ROS production) to support adventitious root elongation. Collectively, these results suggest that ABT improves rooting efficiency by reshaping hormonal homeostasis and coordinating cell-wall reconstruction with a pre-activated defense state, thereby providing a conceptual framework for balancing root induction and defense responses during vegetative propagation in forest trees. Full article

Lupinus angustifolius is an important leguminous ornamental species, but its productivity is often compromised by alkaline soil stress. GsEXPA8, an expansin gene identified in wild soybean (Glycine soja), has been implicated in alkali stress tolerance. In this study, we examined how heterologous expression of GsEXPA8 in lupinus affects its biochemical, molecular, and rhizospheric responses to alkali stress. Under NaHCO₃-induced alkaline conditions, transgenic lines overexpressing GsEXPA8 displayed improved leaf vigor, greater root biomass and length, elevated activities of antioxidant enzymes (CAT and POD), increased proline accumulation, and reduced malondialdehyde levels compared to the wild type. Expression analysis revealed time-dependent up-regulation of several alkali-responsive genes (LaSOS1, LaNCED3, LaMYB39, LaNAC56, LaNHX6, and LaP5CS). Moreover, the rhizosphere microbial community was significantly restructured, with a marked increase in beneficial microbial taxa such as Pseudomonas and Lysobacter. We also found that the endogenous lupinus homolog LaEXPA8 is alkali-inducible. Overexpression of LaEXPA8 similarly enhanced alkaline tolerance, whereas CRISPR/Cas9 knockout lines showed no clear phenotypic alteration, suggesting potential functional redundancy within the expansin family. Notably, LaEXPA8 and GsEXPA8 differed in their temporal regulation of downstream genes, indicating both conserved and distinct regulatory roles. Our results demonstrate that GsEXPA8 improves alkali tolerance in lupinus through integrated mechanisms: promoting root growth, enhancing antioxidant and osmotic adjustment capacity, dynamically modulating stress-related gene expression, and enriching beneficial rhizosphere microbiota. This work provides the critical report of modifying alkali tolerance by manipulating an expansin gene alongside the associated rhizosphere microbiome, offering a combined strategy for breeding stress-resistant ornamentals. Full article

Potassium (K⁺) is essential for plant growth and development, influencing numerous physiological processes and stress responses. While the importance of K⁺ in overall plant performance is well-established, its specific effects on root system architecture and the underlying molecular mechanisms in woody perennials remain poorly understood. This knowledge gap is particularly significant for citrus rootstocks like trifoliate orange (Poncirus trifoliata L.), where root system optimization directly impacts drought resistance, nutrient acquisition, and overall orchard productivity. Here, we investigated how varying K⁺ concentrations (K₀, K₂, K₆, and K₁₂) affect trifoliate orange seedling development by comprehensively analyzing root architecture parameters, root hair morphology, endogenous hormone levels, and expression patterns of cell-wall-modifying and auxin-related genes. We found that moderate K⁺ levels (K₆) optimized root architectural development while both deficiency (K₀, K₂) and excess (K₁₂) inhibited overall growth and root architecture but enhanced root hair development. This morphological dichotomy corresponded to distinct hormonal profiles, showing reduced auxin (IAA), gibberellins (GAs), and zeatin riboside (ZR) levels under K⁺ stress conditions. Gene expression analysis revealed significant upregulation of expansins (PtEXPA4, PtEXPA5, PtEXPA7) and reconfiguration of auxin biosynthesis (TAA/TAR/YUC) and transport (AUX/LAX/ABCB/PIN) machinery under non-optimal K⁺ conditions. Our findings suggest that K⁺ availability modulates trifoliate orange root development through coordinated regulation of hormone homeostasis and gene expression, particularly within the auxin signaling network. These findings elucidate K⁺-responsive root developmental plasticity as a potential adaptive strategy, providing valuable insights for optimizing fertilization strategies in citrus cultivation and identifying potential molecular targets for enhancing potassium use efficiency in woody perennials. Full article

Expansins are crucial cell wall-loosening proteins that play a vital role in various plant developmental processes, including fruit ripening and softening. However, a comprehensive genome-wide analysis of the expansin family in apple (Malus × domestica) and the specific functions of its members in postharvest fruit ripening remain to be explored. In this study, we identified 51 expansin genes in the apple genome and classified them into four subfamilies (EXPA, EXPB, EXLA, and EXLB). Cis-element analysis of the promoters of apple expansin genes showed that these promoters are rich in various hormone-responsive elements, including abscisic acid (ABA)-responsive elements (ABREs) and ethylene-responsive elements (EREs), suggesting potential hormonal regulation of expansin genes. Expression profiling identified six ripening-associated expansin genes. Among them, MdEXPA5, MdEXPA17, and MdEXPA23 were positively regulated by both ethylene and ABA, while being suppressed by the ethylene action inhibitor 1-MCP. Further functional characterization demonstrated that transient overexpression of MdEXPA17 accelerated fruit softening, skin yellowing, ethylene production, and increased total soluble solid (TSS) content. Conversely, silencing of MdEXPA17 significantly delayed these ripening processes. Our study provides a systematic overview of the apple expansin gene family and supports a role for MdEXPA17 in promoting postharvest fruit ripening and softening. These findings offer valuable insights into the molecular mechanisms of apple fruit ripening and provide potential targets for genetic improvement of fruit quality and shelf life. Full article

Background: Cyperus esculentus L. is a unique tuber oil crop, in which tuber size directly determines both yield and oil storage capacity. It is crucial to clarify the tuber expansion pattern and explore the key genes associated with tuber expansion in Cyperus esculentus for crop improvement. Methods: This study conducted comprehensive morphological and cytological observations as well as transcriptomic analysis of tubers at multiple developmental stages. Tubers at 1, 5, 10, and 15 d were collected for transcriptome sequencing to identify differentially expressed genes (DEGs) and differentially expressed transcription factors. Gene ontology (GO) enrichment analysis was used to determine key functional categories. RT-qPCR was employed to verify the expression patterns of key genes. Results: Cyperus esculentus tubers expanded rapidly from 1 d to 15 d after initial tuber formation, and the expansion rate exhibited a trend of increasing first (1~5 d) and then decreasing (5~15 d). Cell expansion, rather than number, mainly contributed to tuber expansion. By combining the analysis of differential expression and the variation pattern of tuber expansion rate, 822 DEGs were identified to be associated with tuber expansion. GO enrichment analysis revealed that 20 genes were significantly enriched in GO:0043231 (cell wall), especially five remarkable genes encoding expansin, which exercise the function of cell wall loosening and have been proven to be associated with cell expansion. In addition, 57 differentially expressed TFs were further identified to be associated with tuber expansion. Conclusions: This study revealed the tuber expansion pattern of Cyperus esculentus and identified several key genes and TFs, which will facilitate the construction of the regulatory network and the analysis of the mechanism of tuber expansion in Cyperus esculentus. Full article

The expansin-like subfamilies (EXLA and EXLB) are vital for plant cell wall dynamics, but it remains uncharacterized in wild tetraploid and hexaploid Ipomoea batatas, and its role in the storage root (SR) development is poorly understood. In this work, we identified 4, 3, 3, and 3 EXLAs, alongside 11, 9, 13, and 8 EXLBs, in diploid I. trifida strain Y22, wild tetraploid I. batatas strain Y428B, and hexaploid I. batatas strain Y601, and cultivated sweet potato ‘Nancy Hall’, respectively. A comprehensive bioinformatic analysis of the expansin-like genes and proteins was performed to reveal their potential roles in SR development. Gene expression profiling showed that EXLA members were expressed during SR development, while approximately half of the EXLB members were expressed in Y22, Y428B (pencil root), Y601, and NH, respectively. Proteomic analysis (4D-DIA) detected 2, 1, 1, and 1 EXLAs, and 3, 3, 3, and 3 EXLBs in the mature SRs of the respective species. Integrated transcriptomic and proteomic analyses suggested that downregulating Iba6xEXLB2 and Iba6xEXLB1 may be associated with SR swelling in sweet potato. Furthermore, subcellular localization assays confirmed that Iba6xEXLB2 and Iba6xEXLB8 are localized to the cell wall/membrane. This study enhances the understanding of the expansin-like gene subfamily in sweet potato and its wild relatives and lays the groundwork for future functional studies on the role of expansin-like genes in SR development. Full article

Ectomycorrhizal (ECM) symbiosis is a fundamental mutualism crucial for forest eco-system health. Its establishment is governed by sophisticated molecular dialogue preceding physical colonization. This review synthesizes this pre-colonization crosstalk, beginning with reciprocal signal exchange where root exudates trigger fungal growth, and fungal lipochitooligosaccharides activate host symbiotic programming, often via the common symbiosis pathway. Successful colonization requires fungi to navigate plant immunity. They employ effectors, notably mycorrhiza-induced small secreted proteins (MiSSPs), to suppress defenses, e.g., by stabilizing jasmonate signaling repressors or inhibiting apoplastic proteases, establishing a localized “mycorrhiza-induced resistance.” Concurrent structural adaptations, including fungal hydrophobins, expansins, and cell wall-modifying enzymes like chitin deacetylase, facilitate adhesion and apoplastic penetration. While this sequential model integrates immune suppression with structural remodeling, current understanding is predominantly derived from a limited set of model systems. Significant knowledge gaps persist regarding species-specific determinants in non-model fungi and hosts, the influence of environmental variability and microbiome interactions, and methodological challenges in capturing early signaling in situ. This review’s main contributions are: providing a synthesized sequential model of molecular crosstalk; elucidating the dual fungal strategy of simultaneous immune suppression and structural remodeling; and identifying crucial knowledge gaps regarding non-model systems and species-specific determinants, establishing a research roadmap with implications for forest management and ecosystem sustainability. Full article

Drought severely limits plant growth, threatening global food security and biodiversity. This review provides a comprehensive overview of the recent advances in plant responses to drought, ranging from initial sensing to physiological adaptation, as well as guidelines for experimental design. We focus on key regulatory components, specifically the ABA signaling core (PYR/PYL/RCARs, PP2C phosphatases, and SnRK2 kinases) and ROS signaling. We provide a detailed description of transcriptional networks, highlighting the pivotal roles of DREB, NAC, and MYB transcription factors in coordinating gene expression. Furthermore, we explore downstream tolerance strategies, including osmoprotectant (e.g., proline) accumulation, cell wall remodeling involving expansins and pectin methylesterases, as well as stomatal regulation. We also discuss how combining genetics with multi-omics and high-throughput phenotyping bridges the gap between molecular mechanisms and whole-plant physiological performance. Ultimately, these insights provide a foundation for refining research approaches and accelerating the development of drought-resilient crops to sustain agricultural productivity and ecosystem stability in increasingly arid environments. Full article

Fruit softening in Carica papaya L. is a significant postharvest limitation, primarily driven by the dynamic remodeling of cell wall polysaccharides. In this study, we conducted a genome-wide identification and in silico characterization of gene families involved in cell wall assembly and disassembly in papaya. A total of 181 genes were identified and classified into metabolic pathways: hemicellulose (58), pectin (69), extensin (24), expansin (13), and cellulose (17). These genes encode 176 predicted proteins, ranging in size from 100 to 1093 amino acids, featuring family-specific catalytic domains, including glycosyl hydrolases, transferases, and serine/threonine kinases. Phylogenetic analyses revealed strong conservation within the expansin-A and pectin polygalacturonase subfamilies, while hemicellulose-related XTH genes exhibited significant diversification. Experimental validation of nine XTH members confirmed this diversification, with amplicons ranging from 322 to 1370 bp, consistent with computational predictions. Notably, CpXTH1 and CpXTH32 produced bands of approximately 1200 and 1400 bp, respectively. These findings underscore the complexity of papaya cell wall gene families and provide a molecular framework for understanding fruit softening. Given that postharvest losses of papaya in Mexico exceed 34.7% of production (approximately 150,000 tons annually), our results offer valuable genomic resources for biotechnological strategies aimed at extending shelf life and reducing economic losses. Full article

Climate change and global warming are deeply impacting natural foraging dependent upon rain fall. To understand how xerophytes cope with these dramatic changes, comparative transcriptomic profiling of Atriplex halimus and Atriplex leucoclada was investigated under drought stress. The data revealed both shared and species-specific adaptive mechanisms. Differentially expressed genes (DEGs) clustered into major conserved gene families, including stress signaling, transcriptional regulation, antioxidant defense, metabolism, transport, and hormone signaling. In A. halimus, drought tolerance was characterized by strong transcriptional regulation, redox balance, and energy homeostasis, highlighted by the up-regulation of WRKY, MYB, and SET-domain transcription factors, calcium transporters, SnRK1 kinases, and stress-protective proteins such as HSPs and LEAs. On the other hand, A. leucoclada exhibited broader signaling flexibility and structural reinforcement through enrichment of MAPKs, CDPKs, 14-3-3 proteins, and cell wall-modifying enzymes (XTHs, expansins, chitinase-like proteins), as well as high expression of transporters and hormone-responsive genes. Such patterns indicated distinct drought adaptation strategies: A. halimus relied on rapid transcriptional and redox adjustments suited for fluctuating moisture regimes, while A. leucoclada employed multi-layered, constitutive defenses for persistent arid conditions. Together, these results elucidate complementary molecular strategies enabling ecological divergence and drought resilience among closely related halophytes. Full article

Watercore disease, a physiological disorder in pineapple (Ananas comosus), manifests during late fruit development. Affected fruits develop water-soaked flesh and reduced storability. (1) Background: To explore underlying molecular mechanisms, comparative proteomic profiling was conducted in this study. (2) Methods: Data-independent acquisition (DIA) strategy was employed for comparative analysis between the resistant germplasm “35-1” and the susceptible germplasm “29-3”, as well as between the healthy and diseased “Paris”. (3) Results: Resistant (“35-1”) versus susceptible (“29-3”) germplasm analysis revealed differentially expressed proteins (DEPs) and unique proteins (SEPs) enriched in cell walls, secretory vesicles, and apoplast, functioning in cell wall loosening, hormone response, isoflavonoid biosynthesis, and farnesyl diphosphate biosynthesis. Healthy versus diseased “Paris” pulp analysis showed DEPs/SEPs enrichment in ribosomal small subunit biogenesis. These proteins form a central regulatory network potentially orchestrating tRNA synthesis, tubulin biosynthesis, and other carbohydrate metabolism. Partial protein overlap occurred in germplasm- and disease-derived differences. Resistant germplasm (“35-1”) and healthy “Paris” accumulated stress-responsive/resistant proteins and cell wall-modifying enzymes (e.g., phenylalanine ammonia-lyase, raffinose synthase, expansins, and mannan hydrolase). Susceptible germplasm (“29-3”) and diseased “Paris” exhibited prominent stress-responsive protein accumulation, such as alcohol dehydrogenase, 1-aminocyclopropane-1-carboxylate oxidase, and hypoxia-induced protein. (4) Conclusions: This comparative proteomics study identifies pineapple watercore resistance/susceptibility-associated proteins, providing a molecular basis for resistant germplasm development and disorder control. Full article

This study aims to compare the transcriptional responses of japonica and indica rice genotypes with contrasting submergence tolerance and to functionally validate the role of OsEXPB3. Flooding is a major abiotic stress limiting stable rice production, and different genotypes show substantial variation in submergence tolerance. However, the transcriptional and molecular regulatory mechanisms underlying subspecies-specific responses remain poorly understood. Here, RNA-seq analysis of japonica and indica accessions with contrasting tolerance levels was performed to construct molecular response networks and identify key tolerance-related genes. Comparative analysis revealed that both subspecies activate biological processes such as stimulus response, redox homeostasis, carbon metabolism, and hormone signaling under submergence. In the analyzed japonica genotypes, plants relied more on integrated hormone-regulated signaling, whereas in the analyzed indica genotypes, metabolic homeostasis was more prominent. Among the identified genes, OsEXPB3, a β-expansin gene, was consistently upregulated in tolerant accessions, whereas osexpb3 mutants displayed suppressed coleoptile and seedling elongation and reduced tolerance. Hormone profiling revealed a 0.1–0.3-fold increase in ethylene (ETH) and a 50–70% reduction in gibberellin (GA) in mutants after submergence. Defense-related hormones, including jasmonic acid (JA) and salicylic acid (SA), were initially higher but declined markedly under stress conditions. Given that the OsEXPB3 promoter contains multiple ETH-, GA-, ABA-, JA- and SA-responsive cis-elements, we propose that OsEXPB3 may coordinate the balance between growth- and defense-related hormones to mediate adaptive responses to flooding. This study reveals conserved and divergent molecular responses between subspecies and suggests that OsEXPB3 may contribute to submergence tolerance in rice, although its regulatory role requires further validation. Full article

Expansins contribute to maize tolerance to salt stress, but the molecular mechanisms by which they function under high-salinity conditions remain poorly understood. In this research, the α-expansin gene ZmEXPA3 was characterized. We obtained overexpression transgenic lines in maize and determined physiological and biochemical indices to elucidate its molecular role in salt stress. Our results confirmed that ZmEXPA3 functioned as a positive salt tolerance regulator and was potentially regulated by abscisic acid (ABA) and methyl jasmonate (MeJA). ZmEXPA3 located to the cytoplasm and cell wall. Overexpression of ZmEXPA3 achieved thicker cell wall and bigger cell size and thereby promoted biomass accumulation. The ZmEXPA3-OE lines showed a marked reduction in malondialdehyde (MDA) and H₂O₂ accumulation compared to the WT under salt stress. Overexpression of ZmEXPA3 elevated the enzyme activity of peroxidase (POD) and superoxide dismutase (SOD) and proline accumulation and decreased the Na⁺/K⁺ ratio in roots. Transcriptome and Gene Ontology (GO) enrichment analysis of ZmEXPA3-OE lines and WT showed that many differentially expressed genes (DEGs) were enriched in cell-wall-related terms, plant hormone response, osmotic stress response, salt stress response, oxidoreductase activity, etc. Changes in these processes may be the primary reasons why ZmEXPA3 overexpression promotes growth and salt tolerance. Full article