Search Results (394)

The premature senescence of red raspberry leaves severely affects plant growth. In this study, the double-season red raspberry cultivar ‘Polka’ was used, with N₁₅₀ (0.10 g N·kg⁻¹) selected as the treatment group (T150) and N₀ (0 g N·kg⁻¹) set as the control (CK). This study systematically investigated the mechanism of premature senescence in red raspberry leaves under different nitrogen application levels by measuring physiological parameters and conducting a combined multi-omics analysis of transcriptomics and metabolomics. Results showed that T150 plants had 8.34 cm greater height and 1.45 cm greater ground diameter than CK. The chlorophyll, carotenoid, soluble protein, and sugar contents in all leaf parts of T150 were significantly higher than those in CK, whereas soluble starch contents were lower. Malondialdehyde (MDA) content and superoxide anion (O₂⁻) generation rate in the lower leaves of T150 were significantly lower than those in CK. Superoxide sismutase (SOD) and peroxidase (POD) activities in the middle and lower functional leaves of T150 were higher than in CK, while catalase (CAT) activity was lower. Transcriptomic analysis identified 4350 significantly differentially expressed genes, including 2062 upregulated and 2288 downregulated genes. Metabolomic analysis identified 135 differential metabolites, out of which 60 were upregulated and 75 were downregulated. Integrated transcriptomic and metabolomic analysis showed enrichment in the phenylpropanoid biosynthesis (ko00940) and flavonoid biosynthesis (ko00941) pathways, with the former acting as an upstream pathway of the latter. A premature senescence pathway was established, and two key metabolites were identified: chlorogenic acid content decreased, and naringenin chalcone content increased in early senescent leaves, suggesting their pivotal roles in the early senescence of red raspberry leaves. Modulating chlorogenic acid and naringenin chalcone levels could delay premature senescence. Optimizing fertilization strategies may thus reduce senescence risk and enhance the productivity, profitability, and sustainability of the red raspberry industry. Full article

Leaf phenology of trees responds to temperature and photoperiod cues, mediated by underlying genes and plasticity. However, uncertainties remain regarding how smaller-scale phenological variation in cold-limited regions has been affected by modified selection pressures from herbivores, pathogens, and climate conditions, and whether this leaves genetic signatures allowing for projections of future responses. We investigated environmental correlates and genetic variation putatively associated with spring and autumn leaf phenology in northern range margin oak (Quercus robur L.) populations in Sweden (55.6° N–60.8° N). Results suggested that budburst occurred later at higher latitudes and in locations with colder spring (April) temperatures, whereas leaf senescence occurred earlier at higher latitudes. Several candidate loci associated with phenology were identified (n = 40 for budburst and 47 for leaf senescence), and significant associations between these loci and latitude were detected. Functions associated with some of the candidate loci, as identified in previous studies, included host defence and heat stress tolerance. The proportion of polymorphic candidate loci associated with budburst decreased with increasing latitude, towards the range margin. Overall, the Swedish oak population seems to comprise genetic diversity in phenology-related traits that may provide resilience to a rapidly changing climate. Full article

Inselbergs are rocky outcrops with specialized vegetation, including woody species growing in poorly developed soils. We investigated whether populations of the lithophytic tree Pseudobombax petropolitanum A. Robyns (Malvaceae), a key species endemic to Atlantic Forest inselbergs, have convergent or divergent patterns of functional traits related to leaf chemistry. This study was carried out on three inselbergs located in southeastern Brazil. Green and senescent leaves from nine healthy trees and soil samples were collected in each inselberg. The carbon, nitrogen, phosphorus, potassium, calcium, and magnesium concentrations, and the natural abundances of δ¹³C and δ¹⁵N, were measured in leaves and soil, and the C/N, C/P, and N/P ratios were calculated. The specific leaf area (SLA) was measured, and the nutrient retranslocation rate between green and senescent leaves was estimated. Divergences between populations were observed in the concentrations of potassium and magnesium in the green and senescent leaves, as well as in the C/P and N/P ratios in senescent leaves. Our results suggest that nutrient and water dynamics may differ in some inselbergs due to specific nutrients or their relationships, even though there were convergences in most functional traits related to leaf chemistry among the Pseudobombax populations. The divergences among the populations could have important implications for species selection in the ecological restoration context. Full article

This study used Xinxin 2 (Juglans regia L. ‘Xinxin2’), a major cultivated walnut variety in Xinjiang, China, to clarify the response and adaptation mechanisms of the anatomical structures of walnut related to source–sink–flow under altered source–sink relationships. We anatomically observed the leaves, fruit stalks, and fruit of bearing branches by artificially adjusting the leaf-to-fruit ratio (LFR). The LFR substantially affected the leaf structure and thickness of the fruit-bearing branches obtained via girdled (p < 0.05). The results of the analysis of the leaf anatomy revealed that a low LFR impeded leaf growth and internal structural development while accelerating senescence, whereas a high LFR promoted leaf growth and delayed senescence. The same trend was observed for the phloem area (PA) of the fruit stalk with the increase in fruit load when the number of leaves on the fruit branch was the same. The maximum PA was reached when the number of fruits was high (except for 4L:3F). This indicates that the micro-anatomical structure of the fruit stalk is more developed under the treatment of a higher number of pinnate compound leaves and fruit level of LFRs. The cells of the 1L:3F and 2L:3F were considerably smaller in the green peel and kernel of the fruit on the branches obtained via girdled than those of 5L:1F plants (p < 0.05). No significant difference was found in the number of cells per unit area or the cross-sectional area of cells in the pericarp and kernel of the fruit under LFRs (p > 0.05); however, a large difference was noted in the microanatomical structure of the pericarp and kernel of fruit. Changes in the structural adaptation characteristics of walnut leaves (source), fruit stalk (flow), and fruit (sink) are related to source–sink regulation. A change in the LFR affects the carbohydrate synthesis in the leaves (source), transport in fruit stalks (flow), and the carbohydrate reception in fruits (sink). Full article

Short fruiting branch cotton (SFBC) has a compact plant architecture suitable for dense planting. Plant population density (PPD) and topping are important agronomic practices to achieve high yielding by optimizing cotton plant structure. However, their individual and interactive effects on SFBC growth and yield are poorly understood. This study aimed to explore cotton growth and yield responses to various combinations of PPD and topping time (TT) and the underlying physio-ecological mechanism. Four combinations were included in a two-year field experiment (2023–2024) involving two PPD levels (5.3 plants m⁻², low density LD; 8 plants m⁻², high density HD) and two TT levels (early topping for leaving ten sympodials per plant ET; late topping for leaving fifteen sympodials per plant LT), and compared in terms of biomass accumulation, photosynthetically active radiation capture, and leaf senescence during entire reproductive growth period. Compared to the other three combinations, the combination of HD and LT (HDLT) achieved a higher lint yield due to a greater biological yield, which was predominantly attributed to the higher average rate during the rapid biomass increasing period. Owing to delayed leaf senescence caused by the HD and the LT, the HDLT performed better in leaf senescence-related attributes at the late growth stage. Moreover, these improved attributes also contributed to a higher radiation interception rate and photosynthetic efficiency at the late growth stage. Taken together, combining high density with later topping tends to increase the lint yield of SFBC through increasing dry matter accumulation, delaying leaf senescence, and enhancing canopy radiation interception rate at the late growth. Full article

Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort., commonly known as Friariello Napoletano, is a traditional Italian landrace valued for its distinctive flavor, nutritional richness, and cultural relevance in Mediterranean cuisine. The present study investigates the biochemical changes during postharvest storage at two temperatures (4 °C and 10 °C) for 2 and 20 days in its inflorescences and leaves. The experiment aimed to evaluate the evolution of primary and secondary metabolites, with a focus on pigments, amino acids, antioxidants, and glucosinolates. Significant degradation of chlorophylls was observed, particularly in leaves, with reductions of over 90% after 20 days at both temperatures. Conversely, α-tocopherol content increased significantly, especially in inflorescences, indicating an antioxidant response to storage stress. Amino acid analysis revealed a sharp decline in glutamate (up to 79%) and glutamine (up to 83%) in leaves, while proline levels increased across both tissues, reflecting an osmoprotective response. Essential amino acids (EAAs) showed variable responses, with certain EAAs, such as histidine and phenylalanine, accumulating under specific storage conditions. Soluble sugars, starch, and glucosinolates also decreased significantly, with soluble sugars dropping by 87% in inflorescences and 90% in leaves after 20 days at 10 °C. Pathway analysis revealed distinct tissue-specific metabolic responses, with inflorescences exhibiting more stable antioxidant levels and greater resilience to oxidative stress compared to leaves. These findings provide insights into the metabolic adjustments during postharvest senescence and may support future strategies aimed at preserving shelf life and nutritional quality of this traditional Mediterranean vegetable. Full article

WRKY transcription factors play a predominant role in plant stress responses, as well as growth and development. Although WRKY genes have been extensively studied in model plants, little is known about them in Brassica rapa. In this study, the BrWRKY22 gene was isolated and characterized. BrWRKY22 is nuclear localized and has self-activation and dimerization activity. BrWRKY22 was highly expressed in young leaves, roots, and stems. The overexpressed BrWRKY22 Arabidopsis and Brassica rapa lines exhibited a dwarfish, delayed flowering and leaf senescence phenotype compared to the wild-type (WT). Molecular evidence showed that the transcript levels of BrCHLP are increased, whereas those of BrLFY, BrSOC1, BrGA20OX2, BrGA3OX1, and BrGASA6 are significantly decreased in BrWRKY22 overexpressing plants compared to the WT. BrWRKY22 can bind directly to the promoters of BrCHLP and BrGA20OX2, activating BrCHLP and repressing BrGA20OX2 gene transcription. The chlorophyll b and tocopherol levels are increased, whereas the GA and ABA levels are significantly decreased, in three-week-old BrWRKY22 overexpressing Brassica lines compared to the WT. Collectively, our results suggest that BrWRKY22 directly controls chlorophyll b and GA biosynthesis and plays a repressive role in leaf senescence and the initiation of flowering in Brassica rapa plant development. Full article

Background: Understanding the mechanisms by which woody perennials adapt to extreme water deficits is important in regions experiencing increasingly frequent and intense droughts. Methods: We investigated the effects of drought severity in the shrubs Corylus avellana L., C. maxima Mill., and their morphological intermediate forms, all from local Belgian origin, and C. avellana from a Spanish-Pyrenean origin. Potted saplings in a common garden were not receiving any water for a duration of 30 days in July 2021 and developed a range of visual stress symptoms. We assessed responses across the various symptom categories. Results: Droughted plants senesced later than the controls (up to 6 days). The most severely affected plants disproportionately displayed the longest delay (21 days). The delayed leaf senescence was reflected in the subsequent bud burst which was delayed for the droughted plants, with again the largest delay observed for the most severely affected plants. Interestingly, radial growth shifted towards the autumn among the drought-treated plants, suggesting compensation growth after growing conditions normalized. The Spanish-Pyrenean provenance, characterized by smaller plants with smaller leaves, developed visual drought symptoms later than the local provenance during the drought. Conclusions: The results indicate that severe early summer drought, followed by rewatering, not only diminishes radial growth but also prolongs the growth period, and delays leaf senescence. A prolonged time frame for radial growth and a delayed leaf senescence indicate a longer period in which carbon is incorporated in woody tissue or in non-structural carbohydrates. This can help the fine tuning of carbon sequestration modeling. The Pyrenean provenance, adapted to high altitude, holds an advantage under water-limited conditions. Full article

Drought stress constitutes one of the most severe constraints to global agricultural productivity. Early drought detection is pivotal for sustainable agriculture, yet current approaches overlook critical dimensions of plant sensitivity. While advancements in photosynthetic parameter analysis (e.g., gas exchange, and chlorophyll fluorescence) have enhanced drought monitoring, three understudied factors limit progress: (1) differential drought sensitivity across plant organs (e.g., root nodules vs. leaves); (2) the selection of sensitive photosynthetic parameters and optimal measurement timing for stress detection; and (3) the identification of leaf layers most responsive to water deficits. By synthesizing insights from nodule physiology in legumes, cross-species evidence on multi-layered leaf senescence, and the temporal dynamics of stress sensitivity, this paper proposes a ‘whole-plant sensitivity analysis’ framework. Integrating organ-, parameter-, and time-specific perspectives, this paper aims to refine early drought detection in the field and enhance plant resilience research. Full article

As a globally important leguminous crop, soybean (Glycine max L.) serves as a vital source of edible oils and proteins for humans and livestock. Oils in leaves can help crops combat fungal infections, adapt to temperature changes via fatty acid modulation, and support resource recycling during leaf senescence. However, accumulating oils in leaves is a fundamental challenge due to the need to balance the inherently competing photosynthesis and fatty acid biosynthesis processes within chloroplasts. RETICULATA-RELATED (RER), known to regulate chloroplast function and plastid metabolism in Arabidopsis, plays an essential role in leaf development. Here, 14 non-redundant GmRER genes were identified in soybean and phylogenetically classified into four subclades. Most Arabidopsis RER genes were evolutionarily preserved as gene duplicates in soybean, except for GmRER5 and GmRER6. RNA secondary structures spanning the coding sequences (CDSs), the 5′- and 3′- untranslated regions (UTRs) of GmRERs, displayed exceptional structural plasticity in CDSs, while exhibiting limited conservation in UTRs. In contrast, protein structures retained conserved folds, underscoring evolutionary constraints on functional domains despite transcriptional plasticity. Notably, GmRER4a and GmRER4b represented an exceptional case of high similarity in both protein and RNA structures. Expression profiling across fourteen tissues and three abiotic stress conditions revealed a dynamic shift in expression levels between leaf-predominant and root-enriched GmRER paralogs after stress treatments. A comparative transcriptome analysis of six soybean landraces further revealed transcriptional polymorphism in the GmRER family, which was associated with the expression patterns of lipid biosynthesis regulators. Our comprehensive characterization of GmRERs may offer potential targets for soybean breeding optimization in overall plant oil production. Full article

This study aimed to investigate the effects of different planting density and row spacing configurations on maize corn yield, leaf photosynthetic parameters, and senescence characteristics; to reveal the purpose of the physiological mechanism of row density interaction regulatsving maize yield; and to clarify the optimal planting combinations for optimizing population structure, delaying leaf senescence, and improving light energy utilization efficiency. In doing so, this study provides a theoretical basis and technical guidance for increasing corn yield, the sustainable development of the maize industry, and improved yield production in Shanxi Province. An experiment was conducted with a two-factor randomized block design, with three planting densities of 60,000 plants/hm² (D1), 67,500 plants/hm² (D2), and 75,000 plants/hm² (D3) in the main area and four-row spacings of 40 + 40 cm, 40 + 80 cm, 50 + 50 cm, and 80 + 80 cm in the secondary area. The maize kernel yield, leaf photosynthetic parameters, malondialdehyde content, and anti-aging key enzyme activities were measured in 2023 and 2024. The results show that with the increase in planting density, the net photosynthetic rate of maize leaves gradually decreased, and the transpiration rate gradually increased. At the same time, too high or too low density will accelerate the aging of maize leaves, which is manifested by the increase in MDA (malondialdehyde) content and the decrease in SOD (superoxide dismutase) and CAT (catalase) activities. The best row spacing configuration performance is 40 + 80 cm, which is conducive to the ventilation and light transmission of maize plants, improves the efficiency of light energy utilization, slows down the aging of plant leaves, and thus promotes maize growth, development, and yield enhancement. The interaction effect between two intercropping maize factors significantly affects corn yield, with a medium density of 67,500, where 6000 is the most effective. Thus, 67,500 plants/hm² combined with a row spacing of 40 + 80 cm significantly increases corn yield. This combination obtained the highest net photosynthesis, SOD, and CAT of 24.33 µmol·m⁻²·s⁻¹, 32.54 U·mg⁻¹ and 1038.99 U·g⁻¹, and the lowest transpiration rate and MDA content of 3.47 mmo·m⁻²·s⁻¹ and 108.95 µmo·L⁻¹, resulting in the highest maize yield of 13,916.46 kg/hm². In summary, a density of 67,500 plants/hm² and 40 + 80 cm row spacing is the best combination, improving light energy utilization efficiency, delaying the leaf senescence process, and increasing the yield, which can provide a theoretical reference for the planting pattern of maize in Shanxi Province. Full article

(1) Background: This study aims to analyze the defoliation and boll opening performance of 123 upland cotton germplasm resources after spraying defoliant, using multispectral data to select relevant vegetation indices and identify germplasm resources sensitive to defoliants, providing methods for cotton variety improvement and high-quality parental resources. (2) Methods: 123 historical upland cotton germplasm resources from Xinjiang were selected, and the defoliation and boll opening of cotton leaves were investigated at 0, 4, 8, 12, 16, and 20 days after defoliant application. Simultaneously, multispectral digital images were collected using drones to obtain 12 vegetation indices. Based on defoliation rate, the optimal vegetation index was selected, and defoliant-sensitive germplasm resources were identified. (3) Results: The most significant difference in defoliation rate of cotton germplasm resources occurred 16 days after application. Cluster analysis grouped the 123 breeding materials into three categories, with Class I showing the best defoliation effect. Among the 12 vegetation indices, the Plant Senescence Reflectance Index (PSRI) has the highest correlation coefficient with the defoliation rate; and when the PSRI value is higher, the defoliation effect of the material is better. By comparing the traditional investigation method with the unmanned aerial vehicle multispectral technology, 15 cotton materials sensitive to defoliants were determined, with a defoliation rate of over 85%, a lint percentage ranging from 76.67% to 98.04%, and a PSRI value ranging from 0.1607 to 0.1984. (4) Conclusions: The study found that the vegetation index with sensitive response can be used as an effective indicator to evaluate the sensitivity of cotton breeding materials to defoliants. Using an unmanned aerial vehicle (UAV) equipped with vegetation indices for screening shows a high consistency with the manual investigation and screening method in screening excellent defoliation materials; it proves that it is feasible to screen cotton breeding materials with excellent defoliation effects using UAV multispectral technology. Full article

In recent years, there has been growing interest in the use of native ground-grown perennials in floral compositions as cut greenery. The easily available plant materials that can replace some exotic species include Hosta leaves and the leafy shoots of Polygonatum multiflorum. Their vase life should be at least as long as that of the flowers, with which they are combined. In order to prolong the vase life of cut greenery, the conditioning of cut plant material in solutions of plant hormones (GA3 and BA) and commercial conditioning substances (8HQC and Chrysal Clear 2) is most commonly performed. The aim of this study was to evaluate the effect of different conditioning solutions on vase life and parameters indicating the progression of the senescence of plant materials. Cut Hosta leaves and leafy shoots of Polygonatum multiflorum were conditioned immediately after cutting for 24 h in aqueous solutions of benzyladenine (BA) and gibberellic acid (GA₃), 8HQC standard medium with the addition of 2% sucrose and 1% Chrysal Clear 2 solution. The post-harvest storage and physiological senescence parameters of the plant materials were analyzed using the following indicators: the vase life, the relative water content (RWC), electrolyte leakage (E_L), and thiobarbituric acid reactive substance (TBARS) and pigment contents (chlorophyll a, chlorophyll b, carotenoids, and anthocyanins). Conditioning Hosta leaves in a BA solution at 100 mg L⁻¹ immediately after cutting more than doubles their post-harvest vase life. The longevity of P. multiflorum shoots can be effectively extended by storage in a BA solution of 400 mg L⁻¹, for 24 h. Both the plant materials responded to the progressive aging process with the disruption of water management, a reduction in cytoplasmic membrane integrity, and a decrease in the plant pigment content. Tissue water retention in the Hosta leaves was most favorably affected by conditioning in the GA₃ solution at a concentration of 400 mg L⁻¹. The P. multiflorum shoots responded with tissue water retention to conditioning in 1% Chrysal Clear 2 solution. The conditioning of Hosta leaves in BA solution at 400 mg L⁻¹ stabilized the cytoplasmic membranes and inhibited E_L most effectively. In P. multiflorum, the lowest E_L level was found as an effect of conditioning the shoots in GA₃ solution at 200 mg L⁻¹. The degradation of assimilation pigments was prevented by conditioning the Hosta leaves in GA₃ solution at 200 mg L⁻¹ and the P. multiflorum leafy shoots in GA₃ solution, regardless of the concentration used. Although the prolongation of the vase life of the cut leaves and the shoots by up to 30 days was achieved, along with an improvement in the appearance of the plant materials, it was not possible to identify a single conditioner that had a positive effect on all the parameters studied. Full article

Understanding how woody plants cope with severe water shortages is critical, especially for regions where droughts are becoming more frequent and intense. We studied the effects of drought intensity, focusing on post-drought resprouting, autumn leaf senescence and the subsequent spring bud burst. Furthermore, we aimed to study population differentiation in the drought and post-drought responses. We performed a summer dry-out experiment in a common garden of potted Prunus spinosa L. (Rosaceae) saplings. We analysed responses across different visual stress symptom categories and examined differentiation between provenances from a local origin (Western Europe, Belgium), a lower latitude (Spain) and a higher latitude (Sweden). The chance of post-drought resprouting was greater for the more severely affected plants than for the less severely affected ones, and it occurred earlier. The plants that displayed wilting of the leaves during the drought had a leaf senescence 2.7 days earlier than the controls, whereas that of plants with 25 to 75% and more than 75% of desiccated leaves was 7 and 15 days later, respectively. During the drought, the local provenance was the first to develop visual symptoms compared to the other two provenances. However, among plants that exhibited no or only mild symptoms, this provenance also had a higher likelihood of post-drought resprouting. Among the control plants, the higher-latitude provenance displayed leaf senescence earlier, while the lower-latitude provenance senesced later compared to the local provenance. However, these differences in the timing of leaf senescence among the three provenances disappeared in treated plants with more than 25% of desiccated leaves due to the drought. Whereas leaf senescence could be earlier or later depending on the developed drought symptoms, the timing of bud burst was only delayed. Results indicate that resprouting and timing of leaf senescence are responsive to the severity of the experienced drought in a provenance-dependent way. Full article

Populus euphratica Oliv, a representative species in arid ecosystems, serves vital ecological functions, including windbreak, sand stabilization and carbon sequestration. Investigating its nutrient resorption mechanisms is important for elucidating plant adaptation and growth strategies in nutrient-deficient environments. This study selected thirty sampling sites in Xinjiang across different locations and collected Populus euphratica leaves. Correlation analysis, regression analysis and redundancy analysis (RDA) were employed to assess the characteristics of nutrient resorption in Populus euphratica and their driving factors. We determined the leaf nitrogen (N) and phosphorus (P) concentrations in plants and then calculated the N:P ratio, nitrogen resorption efficiency (NRE) and phosphorus resorption efficiency (PRE). The results of the correlation analysis indicated that the NRE was not significantly correlated with the N and P contents or the N:P ratio in green leaves but was significantly related to those in senescent leaves. In contrast, the PRE was negatively correlated with the P content in the senescent leaves. The NRE:PRE ratio was positively correlated with the N in the green leaves and the P in the senescent leaves but negatively related to the N:P ratio in the senescent leaves. Nutrient resorption efficiency appeared to change with varying environments. Regression analysis revealed that both the NRE:PRE ratio and the NRE were positively correlated with latitude and mean annual precipitation (MAP) but negatively correlated with altitude and mean annual temperature (MAT). However, the PRE showed a negative correlation with latitude and MAP and positive correlations with altitude and MAT. Among these factors, the contribution of the MAP was the greatest, accounting for 85.1% and thus dominating the nutrient resorption processes in Populus euphratica. This study has enhanced the understanding of nutrient resorption conservation strategy and contributes to revealing the adaptation mechanisms of Populus euphratica under stress conditions such as drought and high temperatures. Full article