Search Results (336)

The increasing demand for sustainable food production has intensified interest in controlled-environment agriculture and soilless cultivation systems. This study evaluated the performance of local chicory (Cichorium intybus L., cultivar “Otrantina”) grown for 45 days in soil, hydroponics, and decoupled aquaponics under two different environments: a fully controlled growth chamber and a naturally variable greenhouse. Morphological, anatomical, biochemical, and physiological traits were analyzed to assess the combined influence of growth environment and cultivation system on plant development and nutritional quality. Across all parameters, the growth environment emerged as the main driver of plant performance. Greenhouse-grown plants exhibited greater leaf expansion, enhanced mesophyll and vascular development, and higher fresh and dry biomass than those cultivated in the growth chamber. Within each environment, hydroponics consistently supported vigorous growth, whereas aquaponics produced smaller leaves and pronounced root elongation, likely reflecting nutrient and pH instability in the decoupled system. Biochemical analyses revealed system-specific adaptive responses. Soilless cultivation promoted higher lipid accumulation and, under growth chamber conditions, increased protein content. Aquaponically grown plants, particularly in the greenhouse, accumulated elevated levels of soluble sugars and phenolic antioxidants, consistent with stress-related metabolic activation. In contrast, soil-grown plants displayed the highest flavonoid concentrations, suggesting a prominent role of rhizosphere–microbiome interactions in modulating secondary metabolism. Overall, these results indicate that, under the tested conditions, environmental control exerts a stronger influence than cultivation systems on chicory growth and metabolism. Hydroponics proved to be the most efficient system for biomass production, whereas aquaponics requires improved nutrient management to ensure stable growth and quality. The distinct metabolic profiles associated with each cultivation system highlight opportunities to tailor chicory nutraceutical traits within sustainable controlled-environment agriculture. Full article

As a typical C3-C4 intermediate plant, cassava (Manihot esculenta Crantz) exhibits high photosynthetic efficiency and low photorespiration. NADP-malic enzyme (NADP-ME) is a key enzyme in the C4 photosynthetic pathway that provides elevated CO${}_2$ concentrations for Rubisco. However, research on NADP-ME in C3-C4 intermediate species remains limited. In this study, we identified four NADP-ME genes in the cassava genome, with segmental duplication serving as the primary driving force for gene evolution. Cis-acting element analysis indicated potential roles of MeNADP-ME genes in environmental adaptation, stress responses, and growth regulation. Expression profiling using bulk RNA sequencing and single-cell RNA sequencing revealed distinct expression patterns in different tissues and cell subsets. Comparative analysis with Arabidopsis (Arabidopsis thaliana) and maize (Zea mays) NADP-ME families demonstrated that MeNADP-ME3 exhibits bundle sheath cell-specific expression analogous to ZmchlC4NADP-ME in maize. Notably, photosynthetic genes and plasmodesmata (PD)-related genes exhibited high co-expression within mesophyll subcluster 13 and bundle sheath cells, providing molecular evidence for a limited C4 photosynthetic pathway in cassava. Protein–protein interaction predictions implicated MeNADP-ME3 in photosynthetic carbon metabolism and photorespiration regulation. Furthermore, qRT-PCR revealed significant responsiveness of MeNADP-ME3 to various abiotic stresses, and confocal imaging confirmed its chloroplast localization. Functional validation demonstrated that Arabidopsis overexpressing MeNADP-ME3 exhibited 30–120% enhanced antioxidant enzyme activities (SOD, POD, CAT) and 20–32% reduced oxidative damage markers (MDA, H${}_2$O${}_2$) under drought and salt stresses. These findings reveal the evolutionary trajectory of NADP-ME genes in C3-C4 intermediate species and provide genetic resources for developing stress-tolerant cassava cultivars. Full article

Coloured and variegated leaves are common in shade-tolerant ornamentals. However, it remains unclear whether their photosynthetic performance is determined mainly by pigment abundance or by the organisation of chloroplasts and thylakoids. We tested this in three Epipremnum aureum phenotypes (‘Neon’, ‘Golden’ and ‘Jade’) that share a genetic background but contrast in leaf colour, chloroplast density and thylakoid membrane abundance. Plants were grown in a greenhouse and assessed by hyperspectral and thermal imaging, infrared gas exchange analysis, chlorophyll a fluorescence measurements, and structural, ultrastructural and biochemical analyses. Traits were integrated by principal component analysis, with the quantum yield of CO₂ assimilation per absorbed photon (αCO_2,abs) as the response variable. ‘Neon’ leaves had high specific leaf area and approximately 55% lower maximum Rubisco carboxylation (Vc_MAX) and electron transport capacity (J_MAX) than ‘Jade’, as well as reduced chloroplast and thylakoid abundance and warmer canopies, despite carotenoid enrichment. JIP-test parameters and fluorescence light–response curves showed high absorption and dissipation per PSII reaction centre, elevated excitation pressure, modest non-photochemical quenching (NPQ), low αCO_2,abs, small carbohydrate pools and low intrinsic water-use efficiency. ‘Jade’ leaves developed thick mesophyll with dense chloroplast populations, extensive thylakoid networks, highest NPQ, cool canopies and large carbohydrate reserves, whereas ‘Golden’ leaves combined thin laminae and intermediate chloroplast–thylakoid organisation with early light saturation of CO₂ assimilation and the highest intrinsic water-use efficiency. Principal component analysis revealed a structural axis of chloroplast and thylakoid organisation that better predicted αCO_2,abs, net carbon gain and canopy temperature than pigment abundance. In variegated E. aureum, ‘photon economy’ is therefore governed primarily by chloroplast and thylakoid membrane organisation and abundance rather than by carotenoid accumulation. Full article

Foliar fertilization, an efficient agricultural production strategy, is relatively rare in bamboo cultivation and management. Phosphorus assumes an indispensable role in controlling plant sugar metabolism and antioxidant defense. Whether foliar application of triple superphosphate (TSP) can enhance carbohydrate metabolism in new bamboo leaves, improve the antioxidant defense system, and thereby promote the growth and development of new leaves remains to be investigated. In this study, we conducted foliar application of TSP on the new leaves of 1-year-old Neosinocalamus affinis culms to analyze the effects of exogenous phosphorus on leaf morphological, anatomical, and physiological characteristics. The results showed that 0.3% TSP was the optimal concentration. This treatment significantly increased leaf length (maximum growth rate of 24.3% on day 21) and mesophyll cell thickness. It also significantly increased total chlorophyll content (maximum increase rate of 71.10% on day 14). The 0.3% TSP treatment significantly enhanced the activities of critical enzymes involved in sucrose biosynthetic and catabolic processes and starch synthesis, inhibited starch degrading enzyme activity, and promoted the accumulation of soluble sugars, starch, and total non-structural carbohydrates. Furthermore, TSP treatment significantly increased the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and significantly reduced the contents of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) (45.11% and 54.64% reduction on day 7, respectively), indicating effective alleviation of oxidative stress and enhanced leaf stress resistance. Generally, foliar application of 0.3% TSP synergistically optimized leaf structure, photosynthetic capacity, sugar metabolism, and antioxidant defense system, comprehensively promoting the development of new N. affinis leaves and enhancing their stress resistance. Full article

The foliar application of various biostimulants, such as protein hydrolysates (PHs), has been associated with improved nutrient uptake efficiency and stress tolerance in perennial crops, like olive (Olea europaea L.). In this study, PHs obtained by enzymatic hydrolysis by Alcalase Pure (referred to as treatment H1), Alcalase Pure and Flavourzyme (referred to as treatment H2), or Alcalase Pure and Protana™ Prime (referred to as treatment H3) with proteins from pumpkin seed cake were tested for their potential beneficial growth, performance, and nutrition effects in one-year-old olive seedlings grown under controlled conditions. Amino acid and element compositions were evaluated in the PHs, which were used for foliar application six times at eight-day intervals. Control (C) plants were treated the same way, but without PHs. Shoot and root growth, leaf reflectance indices, and the composition of micro and macronutrients in different organs and leaf tissues were determined. Plants in the H2 treatment grew significantly better than C plants. They had the highest Photochemical Reflectance Index and a Chlorophyll-Normalized Difference Vegetation Index similar to that of C plants, indicating an optimal growth/photosynthesis balance. A decrease in the concentration of several mineral elements in the lower epidermis in H2- and H3-treated plants compared to C and H1-treated plants was accompanied by their increase in the spongy mesophyll, indicating their redistribution to support increased metabolism, resulting in increased shoot growth in these two treatments. Arguably, these observed effects could be attributed to the amino acid profile of the H2 mixture, which had the highest concentration of L-proline, L-arginine, and L-lysine among the three PH mixtures, and a higher L-asparagine concentration than the H1 mixture. Overall, the results highlight the applicative potential of tailored PH formulations for the optimization of growth, mineral element composition, and physiological performance in olive cultivation. Full article

Cremastra appendiculata (D. Don) Makino, a rare orchid prized for its ornamental and medicinal value, exhibits high sensitivity to light conditions during the seedling stage. To identify optimal light intensity for promoting seedling growth and elucidate the underlying physiological mechanisms, this study exposed C. appendiculata seedlings to three light treatments: low light (LL, 80% shading, 300–350 µmol·m⁻²·s⁻¹), medium light (ML, 60% shading, 600–650 µmol·m⁻²·s⁻¹), and high light (HL, 30% shading, 900–1000 µmol·m⁻²·s⁻¹). Growth and photosynthetic physiological parameters were measured to investigate the regulatory effects of light intensity. Results showed that under LL treatment, plant height, leaf area, and total biomass were significantly higher than those under HL treatment, increasing by 48%, 41%, and 50%, respectively. Leaf anatomical structure under LL displayed tightly arranged epidermal cells and intact mesophyll organization, consistent with typical shade-leaf characteristics. Chlorophyll content analysis revealed that chlorophyll a, chlorophyll b, and total chlorophyll under LL increased significantly by 75%, 35%, and 50%, respectively, compared to HL. Moreover, net photosynthetic rate peaked under LL, exceeding ML and HL by 28% and 17%, respectively. Chlorophyll fluorescence analysis further indicated that LL treatment optimized PSII performance, enhancing maximum photochemical efficiency, photosynthetic performance index, and electron transport rate per reaction center, while maintaining low thermal dissipation, indicating superior light capture and conversion efficiency. In summary, within the experimental gradient established in this study, the LL treatment represents the optimal light environment for the growth of C. appendiculata seedlings. By synergistically promoting plant morphological development, optimizing leaf structure, enhancing photosynthetic pigment content, and improving Photosystem II performance, this treatment facilitates efficient biomass accumulation. These findings provide a critical theoretical basis for the light environment management in both the conservation and artificial propagation of C. appendiculata. Full article

OsHKT1;1, a member of the high-affinity K⁺ transporter (HKT) family, plays a key role in Na⁺ homeostasis and salinity tolerance in rice. In our previous study, multiple potential OsHKT1;1 splicing variants were identified, as well as the full-length (FL) OsHKT1;1 transcript from the salt-tolerant rice Pokkali. However, most previous studies focused solely on the full-length protein, leaving the transport functions of splice variants largely unexamined. In this study, we focused on the splice variant OsHKT1;1-V2 and compared its function and gene expression with those of OsHKT1;1-FL. Two-electrode voltage clamp experiments using Xenopus laevis oocytes revealed that the 1st start codon of OsHKT1;1-V2 is functional to exhibit bidirectional currents in bath solutions containing NaCl. Unlike the Na⁺-selective feature of OsHKT1;1-FL, OsHKT1;1-V2 primarily mediated Cl⁻ transport with weak Na⁺ selectivity, which was supported by the higher Cl⁻ accumulation in OsHKT1;1-V2–expressing oocytes. Subcellular localization analyses using oocytes and Arabidopsis mesophyll cells indicated plasma membrane localization of OsHKT1;1-V2, similar to OsHKT1;1-FL. Functional assays using a yeast mutant further indicated that OsHKT1;1-FL, but not OsHKT1;1-V2, mediates Na⁺ uptake. The same OsHKT1;1 variants were identified in the japonica cultivar Nipponbare, and OsHKT1;1-V2 of the cultivar showed Cl⁻ transport properties similar to the one from Pokkali. Quantitative PCR analyses revealed higher abundance of OsHKT1;1-FL transcripts in Nipponbare than in Pokkali with markedly lower OsHKT1;1-V2 levels in Pokkali under salt stress. This study provides a new insight into HKT-mediated ion homeostasis under salinity stress. Full article

Signaling mediated by CLAVATA3/EMBRYO SURROUNDING REGION-RELATED (CLE) peptides and their receptors is essential for plants to adapt to abiotic stress. To address the global issue of drought-induced growth inhibition and mortality in poplar (Populus spp.), this study investigated the function of the PtrCLE1A gene from Populus trichocarpa Torr. et Gray in drought tolerance regulation. We employed gene cloning, expression vector construction, and genetic transformation of poplar, combined with bioinformatics analysis, subcellular localization, phenotypic observation, physiological index measurement, and gene expression analysis. The results demonstrated that both PtrCLE1A and PtrCLE1B encode pre-propeptides containing a signal peptide, with an identical mature peptide sequence (RLSPGGPDPRHH), and their putative receptors are PtrCLV1/2. Furthermore, the PtrCLE1A pre-propeptide was localized around the plasma membrane in tobacco (Nicotiana benthamiana Domin) mesophyll cells, consistent with its predicted function. PtrCLE1A and PtrCLE1B are primarily expressed in the roots and xylem of P. trichocarpa. Additionally, only the PtrCLE1A promoter contained drought-responsive cis-elements, and its expression was induced by drought stress in root, xylem, and leaf tissues of P. trichocarpa. Overexpression of the PtrCLE1A gene in Populus tomentosa Carrière (triploid) significantly increased adventitious root length under osmotic stress. Overexpression lines exhibited 22.00% to 22.92% longer adventitious roots than EV lines at 50/100 mM mannitol, and 65.12% to 73.17% longer at 150 mM mannitol. The OE lines also exhibited higher photosynthetic capacity and instantaneous water use efficiency (iWUE), along with reduced membrane damage under drought conditions, indicating enhanced drought resistance. This study provides new genetic resources and a theoretical foundation for molecular breeding of drought-tolerant poplar. Full article

Thidiazuron, 6-benzylaminopurine riboside, and meta-topolin are cytokinins often used in apple tissue cultures. Three different CK-containing Murashige and Skoog media were used during the experiments: medium without CK or media containing 4.5 μM thidiazuron, 4.5 μM 6-benzylaminopurine riboside, or 4.5 μM meta-topolin, respectively. Comparative ultrastructural studies across cytokinin types and apple cultivars were lacking. We studied the changes in photosynthetic pigment content of the leaves with absorption spectroscopy and chloroplast structure with light and transmission electron microscopy. At the light microscopy level, large changes were detected in the length and length-to-width ratios of the chloroplasts in the spongy and palisade mesophyll cell sections in 6-benzylaminopurine riboside- and meta-topolin-treated leaves of the McIntosh scion. In the chloroplasts of the McIntosh plants treated with 6-benzylaminopurine riboside and meta-topolin, and Húsvéti rozmaring leaves treated with meta-topolin, the diameter of grana increased. In both cultivars, thidiazuron caused the height of grana to increase. Thidiazuron and 6-benzylaminopurine riboside influenced leaf anatomy both in the Húsvéti rozmaring and McIntosh cultivars. 6-benzylaminopurine riboside and thidiazuron treatments reduced the content of photosynthetic pigments in the in vitro leaves of both cultivars. In contrast, meta-topolin treatment had no significant effect on the chlorophyll content as compared to the control. Differences were observed not only among the effects of cytokinins, but even between the two apple scions examined. In in vitro apple shoot cultures, TOP maintained chloroplast integrity and pigment content, whereas TDZ exerted stress-like effects. Full article

Tolerance to metals develops independently across plant species and even among populations of the same species under strong environmental pressure. This study compares the morphology and leaf anatomy of Dianthus carthusianorum L. originating from a Zn–Pb waste dump (metallicolous ecotype, M) and from unpolluted areas (non-metallicolous ecotype, NM), exposed to toxic concentrations of Cd, Pb, or Zn under chronic (field) and acute (hydroponic) metal stress. The aim was to identify leaf anatomical adaptations that support growth of the M ecotype in metal-polluted environments and to assess structural changes induced by acute exposure in both ecotypes. In both ecotypes, metal exposure caused alterations of mesophyll cells and the formation of abundant calcium oxalate (CaOx) crystals. Two oxalate forms were determined: insoluble (CaOx crystals) and soluble oxalates, with the former predominating. Following metal treatment, the M ecotype accumulated nearly twice as much of both forms as the NM ecotype, indicating a key role of oxalates in metal detoxification via precipitation of excess metal ions as metabolically inactive CaOx. Interestingly, elevated CaOx levels were also observed in M ecotype leaves grown under control (no metal application) conditions, suggesting a genetically fixed adaptation to metal-rich environments. Full article

The large and hard olive pit adversely affects oil quality during traditional crushing, as seed- and pit-derived enzymes modify phenolic profiles and volatile compounds. Polyploid breeding offers a potential means to reduce pit size and improve processing traits, yet cultivated olive (Olea europaea L. subsp. europaea) is a strictly diploid species, and natural polyploids have not been previously documented. To evaluate the potential of triploids in olive improvement, we screened seed-derived progeny from multiple cultivars for polyploidy using flow cytometry and chromosome observation. One naturally occurring triploid seedling (‘Olive-3x’) was identified from a mixed lot of open-pollinated seeds. Whole-genome resequencing was used to develop 64 polymorphic InDel markers, and three markers indicated ‘Koroneiki’ as one putative parent of the triploid. Morphological and cytological analyses showed that the triploid exhibited typical polyploid characteristics, including thicker leaves and enlarged epidermal and palisade mesophyll cells compared with diploid controls. These findings provide the first evidence of a naturally occurring triploid in cultivated olive and show that triploids can arise within seed-derived progeny. The identified triploid plant and the developed markers offer useful resources for future studies on olive polyploidy and provide foundational resources for future research on olive polyploidy and cultivar improvement. Full article

In recent years, extreme climate events such as high temperatures and droughts have become increasingly frequent and intense, posing significant threats to the carbon sink stability of C₃, C₄, and CAM plants. As a result, identifying photosynthetic strategies that balance adaptability with resilience has emerged as a critical focus in carbon sink research. C₂ photosynthesis offers a promising solution by recycling photorespiratory CO₂ through the glycine shuttle between mesophyll cells (MCs) and bundle sheath cells (BSCs), thereby optimizing carbon concentration and recovery without additional ATP expenditure, thus minimizing carbon loss. This review provides a comprehensive analysis of the diversity, distribution, evolutionary status, and regulatory mechanisms of C₂ photosynthesis, emphasizing its physiological and ecological resilience in carbon sequestration. In comparison to C₃ and C₄ pathways, C₂ photosynthesis demonstrates distinct carbon sink resilience, positioning it as a vital strategy for addressing both current and future global climate challenges. The review also highlights existing gaps in C₂ research, particularly in species identification, molecular mechanisms, and ecological studies, and recommends prioritizing these areas to fully harness its potential for enhancing climate resilience. Full article

Salt stress significantly reduces plant growth and yield, which has led to extensive research on the mechanisms underlying plant salinity tolerance. Carrot (Daucus carota ssp. sativus) is a glycophyte highly sensitive to soil salinity. We investigated root and leaf anatomical, histological, and immunohistological alterations in two carrot accessions, previously identified as salt-sensitive (DH1) and salt-tolerant (DLBA), growing under control and salt stress conditions. The results demonstrate that the salt-tolerant DLBA growing under control conditions has trichome-rich leaves, high starch reserves and a hydraulically safer root xylem. Under salt stress, DLBA maintains mesophyll integrity, and increases the number of vessels and deposition of highly esterified pectins, hemicelluloses and spatially regulated AGPs in cell walls. In contrast, DH1 develops thinner, trichome-free leaves, and roots almost free of starch with fewer cambial cells and vessels. Salt stress induces overexpansion of palisade parenchyma, excess starch accumulation, loss of arabinan epitopes, disappearance of extensins in vascular bundles, and changes in hemicellulose and AGP distribution. These findings indicate that salt tolerance of DLBA plants results from the combination of constitutive anatomical characteristics and adaptive responses that together support tissue hydration, wall elasticity and stable water transport when plants are growing in saline soil. Full article

Combining leaf gas exchange with chlorophyll fluorescence, this study quantified the effects of soil water content (SWC) on mesophyll conductance (g_m) and biochemical parameters in 8-year-old pear trees across three soil textures [clay (CS), sandy (SS), loam (LS)], each subjected to three irrigation levels (100%FI, 75%FI, 50%FI). Results showed that SWC differed significantly, with CS > LS > SS, and that the difference in SWC in loam soil was the most obvious among different irrigation levels. The leaf water content (LWC) of SS was higher than that of LS and CS, and SS_50%FI showed 7.53% and 13.30% greater LWC compared to LS_50%FI and CS_50%FI, respectively. Specific leaf area (SLA) peaked at CS_75%FI and SS_100%FI. Soil texture and irrigation level had significant interactive effects on g_m, the product of light absorption coefficient and light energy partitioning ratio (α·β), leaf apparent CO₂ compensation point, dark respiration rate under light, and photosynthetic biochemical parameters. Differences in the values of α·β among the nine treatments were significant and the maximum values in the three soil textures were 0.660 (LS_75%FI), 0.366 (SS_100%FI) and 0.462 (CS_50%FI), respectively. The most sensitive treatment of g_m, responding to photosynthetically active radiation (PAR), was SS_100%FI and the maximal g_m under saturated PAR reached 0.271 molCO₂·m⁻²·s⁻¹, increasing 2.2-fold and 8.8-fold compared to that of SS_75%FI and SS_50%FI, respectively. An underestimation of 26.4% to an overestimation of 30.3% for g_m and an underestimation of 28.8% to an overestimation of 15.5% were observed for biochemical parameters if the empirical value (0.425) of α·β was adopted. Our findings indicated that the maximum leaf g_m could be obtained at 75%FI for loam soil, 100% FI for sandy soil, and 50% FI for clay soil, respectively. Full article

The cereal leaf beetle (CLB; Oulema melanopus L., Coleoptera: Chrysomelidae) is a serious pest of wheat, capable of causing yield losses of up to 40% through photosynthetic impairment. Early detection and severity assessment are essential for effective and sustainable pest management. This study evaluates the potential of hyperspectral remote sensing (RS) combined with machine learning (ML) for non-invasive detection of CLB-induced stress in winter wheat. Spectral reflectance was measured using a full-range spectroradiometer (350–2500 nm) from flag leaves categorized into four damage levels (healthy, slightly, moderately, and severely damaged). Three input datasets were used for ML classification: full spectral reflectance, a set of 13 vegetation indices (VIs), and outputs of dimensionality reduction technique. CLB stress increased reflectance in the visible range (400–700 nm) and reduced it in the near-infrared (700–1400 nm), consistent with chlorophyll degradation and mesophyll damage. Several VIs, including RIGreen, NDVI750, GNDVI, and NDVI, correlated strongly with damage severity (τ = 0.78–0.81). Among the six ML models tested, Support Vector Machine (SVM) achieved the highest classification accuracy of 90.0% (precision = 0.90, recall = 0.90, F1 = 0.90) across the four severity classes, and achieved 91.9% accuracy at the early-detection threshold. As far as the currently available literature indicates, this study provides one of the earliest quantitative assessments of CLB damage severity based on full-spectrum leaf-level hyperspectral reflectance integrated with ML classification. These findings were obtained under controlled, leaf-level measurement conditions and therefore represent a proof-of-concept; future validation using UAV and satellite platforms is needed to assess performance under operational field variability. Overall, our findings highlight the potential of hyperspectral RS and ML for precision pest monitoring, supporting threshold-based decision-making and more sustainable insecticide use. Full article