Sugar Accumulation Research Articles

Cytokinin Biosynthesis Is Affected by Selenium and Nitrate Availabilities to Regulate Shoot and Root Growth in Rice Seedlings

Selenium (Se) and nitrate have the potential to modify rice root architecture, but it is unclear how Se is linked to changes in the rice seedlings nitrate status. Thus, rice seedlings were grown in nutrient solutions containing either 0- or 10-µM Se that were supplemented with 0.05 (low nitrate condition) or 5.0 mM nitrate (high nitrate condition). Se application to seedlings treated with low nitrate led to sugar accumulation in shoot and root and increased cytokinin concentrations in root, while decreasing cytokinin concentrations in shoot compared with seedlings in 0.05 mM nitrate alone. This, in turn, resulted in decreased shoot growth, while downregulation of OsXTH and OsEXP negatively affected root expansion. On the other hand, Se combined with 5.0 mM nitrate did not affect sugar concentration in tissues compared with seedlings in 5.0 mM nitrate. Moreover, Se negatively regulated the cytokinin biosynthesis in shoot and root of seedlings grown under 5.0 mM nitrate. The reduction in cytokinin concentrations by Se under high nitrate condition decreased shoot growth, but increased root growth through induction of OsXTH and OsEXP. Thus, many of the effects of Se in shoot and root growth are due to a shift in nitrate status of the seedlings.

Phosphorylation of sugar transporter TST2 by protein kinase CPK27 enhances drought tolerance in tomato.

Drought is a major environmental stress threatening plant growth and productivity. Calcium-dependent protein kinases (CPKs) are plant-specific Ca2+ sensors with multifaceted roles in signaling drought responses. Nonetheless, the mechanisms underpinning how CPKs transmit downstream drought signaling remain unresolved. Through genetic investigations, our study unveiled that knocking out CPK27 reduced drought tolerance in tomato (Solanum lycopersicum) plants and impaired abscisic acid (ABA)-orchestrated plant response to drought stress. Proteomics and phosphoproteomics revealed that CPK27-dependent drought-induced proteins were highly associated with the sugar metabolism pathway, which was further verified by reduced soluble sugar content in the cpk27 mutant under drought conditions. Using protein-protein interaction assays and phosphorylation assessments, we demonstrated that CPK27 directly interacted with and phosphorylated tonoplast sugar transporter 2 (TST2), promoting intercellular soluble sugar accumulation during drought stress. Furthermore, Ca2+ and ABA enhanced CPK27-mediated interaction and phosphorylation of TST2, thus revealing a role of TST2 in tomato plant drought tolerance. These findings extend the toolbox of potential interventions for enhancing plant drought stress tolerance and provide a target to improve drought tolerance by manipulating CPK27-mediated soluble sugar accumulation for rendering drought tolerance in a changing climate.

Transcriptomics and metabolomics reveal the underlying mechanism of drought treatment on anthocyanin accumulation in postharvest blood orange fruit

BackgroundAnthocyanins are the most important compounds for nutritional quality and economic values of blood orange. However, there are few reports on the pre-harvest treatment accelerating the accumulation of anthocyanins in postharvest blood orange fruit. Here, we performed a comparative transcriptome and metabolomics analysis to elucidate the underlying mechanism involved in seasonal drought (SD) treatment during the fruit expansion stage on anthocyanin accumulation in postharvest ‘Tarocco’ blood orange fruit.ResultsOur results showed that SD treatment slowed down the fruit enlargement and increased the sugar accumulation during the fruit development and maturation period. Obviously, under SD treatment, the accumulation of anthocyanin in blood orange fruit during postharvest storage was significantly accelerated and markedly higher than that in CK. Meanwhile, the total flavonoids and phenols content and antioxidant activity in SD treatment fruits were also sensibly increased during postharvest storage. Based on metabolome analysis, we found that substrates required for anthocyanin biosynthesis, such as amino acids and their derivatives, and phenolic acids, had significantly accumulated and were higher in SD treated mature fruits compared with that of CK. Furthermore, according to the results of the transcriptome data and weighted gene coexpression correlation network analysis (WGCNA) analysis, phenylalanine ammonia-lyase (PAL3) was considered a key structural gene. The qRT-PCR analysis verified that the PAL3 was highly expressed in SD treated postharvest stored fruits, and was significantly positively correlated with the anthocyanin content. Moreover, we found that other structural genes in the anthocyanin biosynthesis pathway were also upregulated under SD treatment, as evidenced by transcriptome data and qRT-PCR analysis.ConclusionsThe findings suggest that SD treatment promotes the accumulation of substrates necessary for anthocyanin biosynthesis during the fruit ripening process, and activates the expression of anthocyanin biosynthesis pathway genes during the postharvest storage period. This is especially true for PAL3, which co-contributed to the rapid accumulation of anthocyanin. The present study provides a theoretical basis for the postharvest quality control and water-saving utilization of blood orange fruit.

Deletion of the sugar importer gene OsSWEET1b accelerates sugar starvation-promoted leaf senescence in rice.

Leaf senescence is a combined response of plant cells stimulated by internal and external signals. Sugars acting as signaling molecules or energy metabolites can influence the progression of leaf senescence. Both sugar starvation and accumulation can promote leaf senescence with diverse mechanisms that are reported in different species. Sugars Will Eventually be Exported Transporters (SWEETs) are proposed to play essential roles in sugar transport, but whether they have roles in senescence and the corresponding mechanism are unclear. Here, we functionally characterized a sugar transporter, OsSWEET1b, which transports sugar and promotes senescence in rice (Oryza sativa L.). OsSWEET1b could import glucose and galactose when heterologously expressed in Xenopus oocytes and translocate glucose and galactose from the extracellular apoplast into the intracellular cytosol in rice. Loss of function of OsSWEET1b decreased glucose and galactose accumulation in leaves. ossweet1b mutants showed accelerated leaf senescence under natural and dark-induced conditions. Exogenous application of glucose and galactose complemented the defect of OsSWEET1b deletion-promoted senescence. Moreover, the senescence-activated transcription factor OsWRKY53, acting as a transcriptional repressor, genetically functions upstream of OsSWEET1b to suppress its expression. OsWRKY53-overexpressing plants had attenuated sugar accumulation, exhibiting a similar phenotype as the ossweet1b mutants. Our findings demonstrate that OsWRKY53 downregulates OsSWEET1b to impair its influx transport activity, leading to compromised sugar accumulation in the cytosol of rice leaves where sugar starvation promotes leaf senescence.

RNA-Seq analysis reveals the mechanism in response to cold stress of peach cv ‘Dingjiaba’

BACKGROUND: ‘Dingjiaba’ is an important Prunus persica cultivar (cv) mainly grown in the Hexi corridor in northwest China, which has an inherited strong cold tolerance. OBJECTIVE: To compare the transcriptome and physiology data of leaves of cvs ‘Dingjiaba’ (D) and ‘Kanoiwa’ (K) following cold treatment at different time periods, in order to gain new insights into the mechanisms of cold adaptation in ‘Dingjiaba’. MATERIALS AND METHODS: We analyzed the transcriptomic and physiological data of leaves of D and K cvs exposed to 0 h (D0/K0), 2 h (D2/K2), 6 h (D6/K6) and 12h (D12/K12) cold stress. RESULTS: Low temperature stress caused membrane damage and led to increased rate of electrolyte leakage and increased MDA content. Cold stress induced the accumulation of soluble sugars, soluble proteins and proline in leaves of both cvs, with a lower increase in K compared to D. Transcriptome analysis identified 4,631, 5,069, 5,662 and 3,886 differentially expressed genes (DEGs) between D0 and K0, D2 and K2, D6 and K6 and D12 and K12, respectively. The differentially expressed genes significantly enriched in metabolic pathways and biosynthesis of secondary metabolites. We further validated the reliability of sequencing data of the RNA-Seq with Real-Time Quantitative PCR, which suggested that the expression trend of the RNASeq were same as RT-PCR. CONCLUSIONS: These results provide novel insights into a series of molecular mechanisms underlying physiological metabolism and defense.

Rubisco and sucrose synthesis and translocation are involved in the regulation of photosynthesis in wheat with different source-sink relationships.

Source-sink relationships influence photosynthesis. So far, the limiting factors for photosynthesis of wheat cultivars with different source-sink relationships have not been determined. We aimed to determine the variation patterns of photosynthetic characteristics of wheat cultivars with different source-sink relationships. In this study, two wheat cultivars with different source-sink relationships were selected for photosynthetic physiological analyses. The results showed that YM25 (source-limited cultivar) had higher photosynthetic efficiency compared to YM1 (sink-limited cultivar). This is mainly due to a stronger photochemical efficiency, electron transfer capacity, and Rubisco carboxylation capacity of YM25. YM25 accumulated less soluble carbohydrates in flag leaves than YM1. This is mainly due to the stronger sucrose synthesis and transport capacity of YM25 by presenting higher sucrose-related enzyme activities and gene expression. A PCA analysis showed that Rubisco was the main factor limiting the photosynthetic capacity of YM25. The soluble sugar accumulation in flag leaves and sink limitation decreased the photosynthetic activity of YM1. Increased N application improved source-sink relationships and increased grain yield and source leaf photosynthetic capacity in both two wheat cultivars. Taken together, our findings suggest that Rubisco and sucrose synthesis and translocation are involved in the regulation of photosynthesis of wheat cultivars with different source-sink relationships and that source and sink limitation effects should be considered in photosynthesis.

Halotolerant PGPB Staphylococcus sciuri ET101 protects photosynthesis through activation of redox dissipation pathways in Lycopersicon esculentum

Photosynthesis is known to be seriously affected by salt stress. The stress induced membrane damage leads to disrupted photosynthetic components causing imbalance between production and utilization of ATP/NADPH with generation of ROS leading to photoinhibition and photodamage. In the current study, role of halotolerant plant growth promoting bacteria (PGPB) Staphylococcus sciuri ET101 in protection of photosynthesis in tomato plants during salinity stress was evaluated by analysing changes in antioxidant defense and activation of redox dissipation pathways. Inoculation of S. sciuri ET101 significantly enhanced the growth of tomato plants with significantly higher photosynthetic rates (PN) under normal and salinity stress conditions. Further, increased membrane stability, soluble sugar accumulation and significant decrease in malondialdehyde (MDA) content in leaves of ET101 inoculated tomato plants under normal and salinity were observed along with increased expression of antioxidant genes for efficient ROS detoxification and suppression of oxidative damage. Additionally, salinity induced decrease in rate of photosynthesis (PN) due to lowered chloroplastic CO2 concentration (Cc) attributed by low mesophyll conductance (gm) in uninoculated plants was alleviated by ET101 inoculation showing significantly higher carboxylation rate (Vcmax), RuBP generation (Jmax) and increased photorespiration (PR). The genes involved in photorespiratory process, cyclic electron flow (CEF), and alternative oxidase (AOX) pathway of mitochondrial respiration were abundantly expressed in leaves of ET101 inoculated plants indicating their involvement in protecting photosynthesis from salt stress induced photoinhibition. Collectively, our results indicated that S. sciuri ET101 has the potential in protecting photosynthesis of tomato plants under salinity stress through activation of redox dissipation pathways.

CPPU Improves Fruit Setting and Growth in Greenhouse-grown Oriental Melons (Cucumis melo L. var. makuwa Makino)

The production of melons (Cucumis melo L.) in greenhouses relies on pollination. Extreme temperature and insufficient light reduce not only flower visitation by pollinators but also pollen viability, resulting in inefficient pollination. In this study, we investigated the effects of forchlorfenuron [(N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU)] on the fruit setting and growth of oriental melons (C. melo L. var. makuwa Makino). The primary objective was to devise a new strategy for the management of oriental melons. Treatment with 5 mg·L−1 CPPU a day before flowering (T1), on the day of flowering (T2), and a day after flowering (T3) increased the fruit setting rate (by 20.1% to 30%) in melons subjected to artificial pollination (AP) or no pollination (NP) compared with the rate in those subjected to only artificial pollination without CPPU (CK). CPPU treatment induced unfertilized seeds; in addition, a tendency toward parthenocarpy was noted. The highest fruit setting rate (∼95%) was noted in plants subjected to the following treatments: AP+T1 and NP+T3. The rates of abnormal fruit formation decreased from 45.2% of CK group to 9.4% in plants subjected to AP+T1 and to 19.4% in those subjected to NP+T3. Elevated exogenous concentrations of CPPU markedly increased fruit weight. Plants subjected to NP+10 mg·L−1 CPPU bore the heaviest fruits (541.0 g), which were heavier than those borne by plants subjected to AP+10 mg·L−1 CPPU. CPPU treatment reduced the fruit cavity ratio in a concentration-dependent manner from 47.3% to 33.6% and increased the pulp thickness from 1.5 to 2.5 cm. Notably, supplementary CPPU treatment exerted no significant effects on fruit traits. Regarding taste, inconsistent results were obtained for sugar accumulation. Although the content of cucurbitacin B increased immediately after the initial CPPU treatment, it markedly decreased after 15 days of CPPU treatment. Therefore, mature melons did not have a bitter taste.

Effects of Potassium-Containing Fertilizers on Sugar and Organic Acid Metabolism in Grape Fruits.

To identify suitable potassium fertilizers for grape (Vitis vinifera L.) production and study their mechanism of action, the effects of four potassium-containing fertilizers (complex fertilizer, potassium nitrate, potassium sulfate, and potassium dihydrogen phosphate) on sugar and organic acid metabolism in grape fruits were investigated. Potassium-containing fertilizers increased the activity of sugar and organic acid metabolism-related enzymes at all stages of grape fruit development. During the later stages of fruit development, potassium-containing fertilizers increased the total soluble solid content and the sugar content of the different sugar fractions and decreased the titratable acid content and organic acid content of the different organic acid fractions. At the ripening stage of grape fruit, compared with the control, complex fertilizer, potassium nitrate, potassium sulfate, and potassium dihydrogen phosphate increased the total soluble solid content by 1.5, 1.2, 3.5, and 3.4 percentage points, decreased the titratable acid content by 0.09, 0.06, 0.18, and 0.17 percentage points, respectively, and also increased the total potassium content in grape fruits to a certain degree. Transcriptome analysis of the differentially expressed genes (DEGs) in the berries showed that applying potassium-containing fertilizers enriched the genes in pathways involved in fruit quality, namely, carbon metabolism, carbon fixation in photosynthetic organisms, glycolysis and gluconeogenesis, and fructose and mannose metabolism. Potassium-containing fertilizers affected the expression levels of genes regulating sugar metabolism and potassium ion uptake and transport. Overall, potassium-containing fertilizers can promote sugar accumulation and reduce acid accumulation in grape fruits, and potassium sulfate and potassium dihydrogen phosphate had the best effects among the fertilizers tested.

UV-A radiation increases biomass yield by enhancing energy flow and carbon assimilation in the edible cyanobacterium Nostoc sphaeroides.

Ultraviolet (UV) A radiation (315-400 nm) is the predominant component of solar UV radiation that reaches the Earth's surface. However, the underlying mechanisms of the positive effects of UV-A on photosynthetic organisms have not yet been elucidated. In this study, we investigated the effects of UV-A radiation on the growth, photosynthetic ability, and metabolome of the edible cyanobacterium Nostoc sphaeroides. Exposures to 5-15 W m-2 (15-46 µmol photons m-2 s-1) UV-A and 4.35 W m-2 (20 μmol photons m-2 s-1) visible light for 16 days significantly increased the growth rate and biomass production of N. sphaeroides cells by 18%-30% and 15%-56%, respectively, compared to the non-UV-A-acclimated cells. Additionally, the UV-A-acclimated cells exhibited a 1.8-fold increase in the cellular nicotinamide adenine dinucleotide phosphate (NADP) pool with an increase in photosynthetic capacity (58%), photosynthetic efficiency (24%), QA re-oxidation, photosystem I abundance, and cyclic electron flow (87%), which further led to an increase in light-induced NADPH generation (31%) and ATP content (83%). Moreover, the UV-A-acclimated cells showed a 2.3-fold increase in ribulose-1,5-bisphosphate carboxylase/oxygenase activity, indicating an increase in their carbon-fixing capacity. Gas chromatography-mass spectrometry-based metabolomics further revealed that UV-A radiation upregulated the energy-storing carbon metabolism, as evidenced by the enhanced accumulation of sugars, fatty acids, and citrate in the UV-A-acclimated cells. Therefore, our results demonstrate that UV-A radiation enhances energy flow and carbon assimilation in the cyanobacterium N. sphaeroides.IMPORTANCEUltraviolet (UV) radiation exerts harmful effects on photo-autotrophs; however, several studies demonstrated the positive effects of UV radiation, especially UV-A radiation (315-400 nm), on primary productivity. Therefore, understanding the underlying mechanisms associated with the promotive effects of UV-A radiation on primary productivity can facilitate the application of UV-A for CO2 sequestration and lead to the advancement of photobiological sciences. In this study, we used the cyanobacterium Nostoc sphaeroides, which has an over 1,700-year history of human use as food and medicine, to explore its photosynthetic acclimation response to UV-A radiation. As per our knowledge, this is the first study to demonstrate that UV-A radiation increases the biomass yield of N. sphaeroides by enhancing energy flow and carbon assimilation. Our findings provide novel insights into UV-A-mediated photosynthetic acclimation and provide a scientific basis for the application of UV-A radiation for optimizing light absorption capacity and enhancing CO2 sequestration in the frame of a future CO2 neutral, circular, and sustainable bioeconomy.

Plant Diseased Lesion Image Segmentation and Recognition Based on Improved Multi-Scale Attention Net

Fallen leaf disease can lead to a decrease in leaf area, a decrease in photosynthetic products, insufficient accumulation of fruit sugar, poor coloring and flavor, and a large number of fruits developing sunburn. To address the aforementioned issue, this article introduces a deep learning algorithm designed for the segmentation and recognition of agricultural disease images, particularly those involving leaf lesions. The essence of this algorithm lies in enhancing the Multi-scale Attention Net (MA-Net) encoder and attention mechanism to improve the model’s performance when processing agricultural disease images. Firstly, an analysis was conducted on MA-Net, and its limitations were identified. Compared to res-block, Mix Vision Transformer (MiT) consumes relatively less time during the training process, can better capture global and contextual information in images, and has better robustness and scalability. Then, the feature extraction parts of different networks were used as encoders to join the MA-Net network. Compared to a Position-wise Attention Block (PAB), which has higher computational complexity and requires a larger amount of computing resources, Effective Channel Attention net (ECANet) reduces the number of model parameters and computation by learning the correlation between channels, as well as having a better denoising ability. The experimental results show that the proposed solution has high accuracy and stability in agricultural disease image segmentation and recognition. The mean Intersection over Union (mIoU) is 98.1%, which is 0.2% higher than traditional MA-Net; Dice Loss is 0.9%, which is 0.1% lower than traditional MA-Net.

Molecular dissection of an intronic enhancer governing cold-induced expression of the vacuolar invertase gene in potato.

Potato (Solanum tuberosum) is the third most important food crop in the world. Potato tubers must be stored at cold temperatures to minimize sprouting and losses due to disease. However, cold temperatures strongly induce the expression of the potato vacuolar invertase gene (VInv) and cause reducing sugar accumulation. This process, referred to as "cold-induced sweetening," is a major postharvest problem for the potato industry. We discovered that the cold-induced expression of VInv is controlled by a 200 bp enhancer, VInvIn2En, located in its second intron. We identified several DNA motifs in VInvIn2En that bind transcription factors involved in the plant cold stress response. Mutation of these DNA motifs abolished VInvIn2En function as a transcriptional enhancer. We developed VInvIn2En deletion lines in both diploid and tetraploid potato using clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated nuclease 9 (Cas9)-mediated gene editing. VInv transcription in cold-stored tubers was significantly reduced in the deletion lines. Interestingly, the VInvIn2En sequence is highly conserved among distantly related Solanum species, including tomato (Solanum lycopersicum) and other non-tuber-bearing species. We conclude that the VInv gene and the VInvIn2En enhancer have adopted distinct roles in the cold stress response in tubers of tuber-bearing Solanum species.

Phytocompounds and Regulation of Flavonoids in In Vitro-Grown Safflower Plant Tissue by Abiotic Elicitor CdCl2.

In this study, a Gas chromatography-mass spectrometry (GC-MS) investigation of embryogenic callus and somatic embryo regenerated shoots of Carthamus tinctorius revealed the presence of a variety of sugars, sugar acids, sugar alcohols, fatty acids, organic acids, and amino acids of broad therapeutic value. The in vitro developed inflorescence contained a wide range of active compounds. In embryogenic calluses, important flavonoids like naringenin, myricetin, kaempferol, epicatechin gallate, rutin, pelargonidin, peonidin, and delphinidin were identified. To augment the synthesis of active compounds, the effect of cadmium chloride (CdCl2) elicitation was tested for various treatments (T1-T4) along with a control (T0). Varying concentrations of CdCl2 [0.05 mM (T1), 0.10 mM (T2), 0.15 mM (T3), and 0.20 mM (T4)] were added to the MS medium, and flavonoid accumulation was quantified through ultra-high-pressure liquid chromatography-tandem mass spectroscopy (UHPLC-MS/MS). The flavonoids naringenin, kaempferol, epicatechin gallate, pelargonidin, cyanidin, and delphinidin increased by 6.7-, 1.9-, 3.3-, 2.1-, 1.9-, and 4.4-fold, respectively, at T3, whereas quercetin, myricetin, rutin, and peonidin showed a linear increase with the increase in CdCl2 levels. The impacts of stress markers, i.e., ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD), on defense responses in triggering synthesis were also evaluated. The maximum APX and SOD activity was observed at T3, while CAT activity was at its maximum at T2. The impact of elicitor on biochemical attributes like protein, proline, sugar, and malondialdehyde (MDA) content was investigated. The maximum protein, proline, and sugar accumulation was noted at high elicitor dose T4, while the maximum MDA content was noted at T3. These elevated levels of biochemical parameters indicated stress in culture, and the amendment of CdCl2 in media thus could be a realistic approach for enhancing secondary metabolite synthesis in safflower.

Cultivar-dependent grape berry dehydration in later ripening phases may be associated with energy regulation and ionic homeostasis

Climate warming and drought may alter the progression of sugar accumulation by the grape berry, and contribute to pre-harvest berry shrivel and cell vitality loss which were hypothesised to be associated with solute accumulation cessation and energy status in the berries. To explore the relationship between energy and cultivar-dependent berry cell death, we characterised the variations of pericarp constituents and energy status across five time points, five ripening phases, and three cultivars with various levels of berry shrivel and cell death. Grape berries of Shiraz, Chardonnay and Flame Seedless at the Eichorn-Lorenz stages 33 to 39 were sampled at 5:00, 9:00, 13:00, 17:00 and 21:00 on each sampling day, which were used in the analysis of water percentage, adenosine triphosphate (ATP), ethanol, sugar, L-malic acid, as well as elements with vascular mobility, including potassium (K) and sodium (Na). Shiraz and Chardonnay ceased accumulating sugar and phloem mobile elements during the later ripening phase, while Flame Seedless did not undergo water loss or cease to accumulate solutes in pericarps. Shiraz berry ripening was distinguished by greater pericarp water loss, ATP reduction, increased ion disorder susceptibility as indicated by a lower K/Na ratio, and higher ethanol concentration in the later ripening phase. The Chardonnay pericarp contained the highest ATP concentration and K/Na ratio among the three cultivars. The Flame Seedless pericarp maintained a low but stable K/Na ratio throughout berry ripening. Berry ripening phase impacted the diurnal variations of pericarp water percentage and ATP concentration. The results indicated that energy regulation and ionic homeostasis may be associated with cultivar-dependent grape pericarp hydration, solute accumulation and cell vitality during berry ripening.

Structural changes in cell wall pectic polymers contribute to freezing tolerance induced by cold acclimation in plants

Subzero temperatures are often lethal to plants. Many temperate herbaceous plants have a cold acclimation mechanism that allows them to sense a drop in temperature and prepare for freezing stress through accumulation of soluble sugars and cryoprotective proteins. As ice formation primarily occurs in the apoplast (the cell wall space), cell wall functional properties are important for plant freezing tolerance. Although previous studies have shown that the amounts of constituent sugars of the cell wall, in particular those of pectic polysaccharides, are altered by cold acclimation, the significance of this change during cold acclimation has not been clarified. We found that β-1,4-galactan, which forms neutral side chains of the acidic pectic rhamnogalacturonan-I, accumulates in the cell walls of Arabidopsis and various freezing-tolerant vegetables during cold acclimation. The gals1 gals2 gals3 triple mutant, which has reduced β-1,4-galactan in the cell wall, exhibited impaired freezing tolerance compared with wild-type Arabidopsis during initial stages of cold acclimation. Expression of genes involved in the galactan biosynthesis pathway, such as galactan synthases and UDP-glucose 4-epimerases, was induced during cold acclimation in Arabidopsis, explaining the galactan accumulation. Cold acclimation resulted in a decrease in extensibility and an increase in rigidity of the cell wall in the wild type, whereas these changes were not observed in the gals1 gals2 gals3 triple mutant. These results indicate that the accumulation of pectic β-1,4-galactan contributes to acquired freezing tolerance by cold acclimation, likely via changes in cell wall mechanical properties.

Hormonal Regulation and Transcriptomic Insights into Flower Development in Hydrangea paniculata 'Vanilla Strawberry'.

Understanding the molecular mechanisms that regulate flower growth, development, and opening is of paramount importance, yet these processes remain less explored at the genetic level. Flower development in Hydrangea paniculata 'Vanilla Strawberry' is finely tuned through hormonal signals, yet the genetic underpinnings are not well defined. This study addresses the gap by examining the influence of gibberellic acid (GA3), salicylic acid (SA), and ethylene (ETH) on the flowering traits and underlying molecular responses. Treatment with 100 mg/L SA significantly improved chlorophyll content and bolstered the accumulation of soluble sugars and proteins, advancing the flowering onset by 6 days and lengthening the flowering period by 11 days. Concurrently, this treatment enhanced inflorescence dimensions, increasing length, width, and petal area by 22.76%, 26.74%, and 27.45%, respectively. Contrastingly, 100 mg/L GA3 expanded inflorescence size but postponed flowering initiation and decreased inflorescence count. Higher concentrations of SA and GA3, as well as any concentration of ETH, resulted in delayed flowering and inferior inflorescence attributes. A physiological analysis over 50 days revealed that these regulators variably affected sugar and protein levels and modified antioxidant enzyme activities. An RNA-seq analysis during floral development highlighted significant transcriptomic reprogramming, with SA treatment downregulating Myb transcription factors, implicating them in the modulation of flowering timing and stress adaptation. These findings illuminate the complex interplay between hormonal treatments, gene expression, and flowering phenotypes in Hydrangea paniculata, offering valuable perspectives for ornamental horticulture optimization.

New challenges for Uruguayan viticulture

Climate scenarios in the medium and long term (2010-2070) foresee increased summer rainfall for Uruguay and the region, with increased water deficits and excess episodes. Although at the international level irrigation in viticulture has a long experience and tradition, at the local level (Uruguay), only 10% of the vineyard surface area implements a fixed or complementary system for water supply in their crops. This work aimed to model the crop water requirements for a vineyard in southern Uruguay based on pedo-climatic variables. In addition, the plant response to controlled deficit irrigation was evaluated in two consecutive seasons. The experiment was conducted in a 1.1 ha commercial vineyard in Canelones, Uruguay (34°36'S, 56°14W), during two successive seasons (2020-2021). The additional irrigation (I) treatment was compared against a control (C) without irrigation. A controlled water deficit was established from flowering to harvest. The adjustment in the demand was made as a function of a percentage of crop evapotranspiration. The Kc of the crop was estimated using digital tools. The simulation of the water balance made it possible to evaluate the vineyard water needs. Plants subjected to controlled deficit irrigation showed higher vegetative growth, positively impacting yield and the accumulation of sugars and anthocyanins in the berry. Based on our results, a supplementary water supply, at the right doses and time, allows us to face water deficit situations, positively impacting the productive and economic variables. Knowing the variability in a vineyard is necessary to achieve proper irrigation scheduling and optimize water use. New technologies applied to irrigation are an opportunity for winegrowers to obtain more sustainable vineyards and production.

Sorbitol metabolism plays a key role in the differential accumulation of sugar in two plum cultivars.

Sugar is vital for plant growth and determines fruit quality via its content and composition. This study explores the differential sugar accumulation in two plum varieties, 'Fengtangli (FTL)' and 'Siyueli (SYL)'. The result showed that 'FTL' fruit displayed higher soluble solids and sugar content at various development stages. Metabolomic analysis indicated increased sorbitol in 'FTL', linked to elevated sorbitol-6-phosphate-dehydrogenase (S6PDH) activity. Transcriptome analysis identified a key gene for sorbitol synthesis, PsS6PDH4, which was significantly higher expressed in 'FTL' than in 'SYL'. The function of the PsS6PDH4 gene was verified in strawberry, apple, and plum fruits using transient overexpression and virus-induced gene silencing techniques. The results showed that overexpression of the PsS6PDH4 gene in strawberry, apple, and plum fruits promoted the accumulation of soluble solids content and sorbitol, while inhibition of the gene reduced soluble solids content and sorbitol content. Meanwhile, analysis of the relationship between PsS6PDH4 gene expression, sorbitol, and soluble solids content in four different plum varieties revealed a significant correlation between PsS6PDH4 gene expression and soluble solids content as well as sorbitol content. This research discovered PsS6PDH4 as a crucial regulator of sugar metabolism in plum, with potential applications in improving fruit sweetness and nutritional value in various fruit species. Understanding these molecular pathways can lead to innovative approaches for enhancing fruit quality, benefiting sustainable agriculture and consumer preferences in the global fruit industry.

Evaluating the effects of azelaic acid in the metabolism of Arabidopsis thaliana seedlings through untargeted metabolomics and ionomics approaches.

The present study demonstrates that low concentrations of azelaic acid (AZA) significantly impact the metabolism of Arabidopsis thaliana seedlings, leading to imbalances in numerous minerals and metabolites due to AZA-induced stress. Untargeted metabolomic analyses were conducted on untreated and AZA-treated seedlings at two time points: 7 and 14 days after treatment initiation. The results revealed a general accumulation of sugars (e.g., glucose, mannose, xylose), amino acids (e.g., lysine, GABA, threonine, glutamine), and organic acids (e.g., glutaric acid, shikimic acid, succinic acid) in AZA treated-seedlings, suggesting that AZA triggers stress responses in Arabidopsis. Ionomic analysis revealed that AZA induces phosphorus deficiency, which plants compensate by increasing malate content in the roots. Additionally, AZA treatment induced putrescine accumulation within the root, a metabolic biomarker of potassium deficiency and plant stress. The metabolomic profile showed elevated levels of different specialized metabolites, such as nitrogen- and sulphur-containing compounds, and altered levels of various phytohormones, including jasmonates and brassinosteroids, implicated in plant protection under biotic and/or abiotic stresses. These findings support the hypothesis that AZA's mode of action is associated with an auxin imbalance, suggesting its function as an auxinic herbicide. The observed increases in starch and jasmonates, coupled with the disruptions in potassium homeostasis, are linked to the previously reported alterations in the auxin transport, root architecture and gravitropic root response. Statistical analyses were applied, including Kruskal-Wallis tests for ionomic data, as well as multifactor analysis, Principal Component Analysis, Orthogonal Partial Least Squares-Discriminant Analysis, and enrichment pathway analysis for metabolomic data, ensuring the robustness and validity of these findings.

The function of an apple ATP-dependent Phosphofructokinase gene MdPFK5 in regulating salt stress.

Salt stress severely affects the growth and yield of apples (Malus domestica Borkh). Although salt-tolerant genes have been extensively studied, documentation on the role of the ATP-dependent phosphofructokinase gene MdPFK5 in salt stress is limited. This study conducted an evolutionary tree and three-dimensional structure analysis of the PFK gene family in Arabidopsis thaliana and MdPFK (MD01G1037400), revealing a close phylogenetic relationship between MdPFK (MD01G1037400) and AtPFK5. Given the similarity in their protein tertiary structures, MdPFK was designated as MdPFK5, suggesting functional similarities with AtPFK5. Further investigation revealed elevated expression levels of MdPFK5 in apple leaves and flowers, particularly showing significant upregulation 120 days after blooming and differential expression beginning at 3 hours of salt stress. Overexpression of MdPFPK5 conferred salt tolerance in both apple calli and transgenic lines of Arabidopsis thaliana. Moreover, NaCl treatment promoted soluble sugar accumulation in apple calli and transgenic lines of Arabidopsis thaliana overexpressing MdPFK5. This study provides new insights into the salt tolerance function of MdPFK5.